Adventures In Audio

Can this tiny amp really produce 600 watts? - Fosi Audio V3

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@petesjk:  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.

@hintoninstruments2369:  There is no such unit as Watts rms. Volts rms x Amps rms = Watts average (x Power factor if not in phase).

@toonertik:  Hahahaha.." I never want to hear them again".... "Me neither".. well played mate LOL ;-)))

@AdamsOlympia:  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)

@zorst99:  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 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 done it sooner I would have never bought the 802Ds. They ended up sounding 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 am using tonight a very small class D amp, which can be had for less than 30 dollars and I like the sound of it better than my other expensive amps.

@zorst99:  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.

@grandadgamer8390:  I've been flying the RMS flag for years, been in decline for years as an honest measure. M
Nice little amp though 😊

@bigcassssino:  OMG Your girls at the end!!!! Priceless!!!! I got a good laugh!! Keep up the good work! Cheers!

@NeverTakeNoShortcuts:  Au contraire , I installed the orange knob, and I got a much more open, velvety sound. You are clearly stupid

@izaakgray1718:  Your physics teacher was right - but you need to extend that analogy. If the amplifier was supposed to deliver a continuous and true 600 watt into a speaker, pretty much any home speaker would set on fire wit the heat produced. The ratings are all based around crest factors, dynamic non sinusoidal waveforms, and burst power ratings. And that actually makes sense because we're trying to put a number on any inherently dynamic signal, and we're concerned with whether it can do that momentarily without distortion, when for instance reproducing a bass drum. At this point, the power supplies burst capability delivered by its cap bank, and not its input power, actually matter a lot more. Please re test for burst capability. If it can deliver that, it's a fair cop, if it can't, it's a lie.

@hs7921:  I’ve got one of these. Bluetooth from my Mac, connected to my Yamaha NS 5X speakers. Unbelievable.

@theno1deejay:  Have owned at least four pair of Sonab OA5 and from now I'm gonna be a lot more questioning about what you state.
That one of the worst speaker I've heard, ok mid but hars treble that bounced all around and totaly absent base. I turn down a pair of version 2 for €70 some day ago. I buy and sell vintage hifi as a hobby and have had a lot of stuff. OA5 is better as a waist basket than a speaker.
Did see Stig in the early 70's, he was a friend of our naighbour, Martin Persson.

@AudioMasterclass replies to @theno1deejay: Don't worry! I'm going to trade them in for a pair of Bose 901 soon.

@samaradaf6640:  its a kid amp

@Coldgecko:  Man, you are great. The best stereo product review I have heard in more than 10 years. You keep the BS out of the discussion.

@r2d3vadar92:  Thank you for saving me form a disaster as I almost purchased these for my JBL modest 1500 dollars floor standing speakers that require a minimum of 100 watts continuous with 400 watts for peaks. This amp would have ruined my speakers form cliping.

@Bastelcontainer:  The Sonab OA5 MK2 are really great. I grew up with the sound of these unusual speakers

@gregbailer8701:  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.

@robertwestinghouse4098:  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.

@chelfyn:  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.

@R3dlined:  Wait so are we saying this will drive a pair of ELAC Uni-Fi 2.0 UB52 just fine?!?!?

@totembarada6900:  32v 5a 95 wat x2 4 Om | 8 Om 53 wat x2

@georgecorey1320:  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.

@user-tv3nu8zs3s:  Why this Fosi looks so ugly? I prefer Mitsubishi M -A04.

@royrogers7644:  It`s 600 mW for headphones......

@dj-kq4fz:  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!

@danieldusentriebjunior6611:  Already 20 years ago Bang&Olufsen introduced 1000 Watt class D amps in the Beolab 5 about the size of a cigarette package.

@edwardasmannjr.2438:  Damn you with you your facts, knowledge, experience, and, and, and, sense of humor! (Crap! Now he knows I’m a Yank.)
Thank you, I thoroughly enjoy these videos, and learn useful things too. : )

@TheEulerID:  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.

