PLEASE Never Stop doing these videos! After 30 years, you always teach me something that I didn't know, that I should have known, that makes perfect sense, but somehow I feel like I'm an apprentice. That's simultaneously humbling and exciting. And we're talking about Phantom Power of all things!
Another home run Dave! Stuff we can use. I would assume that this is a moot point with linked digital consoles -- only one (or a stage box) can actually generate +48V.
@@DaveRat I hope you didn't think I was being sarcastic, I really meant it was useful. I was just thinking about the digital realm and realizing that it's a different situation. Thanks for all you do!
I always love your videos. You always break stuff down and show it, instead of just talk about it. I appreciate that. I watch videos of yours on stuff I already know and still enjoy them and pick stuff up. Quick question though, I didn't think DC could pass through a transformer. Isn't that one of a transformers (isolation transformer) uses is to filter DC out?
Not sure of the specific part you are referring without re watching the vid, but... There is a way to pass a DC voltage through a transforme and have it function correctly for ac by tying the centertaps of the primary and secondary together if one leg of the DC was applied to both sides of the primary in relation to ground. The DC would show up on both sides of the secondary in relation to ground. This is how phantom power can pass through transformers designed to pass phantom work
@@DaveRat Well I learned something new. I didn't think it was possible to pass DC. Thanks for the clarification. You're the man. Love your work and passion for audio. I share it.
I wonder if there is any microphone response difference if 3 or more consoles drag down the voltage enough? Any pro OB set up I've seen always used an active 3rd split anyway. Would having 3 phantom switches on 1channel triple the current then?
Dave, Is there ever any chance of having too many consoles running phantom power in parallel that could possibly cause injury from too much accumulated current due to a faulty snake system?
Two seperate issues. Faulty snake can give annoying shocks to the lips and hurt some mics with phantom. Paralleling 3, 4 or 5 consoles w phantom still has way way less power than a USB
Agreed, power is so low that it is not possible to injure someone. But I have been called out to fix a a system where a gal was getting shocked and fount phantom power and a faulty snake ground was putting 48v on her lips when she sang and held her guitar.
i never use phantom power, but recently the light of the phantom power goes on with my mixer while the switch of the phantom power is off. UB1204 without the fx board.
@@DaveRat so the switch works and there is only 1 powersupply. Only 4 wires go to the mixer. 3 black 1 red. I traced the ground (black)and searched wich one gave 58 volts black. Te red and other black gave 15v now its fixed but now i have -1,5 V ON THE XLR hot vs ground. Well. Its fixed for now
Thanks again , nice experiment. The loading of the second console un-powered phantom is due to the two , normally 6k8 , resistors used and as you showed us the phantom voltages combine when both on to share the microphone load. The idea of phantom power came from Telephone/Telegraph balanced circuits for either powering up repeater circuits or adding dc signalling to a balanced transmission line. Cheers Dude
Two things : Red should be pin 2 (hot) ? And blue pin 3 (Cold) The condenser mic is a Neumann kms105 not a sennheiser kms105😉 And I like your videos Thanks🙏🏼
Thanks Dave. I really enjoyed this chat and demonstration. I've been running PA's and doing all sorts of sound for over 40 years and never really understood what was (technically) going on under the hood. In saying that, I always made sure that my pin to pin wiring was spot on and never had any major issues when running condensers with dynamics. Your bench top demonstrations are excellent, and show that the principles do not need a massive rig or console to explain. Keep up the discussion. Cheers ...
I gotta say when you pulled out the Neumann I'm like whaaaaaat. "If we're going to use something to test, let's use something expensive to do it with." Lol. You are hilarious my friend.
I'm a total novice about this topic but I have a question about using drum mics. The typical kit comes with various dynamic mics for close mics on the drum and two overhead pencil condenser mics that require phantom power. Obviously, when using one mixer, you have to turn on the phantom power for the condenser mics but that means it's on for the dynamic mics too. It sounds like you're saying this is ok as long as the cables are good. I was wondering this is the normal, expected way to use these drum mic kits. I haven't found any source that addresses this specific issue. Thank you.
Mosicers allow 6urn8ng on phantom on each channel seperately. That said, if phantom was dangerous to any mic, that would be a huge problem. Phantom is safe for all mics with properly wired cables and phantom is so low power almost no mics can be damaged by it though there are some older ribbon mics that can be damaged by wind, dropping, blowing into them and potentially miswired phantom. Don't worry, you won't ever encounter these or any mic that can be damaged by phantom unless if you break into the vintage mic section of a recording studio.
Hi Dave, i have a very basic question - if i have a mixer with just one button to turn off phantom power on the whole mixer and i have a device that outputs line level over xlr, should i put a di-box between the mixer and the line level device to prevent damage or can i just connect the line level device directly to the xlr inputs of the mixer that has phantom power turned on?
It won't damage but some output circuits don't perform well when phantom is applied. I would just test and listen to the device with and without phantom. If you don't hear a difference, then I would not worry about it
EXCELLENT video as always! My only comment is that this only works IF everything is properly wired and undamaged. You did touch on what happens if a dynamic mic is in the mix and an unbalanced cable is used...BUT what about the possibility of damaging a console's input or the output on a piece of equipment with improperly wired cables, a damaged cable, or some other issue combined with phantom power? I've just been burned by this one too many times...especially when tying into someone else's gear. If it's all your gear, and all properly maintained, perfect! I still much prefer an active or transformer split for some isolation, but that's just me...
Phantom power should be safe for all pro gear regardless of being wired properly. It is limited by 6800 ohm resistors and gear designers should and almost always take into account the potential existence of phantom Computers, semi pro, super cheap and home hifi gear? Not so much, that will often get cooked by ohantom
I’m wondering what happens when you split the mic cables and have two desks both supplying phantom power ? Ps not finished video yet :-) Haha just watched the rest 👍🏻
Is the ethercon breakout boxes wired T568A or T568B? Would this have something to do with why my ethercon system is not lining up 1 for 1? I wired my whole system T568B.
We just bought a set of drum microphones for a church. Is it safe to use another mixer just for the drum mics for 48v (both the dynamic and OH condenser mics) and use a send for the snake, traveling to the main house console? Otherwise, I'll have to check the wirings of my dynamic mics and xlr cables one by one if we'll gonna be using a single console where both the drum mics, singers instruments will be plugged in. Thanks in advance Dave! Your videos are always helpful!
Yes, all good with using a drum sub mixer and also, with the SoundTools XLR Sniffer/Sender (I designed it) you can test all your lines in a few minutes or less. Just turn on phantom and plug in the sniffer to each channel on the snake and it will tell ya good or no good. Probably worth having one. ua-cam.com/video/bG77DLOTPsQ/v-deo.html
Thanks for the vid, could you help me a bit? I have an effect pedal with constant 24V phantom power, will it make any harm if i use it in a chain like this: Condenser mic --> external power supply with phantom power 48V --> effect pedal with constant 24V --> audio interface with turned off phantom power --> pc
Phantom power into balanced outputs should not hurt anything. I have seen some outputs don't like it and either distort or offer reduced output levels when phantom is went to them. Just try it. If it works and sounds ok, roll with it
I can see that the cats stagebox seems to pass Phantom power. I wanted to know if that same stagebox would be able to pass phantom power across a cat6 cable going into the snake?
Question please. I have a splitter that itself provides phantom for each channel if needed. In your scenario above, I am assuming that a voltage drop occurs because I have two consoles FOH and monitor not turned on for phantom as I have been relying solely on the splitter source for the power. I don't use enough condensers that I think it would cause too far a drop, but with that scenario, should I be keeping it as I have it or should I have phantom on both channels from both boards as well as the phantom on the splitter. My boards allow phantom to be selected for each channel needed vs powering the entire board. Thanks for the explanation, it makes sense, I just never gave it a thought before 🙂
Not sure if anybody else mentioned it in the comments or maybe you followed up Dave but people often forget that if you are using a splitter box with out transformers but does have ground lifts for one or two of three splits phantom power should come from the split that the ground lift does not lift. When the ground gets lifted it breaks the phantom circuit.
I wish obvious phantom power indicator lights were standard on all mixers. A pro tip for club engineers is to mark any channel on the tape when phantom is on so when the band is finished the engineer is reminded to mute the channel immediately. Experienced musicians know that they need to make eye contact with the engineer before unplugging a hot phantom powered instrument, but this will inevitably slip by the most seasoned sound engineer, and that painful pop is a real vibe killer. It happens to me occasionally when someone starts chatting with me at the board at the end of a set and I get distracted.
Whilest I personally don't worry too much about phantom 9n or off, I do make sure channels are muted before swapping mics at a gig. And if I see the peak lights flash on a muted mic, there is a good chance phantom is on. Phantom power is about as dangerous as drinking a soda in a car, all good except if things go terribly wrong
Typically a differing phase is not an issue. Its when the ground for mons and FOH are different and not tied back to the same place that issues arise. Since neutral is tied to ground somewhere in most, if not all, power systems, loads on the neutral can drag it off of zero volts and possibly drag the ground off of zero volts. Or if there is gear that somehow causes the ground to not be zero volts, that can cause issues if the ground at FOH is differing in voltage to the ground at mons. With digital snakes, this is less of an issue and usually a non issue as long as the ground offset voltages are small. With analog snakes and interconnects, even very small offsets in voltage between the ground at FOH and mons can cause hum and buzz issues. Large ground voltage offsets can be dangerous or deadly.
So if I inject phantom power to a mic and use the one side of the xlr output of the mic to the unbalance mic input of a DSLR, ill kill it with 18v in the audio path?
Oh my, yeah, it gets complex but yes, phantom power is not typically compatible with unbalanced. Using a small transformer to convert to unbalanced while phantom and the mic are on the balanced side of the traslnsformer is good.
If you wanted to go from one mic into Y split cable and then onto 2 inputs of the same same mixer ( double patch type thing) Would it be the same as the 2 mixer set up? As I have often thought if doing this one apply 48V to one of the inputs.
