I’m an 60 year old punk rocker who was fortunate enough to have met Dave years ago at shows at the Olympic. As a young guy in a band, you were always sort of in awe of the tech guys at big venues, but Dave was extremely nice and helpful back then as he is in these videos. He obviously is very passionate about his knowledge and sharing that. He is my audio hero. I have been in my job now for 25 years as the house audio engineer myself in a large performing arts center, where I take care of several large venues, including the 70volt stuff, as well as line arrays. When I first started learning and blowing stuff up, I would always use bridged mono set ups ( as I was the only local guy with a crap PA system that would do basement punk rock shows) and this brought back a TON of good memories. Thanks again Dave. Keep up the great work
@@DaveRat My band was the Detonators from Redondo. Early ‘80s. I go out sometimes with DOA, but mostly I sit in the Hult Center in Eugene Oregon. My 20- year old son is interested in audio ( he has never mixed on a console, but has three Dante certifications), and while I have a ton of old gear lying around, I doubt I could teach things better than you do. You’re providing a great service. Thanks again
@@DaveRat Just paying my respects, amigo. The information you provide isn’t lost on me, and VERY important in this “plug and play” world we find ourselves in. It’s the equivalent of getting guitar lessons from Chet Atkins or something like that. I’ll make sure my son watches all of your stuff. Gotta get his mind wrapped around Ohm’s law tho…
Wow! This is really interesting and fun stuff. The best part of the lesson are the slight diversions. All the related side topics Dave speaks about makes it extra interesting. Great teaching gift.👍👍👍
4:16 explains EXACTLY why an amplifier into a single bridged driver sees half the load. There's literally a point at about half the voice coil where it is "center tapped" and there is zero voltage to ground. Dave explained it with two speakers. I like this explanation.
As a matter of fact, I used to use the inverting outputs of my Crown VFX-2A crossover to bridge an amplifier that didn't have a bridging switch. I also used to invert the right channel in a stereo pair, and wire the speaker outputs of the right channel in reverse polarity. It was a cheap trick to give a tiny bit more headroom on transients, so one channel pulled from one power supply rail for the initial impulse, and the other channel pulled from the other rail at the same time. It didn't work with tightly regulated power supplies, but with some amps could deliver just a little more power before clipping that way.
Hi Dave!. Great explenation!....As you know there are too many fake information around... But, if I can, I would like to add some details, starting from voltage side instead of power.... So... Based on your exemple, let's say that the amplifier give to the speaker 70.7V (peak) each channel. Each channel is connected to one 18"@8ohm with two cable of one ohm resistance. So, each channel see 8+1+1=10 ohm resistance load. like you said! 70.7V on 10 ohm meaning (P=V^2/R) 500W. Each cannel delivery 500W to each speaker.. so the amp delivery in total 1000W. Due to loss on cable, on 18" cone we have only 500*8/10= 400W. we loose the 100w on cable. Now. If we connect the amplifier on Bridge mode we have, under the same condition, 70.7*2=141.8V. The amp in this case see 8+8+1+1=18 ohm load On 18ohm load at 141.8v the amp delivery (P=V^2/R) 141.8^2/18= 1110.8W. Here the first point. In dual mono the amp give us 2*500=1000W. In bridge he give us 1110.8, so 110.8W more. At the speaker we have 1110.8*16/18=981W. We lose 1110.8*2/18=123W The second point, at the end, In dual mono we give to a double 18" 800W, in bridge 981W so 181W more, with the same amplifier and with less expensive cable... That's grat!
And damping factor is improved as well and in this example you used one cable for each 18 and in cable for the bridged, so you still have an extra cable that either saves money, weight and time or you can run both cables for bridges and reduce the cable loss to .5 ohms, further improving the output
@@DaveRatYes man!... Speaking about damping factor and slow rate is hard to understand. Also harder is understand how this parameters effects on audio system performance..... Can you explain us?
I also run my bass cabs this way.... LOVE IT!!! I run old school, Crown.. Crest. QSC. Amps with Cerwin Vega earthquake 18"s does the job no doubt, but I'm so tempted to upgrade to some newer rigs! This guy is pretty informative and definitely gets the creativity flowing FoSho! Big ups Dave🤘
Even though, I do know the old school stuff definitely takes the life off the gear at a faster pace it still delivers solid. Power requirements are hefty though. I do have a stack of the newer digital crown amps that are obviously a bit more power friendly and definitely don't create anywhere near as much heat. I back mostly electronic music stuff so the demand for solid power is in full blast beast mode (aka bridged mono lol) for the subs for sure, everything else is run in stereo. I dont do Venues large enough to have to have "traveling" bass movements. I can see how running full digital in stereo for rock or something a bit less demanding on a consistent basis for the low end needs, but I do like the set up the way it is, it sounds really clean and I know it well enough for quick adjustments for different venues, I need a space where I can set up for a while and mess around with other configurations though, I just simply dont have the power where I have space.... its always something lol! MORE MORE and MORE🤣
It all goes back to electrical theory. You have to understand the basic theory or foundation of Ohms law, watts law, etc... Years ago, I was helping a then friend do sound for a small festival. NOT mixing, just setting up. I tried to explain to him that his speaker cables were too light gauge wire, and he should move his PAs up front under the stage and keep the cables as short as possible. The sub cables and connectors would actually get warm. I/2R loss. My background is in industrial electrical and electronics for over 33 years. With years in commercial electrical construction. When you install sound systems in auditoriums, movie theaters, and stadiums, your distances are sometimes very long. Amps are hidden in inconspicuous places. Even inputs are subject to line loss. Its crazy stuff, but very interesting. Dave is a great teacher. Pay attention bc there's a lot to learn!
Dave, good explanations. One minor thing - when talking about power loss due to resistance in the speaker wires. As far as I know (could be wrong), most power amp stages use some sort of voltage feedback for linearity. And, at higher impedance levels (like 8 ohms) the max power they are able to provide will be voltage limited. So if you are talking about power loss vs. max power available, there is actually a squared factor rather than a linear factor. In your example with 8 ohm load, and two wires of 1 ohm each, it's true that 1/5 of the power delivered by the amp will be dissipated in the wires, and 4/5 in the speaker. But also if that amplifier is rated at 500Wrms at 8 ohms, and is voltage limited (at 63Vrms), then loading it with 10 ohms means that it will only be able to deliver 400W. Then, only 80% of that will get to the load because 20% of the voltage drop will be across the wires. So the speaker will only end up with 320W, which is 64% = (0.8)^2 the rated power of the amp driven at max input level. If there was current feedback, then the output voltage would increase automatically with the higher total load resistance to keep the output current constant, and then there would only be a 20% loss.
In either example, is it not true that if the 20% of the load restistance is wire and 80% is speaker, 20% of whatever output watts are being delivered die to the amps capabilities into that load, will be lost to wire?
@@DaveRat it is certainly true that if 20% of the total resistance in the load is due to wires, then only 80% of the total power dissipated in the speaker+wires will be dissipated in the speaker. My only point is that the actual power loss impact of having X% wire resistance in comparison to the power output you might expect to get from the rating of the amplifier, could be (1-X)^2 due to the fact that the amplifier has a maximum output voltage swing (before clipping). So the impact of speaker wire resistance is even worse, as it decreases both the current and voltage seen by the speaker simultaneously by 20% each (assuming constant voltage drive at the PA output). Of course in dB, it's all the same because we'd calc power change at 10log and current change at 20log. So you get 2dB power loss (which is ~40% power loss), and a 2dB current drop (which is 20% current drop). Of course this is all a simplification assuming purely real speaker impedance.
I've used bridge mono to get the full output of a power amp but had no idea you should jump the negative to a hot terminal on the speakers which logically seems weird and counter to layman's polarity know-how to get the most out a matched speaker scenario. I'm gonna have to read-up or maybe you could do a video showing the wiring w/ a small power amp and speakers? I feel like me attempting it would blow something. Always helps to see it vs told. Thanks for the video Dave. I enjoy these.
Dave - great stuff as always. Here is my question; So for example:- running 2x 18” drivers in series on sub duties - uses a lot of power in this cross over band - I’ve always thought that running drivers in sub land in series is a no no - purely due to the reason that once voice coil is essentially acting as a resistor to the other opposing voice coil. For example 4mm speaker wire might have an impedance of say 1 ohm. But the voice coil has a impedance of say 8 ohms… This means in a series configuration one driver 18” driver (let’s say driver B) sees: 1 ohm - cabling (-) 8 ohm - voice coil A (variable to some extent cone moves) Driver B it self - 8 ohms Cabling - 1 ohm (+) So essentially once voice coil is power limiting the other. Aka the dancing electrons/pixies have to pass through a piece of small voice coil wire to get to the next driver - essentially using the thinnest wire you could to complete the circuit. Does this make sense ? In mid and Hf bands - the current draw isn’t as excessive or as large so not so much of a big deal - but in sub land, parallel. If you need more lows, add boxes and amps. However I see no problem using a amp in bridge mode driving a pair of 18” drivers in parallel. Really with the double up of capacitors (of course dependent on amp topology / class) gives a much better damping factor and immediate current draw capabilities! Thoughts 💭🤔?
I think that the bit that you are missing is that when the pixies have to squeeze through the second voice coil, they get another shove from the second amp.
@@dougaltolan3017 Absolutely correct if it’s hanging off a bridged amp. I’m talking more generally with sub drivers in series - even say 2x 16ohm drivers in series of 1 channel of a high powered amp for example. Generally speaking I can’t see ‘series’ wired LF drivers can be a good thing hanging off any amp config…. Unless I’m missing something else
@@dylandylan11731 if your amp can chuck full wallop into 32 ohms then why not? Higher impedance means lower current means lower cable losses. Damping is likely to be cheaper since higher voltage caps are cheaper than higher value caps (less current means a smaller cap can do the job) Although Dave did cover what happens when 1 driver fails.....
If you have one driver and 100volts or 2 in series and 200v or 3 in series and 300v. You get a 100v drop across each. Same output. But if you use the same wire, the % lost in the wire is less for higher voltages. The results of using higher voltages to reduce power lost in the speaker cable and improve damping factor while using the amp more efficiently, combine to provide and audible improvement in many scenarios.
Am I missing something here? I'm not an audio professional, but my understanding was that bridge mono mode flips the phase of one channel and then wires it in series with other channel with positive and negative reversed. It thus becomes a push-pull amplifier with one channel driving positive to ground, the other negative to ground. This is then fed into the speakers wired in parallel to halve the impedance. The advantage is that the speakers are isolated from ground and immune to noise.
Hmmm, that seems about right except noise on the speaker outs is usually not an issue. Sounds like you are combining balanced lines with bridged amps. And the two are basically identical in operation except the reasons to use them differ. Balanced lines help with reducing induced noise using common mode rejection. Bridged mono is more about increasing the output voltage to get more power into a given impedance or to reduce the %of power lost in speaker wire resistance.