@BrianHall-Oklahoma:  I just got one of these to power the monitor speakers in my home recording studio. I'm impressed with it.

@Beautiful_Evil:  they shouldn't even measure amplifiers in wattage at all it's a stupid way to measure power. current is what drives the speakers not wattage.

@peteleoni9665:  A note on your B&W 801s. I too owned a pair. 2 in fact. I bought them to master with. Here is a sad fact about those much vaunted speakers. They do not sound that good, nor and more importantly are they that damn accurate. Here, I am curious as to why you have kept them. It's plain to see you are no one's fool. Please clue me in because I have no doubt that you heard what I did? Did you perhaps modify the crossovers? P.s. I am no audiophile I am a mastering guy, we laugh at audiophiles because we actually know what makes the difference. I am curious?

@AudioMasterclass replies to @peteleoni9665: Sometimes you just like what you like.

@peteleoni9665 replies to @peteleoni9665: @AudioMasterclass 
This is true! There were several versions of the 801s as well both mine were variations of the vented ones and that may be the deal. I thought btw, that the 802's were a lot better and that's what I kept. As far as listening, I just rolled my own with some tad drivers and never looked back after venturing into high efficiency horn land. But you really can't Mix on them because they uncompress things due to the very low excursion and you can't really ref with that.

@peteleoni9665:  The older I get, the less bullshit I can tolerate. Thank you for no bullshit! Subscribed!!!!

@richh650:  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!

@andrii4545:  I keep my Sonab's in a toilet, useful to cover up old fart farts 🥲

@carlsitler9071:  Aesthetics is a factor as well. I prefer an amp that looks a stereo amp rather than a power brick.

@carlsitler9071:  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.

@Smithy225:  I could listen to you all day

@bubbleone6526:  I just love this not an audiophile guy as he claims but the orange volume knob gives him away! But really no joking aside, he’s probably the strangest shooting reviewer on uTube. As far as class D is concerned I’ll stick to my class A and AB amps. Oh 19.38 minutes to say you love the class D amp was a little it much. 😂😂😂

@KG-zh2cg:  this is to good review for that amp

@c.s.herman860:  How much power does it use at idle? I wish it had auto-on

@Douglas_Blake_579 replies to @c.s.herman860: A few milliwatts. idle current is about 30ma.

@c.s.herman860 replies to @c.s.herman860: @@Douglas_Blake_579Is it the same for most class D amps? If I just left it always on, connected to a wifi streamer, it wouldn't be so bad eh?

@Douglas_Blake_579 replies to @c.s.herman860: @@c.s.herman860
The overall idle current will vary from design to design, depending what else is also running (op-amps, tone controls, sub out, wifi, bluetooth, etc) but most class D amplifiers are very efficient.

With the power switch on the volume control, you have to reset your volume every time you turn it on. So I imagine quite a few of these amps will be left idling when not in use. Time will tell us if this particular implementation stands up or not.

@andrejgregoric1324:  Right! It allways amazes me, when I read incredible pwr output numbers, but checking device pwr consumption is mostly up to max 200W. So, how do we get those incredible output numbers... simply adding foot size, house numbers, po numbers 😂

@Douglas_Blake_579 replies to @andrejgregoric1324: The 300 w/ch spec is the Absolute Maximum output of the chip. It's generally taken as a one time pulse at about 10% distortion. So, you might get 300w/ch from the V3 ... once.

The actual low distortion power is spelled out in the "TPA3255 data sheet" (do a search) and tops off at about 50w/ch on 8 ohms, and 90w/ch on 4 ohms with the 32 volt supply. The 48 volt supply bumps that up to about 100 and 200.

@ericbain507:  Omg, absolutely brilliant vid. I laughed, I cried, I learned a thing or two. Finally a review with context.

@owenjbrady:  Class D in the 2020's is nothing like it was years ago

@wcg66:  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.