Is there any way to remove phantom power from the output, I have a mixer that has all phantom on or all phantom off? If I run phantom into a passive DI box, will it damage the input device?
Nice bass test in the end :D Great info, I guess someone who is an electric engineer would have known this already, but developing an intuitive understanding of electricity is Incredibly hard for some (like me) :)
In all my years of Audio engineering (40 odd)I have never been able to grasp the concept of phantom power workings. This has explained it in the most simplistic form ever. Thank you so much and keep up the great work.
This brings back memories of when I was a kid and tore apart the microphone that came with my dad's cassette recorder, saw it was dynamic, and realized that it looked just like a tiny speaker. So I plugged it into the output jack of the recorder and found that I could hear the sound on the tape through the microphone. I'm guessing that the 48V phantom power voltage came from the phone company, that used (and still uses) a -48V battery to power all central office equipment. Long ago (like before any of us were alive), long distance calls used to use a 4 wire cable. When the need for more circuits arose, they added a third circuit (a 4-wire cable could handle 2 calls, just like a regular POTS phone line can) by putting center-tapped transformers at both ends and connecting the third line at the center taps. Because the AC voltage from the center tap was the same at both ends of the other voice circuits, it canceled out and couldn't be heard. Likewise the voltages on the two circuits became zero at the center taps, so there was no crosstalk in any direction.
Your post brings back memories for me. As a child, I also tried the dynamic-mic-as-speaker trick. My favorite "transducer repurposing" is to use a closed-back set of headphones as a microphone to pick up heartbeat sound. In the late 70's when I was studying for my EE degree and working various jobs, I had a short stint at the local telephone company's CO serving the Redmond-Kirkland, WA region. In those days, the equipment was all relay-based, and when you walked into the office, there was a constant noise that sounded like a waterfall. The power room had a huge stack of batteries kept under constant charge by true behemoth TR units, and a diesel generator just outside for longer power interruptions. The 48V power came into the switching office on a pair of copper plates - true power "rails" the likes of which I've never seen since.
@@marianneoelund2940 That's very cool! I was a little behind you. Thanks to some experience while still in high school, I got a little experience in doing sound reinforcement and lighting, and if I had made enough money to eat, I'd be doing it today. During that time I found a volume of books in the local library called "A History of Engineering & Science in the Bell System" and read them cover to cover. That was one of the more useful extracurricular reads for me, as the knowledge that I got from it helped me communicate with telco people when I worked in TV broadcasting and IT. That's where I learned about phantom circuits. One consulting job I had was for an ISP that was moving into an area that was occupied by a brand-new, unused Class 5 Lucent 5ESS switch that had been decertified when someone accidentally discharge the Halon. That thing had two -48V batteries, each cell the size of a small chest freezer. I was licking my chops over the prospect of using them to build a UPS for the facility (there also was a 1 MW Caterpillar Diesel generator downstairs) but whoever bought the junk switch got the batteries as part of the deal. I did manage to get a lifetime supply of silver-plated BNC connectors though. There were a lot of copper bus bars that carried the battery power around to the various cabinets. I wish I could have taken a few of those. I don't recall if I ever was in a working CO with mechanical switching. I do recall that the Chicago Museum of Science and Industry had a piece of a crossbar switch on exhibit for a while. When you pressed the button, the frame would start making a big racket from behind a thick sheet of Plexiglas. Looking back it was amazing that so much was still mechanical back then. When we got Touch Tone phones in 1967, we just assumed that "computers" did all the work.
@@StringerNews1 The equipment I worked around was a bit more modern than the crossbar equipment. It used sets of relays as registers. If someone was dialing a pulse-dial phone and you were standing by their line equipment, you could hear the relays counting up the pulses. Each line-equipment rack unit handled 25 customer lines, and the units were organized into sets of 20 (500 lines). Then there were up to 20 of those sets, to populate one "exchange" of 10,000 lines. The mapping from telephone numbers, to the line equipment numbers, was done by stringing wires through a set of pickup coils mounted on a large board. I think the only computer in the office, at least for the local-line service (toll service was more sophisticated), was the one which scanned the equipment for faults and printed out messages for the service techs on a teletype machine.
That's an interesting question. Since phantom power is 48 volts on both pins two and three and a polarity reverse only switches to with three polarity reverse makes no impact on phantom power. There are several ways to reverse polarity either by swapping pin 2 and 3 or as consoles normally do after the line is unbalanced putting a polarity reverse opamp or circuit there. Either way phantom shows up on both pin 2 and 3 If you have the time check out my videos on phantom power you may find them interesting I did one specifically on powering mics with multiple consoles
Hello good time. Thank you for your professional and excellent content, I had an important question. My friend brought me a Yamaha MG10XU (a baby usb mixer) from the United States yesterday, which has a 120-volt power adapter. But our country's electricity is 220 volts. I plugged in incorrectly for 4-5 minutes, and the device got a little hot and could smell a bit, but not much. I activated the phantom power button for a moment and a soft click was heard just below the spot. Again, my mistake. I quickly turned off the device and unplugged it. The next day I got a low voltage transformer and tried it again, the good news is that the device turned on and it did not seem to have a problem, all parts of the device worked properly, the LED for the Phantom Power also turned on when I turned it on, but the bad news There was no sound from the microphone (condenser RODE NT-1a) when I monitored the sound, while without the phantom, I also tested a typical dynamic microphone, and the sound came. Do you think you can help me? I'm very worried, I'm thinking about it negatively every moment
Hmmm, well it seems you are lucky the unit works. Usually double voltage will at least blow a fuse or some parts and often severely damage gear. Sounds like the 48 bolts phantom has destroyed something inside. Probably not an expensive part, most likely it is fixable but also, unless you know someone good with electronics, this would be a non warranty factory repair. Phantom circuits are not that complex and not too hard to troubleshoot and since you heard a pop, the issue may be visible. You will most likely need soldering skills to fix it or possibly be able to order a replacement board. Your least expensive fix is probably to buy an inexpensive external phantom power source to use instead of the blown internal phantom.
I was really worried and very upset, you really did a very valuable favor for answering, thank you very much. I will not forget this grace of yours , and I will definitely tell you the result of this problem
Great demonstrations thank you! Dave over at EEVBlog invited Doug Ford (from Rode Mics) to explain phantom power and a lot of other microphone design considerations on the EEVBlog channel here on UA-cam. I highly recommend them. (Phantom power is episode #616.)
For the more technically curious, the actual 48v power supply in the mixer feed each channel separately through resistors, typically 20k ohms or more, so that any difference in the multiple supplies will be dissipated in a small amount of heat, and not damage the microphone or mixer. Even If one or more wires is shorted to ground, like using an unbalanced cable, it will not greatly affect other channels. The only possible damage would be if the microphone voice coil or transformer cannot handle the current. For example , a typical mixer feeds pins 2&3 through 47k ohm resistors, and a typical voice coupled is 200 ohms, so 48v would place about 0.2 volts across the microphone voice coil. It would not be healthy, and would push the coil against the end of its space. It would also generate some heat. The actual damage would depend on the specific microphone. Thanks for the excellent demonstration and keeping it simple.
Dave, could you do a comparison between active and passive DI boxes? We use both and can't seem to tell a huge difference on the different instruments we use them on. And also, maybe compare against an instrument amp XLR direct out? Thanks!
I may be late to the party, but here is my 0.02€. From the perspective of a recording studio fix/monkey About phantom and dynamic microphones, the world is full of boffins. I've lost count of the microphones lost to bad cables and phantom power mixed together. Even moreso when some equipment has lower feeding resistor values because they were too cheap to pony up for some real 48v PSUs. Then there's the classical problem with cheap Chinese microphones wired wrong from the factory, including Thomann's own brand stuff. On the other issue, if the phantom power is well executed on the console itself, this means a real pair of 6.81 kiloohm resistors feeding pins 2 and 3 from a real 48v source, there may be two scenarios: One is that the resistors are connected to ground if the p48 is switched off, then tough luck. Your p48 has just been converted into p24. Keep both p48 feeds on if you want to keep the mic preamps happy. The other option is that the 6k81 resistors are left floating when off, then you may or may not want to keep both feeds on. This depends on what's on the other side of the cable... Not much of a problem in live audio, but in a studio, yup, it may hurt something. The misconception is that it doubles the voltage, when, in fact, it doubles the current into a dead short. Instead of 7mA it goes to 14mA. It may be a problem if the circuitry inside the microphone expects exactly 7mA, like some very old versions of the venerable Neumann U87. (It takes the polarisation voltage straight from the number 2 and 3 pin, no regulator, no nothing, and it expects around 39v here). There are some old mixing consoles, like some Telefunken/Siemens and Never broadcast thingies that feed phantom straight thru just one resistor to the center tap of the microphone input transformer. A nice way to fry some mikes AND the console at the same time. Don't even get me started on bantam patchbays that have phantom power going through them. A nice way to fry a ribbon, smoke the preamp and get tinnitus maximus from the monitors trying to expel the woofers at the same time. (Neve 8232, looking at you) On the other hand (third one), there are some really bad implementations on cheap and nasty consoles, like the RF blocking caps on the microphone input being rated only at 50v, really bad tolerances on the feeding resistors and leaky DC blocking caps going to the ultra cheap op-amp pre. Arrrrrgh.... Been there, modded, fixed, cussed off soundcraft/Harman, phonic, mackie and Behringer engineers... As of late, I'm resorting to go all dynamic for the small gigs I sometimes do, just not to get into this very pickle.
Thank you so much for sharing your talents and experience with all of us. I have a question. I want to utilize 2 AT4033 large diaphragm condenser mics in my acoustic trio. I also love the sound of our Meinl slap top cajon with passive pickups connected directly. Im told by percussion dealers that phantom power will damage it and our small Bose digital mixer doesnt have individual channel control of phantom power. How can I protect the cajon? Will the low Z output of any passive direct box isolate and serve the purpose? Do I need a specific device? Thanks again!