These videos help keep the brain in the game while we’re locked down here in OZ. Your mis-matched in a box example was my suspicion with a particular company. All in bridge mode. One OO box in the rig always looked like it was fighting itself. Uneven extrusion. I often disconnected it and ran 3 of 4 boxes. Cheers Dave
Interesting, thanks. My only experiances of bridging (actually, Un-bridging) have been where people have asked me to check their rig out, as it wasn't sounding good. Having found the amps bridged, I've completely re-wired it all for straight forward stereo, checking that all the balanced inputs / outputs are properly balanced (ditching the XLR-TS jacks for example) and it has invariably sounded 10x better, with people generally saying ' :o Wow, what did you do?' or things to that effect. This led me to believe that bridging just sounds rubbish, although I haven't done much experimenting, and most of the rigs I've done this on have been 'average' at best. I brought this up on Speakerplans forum years ago, and pretty much every pro agreed, and it was more the newb's / amateurs / hobbyists that wanted to do it, because, 'double the power for free' sounds like a great idea, doesn't it? in theory. I always figured it was just a cheap trick to make small amps bigger, if you had more amps than speakers, and it would always be better just to get a decent sized amp in the 1st place. Anyone else have any input on sound quality? What happens if you lower the gain control on one of the two amp channels? does DC go off-set? or just quieter?
I've had the opposite experience and bridges amp to make systems come to life. Turning down one side all the way down just makes it the same output as non bridged. Imbalances just put you somewhere in between. The one bigvissue with bridging is if the amp is bridged into a lowwr impedance than it is capable of driving, then they lose power and can sound bad. Many newer amps are permanently in bridged mode by design as it is more efficient.
@@DaveRat interesting. I'll have a try. I've got some 4 ohm PD2450s, and some 2 ohm stable 2kw/ch class ABs. 🙂 'stereo' 2kW into 4ohms x 2 vs bridged 4kW into 8 ohms (2 cones in series) x1 Thanks. For this, and all your other videos :)
Back in the day I ran a 3 wire setup, Bryant 15A 125V twist locks. Ch A lows, Ch B low mids. The - wire served as a neutral more or less. The only time Ch A & Ch B were in phase were at the crossover point which was down -6db. Worked well. Didn't invert Ch B on the amps, the difference was the frequency bands within which they operated.
The concept of a neutral is based on the signals on the hots being equal and opposite. I tried a similar setup with common ground wire and the impact was audible in a non desirable way. I did a a video on 3 wire vs 4 wire headphone cables that shows the issue of common ground wire with dissimilar signals
Dave, I think the power of each amplifier doubles when you run them bridged. So, in your example, if previously each amp is driving 500w into the cabinet, when bridged, they will *each* drive 1000w into the cabinet. The reason for this is that the impedance they each see halves, and so they each produce twice the current, and hence twice the power. Of course it's easy to run out of current delivery in an amp, so it might not be realistic to expect the power to go up by x4, but that's what the math says :) Thanks for an interesting set of articles and sharing your passion for audio.
It was kind glossed over with a simplification in the presentation. Sure Dave did this on purpose to keep things understandable. Bridging gives you double the voltage between the output terminals. Doubling voltage gives 4x the power. So the reason the minimum load impedance doubles is to account for this power increase. Example: Amplifier is rated to do 50v per channel into a 4ohm load. That is 625w per channel (amplifier is producing 1250w total). Bridge the amp, you now have 100v, 100v into 4 ohm is 2500w (twice the amps rated power at 4ohms per channel). So doubling the minimum impedance to 8ohm beings the output back down to the amps max rated output of 1250w. But now you are getting it on a single channel instead of split between 2. Hope that makes sense.
@@jahn-pierrezietsman2293 There are number of factors that will determine the total harmonic distortion. But I doubt bridging will improve thing. At 8ohm bridge as opposed to 4ohm a channel. The amp is still being asked to deliver the same amount of current as if it was running 4 ohms per channel, so it's working just as hard. Since the polarity of one of the inputs is being reversed there is possibility that some noise could be nulled, but I guess this would depend on exactly how the signals are routed inside of the amplified. Also impedance is frequency dependent. Your "8ohm" speakers probably have a impedance curve that ranges between ~6.8ohms and ~40ohms. Bottom line is, to avoid distortion stay well within the limits of both your amplifier and speakers.
Burning question. I haven't been able to get an absolute answer on how the reversed polarity to channel 2 power is being used from a bridged amp. Does channel 1 (+) hit the speaker positive terminal with half the amp power and channel 2 positive act as a negative and pulls the speaker back with the other half of the amp power? Or, does it feed both sides of the power amp to the positive speaker terminal to push the cone and the negative terminal just acts as a neutral/ground path? It wasn't described to that effect but I'd love to know the answer. Thanks Dave. You are the man!
Hmmm. Both of those are kind of the same thing and the way electricity works is the power is delivered by creating a difference of voltage across a load the bigger the difference the more power delivered so when you invert polarity on channel 2 and channel 2 is going negative while channel one is going positive it increases the the voltage difference between the positive and negative speaker leads. by doubling the voltage differential applied to the speaker leads more power is delivered
So basically if your running 2 subs (any size) it’s gonna be more efficient to run them in bridged mode rather than splitting a mono signal into a stereo pair due to the resistance of the speaker wire. Is this something you consider at large events? Because you usually have more than enough budget/gear that this wouldn’t be an issue. Your not limited on amp power when your using top of the line amplifiers. I guess this could possibly play into truck space
Getting more power out of amps is important on all levels. The cost, weight and size of bringing 30% to 50% more amplifiers is significant on all levels
Nice explanation and didn’t know you can bridge separate mono blocks… Question; Wouldn’t running a bridged amp to 2 speakers in parallel give you the most power and least resistance. This would give you a mono 4ohm (plus cable resistance) giving you almost double the wattage… Do I understand this correctly? (assuming the amp is stable/capable of 4ohm bridged)
Bridged into parallel will give max power potential but any internal amp resistance will be a bigger factor as bridged into 4 is the same as 2 ohms per channel
Dave, thank you so much for your response and confirmation I’m thinking of this senecio properly. I just recently found your channel and can’t get enough, I though I knew audio engineering well, but you have elevated my knowledge by at least 10%. Thank you!
I have a question, I have a crown professional series amplifier. How can I connect it to pioneer stereo receiver? There are no RCA hook ups on the back of the crown amp. Only a Phoenix connection.
Get a pair of RCA cables and cut the ends off of one side and why are the ground into the ground of the Phoenix connector and why are the center conductor of the RCA which is the plus to the plus of the Phoenix connector and put a little jumper on the Phoenix connector between the ground and the minus of the Phoenix connector. The pin out of the Phoenix connector should be on the back of the amp or in the manual so you know which is plus minus and ground.
12:24 Maybe I got something wrong here, but if you use a transistor amplifier, it's output is dependent on its load. So at generally speaking at a forum load it will make more power than it will at an 8 ohm load. I know that tube amplifiers have a different apology especially when they use Transformers for their outputs and therefore does not follow the same methodology as in car audio amplifiers where say running at a 2 ohm load will make vastly more power than running at an 8 ohm load. car audio amplifiers are often designed to double their output power generally going to a lower ohm load. (4 to 2 ohms for instance) I'll double-check this with the guys audio science review but as far as I know I believe this is the logic behind the different topologies. ============= *a word about resistance in speaker cables* from my understanding it seems that if you run higher frequency signals, say a 400 Hertz you're not going to get the same amount of resistance that you would when you're running lower frequency content. the cable Still Remains the Same amount of resistance per a given length and gauge of wire. however you may experience some top-end roll-off due to the higher impedance of the high-frequency monitors especially running in an active situation where a passive crossover is not used on the main high-frequency monitors. (this is usually never the case and Pro Audio since most Pro Audio gear automatically includes a minimum of a 2-way crossover generally to protect the high-frequency transducers) basically I'm not sure how you're getting more power out of a transistor amplifier when running at a higher ohm load since generally they produce less power as the ohm rating that the amplifier actually sees Rises . again I want to reiterate that on tube gear because of the topology and that many of them are running a Transformer it doesn't work the same way from my recollection in fact I believe you have to use different Taps on a transformer for the different ohm loads. *ABOUT WHAT AMPS CAN BE BRIDGED* (Big thanks to BareVids in the U.K.) half Bridge designs can be bridged to Mono however I don't believe that you can actually do this on a full Bridge. these are the typical and again forgive me bear if it's for doing this but this is more typical of Brazilian style amplifiers that use a full Bridge topology or circuit design. *HOWEVER* by taking two amplifiers of a fullbride, and then doing as prescribed I'm wondering if this is even possible ? for my basic understanding I believe you actually get less power even though it may actually work in practice but for my understanding from the amplifier design he would only be running one half side of the amplifiers mosfets again in a typical transistor amplifier. since most amplifiers are based on a Class D design due to its efficiency, and usually use a half Bridge due to the Simplicity of the design, ( ahem, cost-effective manufacturing of mass-produced items) it might be a better idea just to internally Bridge a single amplifier then using two separate amplifier modules as finding two that are uniquely balanced and setting up the games on each amplifier can be a crazy amount of work especially if you're dealing with multiple amplifiers in a live production environment. and I think you're also giving up some of the built-in protections for your speakers and your amplifier if you're using this method described but again I'm not a wizard on the subject it's just something to take aim to mind. still, it's a great tool to use when you have limited resources and limited budget and you want to get the maximum out of your equipment that you have on hand. so it's definitely a worthwhile trip. on a side note the only thing that puzzles me about Pro Audio is I wonder why the amplifiers themselves even bother on Class D designs to use inductors especially for low frequency transducers and content since those are usually filtered passively by the speaker itself since _generally_ the carrier wave is (Mostly) inaudible on low-frequency drivers. I think this would increase the efficiency but I don't believe it would result in a higher output generally since the main inductor is the voice coil on the subwoofer itself. I don't think people in the neighborhood or your other equipment might like that very much since you're basically pushing a very high frequency signal down a wire that's probably not shielded but again that's a discussion for another time :-)
Oh my, a bunch of info and much of it quite confusing or based on blurry knowledge. Put more simply, if an amp puts out a certain voltage, the power delivered will increase as the load impedance is decreased. Up to a point where the amp can not maintain the output voltage. Tube amps tend to have a more difficult time driving lower impedance loads but if you put a 32 ohm load on a transistor or tube amp and measure the voltage and calc the power, then use a 16 ohm load, both amps with double or near double the power output, as you get lower impedances, some amps will continue to double or near double the power output as you half the impedance and other amps will not. Factors like the size and max current output of the amp's power supply and the output impedance of the amp play a big part in the capability of the amp to drive lower impedance loads at high current levels
@@DaveRat Thank you Dave. I'm so used to car audio where it is explained simply. (I have trouble understanding stuff sometimes) I talked to some Amp Designers at Audio Science review, and they cleared it up a bit. Still foggy on it. But that's why you are a Pro, and we are the Pupils. :-) My main experience comes from things like Amy Dynos and so forth. (steve meade, and others) I know you explained it correctly, I just can't seem to wrap my head around it. Maybe some day. Again, thank you for replying to me. It means a lot.
Maybe check out this series on impedance and transformers. It's a bit different topic but all the same theory and such. ua-cam.com/video/9zzGSkAvSFQ/v-deo.html
Dave why would it need to be connected in that way (input polarity reversed) why not just leave the inputs the same phase and connect the outputs in series, as if you were putting 2 batteries in series to double the voltage, IE you take the top plus and the bottom minus, and connect the 'middle' plus and minus to each other. As far as I was aware amps (at least some) all the bridged switch does is apply channel A to channel B on the inputs and connect this middle link at the outputs. If you look at pictures of amp terminals they tend to have the bridged option printed on the back as the outer minus and plus terminals. (images search etc) Cheers.
Connecting an amp plus (hot) to an amp minus (typically ground) is not only unwise but will probably blow up most amplifiers. Unlike batteries which are completely floating amplifiers have references to ground and hot more like AC wall voltage.
