Perfect for my future garage system ! I remember an old article interview from an un-named amplifier designer that he could make a decent amp the size of a paperback book but no one would buy it. They would have to put it in a large case and add a metal plate inside to make it heavy.
I've worked in audio electronics manufacturing for donkey's years, and it's common practice to throw in a lump of metal to give a product a sense of "quality". Light plastic is cheap; heavy plastic (light plastic with a metal block) is expensive.
The manufacturer is quoting what Texas Instruments is quoting and then not providing an adequate power supply. TI quote two power figures, one at 10% distortion and another at 1%. Let’s only consider the 1% figure. Remember that this is a full bridge converter so you don’t need to halve the voltage across the load (speaker). So for with a 51V supply with a 8R load then 51V gives 36V RMS and v^2/r = 36*36/8 = 162W and TI quote 150W at 1% distortion. So TI are correct. I get fed up with people saying that they powered it from a galvanised nail and a penny in a lemon and only got 3W. Give it a proper power supply and it will do what it says
You have to cut the average customer some slack though, especially those without much education in the matter. They're fooled by two things: first, the manufacturer/seller claiming a rating at 10% THD, while at 1% is long established industry and commerce standard as a figure. Second, the underpowered 32V PSU coming with it in some markets, and even the 48V 5A one can't logically do more than 250W. It's the manufacturer being a cheapskate. It is not unreasonable for the average customer to assume you buy a thing and it does what it says out of the box. They don't even use the dreaded "up to" phrase. They know exactly what they're doing.
I'm wondering of a power supply that has big caps to handle the peaks well. I'm pretty curious about this brand. Esp the tube preamp. I have three boxes of old tubes.
TPA3255 performance is solid when sticking to the data sheet. All the magic is in the chip, so there isn't much that can go wrong. I bought several 3255 based amps over the years with one of them ending up powering my main listening setup on my work desk. They run cool, they are fast with pretty precise transients. 75W RMS per channel should be enough for most listening situations, so it's a very nice budget solution. And it's very efficient, considered the power supply has decent PFC.
@@bobwa399 Why shouldn't it? You won't be able to reach the maximum sound pressure level without distortion and/or safety-shutdown of the amp for the setup you describe. But those are different problems. Dual 3255 are usually 2x 75W + 150W for a 2.1 setup.
Okay lets untangle this power output and power supply issue... The TPA3255 chip in these amplifiers works in BTL, that is Bridge Tied Load mode. So this is a 4 channel amplifier bridged to 2 stereo channels. This gives you the full power supply voltage on each half cycle effectively doubling the speaker voltage. By measurement ... 32 volt power supply ... 50watts RMS per channel with both channels driven on 8 ohms with less than 0.1% distortion... 100 watts on 4 ohms. 48 volt power supply ... 100 watts RMS per channel with both channels driven on 8 ohms with about 0.1% distortion, 190 watts on 4 ohms. The 300 w/ch measurement is the chip's absolute maximum rating taken at 10% distortion. You might get 300 watts per channel out of it ... *once* Now this business about current... The only time you will have a steady current draw of 400 watts is during bench testing... On music the average power is much lower, often no more than 20 or 25 watts with 400 watt peaks. At that rate the 5 amp power supplies will work just fine since the amplifier's internal bulk capacitors can fill in the extra current for peaks.
As someone (like yourself) who has and still does dabble in audio electronics projects, I have a certain fondness for LM741s. I used them extensively in active filters for in car audio projects with a modicum of success. Also used them in many other applications such as temperature control and regulation in my linear power supply designs. Presently, I work for a well known calibration and precision electrical measurement instrument manufacturer as a repair tech. This is why I note with interest your mention of electrical power output measurement of AC signals. Indeed, as stated elsewhere in the comments, I would always use the Root Mean Square as the calculation for true power of AC signals. It's a measurement industry standard. Also, you are correct about RMS value measurement, within the circuitry of all modern precision electrical measurement equipment, RMS is measured by the thermal conversion method for greater accuracy. I'm also old enough to know the old marketing trick of stating PMPO instead of RMS. Think flashy 1980s boomboxes (yes, I still have one) with big stickers saying "100 Watts*" with the all important asterisk leading to the small print "*PMPO" at the bottom of the sticker. Peak Music Power Output is a cheap audio manufacturer's dream marketing ploy, or as we engineers called it, lying. In engineer parlance "P*ss Miserable Power Output." More on AC RMS power measurement here if you want to nerd out (like me!) eepower.com/technical-articles/how-to-ensure-correct-rms-measurements/#
Engineering, Science, Math, Physics, ...all in one video. Well done David. I'm not a $100 Class D fan currently. My 20-year-old Pro Level A/B stage gear is: Loud, clean, and reliable. The amp gain level is set @ 50% with superb headroom for clarity. Pre-amp level 20%. Easy 80 DB SPL. No flowery adjectives are needed. Seat belt suggested.
LOL that last bit with the girls made me crack up. Terrific review. I'm pretty sure this is the first review on YT I've seen from someone that has the technical knowledge to understand what they are speaking about. Very refreshing.
Believe me there are plenty of people with more technical knowledge than me. What I’ve seen though, in any subject, the real experts are not on UA-cam. DM
Thank you for your 'useful contribution' to the excitement over small amps built around the Ti chips, the last 30 seconds or so of your video added an unexpected amusing finale, I thought you had finished and i nearly missed it!
Thanks for this great review video. I learned good things from you about measurement. I've been using Fosi V3 for a while now. With its 48V power adapter, it surprised me during my first listens. I am very pleased. I have a few different devices at home, and Fosi v3 is quite sufficient for my daily listening.
Love your no BS delivery and content. I have the V3 and the binding posts are a joke. The power is also a little ambiguous. When I swap my circa 1980 Aiwa SA-P22 Power Amp (30 watts stereo into 4 Ohms) within the Aiwa Mini 22, the 44-year-old Power amp was was much louder and drove the speakers with more authority than using the Fosi V3. But using my PC the volume was OK.
Nice review, punchy and to the point and 5532's are a great start. Must admit if somebody is amazed at a volume pot for being Log I would question their background! I'm sure the orange anodised knob will help dissipate free radicals and transit the electrons from your hand more efficiently for cleaner and less veiled sound....cheers.
Oh thanks, I don't have a great deal of experience with many types of equipment, I only have had British stuff that plus an electronics background I suppose I took it for granted !...cheers.@@Douglas_Blake_579
I use a couple of Fosi amps, coupled with small but decent speakers, with my computers. They take very little space, and produce enough volume for near-field listening, sounding pretty good.
Coincidentally I was testing a Fosi V3 today. One of the tests was measuring power consumption and the it was down to a mere 6.4W from the wall (with the 48V PSU), which I think is amazing. When turned off, the PSU only consumes about 0.3W of residual power. Which is nice too. Sound wise I was pleased with the Fosi V3 too.
My man! You and I think a lot alike, from your casual and pragmatic approach to audio tech to the range of system style (JBL in place of Yamaha in studio, Ohm in place of Sonab, Klipsch in place of B&W… not that those are wildly similar…) I like your style, friend.
Great video as usual David. And lovely view of the C414EB, when you spoke about valve mics I hoped it was a C12A, but a screen grab confirmed it’s a 414. Class D seems like the work of the devil, but you can’t argue with the performance & number of Roadie’s backs being preserved by lighter amp racks & PA systems, they are in fact a God send. And even true audiophile manufactures like Bryston use them: PMC speakers recommended brand (and integral in their active speaker systems) PMC are definitely Audiophile, so QED as you put it.
Totally correct what you say. I tend to trust the datasheets from a reputable manufacturer, like TI. Then for any amplifier I look up the chips being used, and whether they are connected Single Ended (SE) or (Bridge Tied Load) BTL. Most datasheets give a method as to how to calculate output power given a certain power supply voltage. So I disregard the amplifier marketing specification which mentions the total output power over 2 channels, preferably at 2 ohms with 10% distortion. Which produces a large figure, but totally unrealistic. I have seem many cass-D amplifier products which verbatim copies the manufacter's applicaiion note. (That is OK, why not) So again, the chip's datasheet provides the best source of information.
As you referenced, Audio Science Review Amir measured this Amp with the 48V power supply where output is much higher. I run a pair of these to biamp my speakers. Ordered direct from Fosi to get the bigger PSU. It works out to about 400W channel of clean power for $200. Amazing value. Plays very loud and clean.
Based on various reviews I bought one for my garage / gym system. They power a couple of old Ruark Prologues. Loud is at about 2 o’clock, further gets too loud! Front end is a raspberry pi 3 with a DAC hat. Whole setup under £300 and sounds as good any 1-2k system I’ve heard.