Yes, the output of a direct box will block phantom. Or use and isolation transformer. Or make a special xlr cable that has 100uf capacitors on pin 2 and pin 3. Phantom won't go through a capacitor.
@@DaveRat Thank you so much! Your approach and egoless attitude are rare and so refreshing in this business. You should write a book or a series. I'm sure they'd be VALUABLE go to resources for all of us. Your knowledge and experience needs to be preserved. Thank you!
nice topic....i have been wonding about it quite a while ago and i didnt found answer, thanks for that another question would be, what will happen if you feed line output signal from one cosole to the phantom powered input of another console?
Sending phantom to electronic outputs can give varied and often undesirable results. Due to the wide diversity of output circuit designs, there is no rule to whether it will have a negative impact, other than avoid it. Phantom can be blocked with a pair of capacitors inline on pins 2 and 3 of an XLR or using an iso transformer
He actually covered that part. In 1/4” patchbays, you can short pins to ground when plugging/unplugging. This causes the mic diaphragm To POP and clip the input of the console
Thanks for teaching me what a balanced cable is. A question... If the two different consoles are at slightly different voltages, theory tells me would that cause some current flow between the two units. Have you any idea how the two different power supplies cope with that? Obviously, no magic smoke is released! Thanks!
All input and output voltages are either floating or references to ground. Inputs look at the differential between the two hots on balanced lines and the diff between hot and ground on unbalanced. Outputs create the same things. As long at the gear is either isolated through a transformer or other method like being battery powered or references to the same ground as the other gear, all good. Differing ground potentials on non isolated gear causes issues
The one with the higher voltage will be providing most of the current. The internal 6.8K resistors help out with current sharing, so the difference will be small.
What about the use of an unbalanced input cable (i.e., RCA phono jack to XLR) for a line in situation, where pin 3 is tied to pin 1 and pin 2 is the "signal line." Pin 3 tied to pin 1 is shorting out the phantom power of a small console (presuming all on/all off environment). I'm guessing that the internal resistor circuit prevents a dead short of the phantom power, but does it reduce the voltage on the other channels? Still got that XLR to bananna plugs cable? Inquiring minds want to know... ;-)
Shorting phantom on one channel has no impact on other channels. But, since phantom has a seperate 48volts on pin 2 and a seperate 48volts on pin3, running phantom to an RCA will put 48 volts on the input of the RCA unit. Generally not good unless the RCA is capacitor coupled which blocks the 48v
hi Dave - thanks for the video. Quick question--when you pass the phantom thru a splitter snake that has transformers on it where you can lift the grounds and all--how does that affect the consoles which deliver phantom? for example, I run a couple different splitters--whirlwind and ramlatch splitters and my to-console splits are 1 direct and 2 isolated. I tend to isolate the house desk from the monitor desk feed and make monitors run phantom. But on occasion, which I haven't been able to figure out, I have to apply phantom from the house desk in order to get a direct box to see power. If my house feed is isolated - that shouldn't work or be needed...but it does. Any thoughts on what is happening here within the transformers or the splits that I am not understanding? I feel like I am missing something obvious..been doing this 40 years but this when it happens (and it is not often) it baffles me. I've tried to figure it out - it isn't only on one llne/channel or with one direct box or from one channel on the split where a wire might be crossed. Any suggestions how to figure this out or track it down? Everything works so I have been hesitant to argue with it - but am I missing something here? Please tell me I am not getting senile.. :) thx!
@@petetrott7568 I dont try it...i have a prof amp rack in my leaving room aprox 6 channels total 3,8 kw, but i have only one 230v phase of 16 amp's...cant do not test at full power. Here small test xd (Notice: the plops in sound are from the camera that cant handeling the sound pressure) ua-cam.com/video/UeJemn-PvZg/v-deo.html
Don't understand how a video on phantom using my personal test mics relates but if there is an issue with a mic you bought from rat, will gladly assist
@@DaveRat Hey Dave! I'm mostly joking here. I did buy an OM7 from y'all a while back. It's been a go-to drum vocal on a festival patch or lead vocal on a super loud stage. It's worked well enough, but I have never been 100% happy with it. I'm not suggesting it's your fault. Just a little tongue and cheeky you know? If you are ever in Denver hit up Mountain West Production Group. We'd love to hang out.
Cool cool, yeah, the big advantage of the om7 is with loud stages and singers that stay on the mic gets you the up close and personal voice in loud roons. That said, many singers and stages are not in the realm
If the mixer produces +48V to the pins 2 and 3 it will add up to 96volts reference to the ground. Should the mixer produce a negative voltage for the pin 3 to cancel each out when you connect a dynamic or condenser microphone to it?
Hmmm, that's a bit off. The 48v on pin 2 is referenced to ground and same with pin 3. It is the same 48 volts sent to both pin 2 and pin 3 so if you measure with a meter, which I suggest you do to see for yourself, pin 2 to ground is 48volts, pin 3 to ground is 48 volts and pin 2 to pin 3 is zero volts.
Hmmm, that's unusual, may be some other issue or a problem with the mixer. Phantom is pretty easy and cheap to create and send and most phantom sources will power 2 or more mics to operate. That said, low phantom voltage can reduce headroom of the mic and multiple phantom source driving a mic does offer a safety net
Thanks Dave! Great video! I have only one question, if you would want to create 96V by running two consoles in series (20:30), how would you do it? would you just revers pins 1 and 2 on one console, or am I missing something? Thanks
It would be tough or not easily possible. You would connect pins 2 and 3 or pin 2 or 3 to the ground pin 1 of the other console and then, if at least one console was battery powered or not grounded in any way, you could see 96 volts between the pin 1 of console 1 and puns 2 and 3 of console 2. Basically you would need to wire the phantom powers in series. But if the pin 1 grounds of both consoles were referenced to each other then the 2nd console would just short the 1st console phantom to ground. That would not hurt anything but you would just get 48v
Hey Dave, super informative, I learned a lot. What about ribbon mics? I know it's more of a studio mic choice but I heard ribbons can be damaged by 48 volts. What's your experience with this and why does it damage a ribbon?
Ribbin mics are delicate and properly wired cables should not damage them. That said, one error can destroy them. Royer ribbons are phantom powered which protect the ribbons and they need phantom
Great explanation of the mysterious phantom power! Also like that you explained that AC and DC can both flow on the same pair of wires. Telephones, old Lionel trains and cable TV are some other examples that take advantage of this too :)
Can remember messing with some awful red plastic mic and a 9v battery as a kid in the 80's. Click click. Still plugging things into each other with not much idea of the maths behind it all 😊 and breaking many 😂
Dave , your videos are getting better and better. I just want you to know I really appreciate that you share your knowledge!. Thank you so much!. If you have time can you please review how to fix problems with getting pops or little shocks on the lips when they touch the mic and also noise or buzz from the monitors but not from the mains.
I am sure that until now, under no circumstances have I seen an explanation as well structured about Phantom Power as this one, particularly on the question of the interconnection FOH /MONITOR mixers. Thanks, Dave. Keep up your good work. Greetings from Portugal
If I were on the road and had money for all the good things, i would chose you. From the few videos I’ve watched, I’m convinced you might very well be one of the best sound guys out there. That’s a big deal! There are many factors to running sound setups... and knowing you’ve got a person who is a Masterful tech is relaxing I’m sure. Thank you for yet another insightful video.
Great question. Phantom is supplied from the console to the output XLR of the DI. Where a phantom DI will grab the phantom to power it's internal circuits. The ground lift on a DI is breaking the ground connection from the input ground to the output pin 1. So the input signal is grabbed by the di and outputted on pins 2 and 3 of the XLR and the input is not connected to the output ground. The isolation of the input to the output can be done with electronics or with a transformer then boosted by electronics.
A lot of DIs don't fully disconnect when the ground lift is engaged. Pin one is still connected via a parallel 100 ohm resistor and 0.1uF capacitor. This allows enough current to pass to power an active DI but is enough resistance to reduce earth loops.
Hi, Dave Rat. I was taught BEFORE you plug in a mic with phantom power, you first plug the mic in WITHOUT phantom power engaged, then engage it. and then when it's time to tear-down, you turn OFF phantom power from your console or whatever source is driving the phantom power, then wait about 1 min (for the voltage to go away from the mic / cable) and THEN it's safe to unplug the mic from the xlr. is that wrong?
@@DaveRat I had no idea, thanks for that info! It's been 20 years though for me of doing it this way that I just have to keep on with that program of the way I do it. I was literally cringing when you just plugged in that $3,000.00+ U-89 mic! .... and then unplugged (with the method I was referring to above). yikes! but I hear you, it doesn't bother the mic and as long as your channel is muted while engaging, plugging in / out, you won't experience the pop noises.
It's safe but won't work. Phantom is not enough power for those lamps. Try it if ya wish, won't hurt the lamp or mixer but won't light either has been my experience
I plugged it into my Scarlett 2i2 and the phantom power does light up the lamp at full brightness but was to afraid it might harm one or other if left plugged in for too long. Was afraid of overpowering the 12V lamp using 48V power, but if you think it's no harm to either than I'll try it on for a longer period. Thanks:)
Interesting. Is it full brightness or dimmer than when plugged into the normal? Phantom is such a low current that most any LED can be put on it and it will light and none will be damaged.
All 4 LED has been on and working fine for the past 2hrs. Output is probably only half as bright compared to using 12V adapter. I'm only using the lamp on my lighting console as it's pitch black on the board. But now I think it would be better if I just stick a LED strip just at the bottom faders on the console instead of using the gooseneck lamp. Thanks Dave.. Huge fan here buddy and was blown away by your DCA techniques mate. Thanks so much for your contributions to the audio industry 😊
Good timing on this one for me Dave. I have a Focusrite 18i20 interface, I run a pair of TRS to XLR cables from its outputs into a snake or inputs on a mixer. I’ve been worried about somebody sending me phantom power to the interface outputs. I doubt the interface outputs are transformer isolated, so because there’s no power on the tip or ring, I should be ok? I’d only have a problem if I was running 1/4” to XLR unbalanced cables, correct? I was thinking about buying or making a two channel transformer isolation box to safeguard against this, but if I run balanced cables I’m ok, unless there’s a problem with the snake?