@@DaveRat OK well that's how car audio amps I've come across do their bridge mode, perhaps that is just on those then. They definitely do not tie one side to ground as the instructions that come with the amp explicitly say not to allow either terminal to come into contact with a ground.
There are amps that have the ch1 plus is hot and in polarity and channel 2 minus is out of polarity hot and with that you can connect the speaker between the ch1 plus and channel 2 minus for bridged. Lab Gruppen is this way Also there are amps that are fully floating like car audio amps where ch1 plus in in polarity hot and ch 1 minus is out of polarity hot and ch2 is the same way. L-Acoustics LA12X is that way. For these amps connect the speaker between ch1 plus and ch 2 minus and connect ch1 minus to Ch 2 plus. And this will creat a bridged output. This would be how some or most amps are and what you describe. Most or at least many amps have a more conventional wiring where ch1 plus is hot and in polarity, ch 1 minus is a ground, ch2 plus is hot and in polarity and ch 2 minus is also a ground. For these amps, if you were to wire them with ch 1 minus connected to ch 2 plus, ch2 would see a dead short and that would not be ideal
Dude..... wish i would know this when i was 16 and had 2 same model 300-200 Watts... great stuff now days everyone is going with active speakers, I see ususally deploy Lacoustics system, passive. I like passive I believe are easier to run,(my system is very small compact. Tri amp, 3 way low, mid, High, thru 12GA) vs active where you have to run power to each box then feed audio signal top and bottom. I seen some DAS have CAT7 ins and out, witch is very cleaver way to reduce cables.... Do you prefer passive or active, I would like to know you opinion pros and cons. Thank you.
For small stuff amps in boxes works well. For big stuff, the added fly weight, size and increased complexity of serviceability, having a whole bunch of small amps versus fewer big amps increases costs size and weight. Plus having to run AC cables in trenches versus speaker cables can be an issue. More things to go wrong way up high in the air with lawn systems. Tell overall having the amps in the boxes creates more problems especially for large format systems
Very true and many amps are designed to mitigate this issue even when not bridged. Powersoft and Lab Gruppen being two examples where ch1 + is in polarity, ch1 - and ch2 + are ground and channel 2 - is out of polarity. This inherently balances the draw on the power supply when both channels are driven with similar signals. Also with these amps you can operate them bridged with just using a Y cable and connecting the load between 1+ and 2-
I keep hearing about "Balanced headphones" in my mind Balanced is an XLR (or TRS) connection at line or Mic level. I see where we're going here and I get how it's balanced and in a way and I see how that's been done in every consumer device with a headphone jack (except the iPhone) but I don't see how a 4 wire headphone cable on crazy audio file headphones is balanced because it seems like they're separating out the left and right speakers and amps on the output side to somehow avoid combining the grounds. Maybe I'm thinking of balanced as in Signal cancellation and not balanced as in flow?
Not sure about the details of balanced headphones but I am guessing they are doing exactly that, eliminating the common ground and having a seperate balanced amp for each ear.
Brilliant video, so fascinating. Can't wait to get my head around this one. Can anyone help? I always thought inverse polarity has a cancelling effect on the signal. I'm assuming one of the 18" speakers is flipped around so both are operating in sync. I love mental challenges like this! 🙂
You can run full voltage "in polarity" to the positive terminal and ground the negative. Or you can run full voltage "out of polarity" to the negative terminal and ground the positive terminal. Or you can run 1/2 voltage "in polarity" to the positive and 1/2 voltage "out of polarity" to the negative terminal. And all of these scenarios will result in the same exact outcome, same power, same polarity.
Thanks for everything dave, 1 question what if we run 2 heats, 1 of them are push-pull in the other one is solid state, both delivery the same amount of power and are bridged in the center tap mode, that could affect the signal the goes to the speaker??👍👌
By heats, I think you mean amps and spell check messed it ? The sound you would hear from connection two amp outputs in series would be the summed signal of the two amps. Amp 1 plus amp 2. Bridging two channels or two amps is just putting the amp outputs in series. Putting two different types of amps in series would result in the summed outputs of those two amps and the minimum load would be 1/2 the minimum load capabilities of the amp that is less load tolerant.
Hey dave. Once again you are too interesting. I should be asleep. Im running conference audio at the swedish pavilion in the expo2020 in dubai tomorrow morning. Just had to see this. Ive only used bridge on too small amps to get more power. Still into parallell loads. For example a 900w crest ca9 amp into a powerful 8 ohm jbl sub. Just a work around with 2 small amps for a setup rather than 1 big. Was 10 years ago and i hardly remember the setup. Think we just changed a switch to bridge and used another nl4 outlet allready there in bridge mode? Now doing it on a serial load is new to me! Reducing cable resistance part is amazing. But serial connection of speakers is + - + -.. you do it + - - + but with a bridged amp? You gotta open each box and redo them and always run them like this? Seems unflexible but its cool if its a fixed setup i guess! Im a bit confused by the jumping the negatives part.. honestly. And when you compare it to a balanced line or mic im even more confused. Cause those are polarity switched a 2nd time to make them in phase again and double the audio signal while cancelling the noise. And now you dont flip it back. Claim it to be nulled between the speakers as in cancelled.. but the spealers themselves still run in phase and aid eachother? It might be that its 4.30 in dubai but i feel im missing some piece of logic here. Haha im sorry. If you can set me straight id be happy! Love!
You wire +-+- for series to double the impedance but keep all in polarity when bridging and using the two amp + hot outs. There are other wirings though as some amps have ch1 + as in polarity and ch 1 - and ch2 + as grounds and ch2 - as out of polarity. The speakers wire the same but you don't need to polarity rev ch 2, you parallel the inputs and wire the speakers between ch1+ and ch2 -
Im running a very powerful sub on an amp bridge as we speak but impedance is too low so amp does get very hot thank goodness i dont go more the 1/4 volume but yeah saving up to upgrade to a 4ohm stable amp to bridge and use cause this sub requires up to 3000watts to really get bumping.
Great question. Since damping factor is dependant and load impedance, if you look at damping with a stereo amp and an 8 ohm speaker per side and 12ga wire pair per speaker. Vs The 2 speakers in series (16 ohms) and using the same wire (2x 12ga) You now have 1/2 the loss in the wire and double the load impedance, both of these will significantly improve damping factor to more than double, some amps more that others.
Hell yeah, ive never thought about it this way, i need to go rewire my amps coz im losing so much free power! My amp has bridge mode which requires only input into channel A, how would I get both left and right outputs into my subs since my processor doesn't have a mono sub out?
Either create a matrix mix on the console for sub out that is a mix of left and right. Or do subs on an aux. Or get a seperate sin processor that will mix left and right.
I have seen that and older crown amps would do parallel mono as do many other amps. That is great for running low impedance loads but you do t get the advantages of reducing the impact of wire resistance
Very interesting video, i run 3 single 18" subs (8ohm each) with a single amp and 25m speakon cable. I've always used the parallel mode so i can keep a minimum of 4ohm load, and i've always avoided 2ohm bridge mono mode since i've been told that the damping factor is reduced in such mode (bridge) which cause less control in the driver movement. Is this way of thinking correct? I always limit half of my amps power per channel into my drivers so i keep headroom and clean signal Respect Dave rat!
Hmmm, three 8 ohm loads in parallel is 2.6 ohms. But to an amp in parallel mode each channel sees 5.6 ohms. Safe impedances not pushing near any limits of most pro amps. conservative headroom is unused acceuvle power but since you are intentionally using limiters to eliminate access to the extra power, it's not headroom you are gaining. You are just reducing the power available to send to the speakers, so that would be protection. If you wanted to hot rod maximum output from the amp and to the speakers and if the amp can handle it. Adding a 4th speaker and running the amp in bridged mode intro two 16 ohm loads would milk more power out of the amp and lose slightly less in speaker linen and get you about the same power you get now per speaker into 4 speakers rather than 3.
Its what we used to do with 8 ohm subs and too small amps to just get more power. Its all ive ever used bridge for. This fewer cable thing dave does is new to me. Also internally jumping the negatives is new
Hi, Dave. Just stumbled upon your channel randomly and actually have a relevant question. Maybe a little out of your wheelhouse, but I suspect you have the answer. I have a small multi function guitar amp that is stereo, but uses two built in 4"speakers. It sounds pretty good, but I'd prefer to be able to connect it to an external cab. Now I can easily install a couple of switching jacks and connect it to two spare 4ohm driver's, but I'd rather bridge it to one cab if possible. So if I have continuity between the negative speaker terminals and the chassis, does that mean I can bridge it? Thanks very much for sharing your experience.
Hmmm, that will be complex unless you can isolate the stereo pre amp from the stereo amp in the cab. If there is a pre amp out and and power amp input, it could be possible depending on the amp design. Then find a way to polarity invert the input to one amp channel. And mono the pre amp out. Sounds more complex than beneficial.
@@DaveRat I think that's beyond my capability right now. The only experience I've had with bridging amplifiers is car stereo amps that you flip a switch and just use a particular set of terminals. I had the guts out of this little amp and it's surface mount components in a pretty small form factor, so probably best to either leave it be or do the two jack modification I mentioned, I think. Thanks so much for the reply, friend. :)
Got two 18inch 8ohms subs in two enclosures wired parallel to 4ohms. Amp runs in bridge mono but when connected to the speakers the load is 1.2 ohms is that right am new to this stuff
Hi Dave, I noticed recently that Berhringer have released a 6,000watt amp, but it only has a 10amp, IEC input @ 240volts. I would expect the input to be more beefy than this - either a 20amp powercon or 32amp cefform. Is the claimed 6,000 watts rating therefore reliable, a complete lie, or am I missing something? Hope you provide some insights on this. Jonathan
Hi Jonathan, Class D Amps always have higher RMS Power than Power Input. There are 12000 Watt Amps (L Acoustics, LAB Gruppen etc.) that run on 16 Amps Breakers in Europe (230V). So you can pull 3680W from the Fuse. This is possible because of the different Ways of measuring Power Output i believe. As far as i know there are Pauses in the Audio for the Measurment of the RMS Power of an Amp. Hope this helps with your thougts. Cheers!
Great observation and yes, it is no possible to get more power out than the power going in. That said, a 20a 120v ac wall plug gas a maximum continuos power capability of 2400 watts. But many power amps are rated with peak power where the amp stores some energy and so it could put out 1500 watts continuous and maybe put out 6000 watts for a short periods of time. And many amp manufacturers will rate the amp on its peaks
@@DaveRat I've shared this before, hope this helps; To avoid nuisance tripping, circuit breakers can pass huge amounts of current past their rated trip amount. For example, when electric motors start, they pull massive amounts of current until they're up to full speed.* A 20a circuit can pass 7-8 times the rated 20a trip amount, .. for up to a full second or more. It will allow up to 3x the rated amount for up to 10sec or so. Most importantly, that 20a circuit can allow up to 2x the rated amount for a period extending as long as 30 seconds. 100amps for around 1-2 secs 60amps for around 10 secs 30-40amps for up to 30 secs Music is transient in nature. The capacitors store, dump, refill. Big iron toroidal amps store in their magnetic field. High speed SMPS amps refill caps so quickly and frequently, their demand from the power line is typically in brief high current spikes. Yes, long term P-out < P-in ... just I²R losses assure that. But other than a 20hz synth note that never stops, music ebbs and flows. *(wires in conduit feeding motors often vibrate intensely upon start up, the high current magnetic fields off each conductor fight each other and will buzz against the interior of the metal conduit)
For shows we need to rely on the long term breaker current handling or else we hit a thermal trip which I believe aligns with the rated current. But yes and thank you. It's interesting because if circuit breakers used the same ratings that many amps use of peak or pulse power, a 20 amp breaker would rate at 100 amps.