@AudioMasterclass replies to @wcg66: "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.

@Douglas_Blake_579 replies to @wcg66: 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.

@mikepxg6406:  Probing Time......

@mike_lowndes:  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.

@lehsu:  Where can I buy a 48V, 10 or 12A power adapter compatible with this V3?

@Douglas_Blake_579 replies to @lehsu: Do a search for "Meanwell power supplies".

But before you do that, you should stop and ask why you think you need that much juice... Yes the V3 and it's kin with the TPA3255 chips can pull 10 to 12 amps during bench testing with sine waves. But music is not sine waves... it is a fairly low average with occasional peaks. The 48 volt 5 amp supply should be adequate for most uses, unless you're planning to build a siren and/or make your ears bleed.

@fins59:  Ha Ha Ha, loved your review especially the last 20secs.

@gregw74:  You ever listen to TOOL on your high end system.... maybe Invincible or Pneuma from their Fear Inoculum album? If not, you owe it to yourself to do so.

@LordPapula:  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.

@Mistermoleymole:  The 120w per channel you think is where we are that max or RMS?

@AudioMasterclass replies to @Mistermoleymole: With very few exceptions I will always refer to average power. This is sometimes incorrectly called RMS as I cover in

@Douglas_Blake_579 replies to @Mistermoleymole: It is calculated measuring rms voltage across an 8 ohm load as...
(30 x 30) / 8 == 112 watts.
Most will call that "RMS Power".

@martingajta:  I wanted to try to clarify power numbers. As far as I understand, there is 4 channels on this chip. Two, and two are bridged. For bridged amplifier, you look at half of an impedance. So if amplifier has 200 watts on 4 ohms, it will be 400 at 8bridged. Beside bridging, TI specify paralleling bridged amplifiers, AT TWO ohms. That means that every channel is working at 1ohm, and they are specifiying at 10% THD (which is unusable in my book), also if you are listening music with 12db of crest factor, 48volts power supply and 10 amperes, theoretically, 600watts is plausable.

@Douglas_Blake_579 replies to @martingajta: Yes there are 4 independent amplifiers on the TPA3255 chip. These are arranged as 2 BTL (bridged) channels for stereo in most of these mini-amps.

By measurement...
With the 32 volt supply you will get about 60 watts RMS per channel at 8 ohms with less than 0.1% distortion or 100 watts on 4 ohms.
With the 48 volter you will get about 110w on 8 ohms and 200 on 4 ohms.

The 2 x 300 watt spec is the chip's Absolute Maximum rating which occurs at more than 10% distortion on 51 volts. So you might get 600 watts out of it ... once.

@user-pp6jd6qj4x:  Loved it, brilliant. I am your age and appreciate your comments very much!

@volkiruski1221:  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.

@1337sim1:  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. 👍

@Douglas_Blake_579 replies to @1337sim1: 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 replies to @1337sim1: @@Douglas_Blake_579 Do you mean the measurements on ASR are not good?

I'm not sure I understand your comment...


@Douglas_Blake_579 replies to @1337sim1: @@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.

@1337sim1 replies to @1337sim1: @@Douglas_Blake_579 ok thanks. So I guess it's in the same ballpark as ASR. :)

@Douglas_Blake_579 replies to @1337sim1: @@1337sim1
And not in the ballpark you started with.

@sonsenthoy7468:  This could easily be the best review of the Fosi V3! Many thanks

@sonsenthoy7468:  Really like your're so humble

@Jimmeh_B:  Irrespective of marketing or measurement methods preferred by marketers (AKA: lies), this one is pretty straight forward. The largest power supply they provide for this (admittedly good for what it is) amp, is 48V 5A. No matter how you look at it, if the amp were 100% efficient, rail to rail... 48x5 = 240W of input power. Case closed.