Avoid running phantom to electronic inputs. Capacitor iso will solve but often electronic inputs don't like the 48 v DC offset that phantom sends and will act strangely
You can test for isolation by checking continuity of the grounds for both the input and the output --- if there is no continuity then they are isolated.
The history of the Phantom power is borrowed from the telephone industry. Classic telephones have carbon microphone elements, which are variable resistors. This is powered by the phone company using 48 volt batteries on a charger, which is why land lines remain working in a power outage. The higher voltage is lower current for the power and best for the long phone lines back to the telephone exchange. 48Volts is low enough to be considered limited energy for class 2 electrical code, which is limited to 50 volts. With condenser microphones, the element is high impedance, often well above 50,000 ohms. This requires an amplifier and transformer with a center tap. The power for the microphone is taken from the center tap, so power used by the microphone, draws power from both sides of the cable equally. As Dave pointed out, if one of the microphone cables has a bad connection, the unbalancing of power draw on the pair, does result in loud pops and crackles in a cable, where without phantom power, the sound would only have dropout from the bad cable. The problem with a Y cable for FOH and Monitor driving one microphone is some microphones expect limited current, and with 2 consoles providing power, the higher current increases heat in the microphone. This depends on the microphone manufacture and what type of amplifier they use in the microphone. Most microphones will not have any issues with higher available current. The issue with powered and un-powered phantom on the consoles, is most consoles are Global phantom power so power feeding into a console from one mic input, will try to power the phantom power rail on the other console. This load draws down the power available for the condenser mic and may result in under-voltage distortion in the mic..
Very cool and agreed on all except the concept that some mics rely upon phantom to limit the current for normal operation. I know of no examples of this and it does not really make electrical sense to design a product that relies on current limiting of the power source, when adding a few current limiting resistors into the mic design is cheap, safer and a better design.
It looked like plugging a mic into both mixers supplying power dropped the voltage less than with one supplying power. Seems like it can only be helpful having every console supplying it, especially if there's a lot of condenser mics being used. Which brings me to my main question, how many mics can one mixer supply power to? At what point do you need to add another supply?
Hey Dave, what is the frequency sweep you use on you intro / outros? Extremely nice for a quick Full range to Sub balance method. It's 4 times faster to just load a video from you before I get started on a session than to open a project setup just for monitor balancing. I bet that's not the compliment you were expecting out of this video, but it occurs to me you might could make a video based around giving the community a common reference point for dialing in drive rack based monitor systems. Although I wield a 7.1 Mastering system, a mono tone set followed by a stereo tone set could help those who either do not have hardware on hand or the know-how to setup a DAW project to do that. I mostly use my system for watching Blu-rays and Prime, sad kinda, but also blows every public movie theater away, also real content helps to hear/feel how closely the system represents other systems my content will play on.
Very cool. The sub outro tine actually comes from a subwoofer test tone sequence I use for testing subwoofers. On the paid members side there is an extended video as well as a link to a wave file. It is 20hz to 100hz
Thanks for taking the time and trouble to do these videos. I learned some things from this one in particular. Even an ol' sound dog like me isn't afraid to admit that I can still learn stuff! Not that it's doing me any good at the moment with nowhere to apply my knowledge, but I remain hopeful.
Many of us share your disappointment from not being able to do live events, Carl. Just hang in there and eventually we'll all be back in action, and probably appreciating what we get to do even more than ever thanks to a shift in perspective from this weird time. Stay strong. 💪🤘🖖
Hi Dave. Thanks for the video! I do not fully understand how everything (phantom)power works, so I have one question. When connecting the two consoles, why doesn’t the phantom power of console 1 hurt the pre amps from console 2? If I am correct, the cables are directly attached to both consoles. Does the XLR split prevent that from happening, or is it completely fine for the pre amps to receive +48 from the other console? Thanks in advance!
All consoles and most if not all mics are designed such that phantom power will not hurt them. Also, phantom power, is very very low power, typically way less than .5 watts per leg. For comparison, a USB -C cable can deliver up to 100W. So USB-C can be 200 x as powerful and damaging as phantom power. Even though phantom is 48v, it is severely current limited so as soon as it sees even the slightest load, it drops in voltage very quickly. It would take a few weeks to charge you phone with phantom power
Chiming in late. I've been watching your videos for several years off and on and they're all great and informative. Regarding this video on phantom supplies, there is one legit issue with not using phantom on inputs not requiring phantom. Such as wireless microphone receivers. As you mentioned, capacitors are used to block DC, protecting a mixer's active input circuitry as well as active devices connected. And in a perfect world this works well. However should a phantom powered microphone, wireless receiver (or any direct connected device with active as opposed to passive outputs) be unplugged or plugged in, the voltage change on the capacitors will cause the capacitors to briefly pass the voltage onto the internal circuitry of the mixer or other devices. This can cause a signal spike to be heard in the sound system as a pop. it can also damage microphones or active devices connected. Rule x; never plug or unplug microphones or devices into a mixer, stage box or sound system while phantom voltage is active. Make all connections first then activate phantom. And then there's the occasional bad mic cable causing loud pops in the sound.
What if the consoles where on different phases of a 3 phase source, would this cause an issue? What if on outside OB truck was on a generator and then production was house power, would there be potential for a cycle or earth issue?
Ideally all analog interconnected audio gear should tie to a common ground point to avoid ground loops. The phases that power the gear tend not to impact. With fiber and digital interconected gear, this is less of an issue or a non issue
Phase of AC should have zero impact. First off the consoles will be isolated from mains via a power transformer or switch mode supply. So it's like they're on separate phases to begin with in Dave's example. Then all of the ground wires on the XLR allow all consoles to have the same reference. Phase would only ever be an issue if you are referenced directly to mains but that's very dangerous and hence why almost every device has galvanic isolation from contacts you can touch to mains.
PLEASE Never Stop doing these videos!
After 30 years, you always teach me something that I didn't know, that I should have known, that makes perfect sense, but somehow I feel like I'm an apprentice. That's simultaneously humbling and exciting. And we're talking about Phantom Power of all things!
Awesome, thank you!
Really cool video. Appreciate the intentional fault to show the mic coil popping.
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Great video Dave. You really made it easy for me to understand how phantom power works, especially with the drawings. Cheers for that.
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Thanks Dave for your continued work. Interesting to see the dual consoles experiment with a Neumann haha
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Another home run Dave! Stuff we can use. I would assume that this is a moot point with linked digital consoles -- only one (or a stage box) can actually generate +48V.
Yes and no. Knowing how things work is not that important in optimum situations. And we all don't always deal with optimum
@@DaveRat I hope you didn't think I was being sarcastic, I really meant it was useful. I was just thinking about the digital realm and realizing that it's a different situation.
Thanks for all you do!
@@ToddWCorey1 no, all good and yes, with linked Digi, no need
Here is a man who has been spending a bit much too long lockdown up at home going "WTF".
Yeah! Finally the time to dive in to all my curiosities!
I always love your videos. You always break stuff down and show it, instead of just talk about it. I appreciate that. I watch videos of yours on stuff I already know and still enjoy them and pick stuff up. Quick question though, I didn't think DC could pass through a transformer. Isn't that one of a transformers (isolation transformer) uses is to filter DC out?
Not sure of the specific part you are referring without re watching the vid, but...
There is a way to pass a DC voltage through a transforme and have it function correctly for ac by tying the centertaps of the primary and secondary together
if one leg of the DC was applied to both sides of the primary in relation to ground. The DC would show up on both sides of the secondary in relation to ground.
This is how phantom power can pass through transformers designed to pass phantom work
@@DaveRat Well I learned something new. I didn't think it was possible to pass DC. Thanks for the clarification. You're the man. Love your work and passion for audio. I share it.
Awesome! Thank Aaron!
Best explanation of this ever. Thank you
Thank you, big smile
great video...
what about mics with batteries. good or bad?
The best mics don't have batteries but having an onboard power source does not make a mic bad
I've had a few cool mics over the years with batteries.
I wonder if there is any microphone response difference if 3 or more consoles drag down the voltage enough?
Any pro OB set up I've seen always used an active 3rd split anyway.
Would having 3 phantom switches on 1channel triple the current then?
3 should triple the current assuming you have a splitter that passes phantom
Dave, Is there ever any chance of having too many consoles running phantom power in parallel that could possibly cause injury from too much accumulated current due to a faulty snake system?
Two seperate issues. Faulty snake can give annoying shocks to the lips and hurt some mics with phantom. Paralleling 3, 4 or 5 consoles w phantom still has way way less power than a USB
@@DaveRat Thank you!
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Not an issue. Current is limited to about 7mA per device.
Agreed, power is so low that it is not possible to injure someone.
But I have been called out to fix a a system where a gal was getting shocked and fount phantom power and a faulty snake ground was putting 48v on her lips when she sang and held her guitar.
i never use phantom power, but recently the light of the phantom power goes on with my mixer while the switch of the phantom power is off. UB1204 without the fx board.
Sounds like the console is connected to another console that has phantom on.
@@DaveRat i unpluggged everything, still same issue. I feel some heat at the xlr inputs. Il will try to disable the 48 volt thing
@@DaveRat i unpluged the phantom switch stil. 57 volts on the xlr inputs.