@@DaveRat Good point That thermal limit .... Perfect example; Big stadium show, Kenny Chesney headlined a multi-act Pirate tour, Keith Urban, Lee Ann Rimes, Luke Bryan, others, a massive touring circus backstage. This was the last night of the tour. For me, this is our venues first concert since opening. The motor coach area was a three day party, 𝙬𝙚 𝙥𝙖𝙧𝙠𝙚𝙙 𝙩𝙝𝙞𝙧𝙩𝙮 𝙥𝙡𝙪𝙨 𝙘𝙤𝙖𝙘𝙝𝙚𝙨 𝙄𝙉𝘿𝙊𝙊𝙍𝙎, 𝙙𝙞𝙧𝙚𝙘𝙩𝙡𝙮 𝙗𝙚𝙝𝙞𝙣𝙙 𝙨𝙩𝙖𝙜𝙚, shore power, water, drain, cable, and internet built in the floor, adjacent to essentially every coach. Very few venues offer that. EVERYONE involved loved that convienance. Brand new stadium sized restrooms for all backstage. It's a convention center hall, backed up to a football stadium end zone. Party party party, last tour stop and it was wild. Oh my gosh great fun. Five headline level acts, it's a busy place backstage. Non-stop limos/vans in and out, celebs, athletes, last tour stop party buzz. Ok, Night before the show, partying, blasting the PA into a big empty indoor stadium, one of the house breakers tripped feeding one aspect of show power. Picture a breaker, feeding a fused safety switch... where we tie in show power tails. This was really embarrassing for us, the house... I believe a 400a breaker opened up. These breaker trip curves are adjustable on the face of the 400a breaker. These small dials establish how quickly and under what circumstances the breaker trips. This one was never set properly. Quickly the production decided against house power for that drop, and went to Aggreko generator power for that load. That was f***ing embarrassing because we bragged we built in all the show power you need... etc. 𝙈𝙤𝙧𝙖𝙡 𝙤𝙛 𝙩𝙝𝙚 𝙨𝙩𝙤𝙧𝙮; Breaker trip curves can allow huge amounts... or if never adjusted correctly, can trip way too soon. So glad it happened before the show. (same wild tour rolled thru the following year too, good times, even more stories)
Si == does the electricity sent to the earth go to earth or transformer> are the electrons the ones on a path or are other electrons present if it goes back to power pole- and do electrons come from earth or do the appear intra-dimensionally...... -WTPOW
Since audio is AC, over time the electrons return to thier original starting point. That means that none come from the amp and none go to ground and in fact you need to bring your own already in the wire.
Yes, volts squared over resistance. So if an amp puts out 100v per channel into 8 ohms then it's 10000 divided by 8 ohms or 1250 watts per channel 100 volts per channel into 4 ohms would be 2500 watts x 2 100v per channel into 2 ohms would be 5000 watts x 2 In bridged you get double the voltage in a perfect world though most amps can't fully double the voltage due to other limitations. So 200v into 8 ohms. Which would be 200 squared or 40000 and if you had the same load of 8 ohms it would be 5,000 watts or 4 x the power but you would only be driving one 8 ohm load instead of two 8 ohm loads If you double the load impedance to 16 ohms by putting the speakers in series, because you are using 2 channels and had speakers on both channels, you would get 2500 watts into one 16ohm load. And if you parallel the two loads down to 4 ohms you would get 10000 watts because you would be running the equivalent of 2 ohms per channel.
Hmmm, not exactly true. Bridged into 8 has the same damping as stereo into 4 ohms Also has the same amount of power bridged I to 8 ve stereo I to 4 But, bridged into 8 has 1/2 the loss into speaker wire if the same wiring is used. Or, you can use thinner wires and have the same loss, saving weight, and money and cable size
@@DaveRat all this may work in pro audio applications, fact is bridging doubled the output impedance of an amplifier and it struggles to control low impedance speakers, using thin and long speaker wire doesn't cut it .
@akhtarizod5802 well, perhaps you may not be aware that many amps are inherently bridged. Wherein each channel is actually two channels that are bridged. Bridged just means is a higher voltage and runs higher impedances. Another way to look at bridged is it is a balanced drive rather than an unbalanced drive. Balanced drive means each terminal has and equal and opposite voltage. Rather than a ground and one line having voltage. Also bridged uses the power supplies more efficiently as one channel uses the positive rail while the other channel uses the negative rail. A non bridged amp both channels use the positive rail at the same time time then the negative rail for signals that are the same to both channels. Bridged has no impact on sound quality, it's just better at running higher impedances loads at higher voltages. This is advantageous for minimizing loss in speaker cables. Having higher voltages available allows better transient response as well. Being more I formed will help you optimize the sound you are able to achieve
Hello Nico. Well, when I was 17 I started building speaker cabinets while I worked at Hughes Aircraft as the youngest guy in the department, electro-optical R and D working on Tow Missile Systems. From there I built up a sound company that provides audio equipment for some of the largest festivals and shows in the world along with providing sound equipment for world wide tours. I also started a manufacturing division in addition doing sales and installations. Along with numerous patents and licensing deals, I also mixed sound for many world class artists such as Chili Peppers, Foo Fighters, Soundgarden, Pearl Jam, Rage Against the Machine and have travelled to 6 of the 7 continents and hundereds of countries over the past 40 years. I dedicate time and energy to sharing insights of what I have learned and how to correlate the specs to real world, based on my hands on experience, to help others along their path. What I don't do is randomly judge others and troll around as as an arrogant ass. So enough about me, from what pedestal of knowledge, experience and authority do you speak and what is it you wish to offer in helpful and kind ways? I welcome any and all knowledge from someone with such a strong depth of knowledge and experience perhaps such as you?
You can't just bridge two amps if they weren't designed to be bridged in the first place, as it will most likely fry them both! And you should never connect two speakers in series, because speakers also have crossover networks which are not designed to be connected in series... Also some of the "math" presented is wrong... Some stereo amps have a bridge or BTL switch. Just stick to those. This is why you should never get any electronics advice on UA-cam, especially from a long haired tattooed dude...
Oh my oh my! At least your lack of understanding and research is consistent with your lack of credibility Are you telling people not to do something because something will most likely happen even though it is something you have never done? I appreciate that consumer point of view where sound system and equipment designers know what's best and you should follow the manual and do what they say to do and nothing more. Which is what makes this all the more fun and interesting because this long haired tattooed guy actually is a sound system designer! Big smile. But not a sound system designer for the consumer toys and such, I actually design and deploy sound systems for large scale rock concerts and festivals. Feel free to do a credibility check. Anyway, I appreciate your caution and clearly as a judgmental person as you seem to be, I can see how you may discount my knowledge and experience based on personal biases against the way I look. I guess it just comes down to credibility. Should people believe long haired tattoo guy with 40 years doing sound for some of the largest shows, festivals and bands on the planet that spends time and energy freely sharing knowledge I have learned over the years helping others in the audio field? Or trust some anonymous guy that is spilling info about things he has neither tested or experienced?
@@DaveRat Didn't you say something like "You get more output power/ Watts at 16 ohms vs 10 ohms (speaker) loads". This would be true only audio amplifiers were current sources, but they're not. Amps are voltage sources. Use treat a 500W amp as if it's a 500W power source. Amp wattage are just rating. Actual power will depend heavily on the speaker and cables length. Some mono amps were designed to be bridged to each other to get twice the possible power. There are actually to bridging configuration: series, which doubles the actual voltage, thus increase power by x4, and parallel, which doubles the current rating, thus allows you to connect 1/2 the rated impedance to get x2 the power. There are many good class D amps today that were designed from bridged operation. I'd avoid trying to bridge any consumer amplifier, which wasn't intended to be bridged. Also series connection of speakers was intended for the speaker drives inside the speaker box, not for speaker boxes, which include the crossover network at the input. Your advice may be more suitable for the professional market , not for home audio...
Lower impedances will tend to output more power up to the point where the amp is unable to output more. The 10 ohm reference I use is an example of how to reduce losses due to speaker wire resistance by running the higher voltages in bridged into higher impedances such that speaker wire resistance is a lower % of the total load. Running identical loads in series or parallel should not be an issue and long as the loads are identical. Running dissimilar loads in series or in parallel will have more complex results. As far as bridging consumer or pro amps in to double the minimum rated single channel impedance, there should not be an issue as long as you are connecting the load between two hots and the amp has a ground and hot on each output.
These videos help keep the brain in the game while we’re locked down here in OZ. Your mis-matched in a box example was my suspicion with a particular company. All in bridge mode. One OO box in the rig always looked like it was fighting itself. Uneven extrusion. I often disconnected it and ran 3 of 4 boxes. Cheers Dave
In all my years of pro audio, speaker electronics always baffled me. Thanks for giving such detailed information!
Thank you Keith
I've been trying to explain this for soooooooo long to so many blank stares. Masterfully explained AGAIN sir!
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Took my understanding to a whole new level Dave!
I will need to watch this one a few tomes over before everything is sunk in my head.
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I’m an 60 year old punk rocker who was fortunate enough to have met Dave years ago at shows at the Olympic. As a young guy in a band, you were always sort of in awe of the tech guys at big venues, but Dave was extremely nice and helpful back then as he is in these videos. He obviously is very passionate about his knowledge and sharing that.
He is my audio hero. I have been in my job now for 25 years as the
house audio engineer myself in a large performing arts center, where I take care of several large venues, including the 70volt stuff, as well as line arrays. When I first started learning and blowing stuff up, I would always use bridged mono set ups ( as I was the only local guy with a crap PA system that would do basement punk rock shows) and this brought back a TON of good memories.
Thanks again Dave. Keep up the great work
Thank you Bruce! That made my day!
@@DaveRat My band was the Detonators from Redondo. Early ‘80s. I go out sometimes with DOA, but mostly I sit in the Hult Center in Eugene Oregon.
My 20- year old son is interested in audio ( he has never mixed on a console, but has three Dante certifications), and while I have a ton of old gear lying around, I doubt I could teach things better than you do. You’re providing a great service. Thanks again
Very cool and I remember providing sound for some shows with the Detonators playing. That's awesome. Great to meet ya again Bruce!
@@DaveRat Just paying my respects, amigo. The information you provide isn’t lost on me, and VERY important in this “plug and play” world we find ourselves in. It’s the equivalent of getting guitar lessons from Chet Atkins or something like that.
I’ll make sure my son watches all of your stuff. Gotta get his mind wrapped around Ohm’s law tho…
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Wow! This is really interesting and fun stuff. The best part of the lesson are the slight diversions. All the related side topics Dave speaks about makes it extra interesting. Great teaching gift.👍👍👍
Thank you John!
I really like how you explained your theory about setting up an amplifier to speakers
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4:16 explains EXACTLY why an amplifier into a single bridged driver sees half the load. There's literally a point at about half the voice coil where it is "center tapped" and there is zero voltage to ground. Dave explained it with two speakers. I like this explanation.