I found out about the logarithmic volume control in the 80s when I was a teenager and fumbled with taken-apart boomboxes and soldering irons. Not knowing any better, I bought a linear potmeter for volume control and thought it was broken because it went from almost silent to maximum volume over the last 2 % of the turning range 😆
i use this amp as a desktop amp with ELAC b6.2 attached to my wall above my monitor. works perfectly with a proper dac preamp to help make sure my noisy pc doesnt introduce a bunch of noise from its onboard , people mention that because TPA3255 designs have never really implemented that volume dial in the past and most are commaring it to the A07 that has prior recommendations over a year or two ago
Last year I returned a $2500 stereo setup w/ KEF 350s, a Cambridge CXA81 + SVS sub, due to buyers remorse. I just couldn’t shake the feeling that I overspent and could achieve just as good sound for a fraction of the price. Though I’ve really missed that sound ever since I let it go! NGL, that setup was the best I had ever heard - But I think I can get damn close with the V3, an entry level SVS sub and KEF 150s for under $600. Just need an HDMI to RCA converter and I’ll be set. (Mostly listening to Apple TV/iTunes content)
Over the decades, via observation and building, I've noticed its difficult to build a superior sounding, low power,6 amp. But its damn near impossible to build an extremely high powered amp that sounds good. "Scale up = screw up". I really enjoy the TS Minibeast, kit, a Single Ended, OTL employing in the output stage, the JJ Electronics EL 509's, whose cathode is directly connected to the loudspeaker terminal. Yet with 4 Watts @ 8 Ohms, 7Watts @16 Ohms, the retail loudspeakers on the market are wanting. A better methodology for generating high SPL's is to employ multiples of the transducers in the typical loudspeaker system. This entails building your own from the myriad of really fantastic drivers available to Us today.
Until today I was the only person I knew that owned Sonabs. I have the OA12 with only 2 tweaters pointing in different directions. They often sound terrible but I love 'èm.
I enjoyed this review, especially the extra information and commentary about power measurement, RMS and all that. Seems the US Federal Trade Commission, a governmental agency that regulates commerce, promulgated a Rule that stereo gear had to be rated for RMS power, and specified a standard technique for measuring the same. I suppose that is historically true, but irrelevant as I see power specs all over the place these days. So, I appreciated your commentary thereon. Great fun. Thanks. TT
I have a Fosi TB10-D, the improved recent version, uses the same TI chipset, and iirc a 32 volt PS brick. Works well, I first hooked it up to a pair of Infinity Reference 2001 8 ohm bookshelf, 6.5" woofers and 1" soft dome. Infinity speakers are not usually noted for high efficiency, but initial testing with some Rush CDs at genre appropriate volume levels, I'm quite happy. The Fosi is currently utilized as a "Handy Amplifier" for various audio shenanigans, and is quite-er- handy.
Check your TB-!0D ... plug it in, use it, then leave the AC on and turn the amp off by the front panel switch ... check it in an hour... is it still warm? If so, contact Fosi for a replacement. Your unit has a known problem in the standby circuits that will eventually result in the amplifier failing.
Thanks for being the voice of logic and sanity in a stadium of "audiophile" twaddle. Amp makers must be peeing themselves with laughter, at just how easily it's been convincing customers that amplifiers have a critical influence on sound "colouration" (beyond distortion). Laughing all the way to the bank.
@@scottlowell493 people pay for distortion “tuning” essentially. We need products that allow us to tailor distortion to our liking. Start from ideal and modify to preference, always the best way to do it.
I don’t really think there’s a flaw in that argument. I have $7000 speakers too and to tell you the truth, if you hook up but a crappy amplifier to it, it knows. It’s all about the bass tones because that’s where the power is needed, down at the lower end. At the higher frequencies, if there’s no noise, you don’t need a $3500 amplifier; but you need that amplifier at the lower frequencies. The irony is that most people don’t have speakers that go low enough; they use subwoofers that have their own amplifiers.😂
I bought the original little powerhouse, the Aiyima A07. The new one (Max) is just like the V3 but can be bridged. My second system has omni-directional speakers as well, the Mirage OM-9s. Not audiophile but good enough.
I used to run a super cheap ($15 ish) class D amp that ran off a wall wart, or 4 AA batteries, into some mid range wharfdales and it sounded fantastic. I couldn't believe the quality for the price. it was about 15W per channel iirc, but loud enough for my tiny apartment.
The peak to peak measure is only valid if the amplifier you are using has differential output. That is one terminal is producing a mirror image output to the other. In effect, the signal across two amplifier outputs with one inverted relative to the other, a configuration known as "bridged mode". The majority of power amplifiers have one fixed voltage reference terminal, often to ground, and only one terminal is actually outputting a varying voltage, then the peak output is the peak voltage to fixed voltage terminal. However, the TPA3255 does have bridge mode output, which means the theoretical maximum voltage range across the load is, effectively, doubled.
Gotta say the current crop of TPA3*** series of chips is really moving forward at a pace. Some serious power levels being achieved in such small packages. I was blown away by the TPA3116, seems everything's moved on once again
IT should be noted that TPA31xx and TPA32xx are two completely different designs. The older TPA3116 was a pretty decent little Class-D chip. The Newer TPA3255 incorporates better feedback and regulation as well as producing a lot more power; clearly a far superior design.
Your analysis of amplifier power ratings and measurements was interesting. Echoed many my own thoughts and experiences. Very recently I watched a UA-cam review of an amplifier which the reviewer confidently claimed output 6000w rms into 2 8 ohm channels. The reviewer is known for reviewing and retailing ‘ultra high end’ components. He is also known for being strongly and controversially opinionated and claims to have won awards for products he’d designed. I commented that his amp would need to be connected to a minimum of 8 US wall mains outlets or 4 UK wall mains outlets to even draw that amount of power and then would need to be 100% efficient to output that power. His response was classic:- “I don’t give a shit. I just know it works”! I’ve recently upgraded my 120w integrated amp for a pair of momoblocs rated at 300w. My normal listening SPL is around 78db. To achieve that using the integrated I needed to turn the volume up to 45% but to achieve that same SPL using the monoblocks, the volume has to be ramped up to 70%! I put this down to the very low gain on the monoblocks of 25db.
I put together a class d tda7498 amp just something to mess with but I was so impressed I now use as me main amp and put it into a case. Watts was not quite how it says but sound wise I liked it and plenty power for my likening as I have very rarely got to quarter of the volume so see no point having more watts. Only thing I hate is when they claim more watts than what it really is.
Sometimes, as straight and no nonsense as you are, it does feel like a subtle dig is being given to those people that insist more expensive is better. Now, I am not saying that dig is not warranted, but I definitely sense that :).
I was coming of age in the Sound By The Pound days. It would be a lot of years before I could afford pounds. I started rolling my own just over a decade ago, and a 45 pounder was first off the workbench. Everything I build has VU meters with bouncing red needles and lights that give a golden glow. They warm my heart. Like you said, you just want what you want. BUT, now that I'm into active open baffle stuff, and also SWARM lusting, it's imperative that I lighten up. Of course, there's also the issue of an old creaky back. I'm using four channels of my diy Big Berthas for highs and mids, AND, four channels of Hypex class D units for woofers. I've used the class Ds for full range duty as well, and I hear a distinct difference from my class AB home grown items which to my ears are better in every category. I even think they do bass better, but not enough to justify the expense of running 8 to 10 channels of them.
Back in the 1970s all reputable manufacturers would specify their outputs in RMS format per channel, usually into 8ohms, with, I seem to remember, around 1% THD. On the other hand the "joke" manufacturers would quote ridiculous figures, usually without any standard specified, although one laughable advert claimed some enormous power figure in IPP: turned out that this meant "instantaneous peak power" with no distortion level quoted, for both channels combined, and into an unspecified impedance. Suffice to say that I still use my 1970s Rotel receiver with quoted 50w per channel RMS and it will simply blow modern devices with supposedly higher outputs out of the water. May be something to do with its overall weight up in the 30+ Kg area and a simply massive power supply inside.
Really enjoyed your review. Your AKG mic sounds terrific! I bought this amp with the 48v supply, and based on similar criteria as yours I found it perfectly capable of driving my vintage Polk RTA 12b's. It also drove my much less efficient Polk SDA SRS 2.3's, although not as loud but still loud enough for everyday listening. I read that the advertised output rating comes from the TI data sheet which lists the output at 315 watts total Output Power at 10%THD+N. Who doesn't love the sound of 10% THD?
Found your channel few weeks ago, I like your style. I explain class D to people as follows, add a HF carrier to the signal run it though the amp then filter off the carrier. I do like how you explained it and mite start doing that instead.
Now that the Master says he is not an audiophile, it makes me more comfortable stating that I am not one. And will wrassle to the ground anyone who accuses me of being one. After all those zero-substance-full-of-noise reviews about the Fosi V3, I am glad we have the Master giving a meaningful opinion on this tiny amp. I think I will buy it for a back up. Thank you. As usual, the ladies have the last word. I always wait for it.