@@stefanie_m466 oh my, that's not optimum
@@DaveRat so the switch works and there is only 1 powersupply. Only 4 wires go to the mixer. 3 black 1 red. I traced the ground (black)and searched wich one gave 58 volts black. Te red and other black gave 15v now its fixed but now i have -1,5 V ON THE XLR hot vs ground. Well. Its fixed for now
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Thanks again , nice experiment. The loading of the second console un-powered phantom is due to the two , normally 6k8 , resistors used and as you showed us the phantom voltages combine when both on to share the microphone load. The idea of phantom power came from Telephone/Telegraph balanced circuits for either powering up repeater circuits or adding dc signalling to a balanced transmission line. Cheers Dude
Awesome. Thank you Dave
Two things : Red should be pin 2 (hot) ? And blue pin 3 (Cold)
The condenser mic is a Neumann kms105 not a sennheiser kms105😉
And I like your videos
Thanks🙏🏼
Cool cool,
Thanks Dave. I really enjoyed this chat and demonstration. I've been running PA's and doing all sorts of sound for over 40 years and never really understood what was (technically) going on under the hood. In saying that, I always made sure that my pin to pin wiring was spot on and never had any major issues when running condensers with dynamics. Your bench top demonstrations are excellent, and show that the principles do not need a massive rig or console to explain. Keep up the discussion. Cheers ...
Thank you Perry
I gotta say when you pulled out the Neumann I'm like whaaaaaat.
"If we're going to use something to test, let's use something expensive to do it with."
Lol. You are hilarious my friend.
Fun!!
I'm a total novice about this topic but I have a question about using drum mics. The typical kit comes with various dynamic mics for close mics on the drum and two overhead pencil condenser mics that require phantom power. Obviously, when using one mixer, you have to turn on the phantom power for the condenser mics but that means it's on for the dynamic mics too. It sounds like you're saying this is ok as long as the cables are good. I was wondering this is the normal, expected way to use these drum mic kits. I haven't found any source that addresses this specific issue. Thank you.
Mosicers allow 6urn8ng on phantom on each channel seperately. That said, if phantom was dangerous to any mic, that would be a huge problem.
Phantom is safe for all mics with properly wired cables and phantom is so low power almost no mics can be damaged by it though there are some older ribbon mics that can be damaged by wind, dropping, blowing into them and potentially miswired phantom.
Don't worry, you won't ever encounter these or any mic that can be damaged by phantom unless if you break into the vintage mic section of a recording studio.
Hi Dave, i have a very basic question - if i have a mixer with just one button to turn off phantom power on the whole mixer and i have a device that outputs line level over xlr, should i put a di-box between the mixer and the line level device to prevent damage or can i just connect the line level device directly to the xlr inputs of the mixer that has phantom power turned on?
It won't damage but some output circuits don't perform well when phantom is applied. I would just test and listen to the device with and without phantom. If you don't hear a difference, then I would not worry about it
@@DaveRat Thank you for the quick response :)
EXCELLENT video as always!
My only comment is that this only works IF everything is properly wired and undamaged. You did touch on what happens if a dynamic mic is in the mix and an unbalanced cable is used...BUT what about the possibility of damaging a console's input or the output on a piece of equipment with improperly wired cables, a damaged cable, or some other issue combined with phantom power? I've just been burned by this one too many times...especially when tying into someone else's gear. If it's all your gear, and all properly maintained, perfect! I still much prefer an active or transformer split for some isolation, but that's just me...
Phantom power should be safe for all pro gear regardless of being wired properly. It is limited by 6800 ohm resistors and gear designers should and almost always take into account the potential existence of phantom
Computers, semi pro, super cheap and home hifi gear? Not so much, that will often get cooked by ohantom
I’m wondering what happens when you split the mic cables and have two desks both supplying phantom power ? Ps not finished video yet :-)
Haha just watched the rest 👍🏻
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Is the ethercon breakout boxes wired T568A or T568B? Would this have something to do with why my ethercon system is not lining up 1 for 1? I wired my whole system T568B.
Shoot me an email at daveratsound@gmail.com and will help ya sort.
We just bought a set of drum microphones for a church. Is it safe to use another mixer just for the drum mics for 48v (both the dynamic and OH condenser mics) and use a send for the snake, traveling to the main house console?
Otherwise, I'll have to check the wirings of my dynamic mics and xlr cables one by one if we'll gonna be using a single console where both the drum mics, singers instruments will be plugged in.
Thanks in advance Dave! Your videos are always helpful!
Yes, all good with using a drum sub mixer and also, with the SoundTools XLR Sniffer/Sender (I designed it) you can test all your lines in a few minutes or less. Just turn on phantom and plug in the sniffer to each channel on the snake and it will tell ya good or no good. Probably worth having one.
ua-cam.com/video/bG77DLOTPsQ/v-deo.html
Thanks for the vid, could you help me a bit?
I have an effect pedal with constant 24V phantom power, will it make any harm if i use it in a chain like this:
Condenser mic --> external power supply with phantom power 48V --> effect pedal with constant 24V --> audio interface with turned off phantom power --> pc
Phantom power into balanced outputs should not hurt anything. I have seen some outputs don't like it and either distort or offer reduced output levels when phantom is went to them.
Just try it. If it works and sounds ok, roll with it
Brilliant teaching of a subject that is obviously a part of you Dave . You could probably make brain surgery simple . Many thanks for what you do .
Honored and humbled thank you Rayviews!
Thanks so much Dave. Love these videos, they're very informative and you're an inspiration to everyone in the industry.
Awesome and thank
I can see that the cats stagebox seems to pass Phantom power. I wanted to know if that same stagebox would be able to pass phantom power across a cat6 cable going into the snake?
Yes, it will pass phantom and each channel can be individually phantom powered, works just like a 4 channel snake with disconnects.
Thank you Dave , I wonted to connect a 15 too 48 source I'm afraid I hope this is what your covering.
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Question please. I have a splitter that itself provides phantom for each channel if needed. In your scenario above, I am assuming that a voltage drop occurs because I have two consoles FOH and monitor not turned on for phantom as I have been relying solely on the splitter source for the power. I don't use enough condensers that I think it would cause too far a drop, but with that scenario, should I be keeping it as I have it or should I have phantom on both channels from both boards as well as the phantom on the splitter. My boards allow phantom to be selected for each channel needed vs powering the entire board. Thanks for the explanation, it makes sense, I just never gave it a thought before 🙂
If your splitter supplies phantom, just use that. The sitter will most surely block the phantom from the consoles so console phantom is not needed
Not sure if anybody else mentioned it in the comments or maybe you followed up Dave but people often forget that if you are using a splitter box with out transformers but does have ground lifts for one or two of three splits phantom power should come from the split that the ground lift does not lift. When the ground gets lifted it breaks the phantom circuit.
this is absolutely correct phantom will not pass with the ground lifts also running phantom to a ground lifted split will not hurt anything
i can't get enough of your videos. does the audio engineering rabbit hole get any deeper than this!
Ha! Awesome!
I wish obvious phantom power indicator lights were standard on all mixers. A pro tip for club engineers is to mark any channel on the tape when phantom is on so when the band is finished the engineer is reminded to mute the channel immediately. Experienced musicians know that they need to make eye contact with the engineer before unplugging a hot phantom powered instrument, but this will inevitably slip by the most seasoned sound engineer, and that painful pop is a real vibe killer. It happens to me occasionally when someone starts chatting with me at the board at the end of a set and I get distracted.
Whilest I personally don't worry too much about phantom 9n or off, I do make sure channels are muted before swapping mics at a gig. And if I see the peak lights flash on a muted mic, there is a good chance phantom is on.
Phantom power is about as dangerous as drinking a soda in a car, all good except if things go terribly wrong
In a large venue where FOH and Monitor World might be on a different Phase/Leg as far as their power source will this cause an issue?
Typically a differing phase is not an issue. Its when the ground for mons and FOH are different and not tied back to the same place that issues arise. Since neutral is tied to ground somewhere in most, if not all, power systems, loads on the neutral can drag it off of zero volts and possibly drag the ground off of zero volts. Or if there is gear that somehow causes the ground to not be zero volts, that can cause issues if the ground at FOH is differing in voltage to the ground at mons. With digital snakes, this is less of an issue and usually a non issue as long as the ground offset voltages are small. With analog snakes and interconnects, even very small offsets in voltage between the ground at FOH and mons can cause hum and buzz issues. Large ground voltage offsets can be dangerous or deadly.
So if I inject phantom power to a mic and use the one side of the xlr output of the mic to the unbalance mic input of a DSLR, ill kill it with 18v in the audio path?
Oh my, yeah, it gets complex but yes, phantom power is not typically compatible with unbalanced.
Using a small transformer to convert to unbalanced while phantom and the mic are on the balanced side of the traslnsformer is good.
If you wanted to go from one mic into Y split cable and then onto 2 inputs of the same same mixer ( double patch type thing)
Would it be the same as the 2 mixer set up?
As I have often thought if doing this one apply 48V to one of the inputs.
Yes, I would supply phantom from both and or all console inputs
Is there any way to remove phantom power from the output, I have a mixer that has all phantom on or all phantom off?
If I run phantom into a passive DI box, will it damage the input device?
A couple of 100uf capacitors, 1 each on pin 2 and 3 will remove 0hantom. But phantom won't hurt a passive di
Nice bass test in the end :D Great info, I guess someone who is an electric engineer would have known this already, but developing an intuitive understanding of electricity is Incredibly hard for some (like me) :)
Fun stuff to learn!
unfortinulaty - there ARE microphones hurt and killed in making this video....haha
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Amazing to get these graduate level info packets from the icon himself.
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In all my years of Audio engineering (40 odd)I have never been able to grasp the concept of phantom power workings. This has explained it in the most simplistic form ever. Thank you so much and keep up the great work.
So cool and thank you! Honored
This brings back memories of when I was a kid and tore apart the microphone that came with my dad's cassette recorder, saw it was dynamic, and realized that it looked just like a tiny speaker. So I plugged it into the output jack of the recorder and found that I could hear the sound on the tape through the microphone.