@Douglas_Blake_579 replies to @Jimmeh_B: Nope ... with a 48v 5a supply when playing music you will find that it can and does reach 400 watt peaks on 4 ohms. How can that be? There are reserve caps in the amplifier that store energy for peaks but when listening to music with reasonable dynamic range you won't hit the limit more than rarely... the average power for 10db of dynamics is 1/10th of the peak so in reality you're only taking 30 to 40 watts of continuous power from the supply.

@Jimmeh_B replies to @Jimmeh_B: @@Douglas_Blake_579 That ain't RMS.
IE: not 400 watts.

PMPO is a gimmick.

@Douglas_Blake_579 replies to @Jimmeh_B: @@Jimmeh_B
Sorry to burst your bubble ... but that is measured and verified on my own test bench.

With a 48 volt supply and 4 ohm dummy load, you can easily get 220w/ch RMS with less than 0.1% distortion out of this little amplifier.

@curtisscott9251:  An amplifier that uses the age old trickery of stating power measurements that are some variant of "PEAK" or unachievable due to power supply constraints is NOT a good sign for establishing credibility. For a cynic like myself, I would be checking the trace thickness on the PCB to see if the physical construction was able to sink the current necessary for achieving stated power ratings. This test is almost always the one that determines if the amplifier is a witch. If it fails, the next test is to throw it into a body of water to see if its lighter than a duck.

@yipfred1751:  I just watched a great lecture here without falling in to sleep XD , well-prepared, no BS, great tone ~

@franklekwan5860:  Can this tiny amp really produce 600 watts? (I will add RMS) to the end of this question). Well, the answer is a very likely no but a slight chance of yes. First, with the 48V 5A power supply, it simply cannot reach anything close to 300W. In fact JohnAudioTech has performed a test using this supply and the result is that the max output is 192W RMS into 4Ω load, 1 channel. If you try to drive the amp with both channels, either the power supply will stop working (due to over power) or the amp will enter into protection mode (due to clipping at output). To achieve 300Wx2 (600W) RMS into 4Ω, you may need a power supply of 50-52V and 15 Amp (or higher), and the input signal has to be at least 2V RMS since the gain of V3 is only about 26.4dB. Really wish someone will perform this test in YouTube. No matter how much "real" output power it is , this amp is a jewel that most people can afford.

@Douglas_Blake_579 replies to @franklekwan5860: Your math is only accurate with sine wave tests on the bench. When playing music the amp will reach 220w per channel, both driven, for short peaks (like snare or gun shots). With even 10db of dynamic range the average power for that would be around 30 watts which the power supply can do easily.

@jayantadakable:  Does the Fosi v3 has better components under the shell than their upgraded versions viz BT20A Pro and BT30D Pro ?

@Douglas_Blake_579 replies to @jayantadakable: They all use the same Class-D chip. There are some improvements in cooling and coil placement but it's still the same TPA3255 chip.

@jayantadakable:  Wouldn't it been a good idea if an 'Optical Toslink' connections too existed along with the RCA Line in ?

@kapysta1984:  Я из России мы живем под "страшными санкциями" и у нас цена этого усилителя с блоком питания 48v 10a сегодня 83$

@bujin5455:  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.

@AudioMasterclass replies to @bujin5455: 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.

@bujin5455 replies to @bujin5455: @@AudioMasterclass So a reference to adding one yourself then?

@willbrown8433:  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.

@gamerman644:  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

@stevenrayphoto1280:  Hi David, I'm a new subscriber and so glad I found you! Your videos are spot on and full of quality information. I monitor at modest volumes and want to fire up a pair of NS10m studio monitors that have been in storage for 20 years. In my studio I originally used a Bryston 4b with them. I realize the Fosi is way less money than the 4B. Do you think at modest volume levels the Fosi will not disappoint with the NS10m Studio monitors?

@AudioMasterclass replies to @stevenrayphoto1280: I tried the Fosi with my NS10M Studios and it was fine. I'm sure audiophiles would have their quibbles but for practical purposes it does the job.