Before social media there was the Saturday afternoons "on location" from the local Fm radio station telling you to come on down to XYZ Electronics store. Spewing all the juicy specs about the prowess of the systems for sale.
Seeing that you have the same 801s that I did I would highly recommend that you upgrade your internal capacitors if you haven't done it already. I used the Solen BP400 series. The clarity and imaging improved dramatically. Bass actually showed up. Then ended up having better bass than I ever remember them having. I had taken them apart a couple of times thinking the woofers might be out of phase. I had purchased these as used speakers a year and a half old. I used them for a long time then bought my 802Ds, then I had the balls to work on the 801s I wish I had don it sooner I would have never bought the 802Ds. They ended up sound as good as the 802s the midrange wasn't as good but I would have to say the bass was a little better. Oh and I using tonight a very small class D amp, can be had for less than 30 dollars and I like the sound of it better than my other expensive amps.
I love the gentle jabs at audiopervs (audiophiles) but don’t gotta be that easy on them! Exposing the flat earthers of audio bafoonery is a good thing!
i'd love to use a power amp for my living room rig (bluesound node 2, kef Q350s, JBL 10" sub), but the only way I can get good bass management is through my Yamaha AVR. It suffices, but I'd love to get an amp that could do that. My room is atrocious for sound. Tile floors with minimal damping, left speaker near a wall, right speaker in an open are. Angular vaulted ceiling...on and on. It's all a compromise on my end. But thanks for another good review/video. I'm a recent subscriber. I enjoy your content. cheers from across the pond.
Fosi _wants_ to be an audiophile company. But given the design errors and silly decisions I've found in many of their products, they have a fair way to go. In the TB-10D I discovered design errors in the standby circuit that could leave the amplifier on and working even with the power switch in the "off" position. They were also overdriving the digital control signals with 5 volts against the chip's recommendation of 3.3. I also saw evidence of a lack of deeper insight when they placed the output filters against the chip's heat sink causing both inductive heating of the heat sink and audible degradation. I've notified them of these problems, of course. It remains to be seen what they do about them.
Is this concerning the old or the newer version oft the TB-10D. Because the "Cheapaudioman" reviewed their first version really badly. And because of this, the released a new version.
@@donalonso2785 This is the updated version. I purchased the units I tested in early 2023. And then dove into examining them more deeply in response to a client inquiry about heat while in standby in July. (Given what I found, it is unlikely they actually upgraded anything)
@@Douglas_Blake_579 Ok, that's interesting. I have the BT20A Pro, don't have any problem so far... In the forums of Amir's website Fosi Audio seems to be very open to suggestions for correcting their former mistakes.
@@donalonso2785 The BT20a is not a TB10D ... so there is no reason to expect that problem in it to begin with. Yes they are very active on the ASR forums. Unfortunately there are enough space cadets and poseurs there that I find the place intolerable. Trust me on this one... Despite Amir's obvious skills, the forums are a very deep swamp of misinformation and worthless posturing. So I've been dealing with Fosi in email, where it is possible to have a reasoned discussion with them. FWIW ... in examining lots of these TPA3255 amps and boards I've encountered what I can only describe as a complete misunderstanding of some aspects of the chip's behaviour. I find circuit segments common to all designs, obviously copied from others that don't work as they should. I find misunderstanding of inverted logic on the control signals over and over again. The chip itself is not hard to work with... so I can only conclude that a significant number of these Chinese "engineers" don't know what they are doing.
I've a Nobsound class D amp, smaller and down market from this and it's great. I have to leave any audiophile pretenses at the door but I have other stuff for that. Come on, it's called a Nobsound, you can forgive a lot for that and it was about £20.
The 600 watts these guys have latched on to is from the TPA3255 specifications sheet ... go ahead, look it up. But it's not an "in use" specification. It is the absolute maximum burst power before the chip destroys itself. The front page of the spec sheet carries a graph that shows what you can expect in real world situations. Fosi also lists the power expectations with differing power supplies both on their website and on their vendor's websites. Yes... that amplifer can give you a burst of 600 watts .... *once*
I definitely agree that the V3 has relatively low gain and you can run out of volume knob before hitting the actual maximum output. Everyone has to realize by now that Chinese Class D amps will never actually have the advertised power and I'm ok with that. As long as they have ample power. I use mine with a separately purchased 48V DC power supply and it has plenty of power. More than I ever need, it can produce ear splitting volume.
You took a very long time to get to whether it meant RMS or not. (Another aspect that used to be [mostly mis]used in the '70s/'80s was peak vs. continuous: mainly influenced by the size of the smoorhing capacitor[s]. Since this has a separate power supply, probably not relevant.) There seem to be a lot of these tiny sinple amplifiers about; I think for _most_ people, they're excellent - other than, as you say, their size isn't going to impress! For someone who knocks audiophiles (I've seen some of your other videos, and you do a bit in this one!), you're well into that area in the way you talk about your various speakers. Keep doing the videos though!
Class D amplifiers are something I’m not familiar with, so thanks for your review of this. I’m also a fan of Audioscience’s reviews, so it’s a nice cross reference. I’m certainly curious about Class D amps, and the price point of this Fosi is nicely accessible. 50-60 wpc amps are also a sweet spot for me, since my listening rooms are usually relatively small, and my ears seem to prefer efficient speakers, so larger rooms still get plenty loud. However, it turns out my ears have also already led me to good amp choices, since my amps have tested well at Audioscience. What I would be more interested in is higher quality lower power amps, maybe in the 30 wpc range, more or less. There are some rooms where 50-60 wpc are just too loud, and one of my setups is so efficient it just doesn’t need 60 wpc to fill any size room. One day I may splurge on some nice B&W speakers like those shown in this video, and I may have to look for more wpc.
I use two similar inexpensive (TPA 3116 D2) digital amps regularly, at home and work. I think that they sound very nice for near field, listening running at up to 4 W per channel. I think that they actually sound excellent in driving speakers that are easy to drive, at a volume suited for conversation. The real discrepancy between their useful output, wattage, and their advertise output wattage comes from two factors, I think. If you test with a dummy load and a sine wave input, for instance, one of my amps will put out 40 W per channel. With music programming, it drops to 4 W. I think that the variable pulse duration mechanism that these amplifiers use does much better with a sine wave because this wave form has a minimum of slew rate for a given amplitude. reproducing, actual music is more challenging. The second major limitation is the limit in increasing current sourcing for demanding speakers and demanding passages of music. And you can demonstrate this easily by diminishing dummy, load, and seeing if the output wattage actually drops fairly sharply. Used with these limitations in mind, I like these amps.
Back in the 1970s, outrageous power claims gave rise to the Federal Trade Commission (FTC) requiring amplifier power claims to be RMS, continuous power, at the rated distortion, from 20Hz to 20KHz, both (or all) channels driven. I think there may have been other requirements, such as warm-up time and stabilization. I don't remember. I do recall, prior to the FTC crack-down, all sorts of power claims, such as peak-to-peak, peak, music power, and rarely continuous RMS. Music power was based on the idea that the filter capacitors in an unregulated power supply would charge up to a higher voltage between musical peaks, and so the amplifier might be able to deliver brief surges of power until the capacitors discharged down to a lower sustaining level under a continuous load. So the FTC refused to allow inflated claims due to bouncy power supplies. You could make any other claims you wanted, but somewhere, your advert had to state the continuous RMS power over the entire audio range at the rated distortion.
Folks, Don't forget that Class-AB also chops up the waveform into 2 distinct parts, and then re-attaches everything, And that is how you answer any AudioPhool having a problem with Class-D, or Digital sources
A “push-pull” “Class B” amp does that. The reason people like Class AB amps is bc if you don’t drive them hard enough, they’re essentially operating Class A anyway, hence, most linear, least efficient. With moderate efficiency speakers on a 100w/channel amp running at 5w/ch average, you get low distortion in your room with the necessary headroom, and your AB amp is running inefficiently and more linear, essentially operating like Class A for the bulk of the signal. No matter what the amplifier Class is, the more efficient the amplifier is, and the harder you drive it, the more difficult it’s going to be to get the optimal linearity.. it’s basically the laws of physics that no human engineering can get around completely.. that’s reality, like it or not. A quality Class D amp is sure to be a lot lighter, less heat dissipation, and a smaller footprint, but it’s certainly not going to be cheaper for a quality sound.
@@shipsahoy1793 Vast majority of Class-AB amps at home don't have class-A deep enough for them not be actually switching all the time. Quality Class-D from ICEPower, Hypex, and pascal, and the TI chip mentioned can be had for silly money and they are superior to any class-ab at this price point, class-AB designs have reached are end of life.