I'm guessing that the 48V phantom power voltage came from the phone company, that used (and still uses) a -48V battery to power all central office equipment. Long ago (like before any of us were alive), long distance calls used to use a 4 wire cable. When the need for more circuits arose, they added a third circuit (a 4-wire cable could handle 2 calls, just like a regular POTS phone line can) by putting center-tapped transformers at both ends and connecting the third line at the center taps. Because the AC voltage from the center tap was the same at both ends of the other voice circuits, it canceled out and couldn't be heard. Likewise the voltages on the two circuits became zero at the center taps, so there was no crosstalk in any direction.
I live this!
Your post brings back memories for me. As a child, I also tried the dynamic-mic-as-speaker trick. My favorite "transducer repurposing" is to use a closed-back set of headphones as a microphone to pick up heartbeat sound.
In the late 70's when I was studying for my EE degree and working various jobs, I had a short stint at the local telephone company's CO serving the Redmond-Kirkland, WA region. In those days, the equipment was all relay-based, and when you walked into the office, there was a constant noise that sounded like a waterfall. The power room had a huge stack of batteries kept under constant charge by true behemoth TR units, and a diesel generator just outside for longer power interruptions. The 48V power came into the switching office on a pair of copper plates - true power "rails" the likes of which I've never seen since.
@@marianneoelund2940 that is so so cool!
@@marianneoelund2940 That's very cool! I was a little behind you. Thanks to some experience while still in high school, I got a little experience in doing sound reinforcement and lighting, and if I had made enough money to eat, I'd be doing it today. During that time I found a volume of books in the local library called "A History of Engineering & Science in the Bell System" and read them cover to cover. That was one of the more useful extracurricular reads for me, as the knowledge that I got from it helped me communicate with telco people when I worked in TV broadcasting and IT. That's where I learned about phantom circuits.
One consulting job I had was for an ISP that was moving into an area that was occupied by a brand-new, unused Class 5 Lucent 5ESS switch that had been decertified when someone accidentally discharge the Halon. That thing had two -48V batteries, each cell the size of a small chest freezer. I was licking my chops over the prospect of using them to build a UPS for the facility (there also was a 1 MW Caterpillar Diesel generator downstairs) but whoever bought the junk switch got the batteries as part of the deal. I did manage to get a lifetime supply of silver-plated BNC connectors though. There were a lot of copper bus bars that carried the battery power around to the various cabinets. I wish I could have taken a few of those.
I don't recall if I ever was in a working CO with mechanical switching. I do recall that the Chicago Museum of Science and Industry had a piece of a crossbar switch on exhibit for a while. When you pressed the button, the frame would start making a big racket from behind a thick sheet of Plexiglas. Looking back it was amazing that so much was still mechanical back then. When we got Touch Tone phones in 1967, we just assumed that "computers" did all the work.
@@StringerNews1
The equipment I worked around was a bit more modern than the crossbar equipment. It used sets of relays as registers. If someone was dialing a pulse-dial phone and you were standing by their line equipment, you could hear the relays counting up the pulses.
Each line-equipment rack unit handled 25 customer lines, and the units were organized into sets of 20 (500 lines). Then there were up to 20 of those sets, to populate one "exchange" of 10,000 lines. The mapping from telephone numbers, to the line equipment numbers, was done by stringing wires through a set of pickup coils mounted on a large board.
I think the only computer in the office, at least for the local-line service (toll service was more sophisticated), was the one which scanned the equipment for faults and printed out messages for the service techs on a teletype machine.
Great episode 👏 what would happen if both desks had phantom power on but one desk had phase reverse on ?
That's an interesting question. Since phantom power is 48 volts on both pins two and three and a polarity reverse only switches to with three polarity reverse makes no impact on phantom power.
There are several ways to reverse polarity either by swapping pin 2 and 3 or as consoles normally do after the line is unbalanced putting a polarity reverse opamp or circuit there.
Either way phantom shows up on both pin 2 and 3
If you have the time check out my videos on phantom power you may find them interesting I did one specifically on powering mics with multiple consoles
Hello good time. Thank you for your professional and excellent content,
I had an important question.
My friend brought me a Yamaha MG10XU (a baby usb mixer) from the United States yesterday, which has a 120-volt power adapter.
But our country's electricity is 220 volts.
I plugged in incorrectly for 4-5 minutes, and the device got a little hot and could smell a bit, but not much.
I activated the phantom power button for a moment and a soft click was heard just below the spot. Again, my mistake.
I quickly turned off the device and unplugged it.
The next day I got a low voltage transformer and tried it again, the good news is that the device turned on and it did not seem to have a problem, all parts of the device worked properly, the LED for the Phantom Power also turned on when I turned it on, but the bad news There was no sound from the microphone (condenser RODE NT-1a) when I monitored the sound, while without the phantom, I also tested a typical dynamic microphone, and the sound came.
Do you think you can help me?
I'm very worried, I'm thinking about it negatively every moment
Hmmm, well it seems you are lucky the unit works. Usually double voltage will at least blow a fuse or some parts and often severely damage gear.
Sounds like the 48 bolts phantom has destroyed something inside. Probably not an expensive part, most likely it is fixable but also, unless you know someone good with electronics, this would be a non warranty factory repair. Phantom circuits are not that complex and not too hard to troubleshoot and since you heard a pop, the issue may be visible. You will most likely need soldering skills to fix it or possibly be able to order a replacement board.
Your least expensive fix is probably to buy an inexpensive external phantom power source to use instead of the blown internal phantom.
I was really worried and very upset, you really did a very valuable favor for answering, thank you very much.
I will not forget this grace of yours , and I will definitely tell you the result of this problem
Cool cool and I would help more if I was familiar with that unit. Good luck
Great demonstrations thank you! Dave over at EEVBlog invited Doug Ford (from Rode Mics) to explain phantom power and a lot of other microphone design considerations on the EEVBlog channel here on UA-cam. I highly recommend them. (Phantom power is episode #616.)
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For the more technically curious, the actual 48v power supply in the mixer feed each channel separately through resistors, typically 20k ohms or more, so that any difference in the multiple supplies will be dissipated in a small amount of heat, and not damage the microphone or mixer. Even If one or more wires is shorted to ground, like using an unbalanced cable, it will not greatly affect other channels. The only possible damage would be if the microphone voice coil or transformer cannot handle the current. For example , a typical mixer feeds pins 2&3 through 47k ohm resistors, and a typical voice coupled is 200 ohms, so 48v would place about 0.2 volts across the microphone voice coil. It would not be healthy, and would push the coil against the end of its space. It would also generate some heat. The actual damage would depend on the specific microphone.
Thanks for the excellent demonstration and keeping it simple.
Agreed and I believe the phantom power spec calls for 6.8k ohm matched pair resistors
@@DaveRat thanks, I couldn’t remember off the top of my head.
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Dave, could you do a comparison between active and passive DI boxes? We use both and can't seem to tell a huge difference on the different instruments we use them on. And also, maybe compare against an instrument amp XLR direct out? Thanks!
I will ponder some DI box demos
I may be late to the party, but here is my 0.02€.
From the perspective of a recording studio fix/monkey
About phantom and dynamic microphones, the world is full of boffins. I've lost count of the microphones lost to bad cables and phantom power mixed together. Even moreso when some equipment has lower feeding resistor values because they were too cheap to pony up for some real 48v PSUs.
Then there's the classical problem with cheap Chinese microphones wired wrong from the factory, including Thomann's own brand stuff.
On the other issue, if the phantom power is well executed on the console itself, this means a real pair of 6.81 kiloohm resistors feeding pins 2 and 3 from a real 48v source, there may be two scenarios:
One is that the resistors are connected to ground if the p48 is switched off, then tough luck. Your p48 has just been converted into p24.
Keep both p48 feeds on if you want to keep the mic preamps happy.
The other option is that the 6k81 resistors are left floating when off, then you may or may not want to keep both feeds on. This depends on what's on the other side of the cable... Not much of a problem in live audio, but in a studio, yup, it may hurt something. The misconception is that it doubles the voltage, when, in fact, it doubles the current into a dead short. Instead of 7mA it goes to 14mA. It may be a problem if the circuitry inside the microphone expects exactly 7mA, like some very old versions of the venerable Neumann U87. (It takes the polarisation voltage straight from the number 2 and 3 pin, no regulator, no nothing, and it expects around 39v here).
There are some old mixing consoles, like some Telefunken/Siemens and Never broadcast thingies that feed phantom straight thru just one resistor to the center tap of the microphone input transformer. A nice way to fry some mikes AND the console at the same time.
Don't even get me started on bantam patchbays that have phantom power going through them. A nice way to fry a ribbon, smoke the preamp and get tinnitus maximus from the monitors trying to expel the woofers at the same time. (Neve 8232, looking at you)
On the other hand (third one), there are some really bad implementations on cheap and nasty consoles, like the RF blocking caps on the microphone input being rated only at 50v, really bad tolerances on the feeding resistors and leaky DC blocking caps going to the ultra cheap op-amp pre. Arrrrrgh.... Been there, modded, fixed, cussed off soundcraft/Harman, phonic, mackie and Behringer engineers...
As of late, I'm resorting to go all dynamic for the small gigs I sometimes do, just not to get into this very pickle.
Thank you so much for sharing your talents and experience with all of us.
I have a question. I want to utilize 2 AT4033 large diaphragm condenser mics in my acoustic trio. I also love the sound of our Meinl slap top cajon with passive pickups connected directly. Im told by percussion dealers that phantom power will damage it and our small Bose digital mixer doesnt have individual channel control of phantom power. How can I protect the cajon? Will the low Z output of any passive direct box isolate and serve the purpose? Do I need a specific device?
Thanks again!
Yes, the output of a direct box will block phantom. Or use and isolation transformer. Or make a special xlr cable that has 100uf capacitors on pin 2 and pin 3. Phantom won't go through a capacitor.
@@DaveRat Thank you so much! Your approach and egoless attitude are rare and so refreshing in this business. You should write a book or a series. I'm sure they'd be VALUABLE go to resources for all of us. Your knowledge and experience needs to be preserved.