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And this is why I like how easy it is to rewire NL4 connectors. Nice one sir Dave :-D
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As a matter of fact, I used to use the inverting outputs of my Crown VFX-2A crossover to bridge an amplifier that didn't have a bridging switch. I also used to invert the right channel in a stereo pair, and wire the speaker outputs of the right channel in reverse polarity. It was a cheap trick to give a tiny bit more headroom on transients, so one channel pulled from one power supply rail for the initial impulse, and the other channel pulled from the other rail at the same time. It didn't work with tightly regulated power supplies, but with some amps could deliver just a little more power before clipping that way.
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Ah that was the missing bit of info I couldn't quite work out. How it worked out of phase. Pulling and pushing explains it.
Hi Dave!. Great explenation!....As you know there are too many fake information around...
But, if I can, I would like to add some details, starting from voltage side instead of power....
So...
Based on your exemple, let's say that the amplifier give to the speaker 70.7V (peak) each channel.
Each channel is connected to one 18"@8ohm with two cable of one ohm resistance. So, each channel see 8+1+1=10 ohm resistance load. like you said!
70.7V on 10 ohm meaning (P=V^2/R) 500W. Each cannel delivery 500W to each speaker.. so the amp delivery in total 1000W.
Due to loss on cable, on 18" cone we have only 500*8/10= 400W. we loose the 100w on cable.
Now. If we connect the amplifier on Bridge mode we have, under the same condition, 70.7*2=141.8V.
The amp in this case see 8+8+1+1=18 ohm load
On 18ohm load at 141.8v the amp delivery (P=V^2/R) 141.8^2/18= 1110.8W.
Here the first point. In dual mono the amp give us 2*500=1000W. In bridge he give us 1110.8, so 110.8W more.
At the speaker we have 1110.8*16/18=981W. We lose 1110.8*2/18=123W
The second point, at the end, In dual mono we give to a double 18" 800W, in bridge 981W so 181W more, with the same amplifier and with less expensive cable...
That's grat!
And damping factor is improved as well and in this example you used one cable for each 18 and in cable for the bridged, so you still have an extra cable that either saves money, weight and time or you can run both cables for bridges and reduce the cable loss to .5 ohms, further improving the output
@@DaveRatYes man!...
Speaking about damping factor and slow rate is hard to understand. Also harder is understand how this parameters effects on audio system performance..... Can you explain us?
I will ponder that and see if I can come up with a clear explanation and test
I also run my bass cabs this way.... LOVE IT!!! I run old school, Crown.. Crest. QSC. Amps with Cerwin Vega earthquake 18"s does the job no doubt, but I'm so tempted to upgrade to some newer rigs! This guy is pretty informative and definitely gets the creativity flowing FoSho! Big ups Dave🤘
Even though, I do know the old school stuff definitely takes the life off the gear at a faster pace it still delivers solid. Power requirements are hefty though. I do have a stack of the newer digital crown amps that are obviously a bit more power friendly and definitely don't create anywhere near as much heat. I back mostly electronic music stuff so the demand for solid power is in full blast beast mode (aka bridged mono lol) for the subs for sure, everything else is run in stereo. I dont do Venues large enough to have to have "traveling" bass movements. I can see how running full digital in stereo for rock or something a bit less demanding on a consistent basis for the low end needs, but I do like the set up the way it is, it sounds really clean and I know it well enough for quick adjustments for different venues, I need a space where I can set up for a while and mess around with other configurations though, I just simply dont have the power where I have space.... its always something lol! MORE MORE and MORE🤣
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It all goes back to electrical theory. You have to understand the basic theory or foundation of Ohms law, watts law, etc... Years ago, I was helping a then friend do sound for a small festival. NOT mixing, just setting up. I tried to explain to him that his speaker cables were too light gauge wire, and he should move his PAs up front under the stage and keep the cables as short as possible. The sub cables and connectors would actually get warm. I/2R loss.
My background is in industrial electrical and electronics for over 33 years. With years in commercial electrical construction. When you install sound systems in auditoriums, movie theaters, and stadiums, your distances are sometimes very long. Amps are hidden in inconspicuous places. Even inputs are subject to line loss. Its crazy stuff, but very interesting. Dave is a great teacher. Pay attention bc there's a lot to learn!
1000W balanced line 😂 So funny... but so true.
Thank you Dave for your crazy, fresh and useful videos, I never miss one !
Awesome and thank you! Positive comments like yours make this fun to do
Dave, good explanations. One minor thing - when talking about power loss due to resistance in the speaker wires. As far as I know (could be wrong), most power amp stages use some sort of voltage feedback for linearity. And, at higher impedance levels (like 8 ohms) the max power they are able to provide will be voltage limited. So if you are talking about power loss vs. max power available, there is actually a squared factor rather than a linear factor. In your example with 8 ohm load, and two wires of 1 ohm each, it's true that 1/5 of the power delivered by the amp will be dissipated in the wires, and 4/5 in the speaker. But also if that amplifier is rated at 500Wrms at 8 ohms, and is voltage limited (at 63Vrms), then loading it with 10 ohms means that it will only be able to deliver 400W. Then, only 80% of that will get to the load because 20% of the voltage drop will be across the wires. So the speaker will only end up with 320W, which is 64% = (0.8)^2 the rated power of the amp driven at max input level. If there was current feedback, then the output voltage would increase automatically with the higher total load resistance to keep the output current constant, and then there would only be a 20% loss.
In either example, is it not true that if the 20% of the load restistance is wire and 80% is speaker, 20% of whatever output watts are being delivered die to the amps capabilities into that load, will be lost to wire?
@@DaveRat it is certainly true that if 20% of the total resistance in the load is due to wires, then only 80% of the total power dissipated in the speaker+wires will be dissipated in the speaker. My only point is that the actual power loss impact of having X% wire resistance in comparison to the power output you might expect to get from the rating of the amplifier, could be (1-X)^2 due to the fact that the amplifier has a maximum output voltage swing (before clipping). So the impact of speaker wire resistance is even worse, as it decreases both the current and voltage seen by the speaker simultaneously by 20% each (assuming constant voltage drive at the PA output). Of course in dB, it's all the same because we'd calc power change at 10log and current change at 20log. So you get 2dB power loss (which is ~40% power loss), and a 2dB current drop (which is 20% current drop). Of course this is all a simplification assuming purely real speaker impedance.
I've used bridge mono to get the full output of a power amp but had no idea you should jump the negative to a hot terminal on the speakers which logically seems weird and counter to layman's polarity know-how to get the most out a matched speaker scenario. I'm gonna have to read-up or maybe you could do a video showing the wiring w/ a small power amp and speakers? I feel like me attempting it would blow something. Always helps to see it vs told. Thanks for the video Dave. I enjoy these.
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Fantastic stuff Dave, I have never used bridged mode on my amps, you have tempted me to give it a go..... Smashing
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Dave - great stuff as always.
Here is my question;
So for example:- running 2x 18” drivers in series on sub duties - uses a lot of power in this cross over band -
I’ve always thought that running drivers in sub land in series is a no no - purely due to the reason that once voice coil is essentially acting as a resistor to the other opposing voice coil.
For example 4mm speaker wire might have an impedance of say 1 ohm. But the voice coil has a impedance of say 8 ohms…
This means in a series configuration one driver 18” driver (let’s say driver B) sees:
1 ohm - cabling (-)
8 ohm - voice coil A (variable to some extent cone moves)
Driver B it self - 8 ohms
Cabling - 1 ohm (+)
So essentially once voice coil is power limiting the other.
Aka the dancing electrons/pixies have to pass through a piece of small voice coil wire to get to the next driver - essentially using the thinnest wire you could to complete the circuit.
Does this make sense ?
In mid and Hf bands - the current draw isn’t as excessive or as large so not so much of a big deal - but in sub land, parallel. If you need more lows, add boxes and amps.
However I see no problem using a amp in bridge mode driving a pair of 18” drivers in parallel.
Really with the double up of capacitors (of course dependent on amp topology / class) gives a much better damping factor and immediate current draw capabilities!
Thoughts 💭🤔?
I think that the bit that you are missing is that when the pixies have to squeeze through the second voice coil, they get another shove from the second amp.
@@dougaltolan3017
Absolutely correct if it’s hanging off a bridged amp.
I’m talking more generally with sub drivers in series - even say 2x 16ohm drivers in series of 1 channel of a high powered amp for example.
Generally speaking I can’t see ‘series’ wired LF drivers can be a good thing hanging off any amp config….
Unless I’m missing something else
@@dylandylan11731 if your amp can chuck full wallop into 32 ohms then why not? Higher impedance means lower current means lower cable losses. Damping is likely to be cheaper since higher voltage caps are cheaper than higher value caps (less current means a smaller cap can do the job)
Although Dave did cover what happens when 1 driver fails.....
If you have one driver and 100volts or 2 in series and 200v or 3 in series and 300v.
You get a 100v drop across each.
Same output.
But if you use the same wire, the % lost in the wire is less for higher voltages.
The results of using higher voltages to reduce power lost in the speaker cable and improve damping factor while using the amp more efficiently, combine to provide and audible improvement in many scenarios.
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Am I missing something here? I'm not an audio professional, but my understanding was that bridge mono mode flips the phase of one channel and then wires it in series with other channel with positive and negative reversed. It thus becomes a push-pull amplifier with one channel driving positive to ground, the other negative to ground. This is then fed into the speakers wired in parallel to halve the impedance. The advantage is that the speakers are isolated from ground and immune to noise.
Hmmm, that seems about right except noise on the speaker outs is usually not an issue. Sounds like you are combining balanced lines with bridged amps. And the two are basically identical in operation except the reasons to use them differ.
Balanced lines help with reducing induced noise using common mode rejection.
Bridged mono is more about increasing the output voltage to get more power into a given impedance or to reduce the %of power lost in speaker wire resistance.
These videos help keep the brain in the game while we’re locked down here in OZ. Your mis-matched in a box example was my suspicion with a particular company. All in bridge mode. One OO box in the rig always looked like it was fighting itself. Uneven extrusion. I often disconnected it and ran 3 of 4 boxes. Cheers Dave
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Hey John!
@@dylandylan11731 Hey Bro!
Damn, I need to come back to this video some time later.
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Interesting, thanks.
My only experiances of bridging (actually, Un-bridging) have been where people have asked me to check their rig out, as it wasn't sounding good.
Having found the amps bridged, I've completely re-wired it all for straight forward stereo, checking that all the balanced inputs / outputs are properly balanced (ditching the XLR-TS jacks for example) and it has invariably sounded 10x better, with people generally saying ' :o Wow, what did you do?' or things to that effect.
This led me to believe that bridging just sounds rubbish, although I haven't done much experimenting, and most of the rigs I've done this on have been 'average' at best.
I brought this up on Speakerplans forum years ago, and pretty much every pro agreed, and it was more the newb's / amateurs / hobbyists that wanted to do it, because, 'double the power for free' sounds like a great idea, doesn't it? in theory.
I always figured it was just a cheap trick to make small amps bigger, if you had more amps than speakers, and it would always be better just to get a decent sized amp in the 1st place.
Anyone else have any input on sound quality?
What happens if you lower the gain control on one of the two amp channels? does DC go off-set? or just quieter?
I've had the opposite experience and bridges amp to make systems come to life.
Turning down one side all the way down just makes it the same output as non bridged. Imbalances just put you somewhere in between.
The one bigvissue with bridging is if the amp is bridged into a lowwr impedance than it is capable of driving, then they lose power and can sound bad.
Many newer amps are permanently in bridged mode by design as it is more efficient.