AND ... they do that at the audio frequency ... not 300khz like class D. But it's important to understand that class-d is NOT digital. D was simply the next available letter in the alphabet.
@@shipsahoy1793 This is a very well thought-out explanation of the usefulness of AB1 amplifiers used at moderate volume levels. The amplifier is operating as a Class A amplifier until the idle point is reached. At moderate listening levels, with efficient loudspeakers, this may never happen.
@Douglas_Blake_579 True. And class-D amplifiers can be purely analogue in design if the design engineer so wishes. Or purely digital. Or some combination.
I use Class C - for transmitting Morse Code at radio frequencies 🙂 300W is ridiculous. We used to fill a theatre on a few channels of 150W stage amplifiers. We barely warmed them up. Back in the 80s we had advertisers using "Music Power" and "PMPO". They cover things like "Hey - we have 2 drivers on these speakers, and there are two speakers, and PMPO is peak to peak, so let's multiply!!!"
With a volume control you can still use it as an integrated amp by plugging it into the headphone jack on your phone. I got one and going to buy a tiny cheap Blutooth dac unit for it.
Sounds like you need to come up with a larger enclosure for the amp. Just mount the knobs and buttons to the faceplate, hot glue the remainder to the base, add two or three various LEDs for effect, and presto-chango you have an impressive new piece of kit. Give it a respectable sounding name (letter and number combos work well, ala Jaguar), fix up a nameplate and Bob's yer uncle (or aunt or whatever the kids prefer these days.)
Oh what a great review. Glad to see you mention Yamaha NS-10s. I have this idea to use one of these D-class mini amps to drive my guitar cabinet. Recently got a guitar modeling pre-amp and looking for a small amp to drive to 12" speakers which can be wired at 4 or 16 ohms. Wonder if you have and advice? There are multiple modeling amps that use d-class power and mark up the price to "guitar players do not understand" prices.
Free advice comes without guarantee but I can't see why this wouldn't work, and work well. If you go for it, I'd be interested to know how it works out.
@@AudioMasterclass Thanks for your reply. Looking at Fosi ZA3, AIYIMA A07 Max 2. Love the high power and bridge-able. Also looking at the amps with bass/treble amps.
I carefully positioned my speakers in a mid-size room so that they were "kind of near field" and angled them strategically towards my ears. This "pulled back the veil and opened up the sound stage" and "made instruments seem as if they were actually coming from different points in space". I was careful to put masking tape on the floor to mark optimal positioning so the setup could be duplicated whenever I wanted to listen to a couple tracks. (I also sit bolt-upright in a chair and don't move my head at all while listening....lest I risk spoiling my relaxation.) The speakers are then moved back into a more "this room needs to be practical as well" arrangement when I'm not listening to music so the space doesn't resemble an obstacle course on American Ninja Warrior. My vehicle is another situation altogether. My desire to have true audiophile credibility means I have to sit in the middle of the seat while driving. Still working out some kinks there....
I always turn my power amp up full by default and use the mixer to control volume. It remains quiet if no signal is going into it. I have another amp for the woofers, and a built in amp for my sub woofer which doubles as a table.
Bought it along with the 48 volt power supply to try it out. Amazing for the money, the perfect first amp. Beyond ridiculously good for the money. Although I returned it, to stay with my $390 from Ebay, Crown XLS 2002 Drivecore pushing 600 watts per channel.
Good one! This reminds me of the 1980's "ghetto blasters" portable all in one "Boom Box" that presented/announced many hundred watts (!!!) on 10x "D" 1.5 volt batteries! RMS and PMPO wattage ratings are worlds apart, but that never stopped the good people in the marketing departments to not give their target potential clients the real info. By the way, you do not need tons of watts if you have good efficiency loudspeakers and you like to remain in good terms with other tenants in your building... Just saying ;) Plus room saturation and distortion sucksé ;) As for Class D amps, in general, they are getting better. Me, I still prefer a good Class A or AB, but I do own 2 Class D amp units for convenience's sake... Those are for my computers. Cheers! :)
10:23. I would absolutely prefer not to wear out the volume control just to turn the device on and off, not to mention, keep my volume setting. But "wax pencils"? I don't get the reference here.
What's more important: NOBODY needs actual 600 watts, unless you have very badly constructed speakers. ALL the companies lie about wattage. Who cares? This tiny amp will easily drive any decently constructed (i.e. 88db and up) speaker, with no effort at all. I got the Fosi BT20 Pro, another tiny amp that can drive my Q Acoustics 3030i's to ear-splitting levels without distortion. THAT'S what matters.
The V3 together with the new P3 and the recent K5Pro DAC, all together would be a perfect system for new users but also experienced users. Find some nice speakers and you go....musthaves from Fosi.
When you tube first started "suggesting" your channel I thought it might be another grumpy boomer yells at audiophiiles deal..but this was a great review with the right mix of wit ,tech stuff and of course the two digital women at the end...good stuff,I'm subscribing
For some reason with this unit, the power depends on the power supply you use. 32V/5A outputs 34/62W in 8/4 ohms 48V/5A outputs 89/141W in 8/4 ohms You can look at ASR for the full review. 👍
The outputs of this amplifier are in BTL (Bridge Tied Load) mode... so the only way to accurately read the power is to take it up to clipping, back it down just a hair and use a volt meter to actually read the RMS voltage across the speaker. If you do, you will find that your power readings were half of what they should be.
@@1337sim1 I followed the procedure I detailed... With the 32 volt supply you should get at least 50w/ch on 8 ohms and 90 on 4, with very low distortion. These are bridged amplifiers, you cannot accurately read the outputs by measuring only one of the output posts. The actual voltage will be double that. Output power always depends on the power supply you use.
Any OPA recommendations? I just found BURSON AUDIO V7 VIVID PRO Dual OPA.. but idk if it's worth the investment.. I use Fosi Audio ZA3 with monitor audio bronze 50 (wanna upgrade later to 100/200 or silver 100)
It’s the Peak Maximum Power Output…at 1ohm, for 1 millisecond…if you have low air pressure…at 1m and using the larger power brick with 240v. Then you get 600w 😅
I really enjoyed the straight no nonsense no bs review style and his clear enthusiasm for a good bargain in high fi sound, well done!
I have watched V3 reviews all over YT and I must say, your reviews are by far better and more enjoyable than any others. Very well done!
Perfect for my future garage system ! I remember an old article interview from an un-named amplifier designer that he could make a decent amp the size of a paperback book but no one would buy it. They would have to put it in a large case and add a metal plate inside to make it heavy.
I've worked in audio electronics manufacturing for donkey's years, and it's common practice to throw in a lump of metal to give a product a sense of "quality". Light plastic is cheap; heavy plastic (light plastic with a metal block) is expensive.
The manufacturer is quoting what Texas Instruments is quoting and then not providing an adequate power supply. TI quote two power figures, one at 10% distortion and another at 1%. Let’s only consider the 1% figure. Remember that this is a full bridge converter so you don’t need to halve the voltage across the load (speaker). So for with a 51V supply with a 8R load then 51V gives 36V RMS and v^2/r = 36*36/8 = 162W and TI quote 150W at 1% distortion. So TI are correct. I get fed up with people saying that they powered it from a galvanised nail and a penny in a lemon and only got 3W. Give it a proper power supply and it will do what it says
Have you tried retesting it?
You have to cut the average customer some slack though, especially those without much education in the matter. They're fooled by two things: first, the manufacturer/seller claiming a rating at 10% THD, while at 1% is long established industry and commerce standard as a figure. Second, the underpowered 32V PSU coming with it in some markets, and even the 48V 5A one can't logically do more than 250W.
It's the manufacturer being a cheapskate. It is not unreasonable for the average customer to assume you buy a thing and it does what it says out of the box. They don't even use the dreaded "up to" phrase. They know exactly what they're doing.
Anyone tried the 48v 10a power supply?
I'm wondering of a power supply that has big caps to handle the peaks well. I'm pretty curious about this brand. Esp the tube preamp. I have three boxes of old tubes.
TPA3255 performance is solid when sticking to the data sheet. All the magic is in the chip, so there isn't much that can go wrong. I bought several 3255 based amps over the years with one of them ending up powering my main listening setup on my work desk. They run cool, they are fast with pretty precise transients. 75W RMS per channel should be enough for most listening situations, so it's a very nice budget solution. And it's very efficient, considered the power supply has decent PFC.
But will it play 100w 3way speakers with 10inch woofers?
@@bobwa399 Why shouldn't it? You won't be able to reach the maximum sound pressure level without distortion and/or safety-shutdown of the amp for the setup you describe. But those are different problems. Dual 3255 are usually 2x 75W + 150W for a 2.1 setup.
This is my first time watching your videos. I thoroughly enjoyed the review and your sense of humour. The end caught me by surprise. Well done, sir!