Thank you!
@@tlb2732 thank you Tony and much appreciated!
nice topic....i have been wonding about it quite a while ago and i didnt found answer, thanks for that
another question would be, what will happen if you feed line output signal from one cosole to the phantom powered input of another console?
Sending phantom to electronic outputs can give varied and often undesirable results. Due to the wide diversity of output circuit designs, there is no rule to whether it will have a negative impact, other than avoid it.
Phantom can be blocked with a pair of capacitors inline on pins 2 and 3 of an XLR or using an iso transformer
@@DaveRat thanks, that what I was thinking about it. I didn't try it though I always used active DI box because I was not sure what is gonna happen.
Phantom can be nasty if fed through Patch bays, the spikes caused by repatching can DAMAGE stuff including SPEAKERS & your audiences Hearing : )
He actually covered that part. In 1/4” patchbays, you can short pins to ground when plugging/unplugging. This causes the mic diaphragm To POP and clip the input of the console
Yes, patch bays and phantom are like a mine field.
Yes, and the detail of 1/4" with phantom in a patchbay is a great point.
Thanks for teaching me what a balanced cable is. A question... If the two different consoles are at slightly different voltages, theory tells me would that cause some current flow between the two units. Have you any idea how the two different power supplies cope with that? Obviously, no magic smoke is released! Thanks!
All input and output voltages are either floating or references to ground. Inputs look at the differential between the two hots on balanced lines and the diff between hot and ground on unbalanced.
Outputs create the same things.
As long at the gear is either isolated through a transformer or other method like being battery powered or references to the same ground as the other gear, all good.
Differing ground potentials on non isolated gear causes issues
The one with the higher voltage will be providing most of the current. The internal 6.8K resistors help out with current sharing, so the difference will be small.
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What about the use of an unbalanced input cable (i.e., RCA phono jack to XLR) for a line in situation, where pin 3 is tied to pin 1 and pin 2 is the "signal line." Pin 3 tied to pin 1 is shorting out the phantom power of a small console (presuming all on/all off environment). I'm guessing that the internal resistor circuit prevents a dead short of the phantom power, but does it reduce the voltage on the other channels? Still got that XLR to bananna plugs cable? Inquiring minds want to know... ;-)
Shorting phantom on one channel has no impact on other channels. But, since phantom has a seperate 48volts on pin 2 and a seperate 48volts on pin3, running phantom to an RCA will put 48 volts on the input of the RCA unit. Generally not good unless the RCA is capacitor coupled which blocks the 48v
@@DaveRat Makes sense. Obviously, a DI box is a better option...
Yes, absolutely
hi Dave - thanks for the video. Quick question--when you pass the phantom thru a splitter snake that has transformers on it where you can lift the grounds and all--how does that affect the consoles which deliver phantom? for example, I run a couple different splitters--whirlwind and ramlatch splitters and my to-console splits are 1 direct and 2 isolated. I tend to isolate the house desk from the monitor desk feed and make monitors run phantom. But on occasion, which I haven't been able to figure out, I have to apply phantom from the house desk in order to get a direct box to see power. If my house feed is isolated - that shouldn't work or be needed...but it does. Any thoughts on what is happening here within the transformers or the splits that I am not understanding? I feel like I am missing something obvious..been doing this 40 years but this when it happens (and it is not often) it baffles me. I've tried to figure it out - it isn't only on one llne/channel or with one direct box or from one channel on the split where a wire might be crossed. Any suggestions how to figure this out or track it down? Everything works so I have been hesitant to argue with it - but am I missing something here? Please tell me I am not getting senile.. :) thx!
A transformer iso or split that has centertaps tied together on the inputs and outputs(s) will pass phantom.
@@DaveRat AHAH!! YES...ok thanks Dave. Sorry if this was a stupid question. Appreciate your response.
22:40 Nice sweep of 86hz - 21hz and back at the end... its sound lower but the meter no longer measures. lol
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My computer audio has a 400W JBL sub on it. That sweep really shakes the house!
@@petetrott7568 I dont try it...i have a prof amp rack in my leaving room aprox 6 channels total 3,8 kw, but i have only one 230v phase of 16 amp's...cant do not test at full power. Here small test xd (Notice: the plops in sound are from the camera that cant handeling the sound pressure) ua-cam.com/video/UeJemn-PvZg/v-deo.html
@@petetrott7568 so cool!
@@JohnvL 👍
I bought a used OM7 from Rat Sound on eBay a couple years back. I've never been really happy with it. Maybe this is why!
Don't understand how a video on phantom using my personal test mics relates but if there is an issue with a mic you bought from rat, will gladly assist
@@DaveRat Hey Dave! I'm mostly joking here. I did buy an OM7 from y'all a while back. It's been a go-to drum vocal on a festival patch or lead vocal on a super loud stage. It's worked well enough, but I have never been 100% happy with it. I'm not suggesting it's your fault. Just a little tongue and cheeky you know? If you are ever in Denver hit up Mountain West Production Group. We'd love to hang out.
Cool cool, yeah, the big advantage of the om7 is with loud stages and singers that stay on the mic gets you the up close and personal voice in loud roons.
That said, many singers and stages are not in the realm
If the mixer produces +48V to the pins 2 and 3 it will add up to 96volts reference to the ground. Should the mixer produce a negative voltage for the pin 3 to cancel each out when you connect a dynamic or condenser microphone to it?
Hmmm, that's a bit off.
The 48v on pin 2 is referenced to ground and same with pin 3.
It is the same 48 volts sent to both pin 2 and pin 3 so if you measure with a meter, which I suggest you do to see for yourself, pin 2 to ground is 48volts, pin 3 to ground is 48 volts and pin 2 to pin 3 is zero volts.
@@DaveRat Yeah, i had to draw a picture and do the math and you are absolutely right, couse there’s only one voltage source for both pin 2 and 3.
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I have a Behringer 1002b and my cad mic wont work because of low voltage on phantom power even not using batteries and plugging it in
Hmmm, that's unusual, may be some other issue or a problem with the mixer. Phantom is pretty easy and cheap to create and send and most phantom sources will power 2 or more mics to operate. That said, low phantom voltage can reduce headroom of the mic and multiple phantom source driving a mic does offer a safety net
@@DaveRat it might be the mic but a long time ago I saw a video saying it's only 18 volts . I use the mixer for live music in a line array .
Get that volt meter out and measure it!
A most brilliant video.a superb production.
Thank you Stephen!
Thanks Dave! Great video! I have only one question, if you would want to create 96V by running two consoles in series (20:30), how would you do it? would you just revers pins 1 and 2 on one console, or am I missing something? Thanks
It would be tough or not easily possible. You would connect pins 2 and 3 or pin 2 or 3 to the ground pin 1 of the other console and then, if at least one console was battery powered or not grounded in any way, you could see 96 volts between the pin 1 of console 1 and puns 2 and 3 of console 2.
Basically you would need to wire the phantom powers in series.
But if the pin 1 grounds of both consoles were referenced to each other then the 2nd console would just short the 1st console phantom to ground.
That would not hurt anything but you would just get 48v
Hey Dave, super informative, I learned a lot. What about ribbon mics? I know it's more of a studio mic choice but I heard ribbons can be damaged by 48 volts. What's your experience with this and why does it damage a ribbon?
Ribbin mics are delicate and properly wired cables should not damage them. That said, one error can destroy them. Royer ribbons are phantom powered which protect the ribbons and they need phantom
Great explanation of the mysterious phantom power! Also like that you explained that AC and DC can both flow on the same pair of wires. Telephones, old Lionel trains and cable TV are some other examples that take advantage of this too :)
Awesome!
Can remember messing with some awful red plastic mic and a 9v battery as a kid in the 80's. Click click. Still plugging things into each other with not much idea of the maths behind it all 😊 and breaking many 😂
You haven’t said if the phantom power is AC or DC
Good point and it's dc
Dave , your videos are getting better and better. I just want you to know I really appreciate that you share your knowledge!. Thank you so much!.
If you have time can you please review how to fix problems with getting pops or little shocks on the lips when they touch the mic and also noise or buzz from the monitors but not from the mains.
Yeah, I can do a pop shock vid
I am sure that until now, under no circumstances have I seen an explanation as well structured about Phantom Power as this one, particularly on the question of the interconnection FOH /MONITOR mixers.
Thanks, Dave.
Keep up your good work.
Greetings from Portugal
Awesome, thank you
You rock. The deep dive, your personality, and the outro with low freq sweep etc., I love it!
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If I were on the road and had money for all the good things, i would chose you. From the few videos I’ve watched, I’m convinced you might very well be one of the best sound guys out there. That’s a big deal! There are many factors to running sound setups... and knowing you’ve got a person who is a Masterful tech is relaxing I’m sure. Thank you for yet another insightful video.
Hell yeah and thank you!
Between monitor and foh, do separate mains power/phases create any audible issues?
They shouldn't as long as the grounds and feeds come from the same general source or as long as foh and mons are well isolated.
Thanks for the video, what happens if you supply phantom to a DI box with the ground lift switch engaged, how does the direct box get voltage?
Great question. Phantom is supplied from the console to the output XLR of the DI. Where a phantom DI will grab the phantom to power it's internal circuits.
The ground lift on a DI is breaking the ground connection from the input ground to the output pin 1. So the input signal is grabbed by the di and outputted on pins 2 and 3 of the XLR and the input is not connected to the output ground.
The isolation of the input to the output can be done with electronics or with a transformer then boosted by electronics.
Thanks!
Cool cool
A lot of DIs don't fully disconnect when the ground lift is engaged. Pin one is still connected via a parallel 100 ohm resistor and 0.1uF capacitor. This allows enough current to pass to power an active DI but is enough resistance to reduce earth loops.
nice! the more I watch your videos, the more I realize how important it is to get a practical understanding of electrical connections and signal flow.