@@DaveRat interesting. I'll have a try. I've got some 4 ohm PD2450s, and some 2 ohm stable 2kw/ch class ABs. 🙂
'stereo' 2kW into 4ohms x 2
vs bridged 4kW into 8 ohms (2 cones in series) x1
Thanks. For this, and all your other videos :)
Awesome. And if you use the same amount of copper, you will reduce damping and power losses in the cable
Dave knows his shit!
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Awesome! 🤯
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Wow this was interesting thanks Dave. Cheers!
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Such an eye opener.
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It's always a pleasure watching your videos. Thank You
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Back in the day I ran a 3 wire setup, Bryant 15A 125V twist locks. Ch A lows, Ch B low mids. The - wire served as a neutral more or less. The only time Ch A & Ch B were in phase were at the crossover point which was down -6db. Worked well. Didn't invert Ch B on the amps, the difference was the frequency bands within which they operated.
The concept of a neutral is based on the signals on the hots being equal and opposite.
I tried a similar setup with common ground wire and the impact was audible in a non desirable way.
I did a a video on 3 wire vs 4 wire headphone cables that shows the issue of common ground wire with dissimilar signals
@@DaveRat What's the title Dave, I would like to have a look. Always things to learn sir. Thx.
I think this is it
ua-cam.com/video/EchK1NI5X5c/v-deo.html
@@DaveRat Thanks. I should have bridged the amps for optimal results with a 3-wire setup. Doing it right these days with 4-wire setups on everything.
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Dave, I think the power of each amplifier doubles when you run them bridged. So, in your example, if previously each amp is driving 500w into the cabinet, when bridged, they will *each* drive 1000w into the cabinet. The reason for this is that the impedance they each see halves, and so they each produce twice the current, and hence twice the power. Of course it's easy to run out of current delivery in an amp, so it might not be realistic to expect the power to go up by x4, but that's what the math says :)
Thanks for an interesting set of articles and sharing your passion for audio.
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It was kind glossed over with a simplification in the presentation. Sure Dave did this on purpose to keep things understandable.
Bridging gives you double the voltage between the output terminals.
Doubling voltage gives 4x the power.
So the reason the minimum load impedance doubles is to account for this power increase.
Example:
Amplifier is rated to do 50v per channel into a 4ohm load. That is 625w per channel (amplifier is producing 1250w total).
Bridge the amp, you now have 100v,
100v into 4 ohm is 2500w (twice the amps rated power at 4ohms per channel).
So doubling the minimum impedance to 8ohm beings the output back down to the amps max rated output of 1250w.
But now you are getting it on a single channel instead of split between 2.
Hope that makes sense.
@@Solmbarnes thank you. Your explanation makes sense.. Would that also cause less distortion since the the independence is higher?
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@@jahn-pierrezietsman2293 There are number of factors that will determine the total harmonic distortion.
But I doubt bridging will improve thing.
At 8ohm bridge as opposed to 4ohm a channel. The amp is still being asked to deliver the same amount of current as if it was running 4 ohms per channel, so it's working just as hard.
Since the polarity of one of the inputs is being reversed there is possibility that some noise could be nulled, but I guess this would depend on exactly how the signals are routed inside of the amplified.
Also impedance is frequency dependent. Your "8ohm" speakers probably have a impedance curve that ranges between ~6.8ohms and ~40ohms.
Bottom line is, to avoid distortion stay well within the limits of both your amplifier and speakers.
I sure would love to see Dave put out a video telling stories from when he did sound for Black Flag!
Ha! I will throw some in future vida
I rum a 15 inch sub at 8 ohms on a class D bridged amo. The sub is 600 watts and the amp 1200 watts. Sound great with good headroom
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Burning question. I haven't been able to get an absolute answer on how the reversed polarity to channel 2 power is being used from a bridged amp. Does channel 1 (+) hit the speaker positive terminal with half the amp power and channel 2 positive act as a negative and pulls the speaker back with the other half of the amp power? Or, does it feed both sides of the power amp to the positive speaker terminal to push the cone and the negative terminal just acts as a neutral/ground path? It wasn't described to that effect but I'd love to know the answer. Thanks Dave. You are the man!
Hmmm. Both of those are kind of the same thing and the way electricity works is the power is delivered by creating a difference of voltage across a load the bigger the difference the more power delivered so when you invert polarity on channel 2 and channel 2 is going negative while channel one is going positive it increases the the voltage difference between the positive and negative speaker leads.
by doubling the voltage differential applied to the speaker leads more power is delivered
Probably a better education than paying for a Studio Engineering degree
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So basically if your running 2 subs (any size) it’s gonna be more efficient to run them in bridged mode rather than splitting a mono signal into a stereo pair due to the resistance of the speaker wire. Is this something you consider at large events? Because you usually have more than enough budget/gear that this wouldn’t be an issue. Your not limited on amp power when your using top of the line amplifiers. I guess this could possibly play into truck space
Getting more power out of amps is important on all levels. The cost, weight and size of bringing 30% to 50% more amplifiers is significant on all levels
Wow! Good stuff Dave 👍🏻
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Thank you for your videos mister Rat, I am learning a lot from them 👍
Awesome and thank you!
Nice explanation and didn’t know you can bridge separate mono blocks… Question; Wouldn’t running a bridged amp to 2 speakers in parallel give you the most power and least resistance. This would give you a mono 4ohm (plus cable resistance) giving you almost double the wattage… Do I understand this correctly? (assuming the amp is stable/capable of 4ohm bridged)
Bridged into parallel will give max power potential but any internal amp resistance will be a bigger factor as bridged into 4 is the same as 2 ohms per channel
Dave, thank you so much for your response and confirmation I’m thinking of this senecio properly. I just recently found your channel and can’t get enough, I though I knew audio engineering well, but you have elevated my knowledge by at least 10%. Thank you!
I have a question, I have a crown professional series amplifier. How can I connect it to pioneer stereo receiver? There are no RCA hook ups on the back of the crown amp. Only a Phoenix connection.
Get a pair of RCA cables and cut the ends off of one side and why are the ground into the ground of the Phoenix connector and why are the center conductor of the RCA which is the plus to the plus of the Phoenix connector and put a little jumper on the Phoenix connector between the ground and the minus of the Phoenix connector.
The pin out of the Phoenix connector should be on the back of the amp or in the manual so you know which is plus minus and ground.
This is similar to how the 240V stove circuit works in your house.
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12:24 Maybe I got something wrong here, but if you use a transistor amplifier, it's output is dependent on its load. So at generally speaking at a forum load it will make more power than it will at an 8 ohm load.
I know that tube amplifiers have a different apology especially when they use Transformers for their outputs and therefore does not follow the same methodology as in car audio amplifiers where say running at a 2 ohm load will make vastly more power than running at an 8 ohm load.
car audio amplifiers are often designed to double their output power generally going to a lower ohm load. (4 to 2 ohms for instance)
I'll double-check this with the guys audio science review but as far as I know I believe this is the logic behind the different topologies.
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*a word about resistance in speaker cables*
from my understanding it seems that if you run higher frequency signals, say a 400 Hertz you're not going to get the same amount of resistance that you would when you're running lower frequency content.
the cable Still Remains the Same amount of resistance per a given length and gauge of wire.
however you may experience some top-end roll-off due to the higher impedance of the high-frequency monitors especially running in an active situation where a passive crossover is not used on the main high-frequency monitors. (this is usually never the case and Pro Audio since most Pro Audio gear automatically includes a minimum of a 2-way crossover generally to protect the high-frequency transducers)
basically I'm not sure how you're getting more power out of a transistor amplifier when running at a higher ohm load since generally they produce less power as the ohm rating that the amplifier actually sees Rises . again I want to reiterate that on tube gear because of the topology and that many of them are running a Transformer it doesn't work the same way from my recollection in fact I believe you have to use different Taps on a transformer for the different ohm loads.
*ABOUT WHAT AMPS CAN BE BRIDGED*
(Big thanks to BareVids in the U.K.)
half Bridge designs can be bridged to Mono however I don't believe that you can actually do this on a full Bridge. these are the typical and again forgive me bear if it's for doing this but this is more typical of Brazilian style amplifiers that use a full Bridge topology or circuit design.
*HOWEVER* by taking two amplifiers of a fullbride, and then doing as prescribed I'm wondering if this is even possible ? for my basic understanding I believe you actually get less power even though it may actually work in practice but for my understanding from the amplifier design he would only be running one half side of the amplifiers mosfets again in a typical transistor amplifier.
since most amplifiers are based on a Class D design due to its efficiency, and usually use a half Bridge due to the Simplicity of the design, ( ahem, cost-effective manufacturing of mass-produced items) it might be a better idea just to internally Bridge a single amplifier then using two separate amplifier modules as finding two that are uniquely balanced and setting up the games on each amplifier can be a crazy amount of work especially if you're dealing with multiple amplifiers in a live production environment.
and I think you're also giving up some of the built-in protections for your speakers and your amplifier if you're using this method described but again I'm not a wizard on the subject it's just something to take aim to mind.
still, it's a great tool to use when you have limited resources and limited budget and you want to get the maximum out of your equipment that you have on hand. so it's definitely a worthwhile trip.
on a side note the only thing that puzzles me about Pro Audio is I wonder why the amplifiers themselves even bother on Class D designs to use inductors especially for low frequency transducers and content since those are usually filtered passively by the speaker itself since _generally_ the carrier wave is (Mostly) inaudible on low-frequency drivers.
I think this would increase the efficiency but I don't believe it would result in a higher output generally since the main inductor is the voice coil on the subwoofer itself.
I don't think people in the neighborhood or your other equipment might like that very much since you're basically pushing a very high frequency signal down a wire that's probably not shielded but again that's a discussion for another time :-)
Oh my, a bunch of info and much of it quite confusing or based on blurry knowledge.
Put more simply, if an amp puts out a certain voltage, the power delivered will increase as the load impedance is decreased.
Up to a point where the amp can not maintain the output voltage.
Tube amps tend to have a more difficult time driving lower impedance loads but if you put a 32 ohm load on a transistor or tube amp and measure the voltage and calc the power, then use a 16 ohm load, both amps with double or near double the power output, as you get lower impedances, some amps will continue to double or near double the power output as you half the impedance and other amps will not.
Factors like the size and max current output of the amp's power supply and the output impedance of the amp play a big part in the capability of the amp to drive lower impedance loads at high current levels
@@DaveRat Thank you Dave. I'm so used to car audio where it is explained simply. (I have trouble understanding stuff sometimes) I talked to some Amp Designers at Audio Science review, and they cleared it up a bit. Still foggy on it. But that's why you are a Pro, and we are the Pupils. :-)
My main experience comes from things like Amy Dynos and so forth. (steve meade, and others) I know you explained it correctly, I just can't seem to wrap my head around it. Maybe some day. Again, thank you for replying to me. It means a lot.
Maybe check out this series on impedance and transformers. It's a bit different topic but all the same theory and such.
ua-cam.com/video/9zzGSkAvSFQ/v-deo.html
Thank one more time!
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Dave why would it need to be connected in that way (input polarity reversed) why not just leave the inputs the same phase and connect the outputs in series, as if you were putting 2 batteries in series to double the voltage, IE you take the top plus and the bottom minus, and connect the 'middle' plus and minus to each other. As far as I was aware amps (at least some) all the bridged switch does is apply channel A to channel B on the inputs and connect this middle link at the outputs. If you look at pictures of amp terminals they tend to have the bridged option printed on the back as the outer minus and plus terminals. (images search etc) Cheers.