Okay lets untangle this power output and power supply issue...
The TPA3255 chip in these amplifiers works in BTL, that is Bridge Tied Load mode. So this is a 4 channel amplifier bridged to 2 stereo channels. This gives you the full power supply voltage on each half cycle effectively doubling the speaker voltage.
By measurement ...
32 volt power supply ... 50watts RMS per channel with both channels driven on 8 ohms with less than 0.1% distortion... 100 watts on 4 ohms.
48 volt power supply ... 100 watts RMS per channel with both channels driven on 8 ohms with about 0.1% distortion, 190 watts on 4 ohms.
The 300 w/ch measurement is the chip's absolute maximum rating taken at 10% distortion. You might get 300 watts per channel out of it ... *once*
Now this business about current... The only time you will have a steady current draw of 400 watts is during bench testing... On music the average power is much lower, often no more than 20 or 25 watts with 400 watt peaks. At that rate the 5 amp power supplies will work just fine since the amplifier's internal bulk capacitors can fill in the extra current for peaks.
As someone (like yourself) who has and still does dabble in audio electronics projects, I have a certain fondness for LM741s. I used them extensively in active filters for in car audio projects with a modicum of success. Also used them in many other applications such as temperature control and regulation in my linear power supply designs.
Presently, I work for a well known calibration and precision electrical measurement instrument manufacturer as a repair tech. This is why I note with interest your mention of electrical power output measurement of AC signals. Indeed, as stated elsewhere in the comments, I would always use the Root Mean Square as the calculation for true power of AC signals. It's a measurement industry standard.
Also, you are correct about RMS value measurement, within the circuitry of all modern precision electrical measurement equipment, RMS is measured by the thermal conversion method for greater accuracy.
I'm also old enough to know the old marketing trick of stating PMPO instead of RMS. Think flashy 1980s boomboxes (yes, I still have one) with big stickers saying "100 Watts*" with the all important asterisk leading to the small print "*PMPO" at the bottom of the sticker. Peak Music Power Output is a cheap audio manufacturer's dream marketing ploy, or as we engineers called it, lying. In engineer parlance "P*ss Miserable Power Output."
More on AC RMS power measurement here if you want to nerd out (like me!)
eepower.com/technical-articles/how-to-ensure-correct-rms-measurements/#
Engineering, Science, Math, Physics, ...all in one video. Well done David. I'm not a $100 Class D fan currently. My 20-year-old Pro Level A/B stage gear is: Loud, clean, and reliable. The amp gain level is set @ 50% with superb headroom for clarity. Pre-amp level 20%. Easy 80 DB SPL. No flowery adjectives are needed. Seat belt suggested.
LOL that last bit with the girls made me crack up. Terrific review. I'm pretty sure this is the first review on YT I've seen from someone that has the technical knowledge to understand what they are speaking about. Very refreshing.
Believe me there are plenty of people with more technical knowledge than me. What I’ve seen though, in any subject, the real experts are not on UA-cam. DM
Omg, absolutely brilliant vid. I laughed, I cried, I learned a thing or two. Finally a review with context.
This could easily be the best review of the Fosi V3! Many thanks
I just watched a great lecture here without falling in to sleep XD , well-prepared, no BS, great tone ~
Thank you for your 'useful contribution' to the excitement over small amps built around the Ti chips, the last 30 seconds or so of your video added an unexpected amusing finale, I thought you had finished and i nearly missed it!
Thanks for this great review video. I learned good things from you about measurement.
I've been using Fosi V3 for a while now. With its 48V power adapter, it surprised me during my first listens. I am very pleased. I have a few different devices at home, and Fosi v3 is quite sufficient for my daily listening.
Love your no BS delivery and content. I have the V3 and the binding posts are a joke. The power is also a little ambiguous. When I swap my circa 1980 Aiwa SA-P22 Power Amp (30 watts stereo into 4 Ohms) within the Aiwa Mini 22, the 44-year-old Power amp was was much louder and drove the speakers with more authority than using the Fosi V3. But using my PC the volume was OK.
Nice review, punchy and to the point and 5532's are a great start. Must admit if somebody is amazed at a volume pot for being Log I would question their background! I'm sure the orange anodised knob will help dissipate free radicals and transit the electrons from your hand more efficiently for cleaner and less veiled sound....cheers.
Audio taper pots are not a universal standard. Much of the HiFi gear produced in the orient has always used linear pots.
Oh thanks, I don't have a great deal of experience with many types of equipment, I only have had British stuff that plus an electronics background I suppose I took it for granted !...cheers.@@Douglas_Blake_579
@@andymouse
Hey no worries ... I did the same thing until an oriental friend of mine clued me in.
My heavy class A/B amp makes 200 watts per channel (RMS). And I'm happy with it.
I use a couple of Fosi amps, coupled with small but decent speakers, with my computers. They take very little space, and produce enough volume for near-field listening, sounding pretty good.
It's good to see that class D amps continue to improve.
My power bill needs all the help it can get.
Coincidentally I was testing a Fosi V3 today. One of the tests was measuring power consumption and the it was down to a mere 6.4W from the wall (with the 48V PSU), which I think is amazing. When turned off, the PSU only consumes about 0.3W of residual power. Which is nice too. Sound wise I was pleased with the Fosi V3 too.
This guy is my favorite for audio info.
Really like your review..you're so humble
My man! You and I think a lot alike, from your casual and pragmatic approach to audio tech to the range of system style (JBL in place of Yamaha in studio, Ohm in place of Sonab, Klipsch in place of B&W… not that those are wildly similar…) I like your style, friend.
Thanks for your time. Good and clear review. I fired mine up for the first time today.
Great video as usual David.
And lovely view of the C414EB, when you spoke about valve mics I hoped it was a C12A, but a screen grab confirmed it’s a 414.
Class D seems like the work of the devil, but you can’t argue with the performance & number of Roadie’s backs being preserved by lighter amp racks & PA systems, they are in fact a God send.
And even true audiophile manufactures like Bryston use them: PMC speakers recommended brand (and integral in their active speaker systems) PMC are definitely Audiophile, so QED as you put it.
The C12A is a very nice mic. I've used them but I very much doubt I'll ever own one myself. DM
Totally correct what you say. I tend to trust the datasheets from a reputable manufacturer, like TI. Then for any amplifier I look up the chips being used, and whether they are connected Single Ended (SE) or (Bridge Tied Load) BTL. Most datasheets give a method as to how to calculate output power given a certain power supply voltage. So I disregard the amplifier marketing specification which mentions the total output power over 2 channels, preferably at 2 ohms with 10% distortion. Which produces a large figure, but totally unrealistic. I have seem many cass-D amplifier products which verbatim copies the manufacter's applicaiion note. (That is OK, why not) So again, the chip's datasheet provides the best source of information.
As you referenced, Audio Science Review Amir measured this Amp with the 48V power supply where output is much higher. I run a pair of these to biamp my speakers. Ordered direct from Fosi to get the bigger PSU. It works out to about 400W channel of clean power for $200. Amazing value. Plays very loud and clean.
Based on various reviews I bought one for my garage / gym system. They power a couple of old Ruark Prologues. Loud is at about 2 o’clock, further gets too loud! Front end is a raspberry pi 3 with a DAC hat. Whole setup under £300 and sounds as good any 1-2k system I’ve heard.
I just got one of these to power the monitor speakers in my home recording studio. I'm impressed with it.
I found out about the logarithmic volume control in the 80s when I was a teenager and fumbled with taken-apart boomboxes and soldering irons. Not knowing any better, I bought a linear potmeter for volume control and thought it was broken because it went from almost silent to maximum volume over the last 2 % of the turning range 😆
i use this amp as a desktop amp with ELAC b6.2 attached to my wall above my monitor. works perfectly with a proper dac preamp to help make sure my noisy pc doesnt introduce a bunch of noise from its onboard , people mention that because TPA3255 designs have never really implemented that volume dial in the past and most are commaring it to the A07 that has prior recommendations over a year or two ago
Last year I returned a $2500 stereo setup w/ KEF 350s, a Cambridge CXA81 + SVS sub, due to buyers remorse. I just couldn’t shake the feeling that I overspent and could achieve just as good sound for a fraction of the price. Though I’ve really missed that sound ever since I let it go! NGL, that setup was the best I had ever heard - But I think I can get damn close with the V3, an entry level SVS sub and KEF 150s for under $600. Just need an HDMI to RCA converter and I’ll be set. (Mostly listening to Apple TV/iTunes content)
Thank you for the review, really honest i thought, and the hilarious ending, I laughed a lot!