So cool and yes and thank you!
wow i was just talking about this last night over a beer/s... thanks for the video
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Finally I have support when I’m arguing with other engineers claiming phantom power is bad for mics that don’t need it
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Super explanation. simple and easy
Thank you 🙂
From 22:43. There's a DC offset in the audio. Makes a pop when you pause/play. Are you getting meta on us, Dave?
Interesting and I wish that was planned
Thanks Dave, that was brilliant that!
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Hey!…you’re doing a good job
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Hi, Dave Rat. I was taught BEFORE you plug in a mic with phantom power, you first plug the mic in WITHOUT phantom power engaged, then engage it. and then when it's time to tear-down, you turn OFF phantom power from your console or whatever source is driving the phantom power, then wait about 1 min (for the voltage to go away from the mic / cable) and THEN it's safe to unplug the mic from the xlr. is that wrong?
Nothing wrong with that plan but as long as you are muted, the mic doesn't care if phantom gets turned on with a switch or by plugging in
@@DaveRat I had no idea, thanks for that info! It's been 20 years though for me of doing it this way that I just have to keep on with that program of the way I do it. I was literally cringing when you just plugged in that $3,000.00+ U-89 mic! .... and then unplugged (with the method I was referring to above). yikes! but I hear you, it doesn't bother the mic and as long as your channel is muted while engaging, plugging in / out, you won't experience the pop noises.
@@coffeehigh420 👍
Hi Dave,
Is it safe if I plug a 12VDC 3 pin LED XLR lamp in a mic input on a mixer or an audio interface and power it with phantom power?
It's safe but won't work.
Phantom is not enough power for those lamps.
Try it if ya wish, won't hurt the lamp or mixer but won't light either has been my experience
I plugged it into my Scarlett 2i2 and the phantom power does light up the lamp at full brightness but was to afraid it might harm one or other if left plugged in for too long. Was afraid of overpowering the 12V lamp using 48V power, but if you think it's no harm to either than I'll try it on for a longer period. Thanks:)
Interesting. Is it full brightness or dimmer than when plugged into the normal?
Phantom is such a low current that most any LED can be put on it and it will light and none will be damaged.
All 4 LED has been on and working fine for the past 2hrs. Output is probably only half as bright compared to using 12V adapter. I'm only using the lamp on my lighting console as it's pitch black on the board. But now I think it would be better if I just stick a LED strip just at the bottom faders on the console instead of using the gooseneck lamp. Thanks Dave.. Huge fan here buddy and was blown away by your DCA techniques mate. Thanks so much for your contributions to the audio industry 😊
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Good timing on this one for me Dave. I have a Focusrite 18i20 interface, I run a pair of TRS to XLR cables from its outputs into a snake or inputs on a mixer. I’ve been worried about somebody sending me phantom power to the interface outputs. I doubt the interface outputs are transformer isolated, so because there’s no power on the tip or ring, I should be ok? I’d only have a problem if I was running 1/4” to XLR unbalanced cables, correct? I was thinking about buying or making a two channel transformer isolation box to safeguard against this, but if I run balanced cables I’m ok, unless there’s a problem with the snake?
Avoid running phantom to electronic inputs. Capacitor iso will solve but often electronic inputs don't like the 48 v DC offset that phantom sends and will act strangely
Dave Rat - yeah I would never intentionally run phantom power to them, I’m just concerned if it happens accidentally. Thanks Dave.
You can test for isolation by checking continuity of the grounds for both the input and the output --- if there is no continuity then they are isolated.
@@HazeAnderson 👍
Great Video. 😃👍♥️
Thank you Kevin!
Cool cool...
Cool cool cool! Thank you!
eletrickery at it's finest
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Awesome explanation!
Awesome and thank you
The history of the Phantom power is borrowed from the telephone industry. Classic telephones have carbon microphone elements, which are variable resistors. This is powered by the phone company using 48 volt batteries on a charger, which is why land lines remain working in a power outage. The higher voltage is lower current for the power and best for the long phone lines back to the telephone exchange. 48Volts is low enough to be considered limited energy for class 2 electrical code, which is limited to 50 volts.
With condenser microphones, the element is high impedance, often well above 50,000 ohms. This requires an amplifier and transformer with a center tap. The power for the microphone is taken from the center tap, so power used by the microphone, draws power from both sides of the cable equally.
As Dave pointed out, if one of the microphone cables has a bad connection, the unbalancing of power draw on the pair, does result in loud pops and crackles in a cable, where without phantom power, the sound would only have dropout from the bad cable.
The problem with a Y cable for FOH and Monitor driving one microphone is some microphones expect limited current, and with 2 consoles providing power, the higher current increases heat in the microphone. This depends on the microphone manufacture and what type of amplifier they use in the microphone. Most microphones will not have any issues with higher available current.
The issue with powered and un-powered phantom on the consoles, is most consoles are Global phantom power so power feeding into a console from one mic input, will try to power the phantom power rail on the other console. This load draws down the power available for the condenser mic and may result in under-voltage distortion in the mic..
Very cool and agreed on all except the concept that some mics rely upon phantom to limit the current for normal operation. I know of no examples of this and it does not really make electrical sense to design a product that relies on current limiting of the power source, when adding a few current limiting resistors into the mic design is cheap, safer and a better design.
Great video. I learned a lot and will implement using phantom from both mixers on a non transformer isolated splitter snake I have.
Excellent
It looked like plugging a mic into both mixers supplying power dropped the voltage less than with one supplying power. Seems like it can only be helpful having every console supplying it, especially if there's a lot of condenser mics being used. Which brings me to my main question, how many mics can one mixer supply power to? At what point do you need to add another supply?
Each mic channel is independently current limited by the console Thule console can supply power to as many Mike's is there are channels.
Great work as always, Dave!
Thank you!
very helpful video👍
Thank you Mika!
Hey Dave, what is the frequency sweep you use on you intro / outros? Extremely nice for a quick Full range to Sub balance method. It's 4 times faster to just load a video from you before I get started on a session than to open a project setup just for monitor balancing. I bet that's not the compliment you were expecting out of this video, but it occurs to me you might could make a video based around giving the community a common reference point for dialing in drive rack based monitor systems. Although I wield a 7.1 Mastering system, a mono tone set followed by a stereo tone set could help those who either do not have hardware on hand or the know-how to setup a DAW project to do that. I mostly use my system for watching Blu-rays and Prime, sad kinda, but also blows every public movie theater away, also real content helps to hear/feel how closely the system represents other systems my content will play on.
Very cool. The sub outro tine actually comes from a subwoofer test tone sequence I use for testing subwoofers. On the paid members side there is an extended video as well as a link to a wave file.
It is 20hz to 100hz
Fantastic video.
😉👍🤙
Thanks for taking the time and trouble to do these videos. I learned some things from this one in particular. Even an ol' sound dog like me isn't afraid to admit that I can still learn stuff! Not that it's doing me any good at the moment with nowhere to apply my knowledge, but I remain hopeful.
Very cool and thank you!
Many of us share your disappointment from not being able to do live events, Carl. Just hang in there and eventually we'll all be back in action, and probably appreciating what we get to do even more than ever thanks to a shift in perspective from this weird time. Stay strong. 💪🤘🖖
Lets get the U89... :)
Fun!
Hi Dave. Thanks for the video! I do not fully understand how everything (phantom)power works, so I have one question.
When connecting the two consoles, why doesn’t the phantom power of console 1 hurt the pre amps from console 2? If I am correct, the cables are directly attached to both consoles. Does the XLR split prevent that from happening, or is it completely fine for the pre amps to receive +48 from the other console?
Thanks in advance!
All consoles and most if not all mics are designed such that phantom power will not hurt them. Also, phantom power, is very very low power, typically way less than .5 watts per leg. For comparison, a USB -C cable can deliver up to 100W. So USB-C can be 200 x as powerful and damaging as phantom power. Even though phantom is 48v, it is severely current limited so as soon as it sees even the slightest load, it drops in voltage very quickly.
It would take a few weeks to charge you phone with phantom power
Hey Dave, thanks for this ! greetings from Berlin
Greetings Curtis!
Great as alway .
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Chiming in late. I've been watching your videos for several years off and on and they're all great and informative. Regarding this video on phantom supplies, there is one legit issue with not using phantom on inputs not requiring phantom. Such as wireless microphone receivers. As you mentioned, capacitors are used to block DC, protecting a mixer's active input circuitry as well as active devices connected. And in a perfect world this works well. However should a phantom powered microphone, wireless receiver (or any direct connected device with active as opposed to passive outputs) be unplugged or plugged in, the voltage change on the capacitors will cause the capacitors to briefly pass the voltage onto the internal circuitry of the mixer or other devices. This can cause a signal spike to be heard in the sound system as a pop. it can also damage microphones or active devices connected. Rule x; never plug or unplug microphones or devices into a mixer, stage box or sound system while phantom voltage is active. Make all connections first then activate phantom. And then there's the occasional bad mic cable causing loud pops in the sound.
Totally agree. Phantom applied to electronic inputs or outputs that are not designed for phantom is a common issue. Great points!
I really enjoy your channel. I’m always learning! Thank you!
Thank you!
This is great! Thank you for this video. When I saw the two 9v batteries in parallel, I knew exactly what’s going on.
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What if the consoles where on different phases of a 3 phase source, would this cause an issue?
What if on outside OB truck was on a generator and then production was house power, would there be potential for a cycle or earth issue?
Ideally all analog interconnected audio gear should tie to a common ground point to avoid ground loops. The phases that power the gear tend not to impact. With fiber and digital interconected gear, this is less of an issue or a non issue
Phase of AC should have zero impact. First off the consoles will be isolated from mains via a power transformer or switch mode supply. So it's like they're on separate phases to begin with in Dave's example. Then all of the ground wires on the XLR allow all consoles to have the same reference. Phase would only ever be an issue if you are referenced directly to mains but that's very dangerous and hence why almost every device has galvanic isolation from contacts you can touch to mains.
Love you man!
Thank you!