Connecting an amp plus (hot) to an amp minus (typically ground) is not only unwise but will probably blow up most amplifiers.
Unlike batteries which are completely floating amplifiers have references to ground and hot more like AC wall voltage.
@@DaveRat OK well that's how car audio amps I've come across do their bridge mode, perhaps that is just on those then. They definitely do not tie one side to ground as the instructions that come with the amp explicitly say not to allow either terminal to come into contact with a ground.
There are amps that have the ch1 plus is hot and in polarity and channel 2 minus is out of polarity hot and with that you can connect the speaker between the ch1 plus and channel 2 minus for bridged. Lab Gruppen is this way
Also there are amps that are fully floating like car audio amps where ch1 plus in in polarity hot and ch 1 minus is out of polarity hot and ch2 is the same way. L-Acoustics LA12X is that way.
For these amps connect the speaker between ch1 plus and ch 2 minus and connect ch1 minus to Ch 2 plus. And this will creat a bridged output.
This would be how some or most amps are and what you describe.
Most or at least many amps have a more conventional wiring where ch1 plus is hot and in polarity, ch 1 minus is a ground, ch2 plus is hot and in polarity and ch 2 minus is also a ground.
For these amps, if you were to wire them with ch 1 minus connected to ch 2 plus, ch2 would see a dead short and that would not be ideal
Dude..... wish i would know this when i was 16 and had 2 same model 300-200 Watts...
great stuff
now days everyone is going with active speakers, I see ususally deploy Lacoustics system, passive. I like passive I believe are easier to run,(my system is very small compact. Tri amp, 3 way low, mid, High, thru 12GA) vs active where you have to run power to each box then feed audio signal top and bottom. I seen some DAS have CAT7 ins and out, witch is very cleaver way to reduce cables....
Do you prefer passive or active, I would like to know you opinion pros and cons.
Thank you.
For small stuff amps in boxes works well.
For big stuff, the added fly weight, size and increased complexity of serviceability, having a whole bunch of small amps versus fewer big amps increases costs size and weight.
Plus having to run AC cables in trenches versus speaker cables can be an issue.
More things to go wrong way up high in the air with lawn systems.
Tell overall having the amps in the boxes creates more problems especially for large format systems
One significant reason to bridge, ... especially feeding subs, is eliminating potential bus pumping within the power supply.
Very true and many amps are designed to mitigate this issue even when not bridged. Powersoft and Lab Gruppen being two examples where ch1 + is in polarity, ch1 - and ch2 + are ground and channel 2 - is out of polarity. This inherently balances the draw on the power supply when both channels are driven with similar signals. Also with these amps you can operate them bridged with just using a Y cable and connecting the load between 1+ and 2-
@@DaveRat
Good stuff...
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I keep hearing about "Balanced headphones" in my mind Balanced is an XLR (or TRS) connection at line or Mic level. I see where we're going here and I get how it's balanced and in a way and I see how that's been done in every consumer device with a headphone jack (except the iPhone) but I don't see how a 4 wire headphone cable on crazy audio file headphones is balanced because it seems like they're separating out the left and right speakers and amps on the output side to somehow avoid combining the grounds. Maybe I'm thinking of balanced as in Signal cancellation and not balanced as in flow?
Not sure about the details of balanced headphones but I am guessing they are doing exactly that, eliminating the common ground and having a seperate balanced amp for each ear.
My friend blue out his speaker his thinkng.. was since the speaker can handle it but also had to lower its power the amp gave out..RocknRollFlat5
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Brilliant video, so fascinating.
Can't wait to get my head around this one.
Can anyone help?
I always thought inverse polarity has a cancelling effect on the signal. I'm assuming one of the 18" speakers is flipped around so both are operating in sync.
I love mental challenges like this! 🙂
You can run full voltage "in polarity" to the positive terminal and ground the negative.
Or you can run full voltage "out of polarity" to the negative terminal and ground the positive terminal.
Or you can run 1/2 voltage "in polarity" to the positive and 1/2 voltage "out of polarity" to the negative terminal.
And all of these scenarios will result in the same exact outcome, same power, same polarity.
@@DaveRat - Thanks for taking the time to explain, there'll be massive benefits to this system! 😊
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Great video. 😀👍♥️
Thank you Kevin!
Thanks for everything dave, 1 question what if we run 2 heats, 1 of them are push-pull in the other one is solid state, both delivery the same amount of power and are bridged in the center tap mode, that could affect the signal the goes to the speaker??👍👌
By heats, I think you mean amps and spell check messed it ?
The sound you would hear from connection two amp outputs in series would be the summed signal of the two amps. Amp 1 plus amp 2.
Bridging two channels or two amps is just putting the amp outputs in series.
Putting two different types of amps in series would result in the summed outputs of those two amps and the minimum load would be 1/2 the minimum load capabilities of the amp that is less load tolerant.
Hey dave. Once again you are too interesting. I should be asleep. Im running conference audio at the swedish pavilion in the expo2020 in dubai tomorrow morning.
Just had to see this. Ive only used bridge on too small amps to get more power. Still into parallell loads. For example a 900w crest ca9 amp into a powerful 8 ohm jbl sub. Just a work around with 2 small amps for a setup rather than 1 big. Was 10 years ago and i hardly remember the setup. Think we just changed a switch to bridge and used another nl4 outlet allready there in bridge mode?
Now doing it on a serial load is new to me! Reducing cable resistance part is amazing. But serial connection of speakers is + - + -.. you do it + - - + but with a bridged amp? You gotta open each box and redo them and always run them like this? Seems unflexible but its cool if its a fixed setup i guess!
Im a bit confused by the jumping the negatives part.. honestly.
And when you compare it to a balanced line or mic im even more confused. Cause those are polarity switched a 2nd time to make them in phase again and double the audio signal while cancelling the noise.
And now you dont flip it back. Claim it to be nulled between the speakers as in cancelled.. but the spealers themselves still run in phase and aid eachother?
It might be that its 4.30 in dubai but i feel im missing some piece of logic here. Haha im sorry.
If you can set me straight id be happy!
Love!
You wire +-+- for series to double the impedance but keep all in polarity when bridging and using the two amp + hot outs.
There are other wirings though as some amps have ch1 + as in polarity and ch 1 - and ch2 + as grounds and ch2 - as out of polarity.
The speakers wire the same but you don't need to polarity rev ch 2, you parallel the inputs and wire the speakers between ch1+ and ch2 -
Im running a very powerful sub on an amp bridge as we speak but impedance is too low so amp does get very hot thank goodness i dont go more the 1/4 volume but yeah saving up to upgrade to a 4ohm stable amp to bridge and use cause this sub requires up to 3000watts to really get bumping.
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I always enjoy the sine wave at the end of your videos. :)
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superb video! thank you
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What about damping factor when bridged?
Great question. Since damping factor is dependant and load impedance, if you look at damping with a stereo amp and an 8 ohm speaker per side and 12ga wire pair per speaker.
Vs
The 2 speakers in series (16 ohms) and using the same wire (2x 12ga)
You now have 1/2 the loss in the wire and double the load impedance, both of these will significantly improve damping factor to more than double, some amps more that others.
@@DaveRat thanks for the reply!
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Woow!!
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Hell yeah, ive never thought about it this way, i need to go rewire my amps coz im losing so much free power!
My amp has bridge mode which requires only input into channel A, how would I get both left and right outputs into my subs since my processor doesn't have a mono sub out?
Either create a matrix mix on the console for sub out that is a mix of left and right. Or do subs on an aux. Or get a seperate sin processor that will mix left and right.
What do you think of the newer amps (like QSC CX-Q) that can run channel pairs in parallel? Have you seen that?
I have seen that and older crown amps would do parallel mono as do many other amps.
That is great for running low impedance loads but you do t get the advantages of reducing the impact of wire resistance
Very interesting video, i run 3 single 18" subs (8ohm each) with a single amp and 25m speakon cable.
I've always used the parallel mode so i can keep a minimum of 4ohm load, and i've always avoided 2ohm bridge mono mode since i've been told that the damping factor is reduced in such mode (bridge) which cause less control in the driver movement.
Is this way of thinking correct?
I always limit half of my amps power per channel into my drivers so i keep headroom and clean signal
Respect Dave rat!
Hmmm, three 8 ohm loads in parallel is 2.6 ohms. But to an amp in parallel mode each channel sees 5.6 ohms. Safe impedances not pushing near any limits of most pro amps. conservative
headroom is unused acceuvle power but since you are intentionally using limiters to eliminate access to the extra power, it's not headroom you are gaining. You are just reducing the power available to send to the speakers, so that would be protection.
If you wanted to hot rod maximum output from the amp and to the speakers and if the amp can handle it. Adding a 4th speaker and running the amp in bridged mode intro two 16 ohm loads would milk more power out of the amp and lose slightly less in speaker linen and get you about the same power you get now per speaker into 4 speakers rather than 3.
What about running bridged mono into parallel woofers at 4 ohms?
That's the way to get max power out of amps that can run 2ohms
Its what we used to do with 8 ohm subs and too small amps to just get more power. Its all ive ever used bridge for. This fewer cable thing dave does is new to me. Also internally jumping the negatives is new
Hi, Dave. Just stumbled upon your channel randomly and actually have a relevant question.
Maybe a little out of your wheelhouse, but I suspect you have the answer.
I have a small multi function guitar amp that is stereo, but uses two built in 4"speakers. It sounds pretty good, but I'd prefer to be able to connect it to an external cab. Now I can easily install a couple of switching jacks and connect it to two spare 4ohm driver's, but I'd rather bridge it to one cab if possible. So if I have continuity between the negative speaker terminals and the chassis, does that mean I can bridge it?
Thanks very much for sharing your experience.
Hmmm, that will be complex unless you can isolate the stereo pre amp from the stereo amp in the cab. If there is a pre amp out and and power amp input, it could be possible depending on the amp design. Then find a way to polarity invert the input to one amp channel. And mono the pre amp out.
Sounds more complex than beneficial.
@@DaveRat I think that's beyond my capability right now. The only experience I've had with bridging amplifiers is car stereo amps that you flip a switch and just use a particular set of terminals. I had the guts out of this little amp and it's surface mount components in a pretty small form factor, so probably best to either leave it be or do the two jack modification I mentioned, I think.
Thanks so much for the reply, friend. :)
Understood and yes, not worth the work and complexity vs the value of the outcome
What blows the amp?.RocknRollFlat5
Would the bridged configuration be appropriate for a marble rye?
...as opposed to a sub. I got it.
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Okay I’m grinning, off course!
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Got two 18inch 8ohms subs in two enclosures wired parallel to 4ohms. Amp runs in bridge mono but when connected to the speakers the load is 1.2 ohms is that right am new to this stuff
1 2 ohms dc resistance could be an 8 ohm load though usually a 4 ohm load will measure around 2.4 to 3 ohms
Thanks for the reply
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very interesting - so is there a way to bridge an already bridged amp, like hooking them up in parallel?
Typically, no.
Agreed, that would be doable but sketchy
Hi Dave, I noticed recently that Berhringer have released a 6,000watt amp, but it only has a 10amp, IEC input @ 240volts. I would expect the input to be more beefy than this - either a 20amp powercon or 32amp cefform. Is the claimed 6,000 watts rating therefore reliable, a complete lie, or am I missing something?