Over the decades, via observation and building, I've noticed its difficult to build a superior sounding, low power,6 amp. But its damn near impossible to build an extremely high powered amp that sounds good. "Scale up = screw up". I really enjoy the TS Minibeast, kit, a Single Ended, OTL employing in the output stage, the JJ Electronics EL 509's, whose cathode is directly connected to the loudspeaker terminal. Yet with 4 Watts @ 8 Ohms, 7Watts @16 Ohms, the retail loudspeakers on the market are wanting. A better methodology for generating high SPL's is to employ multiples of the transducers in the typical loudspeaker system. This entails building your own from the myriad of really fantastic drivers available to Us today.
Until today I was the only person I knew that owned Sonabs. I have the OA12 with only 2 tweaters pointing in different directions. They often sound terrible but I love 'èm.
I enjoyed this review, especially the extra information and commentary about power measurement, RMS and all that. Seems the US Federal Trade Commission, a governmental agency that regulates commerce, promulgated a Rule that stereo gear had to be rated for RMS power, and specified a standard technique for measuring the same. I suppose that is historically true, but irrelevant as I see power specs all over the place these days. So, I appreciated your commentary thereon. Great fun. Thanks. TT
I have a Fosi TB10-D, the improved recent version, uses the same TI chipset, and iirc a 32 volt PS brick. Works well, I first hooked it up to a pair of Infinity Reference 2001 8 ohm bookshelf, 6.5" woofers and 1" soft dome. Infinity speakers are not usually noted for high efficiency, but initial testing with some Rush CDs at genre appropriate volume levels, I'm quite happy. The Fosi is currently utilized as a "Handy Amplifier" for various audio shenanigans, and is quite-er- handy.
Check your TB-!0D ... plug it in, use it, then leave the AC on and turn the amp off by the front panel switch ... check it in an hour... is it still warm?
If so, contact Fosi for a replacement. Your unit has a known problem in the standby circuits that will eventually result in the amplifier failing.
A master class in audio. With a human touch..
Thanks for being the voice of logic and sanity in a stadium of "audiophile" twaddle. Amp makers must be peeing themselves with laughter, at just how easily it's been convincing customers that amplifiers have a critical influence on sound "colouration" (beyond distortion). Laughing all the way to the bank.
Only when the amp is strained or distorted, otherwise....it's pretty much impossible for a human to hear the difference.
But i hear the bass control at high volumes is better with my much more expensive Burson Audio monoblocks class AB
@@scottlowell493 people pay for distortion “tuning” essentially. We need products that allow us to tailor distortion to our liking. Start from ideal and modify to preference, always the best way to do it.
I don’t really think there’s a flaw in that argument.
I have $7000 speakers too and to tell you the truth, if you hook up but a crappy amplifier to it, it knows. It’s all about the bass tones because that’s where the power is needed, down at the lower end. At the higher frequencies, if there’s no noise, you don’t need a $3500 amplifier; but you need that amplifier at the lower frequencies. The irony is that most people don’t have speakers that go low enough; they use subwoofers that have their own amplifiers.😂
I bought the original little powerhouse, the Aiyima A07. The new one (Max) is just like the V3 but can be bridged. My second system has omni-directional speakers as well, the Mirage OM-9s. Not audiophile but good enough.
I used to run a super cheap ($15 ish) class D amp that ran off a wall wart, or 4 AA batteries, into some mid range wharfdales and it sounded fantastic. I couldn't believe the quality for the price. it was about 15W per channel iirc, but loud enough for my tiny apartment.
Yes it can drive a pair of speakers, my main gripe is it´s tonality as well as how it is handling speakers when reaching higher volumes
The peak to peak measure is only valid if the amplifier you are using has differential output. That is one terminal is producing a mirror image output to the other. In effect, the signal across two amplifier outputs with one inverted relative to the other, a configuration known as "bridged mode". The majority of power amplifiers have one fixed voltage reference terminal, often to ground, and only one terminal is actually outputting a varying voltage, then the peak output is the peak voltage to fixed voltage terminal. However, the TPA3255 does have bridge mode output, which means the theoretical maximum voltage range across the load is, effectively, doubled.
Gotta say the current crop of TPA3*** series of chips is really moving forward at a pace. Some serious power levels being achieved in such small packages. I was blown away by the TPA3116, seems everything's moved on once again
IT should be noted that TPA31xx and TPA32xx are two completely different designs. The older TPA3116 was a pretty decent little Class-D chip. The Newer TPA3255 incorporates better feedback and regulation as well as producing a lot more power; clearly a far superior design.
Your analysis of amplifier power ratings and measurements was interesting. Echoed many my own thoughts and experiences.
Very recently I watched a UA-cam review of an amplifier which the reviewer confidently claimed output 6000w rms into 2 8 ohm channels.
The reviewer is known for reviewing and retailing ‘ultra high end’ components. He is also known for being strongly and controversially opinionated and claims to have won awards for products he’d designed.
I commented that his amp would need to be connected to a minimum of 8 US wall mains outlets or 4 UK wall mains outlets to even draw that amount of power and then would need to be 100% efficient to output that power. His response was classic:- “I don’t give a shit. I just know it works”!
I’ve recently upgraded my 120w integrated amp for a pair of momoblocs rated at 300w. My normal listening SPL is around 78db. To achieve that using the integrated I needed to turn the volume up to 45% but to achieve that same SPL using the monoblocks, the volume has to be ramped up to 70%! I put this down to the very low gain on the monoblocks of 25db.
I put together a class d tda7498 amp just something to mess with but I was so impressed I now use as me main amp and put it into a case. Watts was not quite how it says but sound wise I liked it and plenty power for my likening as I have very rarely got to quarter of the volume so see no point having more watts. Only thing I hate is when they claim more watts than what it really is.
Sometimes, as straight and no nonsense as you are, it does feel like a subtle dig is being given to those people that insist more expensive is better. Now, I am not saying that dig is not warranted, but I definitely sense that :).
The plain truth, if you are keeping up, is that cheap audio is getting better and better audio is getting cheaper every day.
OMG Your girls at the end!!!! Priceless!!!! I got a good laugh!! Keep up the good work! Cheers!
I was coming of age in the Sound By The Pound days. It would be a lot of years before I could afford pounds. I started rolling my own just over a decade ago, and a 45 pounder was first off the workbench. Everything I build has VU meters with bouncing red needles and lights that give a golden glow. They warm my heart. Like you said, you just want what you want.
BUT, now that I'm into active open baffle stuff, and also SWARM lusting, it's imperative that I lighten up. Of course, there's also the issue of an old creaky back. I'm using four channels of my diy Big Berthas for highs and mids, AND, four channels of Hypex class D units for woofers. I've used the class Ds for full range duty as well, and I hear a distinct difference from my class AB home grown items which to my ears are better in every category. I even think they do bass better, but not enough to justify the expense of running 8 to 10 channels of them.
Back in the 1970s all reputable manufacturers would specify their outputs in RMS format per channel, usually into 8ohms, with, I seem to remember, around 1% THD. On the other hand the "joke" manufacturers would quote ridiculous figures, usually without any standard specified, although one laughable advert claimed some enormous power figure in IPP: turned out that this meant "instantaneous peak power" with no distortion level quoted, for both channels combined, and into an unspecified impedance. Suffice to say that I still use my 1970s Rotel receiver with quoted 50w per channel RMS and it will simply blow modern devices with supposedly higher outputs out of the water. May be something to do with its overall weight up in the 30+ Kg area and a simply massive power supply inside.
The Sonab OA5 MK2 are really great. I grew up with the sound of these unusual speakers
Really enjoyed your review. Your AKG mic sounds terrific! I bought this amp with the 48v supply, and based on similar criteria as yours I found it perfectly capable of driving my vintage Polk RTA 12b's. It also drove my much less efficient Polk SDA SRS 2.3's, although not as loud but still loud enough for everyday listening. I read that the advertised output rating comes from the TI data sheet which lists the output at 315 watts total Output Power at 10%THD+N. Who doesn't love the sound of 10% THD?
Heavy metal guitarists love the sound of 10% THD. Things can only get better from there. DM
Found your channel few weeks ago, I like your style.
I explain class D to people as follows, add a HF carrier to the signal run it though the amp then filter off the carrier.
I do like how you explained it and mite start doing that instead.
Now that the Master says he is not an audiophile, it makes me more comfortable stating that I am not one. And will wrassle to the ground anyone who accuses me of being one. After all those zero-substance-full-of-noise reviews about the Fosi V3, I am glad we have the Master giving a meaningful opinion on this tiny amp. I think I will buy it for a back up. Thank you. As usual, the ladies have the last word. I always wait for it.
Before social media there was the Saturday afternoons "on location" from the local Fm radio station telling you to come on down to XYZ Electronics store. Spewing all the juicy specs about the prowess of the systems for sale.
I could listen to you all day
Some of my favourite opamps for audio in the order of preference.. OPA2228, OPA1612, LM4562, TL072, NE5532.
I have heard a couple of class D amplifiers that sounded pretty good,
but I haven't yet heard one that was as good as a well-designed AB model.
There is zero chance you could consistently tell the difference blindfolded.
@@alittlebitgoneGarbage.
Use the class D in a bi-amp setup to drive the woofers and use a class AB to drive the tweeters.
Love mine, perfect for my bedroom streaming music from my iPhone phone. Well recommended.
Seeing that you have the same 801s that I did I would highly recommend that you upgrade your internal capacitors if you haven't done it already. I used the Solen BP400 series. The clarity and imaging improved dramatically. Bass actually showed up. Then ended up having better bass than I ever remember them having. I had taken them apart a couple of times thinking the woofers might be out of phase. I had purchased these as used speakers a year and a half old. I used them for a long time then bought my 802Ds, then I had the balls to work on the 801s I wish I had don it sooner I would have never bought the 802Ds. They ended up sound as good as the 802s the midrange wasn't as good but I would have to say the bass was a little better. Oh and I using tonight a very small class D amp, can be had for less than 30 dollars and I like the sound of it better than my other expensive amps.
great stuff along with the interspersed puns. the end was icing on the cake. 🤣
I love the gentle jabs at audiopervs (audiophiles) but don’t gotta be that easy on them! Exposing the flat earthers of audio bafoonery is a good thing!
i'd love to use a power amp for my living room rig (bluesound node 2, kef Q350s, JBL 10" sub), but the only way I can get good bass management is through my Yamaha AVR. It suffices, but I'd love to get an amp that could do that.
My room is atrocious for sound. Tile floors with minimal damping, left speaker near a wall, right speaker in an open are. Angular vaulted ceiling...on and on.
It's all a compromise on my end.
But thanks for another good review/video. I'm a recent subscriber. I enjoy your content.
cheers from across the pond.
Fosi _wants_ to be an audiophile company. But given the design errors and silly decisions I've found in many of their products, they have a fair way to go.
In the TB-10D I discovered design errors in the standby circuit that could leave the amplifier on and working even with the power switch in the "off" position. They were also overdriving the digital control signals with 5 volts against the chip's recommendation of 3.3. I also saw evidence of a lack of deeper insight when they placed the output filters against the chip's heat sink causing both inductive heating of the heat sink and audible degradation.
I've notified them of these problems, of course. It remains to be seen what they do about them.
Is this concerning the old or the newer version oft the TB-10D. Because the "Cheapaudioman" reviewed their first version really badly. And because of this, the released a new version.
@@donalonso2785
This is the updated version.
I purchased the units I tested in early 2023. And then dove into examining them more deeply in response to a client inquiry about heat while in standby in July.
(Given what I found, it is unlikely they actually upgraded anything)
@@Douglas_Blake_579 Ok, that's interesting. I have the BT20A Pro, don't have any problem so far...
In the forums of Amir's website Fosi Audio seems to be very open to suggestions for correcting their former mistakes.
@@donalonso2785
The BT20a is not a TB10D ... so there is no reason to expect that problem in it to begin with.
Yes they are very active on the ASR forums. Unfortunately there are enough space cadets and poseurs there that I find the place intolerable. Trust me on this one... Despite Amir's obvious skills, the forums are a very deep swamp of misinformation and worthless posturing.
So I've been dealing with Fosi in email, where it is possible to have a reasoned discussion with them.
FWIW ... in examining lots of these TPA3255 amps and boards I've encountered what I can only describe as a complete misunderstanding of some aspects of the chip's behaviour. I find circuit segments common to all designs, obviously copied from others that don't work as they should. I find misunderstanding of inverted logic on the control signals over and over again. The chip itself is not hard to work with... so I can only conclude that a significant number of these Chinese "engineers" don't know what they are doing.
Already 20 years ago Bang&Olufsen introduced 1000 Watt class D amps in the Beolab 5 about the size of a cigarette package.
I've a Nobsound class D amp, smaller and down market from this and it's great. I have to leave any audiophile pretenses at the door but I have other stuff for that. Come on, it's called a Nobsound, you can forgive a lot for that and it was about £20.
Excellent as usual, the Edgar Winter Frankenstein bit was comedy gold
I think it is rated at 600 watts (or 600 joules per second) in heat output when it catches fire.
The 600 watts these guys have latched on to is from the TPA3255 specifications sheet ... go ahead, look it up. But it's not an "in use" specification. It is the absolute maximum burst power before the chip destroys itself. The front page of the spec sheet carries a graph that shows what you can expect in real world situations. Fosi also lists the power expectations with differing power supplies both on their website and on their vendor's websites.
Yes... that amplifer can give you a burst of 600 watts .... *once*
Bought one of those. Sound is very good.
I definitely agree that the V3 has relatively low gain and you can run out of volume knob before hitting the actual maximum output. Everyone has to realize by now that Chinese Class D amps will never actually have the advertised power and I'm ok with that. As long as they have ample power. I use mine with a separately purchased 48V DC power supply and it has plenty of power. More than I ever need, it can produce ear splitting volume.
"Run out of volume knob" is a phrase I haven't heard before but it's very clear what it means and I'm sure I'll be using it in future.
FWIW the TPA3255 chip is fixed gain at 21.5db. So with a 48 volt supply it takes about 2 volts of input to clip it.
You took a very long time to get to whether it meant RMS or not. (Another aspect that used to be [mostly mis]used in the '70s/'80s was peak vs. continuous: mainly influenced by the size of the smoorhing capacitor[s]. Since this has a separate power supply, probably not relevant.)
There seem to be a lot of these tiny sinple amplifiers about; I think for _most_ people, they're excellent - other than, as you say, their size isn't going to impress!
For someone who knocks audiophiles (I've seen some of your other videos, and you do a bit in this one!), you're well into that area in the way you talk about your various speakers.
Keep doing the videos though!
Yes I should have mentioned that I’m only scratching the surface of power measurement. I’ll definitely be diving deeper in a future video. DM
Wouldn't it been a good idea if an 'Optical Toslink' connections too existed along with the RCA Line in ?
Mate. I stayed with you there until at least 5 minutes in 😃. Doesn’t matter. I’ll listen to you all night mate. Brilliant. (Ade, 1968)
Class D amplifiers are something I’m not familiar with, so thanks for your review of this. I’m also a fan of Audioscience’s reviews, so it’s a nice cross reference. I’m certainly curious about Class D amps, and the price point of this Fosi is nicely accessible. 50-60 wpc amps are also a sweet spot for me, since my listening rooms are usually relatively small, and my ears seem to prefer efficient speakers, so larger rooms still get plenty loud. However, it turns out my ears have also already led me to good amp choices, since my amps have tested well at Audioscience. What I would be more interested in is higher quality lower power amps, maybe in the 30 wpc range, more or less. There are some rooms where 50-60 wpc are just too loud, and one of my setups is so efficient it just doesn’t need 60 wpc to fill any size room. One day I may splurge on some nice B&W speakers like those shown in this video, and I may have to look for more wpc.
I use two similar inexpensive (TPA 3116 D2) digital amps regularly, at home and work. I think that they sound very nice for near field, listening running at up to 4 W per channel. I think that they actually sound excellent in driving speakers that are easy to drive, at a volume suited for conversation. The real discrepancy between their useful output, wattage, and their advertise output wattage comes from two factors, I think. If you test with a dummy load and a sine wave input, for instance, one of my amps will put out 40 W per channel. With music programming, it drops to 4 W. I think that the variable pulse duration mechanism that these amplifiers use does much better with a sine wave because this wave form has a minimum of slew rate for a given amplitude. reproducing, actual music is more challenging. The second major limitation is the limit in increasing current sourcing for demanding speakers and demanding passages of music. And you can demonstrate this easily by diminishing dummy, load, and seeing if the output wattage actually drops fairly sharply. Used with these limitations in mind, I like these amps.
Back in the 1970s, outrageous power claims gave rise to the Federal Trade Commission (FTC) requiring amplifier power claims to be RMS, continuous power, at the rated distortion, from 20Hz to 20KHz, both (or all) channels driven. I think there may have been other requirements, such as warm-up time and stabilization. I don't remember. I do recall, prior to the FTC crack-down, all sorts of power claims, such as peak-to-peak, peak, music power, and rarely continuous RMS.
Music power was based on the idea that the filter capacitors in an unregulated power supply would charge up to a higher voltage between musical peaks, and so the amplifier might be able to deliver brief surges of power until the capacitors discharged down to a lower sustaining level under a continuous load. So the FTC refused to allow inflated claims due to bouncy power supplies. You could make any other claims you wanted, but somewhere, your advert had to state the continuous RMS power over the entire audio range at the rated distortion.