Hope you provide some insights on this. Jonathan
Hi Jonathan,
Class D Amps always have higher RMS Power than Power Input. There are 12000 Watt Amps (L Acoustics, LAB Gruppen etc.) that run on 16 Amps Breakers in Europe (230V). So you can pull 3680W from the Fuse. This is possible because of the different Ways of measuring Power Output i believe. As far as i know there are Pauses in the Audio for the Measurment of the RMS Power of an Amp.
Hope this helps with your thougts. Cheers!
Great observation and yes, it is no possible to get more power out than the power going in.
That said, a 20a 120v ac wall plug gas a maximum continuos power capability of 2400 watts.
But many power amps are rated with peak power where the amp stores some energy and so it could put out 1500 watts continuous and maybe put out 6000 watts for a short periods of time. And many amp manufacturers will rate the amp on its peaks
@@DaveRat
I've shared this before, hope this helps;
To avoid nuisance tripping, circuit breakers can pass huge amounts of current past their rated trip amount.
For example, when electric motors start, they pull massive amounts of current until they're up to full speed.*
A 20a circuit can pass 7-8 times the rated 20a trip amount, .. for up to a full second or more.
It will allow up to 3x the rated amount for up to 10sec or so.
Most importantly, that 20a circuit can allow up to 2x the rated amount for a period extending as long as 30 seconds.
100amps for around 1-2 secs
60amps for around 10 secs 30-40amps for up to 30 secs
Music is transient in nature.
The capacitors store, dump, refill.
Big iron toroidal amps store in their magnetic field.
High speed SMPS amps refill caps so quickly and frequently, their demand from the power line is typically in brief high current spikes.
Yes, long term P-out < P-in ...
just I²R losses assure that.
But other than a 20hz synth note that never stops, music ebbs and flows.
*(wires in conduit feeding motors often vibrate intensely upon start up, the high current magnetic fields off each conductor fight each other and will buzz against the interior of the metal conduit)
For shows we need to rely on the long term breaker current handling or else we hit a thermal trip which I believe aligns with the rated current.
But yes and thank you. It's interesting because if circuit breakers used the same ratings that many amps use of peak or pulse power, a 20 amp breaker would rate at 100 amps.
@@DaveRat
Good point
That thermal limit ....
Perfect example;
Big stadium show, Kenny Chesney headlined a multi-act Pirate tour, Keith Urban, Lee Ann Rimes, Luke Bryan, others, a massive touring circus backstage.
This was the last night of the tour.
For me, this is our venues first concert since opening. The motor coach area was a three day party, 𝙬𝙚 𝙥𝙖𝙧𝙠𝙚𝙙 𝙩𝙝𝙞𝙧𝙩𝙮 𝙥𝙡𝙪𝙨 𝙘𝙤𝙖𝙘𝙝𝙚𝙨 𝙄𝙉𝘿𝙊𝙊𝙍𝙎, 𝙙𝙞𝙧𝙚𝙘𝙩𝙡𝙮 𝙗𝙚𝙝𝙞𝙣𝙙 𝙨𝙩𝙖𝙜𝙚, shore power, water, drain, cable, and internet built in the floor, adjacent to essentially every coach.
Very few venues offer that.
EVERYONE involved loved that convienance. Brand new stadium sized restrooms for all backstage.
It's a convention center hall, backed up to a football stadium end zone.
Party party party, last tour stop and it was wild. Oh my gosh great fun.
Five headline level acts, it's a busy place backstage.
Non-stop limos/vans in and out, celebs, athletes, last tour stop party buzz.
Ok,
Night before the show, partying, blasting the PA into a big empty indoor stadium, one of the house breakers tripped feeding one aspect of show power.
Picture a breaker, feeding a fused safety switch... where we tie in show power tails.
This was really embarrassing for us, the house... I believe a 400a breaker opened up.
These breaker trip curves are adjustable on the face of the 400a breaker. These small dials establish how quickly and under what circumstances the breaker trips.
This one was never set properly.
Quickly the production decided against house power for that drop, and went to Aggreko generator power for that load.
That was f***ing embarrassing because we bragged we built in all the show power you need... etc.
𝙈𝙤𝙧𝙖𝙡 𝙤𝙛 𝙩𝙝𝙚 𝙨𝙩𝙤𝙧𝙮;
Breaker trip curves can allow huge amounts... or if never adjusted correctly, can trip way too soon.
So glad it happened before the show.
(same wild tour rolled thru the following year too, good times, even more stories)
Si == does the electricity sent to the earth go to earth or transformer> are the electrons the ones on a path or are other electrons present if it goes back to power pole- and do electrons come from earth or do the appear intra-dimensionally...... -WTPOW
Oh my
Since audio is AC, over time the electrons return to thier original starting point. That means that none come from the amp and none go to ground and in fact you need to bring your own already in the wire.
I get the feeling that amplifier damping factor is next...
Yeah, if I can figure out a test so it can be heard, I will do
I love running amps in bridged mono because I can often get 3x the power into the same load
Or at least near double the power.
V²/R = P
Overall current capability remains, but yes with bridging, it'll swing a lot of voltage.
Yeah I guess when I said that I was thinking of the difference between 1 channel by itself and a bridged amp
@@jakesterfiddle
gotcha 👍
Yes, volts squared over resistance.
So if an amp puts out 100v per channel into 8 ohms then it's 10000 divided by 8 ohms or 1250 watts per channel
100 volts per channel into 4 ohms would be 2500 watts x 2
100v per channel into 2 ohms would be 5000 watts x 2
In bridged you get double the voltage in a perfect world though most amps can't fully double the voltage due to other limitations. So 200v into 8 ohms.
Which would be 200 squared or 40000 and if you had the same load of 8 ohms it would be 5,000 watts or 4 x the power but you would only be driving one 8 ohm load instead of two 8 ohm loads
If you double the load impedance to 16 ohms by putting the speakers in series, because you are using 2 channels and had speakers on both channels, you would get 2500 watts into one 16ohm load.
And if you parallel the two loads down to 4 ohms you would get 10000 watts because you would be running the equivalent of 2 ohms per channel.
I want to be like Dave when I grow up
👍
No its not better, they sound horrible, bridge may increase the power but half the demping factor and struggles to handle low impedance speakers !
Hmmm, not exactly true.
Bridged into 8 has the same damping as stereo into 4 ohms
Also has the same amount of power bridged I to 8 ve stereo I to 4
But, bridged into 8 has 1/2 the loss into speaker wire if the same wiring is used.
Or, you can use thinner wires and have the same loss, saving weight, and money and cable size
@@DaveRat all this may work in pro audio applications, fact is bridging doubled the output impedance of an amplifier and it struggles to control low impedance speakers, using thin and long speaker wire doesn't cut it .
@akhtarizod5802 well, perhaps you may not be aware that many amps are inherently bridged. Wherein each channel is actually two channels that are bridged. Bridged just means is a higher voltage and runs higher impedances.
Another way to look at bridged is it is a balanced drive rather than an unbalanced drive.
Balanced drive means each terminal has and equal and opposite voltage. Rather than a ground and one line having voltage.
Also bridged uses the power supplies more efficiently as one channel uses the positive rail while the other channel uses the negative rail. A non bridged amp both channels use the positive rail at the same time time then the negative rail for signals that are the same to both channels.
Bridged has no impact on sound quality, it's just better at running higher impedances loads at higher voltages.
This is advantageous for minimizing loss in speaker cables.
Having higher voltages available allows better transient response as well.
Being more I formed will help you optimize the sound you are able to achieve
where did you gain your non-technical crap from.
Hello Nico. Well, when I was 17 I started building speaker cabinets while I worked at Hughes Aircraft as the youngest guy in the department, electro-optical R and D working on Tow Missile Systems.
From there I built up a sound company that provides audio equipment for some of the largest festivals and shows in the world along with providing sound equipment for world wide tours. I also started a manufacturing division in addition doing sales and installations. Along with numerous patents and licensing deals, I also mixed sound for many world class artists such as Chili Peppers, Foo Fighters, Soundgarden, Pearl Jam, Rage Against the Machine and have travelled to 6 of the 7 continents and hundereds of countries over the past 40 years. I dedicate time and energy to sharing insights of what I have learned and how to correlate the specs to real world, based on my hands on experience, to help others along their path.
What I don't do is randomly judge others and troll around as as an arrogant ass.
So enough about me, from what pedestal of knowledge, experience and authority do you speak and what is it you wish to offer in helpful and kind ways?
I welcome any and all knowledge from someone with such a strong depth of knowledge and experience perhaps such as you?
You can't just bridge two amps if they weren't designed to be bridged in the first place, as it will most likely fry them both! And you should never connect two speakers in series, because speakers also have crossover networks which are not designed to be connected in series...
Also some of the "math" presented is wrong...
Some stereo amps have a bridge or BTL switch. Just stick to those.
This is why you should never get any electronics advice on UA-cam, especially from a long haired tattooed dude...
Oh my oh my!
At least your lack of understanding and research is consistent with your lack of credibility
Are you telling people not to do something because something will most likely happen even though it is something you have never done?
I appreciate that consumer point of view where sound system and equipment designers know what's best and you should follow the manual and do what they say to do and nothing more.
Which is what makes this all the more fun and interesting because this long haired tattooed guy actually is a sound system designer! Big smile. But not a sound system designer for the consumer toys and such, I actually design and deploy sound systems for large scale rock concerts and festivals. Feel free to do a credibility check.
Anyway, I appreciate your caution and clearly as a judgmental person as you seem to be, I can see how you may discount my knowledge and experience based on personal biases against the way I look.
I guess it just comes down to credibility. Should people believe long haired tattoo guy with 40 years doing sound for some of the largest shows, festivals and bands on the planet that spends time and energy freely sharing knowledge I have learned over the years helping others in the audio field?
Or trust some anonymous guy that is spilling info about things he has neither tested or experienced?
@@DaveRat
Didn't you say something like "You get more output power/ Watts at 16 ohms vs 10 ohms (speaker) loads".
This would be true only audio amplifiers were current sources, but they're not. Amps are voltage sources.
Use treat a 500W amp as if it's a 500W power source. Amp wattage are just rating. Actual power will depend heavily on the speaker and cables length.
Some mono amps were designed to be bridged to each other to get twice the possible power. There are actually to bridging configuration: series, which doubles the actual voltage, thus increase power by x4, and parallel, which doubles the current rating, thus allows you to connect 1/2 the rated impedance to get x2 the power.
There are many good class D amps today that were designed from bridged operation. I'd avoid trying to bridge any consumer amplifier, which wasn't intended to be bridged.
Also series connection of speakers was intended for the speaker drives inside the speaker box, not for speaker boxes, which include the crossover network at the input.
Your advice may be more suitable for the professional market , not for home audio...
Lower impedances will tend to output more power up to the point where the amp is unable to output more.
The 10 ohm reference I use is an example of how to reduce losses due to speaker wire resistance by running the higher voltages in bridged into higher impedances such that speaker wire resistance is a lower % of the total load.
Running identical loads in series or parallel should not be an issue and long as the loads are identical. Running dissimilar loads in series or in parallel will have more complex results.
As far as bridging consumer or pro amps in to double the minimum rated single channel impedance, there should not be an issue as long as you are connecting the load between two hots and the amp has a ground and hot on each output.
These videos help keep the brain in the game while we’re locked down here in OZ. Your mis-matched in a box example was my suspicion with a particular company. All in bridge mode. One OO box in the rig always looked like it was fighting itself. Uneven extrusion. I often disconnected it and ran 3 of 4 boxes. Cheers Dave
Thank you Jon!