This is a topic I'll be covering in a future video. I say 'covering' but there's so much to it I think it will be merely dipping in. DM
Folks, Don't forget that Class-AB also chops up the waveform into 2 distinct parts, and then re-attaches everything,
And that is how you answer any AudioPhool having a problem with Class-D, or Digital sources
A “push-pull”
“Class B” amp does that. The reason people like Class AB amps is bc if you don’t drive them hard enough, they’re essentially operating Class A anyway, hence, most linear, least efficient. With moderate efficiency speakers on a 100w/channel amp running at 5w/ch average, you get low distortion in your room with the necessary headroom, and your AB amp is running inefficiently and more linear, essentially operating like Class A for the bulk of the signal. No matter what the amplifier Class is, the more efficient the amplifier is, and the harder you drive it, the more difficult it’s going to be to get the optimal linearity.. it’s basically the laws of physics that no human engineering can get around completely.. that’s reality,
like it or not.
A quality Class D amp is sure to be a lot lighter, less heat dissipation, and a smaller footprint, but it’s certainly not going to be cheaper for a quality sound.
@@shipsahoy1793 Vast majority of Class-AB amps at home don't have class-A deep enough for them not be actually switching all the time. Quality Class-D from ICEPower, Hypex, and pascal, and the TI chip mentioned can be had for silly money and they are superior to any class-ab at this price point, class-AB designs have reached are end of life.
AND ... they do that at the audio frequency ... not 300khz like class D.
But it's important to understand that class-d is NOT digital. D was simply the next available letter in the alphabet.
@@shipsahoy1793 This is a very well thought-out explanation of the usefulness of AB1 amplifiers used at moderate volume levels. The amplifier is operating as a Class A amplifier until the idle point is reached. At moderate listening levels, with efficient loudspeakers, this may never happen.
@Douglas_Blake_579 True. And class-D amplifiers can be purely analogue in design if the design engineer so wishes. Or purely digital. Or some combination.
I use Class C - for transmitting Morse Code at radio frequencies 🙂
300W is ridiculous. We used to fill a theatre on a few channels of 150W stage amplifiers. We barely warmed them up.
Back in the 80s we had advertisers using "Music Power" and "PMPO". They cover things like "Hey - we have 2 drivers on these speakers, and there are two speakers, and PMPO is peak to peak, so let's multiply!!!"
It would be great if you could use an oscilloscope to show the clipping point of this amp
With a volume control you can still use it as an integrated amp by plugging it into the headphone jack on your phone. I got one and going to buy a tiny cheap Blutooth dac unit for it.
Sounds like you need to come up with a larger enclosure for the amp. Just mount the knobs and buttons to the faceplate, hot glue the remainder to the base, add two or three various LEDs for effect, and presto-chango you have an impressive new piece of kit. Give it a respectable sounding name (letter and number combos work well, ala Jaguar), fix up a nameplate and Bob's yer uncle (or aunt or whatever the kids prefer these days.)
Don't forget to bolt something from the garage weight set to the inside, for heft, with a significant mismatch between the sides.
@@tactileslut Yes! You clearly have a knack for engineering!
Oh what a great review. Glad to see you mention Yamaha NS-10s. I have this idea to use one of these D-class mini amps to drive my guitar cabinet. Recently got a guitar modeling pre-amp and looking for a small amp to drive to 12" speakers which can be wired at 4 or 16 ohms. Wonder if you have and advice? There are multiple modeling amps that use d-class power and mark up the price to "guitar players do not understand" prices.
Free advice comes without guarantee but I can't see why this wouldn't work, and work well. If you go for it, I'd be interested to know how it works out.
@@AudioMasterclass Thanks for your reply. Looking at Fosi ZA3, AIYIMA A07 Max 2. Love the high power and bridge-able. Also looking at the amps with bass/treble amps.
I carefully positioned my speakers in a mid-size room so that they were "kind of near field" and angled them strategically towards my ears. This "pulled back the veil and opened up the sound stage" and "made instruments seem as if they were actually coming from different points in space". I was careful to put masking tape on the floor to mark optimal positioning so the setup could be duplicated whenever I wanted to listen to a couple tracks. (I also sit bolt-upright in a chair and don't move my head at all while listening....lest I risk spoiling my relaxation.)
The speakers are then moved back into a more "this room needs to be practical as well" arrangement when I'm not listening to music so the space doesn't resemble an obstacle course on American Ninja Warrior.
My vehicle is another situation altogether. My desire to have true audiophile credibility means I have to sit in the middle of the seat while driving. Still working out some kinks there....
I always turn my power amp up full by default and use the mixer to control volume. It remains quiet if no signal is going into it. I have another amp for the woofers, and a built in amp for my sub woofer which doubles as a table.
It’s a practical way to work. DM
I just bought from the Fosi Ebay store for $86.50 AUD, with the 48V supply!
It's a nice little amp. I use the review sample every day.
Bought it along with the 48 volt power supply to try it out. Amazing for the money, the perfect first amp. Beyond ridiculously good for the money. Although I returned it, to stay with my $390 from Ebay, Crown XLS 2002 Drivecore pushing 600 watts per channel.
hi, does the fan loud noises from this crown amp `?
Crown is not comparable to fosi
Good one! This reminds me of the 1980's "ghetto blasters" portable all in one "Boom Box" that presented/announced many hundred watts (!!!) on 10x "D" 1.5 volt batteries!
RMS and PMPO wattage ratings are worlds apart, but that never stopped the good people in the marketing departments to not give their target potential clients the real info.
By the way, you do not need tons of watts if you have good efficiency loudspeakers and you like to remain in good terms with other tenants in your building... Just saying ;)
Plus room saturation and distortion sucksé ;)
As for Class D amps, in general, they are getting better.
Me, I still prefer a good Class A or AB, but I do own 2 Class D amp units for convenience's sake... Those are for my computers.
Cheers!
:)
10:23. I would absolutely prefer not to wear out the volume control just to turn the device on and off, not to mention, keep my volume setting. But "wax pencils"? I don't get the reference here.
In the olden days of pro audio we would commonly mark the desired position of a knob or fader with a wax pencil, usually the Chinagraph brand.
@@AudioMasterclass So a reference to adding one yourself then?
Loud and CLEAN explosions! Indeed!
I have a 500W lightbulb in my garage - although to be fair it doesn't go very loud
Watts have always meant nothing in Hi-Fi Terms
What's more important: NOBODY needs actual 600 watts, unless you have very badly constructed speakers. ALL the companies lie about wattage. Who cares? This tiny amp will easily drive any decently constructed (i.e. 88db and up) speaker, with no effort at all. I got the Fosi BT20 Pro, another tiny amp that can drive my Q Acoustics 3030i's to ear-splitting levels without distortion. THAT'S what matters.
The V3 together with the new P3 and the recent K5Pro DAC, all together would be a perfect system for new users but also experienced users. Find some nice speakers and you go....musthaves from Fosi.
very good review!!
love your delivery and the tongue in cheek mate. haha Do you have a lecture on Amp classes and calculating apparent wattages between classes...
That would be a complex topic considering that some people believe that tube watts are louder than transistor watts. I might bear it in mind. DM
Bless @@AudioMasterclass
When you tube first started "suggesting" your channel I thought it might be another grumpy boomer yells at audiophiiles deal..but this was a great review with the right mix of wit ,tech stuff and of course the two digital women at the end...good stuff,I'm subscribing
For some reason with this unit, the power depends on the power supply you use.
32V/5A outputs 34/62W in 8/4 ohms
48V/5A outputs 89/141W in 8/4 ohms
You can look at ASR for the full review. 👍
The outputs of this amplifier are in BTL (Bridge Tied Load) mode... so the only way to accurately read the power is to take it up to clipping, back it down just a hair and use a volt meter to actually read the RMS voltage across the speaker. If you do, you will find that your power readings were half of what they should be.
@@Douglas_Blake_579 Do you mean the measurements on ASR are not good?
I'm not sure I understand your comment...
Thanks
@@1337sim1
I followed the procedure I detailed...
With the 32 volt supply you should get at least 50w/ch on 8 ohms and 90 on 4, with very low distortion.
These are bridged amplifiers, you cannot accurately read the outputs by measuring only one of the output posts. The actual voltage will be double that.
Output power always depends on the power supply you use.
@@Douglas_Blake_579 ok thanks. So I guess it's in the same ballpark as ASR. :)
@@1337sim1
And not in the ballpark you started with.
Any OPA recommendations? I just found BURSON AUDIO V7 VIVID PRO Dual OPA.. but idk if it's worth the investment..
I use Fosi Audio ZA3 with monitor audio bronze 50 (wanna upgrade later to 100/200 or silver 100)
I have one of these. It sounds absolutely fine. However, my 53-year-old A/B Sansui integrated amp is quite a bit louder (and beefier).
It’s the Peak Maximum Power Output…at 1ohm, for 1 millisecond…if you have low air pressure…at 1m and using the larger power brick with 240v. Then you get 600w 😅