@stevenrayphoto1280 replies to @stevenrayphoto1280: ​@@AudioMasterclass Thank you for the response. I just received my Fosi V3 with the 48v power supply and shot my room with Sonarworks. The frequency graph I got from Sonarworks looks pretty much the same as the published specifications for the NS10's so I think the Fosi is doing fine.

@stevenrayphoto1280 replies to @stevenrayphoto1280: Here is the graph

@avasolaris1:  Thanks for your time. Good and clear review. I fired mine up for the first time today.

@m0rjc:  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!!!"

@EsotericArctos:  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 :).

@Douglas_Blake_579 replies to @EsotericArctos: The plain truth, if you are keeping up, is that cheap audio is getting better and better audio is getting cheaper every day.

@AstrosElectronicsLab:  Um, power output is not measured from the peak to the trough (peak to peak), it's halved (0 to peak) Power = Vpeak^2/R. Also, it better to take the RMS value of voltage and calculate it from that. In your example of 34.6V that'd be 17.3 = 17.3^2 = 299.29 / 4 = 75W (rounded). Now, I'm not sure where you got that 34.6V figure from, but the amp really should be put in to a 4 ohm dummy load with an oscilloscope connected across it to take a correct peak to peak voltage measurement before clipping. I would not substitute an NE5532 with a dual 741 (MC1458CP1 which are obsolete now). It uses the same circuitry as the original LM741 and are not the best sounding opamp for audio. They're noisy.

@joedennehy386:  Wattage at 8 ohms 20 hz to 20khz at 0.1% thd wrms is about 40 watts per channel

@byteborg:  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.

@Dj-Jon-E-C:  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.

@harrybaque5502:  “Again…” 😂

@johnanthonycolley3803:  " 300w X 2 " LoL

Obviously wee Chinese Watts .. 😅

@Douglas_Blake_579 replies to @johnanthonycolley3803: Nope ... the chip's absolute maximum rating. You won't see that in day to day use, but under laboratory conditions it actually can produce 300 watts per channel, for about 3 seconds.... *once*.

In normal use with the power supply they include you can expect an honest 50watts RMS per channel on 8 ohms with less than 0.1% distortion, 100 watts on 4 ohms.

@DinLaban:  Say, I like your microphone...

@dannyverhamme7970:  To me it all sounds like an Alice in Wonderland riddle. 😅 So sorry.

@leeoooooooooooo:  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

@Douglas_Blake_579 replies to @leeoooooooooooo: 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.

@zackreuter6344:  That 600 watts isn't quite a WSBL* rating, but I have a hard time trusting a manufacturer that uses such BS. I have several similar little chip amps like this one, and they are surprisingly good and cheap. They don't tend to last very long, but it's pretty painless when they do pop.

*When Struck By Lightning

@tekanova7480:  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.

@amazoidal:  Bruno Putzeys is God.

@erwintimmerman6466:  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 😆

@richardaling5278:  The power consumption might be 600 watts. It won't produce it! Amateur...

@Douglas_Blake_579 replies to @richardaling5278: Actually it does ... 300 x 2 is TPA3255 chip's absolute maximum rating. You won't see that in normal use... but it can do it.

Search for the "tpa3255 data sheet" you'll see.

@jimw7ry:  Loud and CLEAN explosions! Indeed!

@zoundsic:  Peak power of 600 watt, I need it's RMS.

@grhaggerty:  How is the headroom on that little giant?

@Douglas_Blake_579 replies to @grhaggerty: Headroom works differently on Class-D ... In class A and AB amplifiers the power supply is unregulated. This means your amp might sustaining 100 watts but be able to deliver short bursts of 150 watts. But in Class D the power supplies are almost always very well regulated so, that maximum 105 watts is available continuously.

@duncan-rmi:  how did you get chocolate on the top of your mic?

@duncan-rmi replies to @duncan-rmi: also, what's the power supply rated at? it can't go louder than that, can it?

@duncan-rmi replies to @duncan-rmi: also, "I'm not an audiophile" but "textures" in the context of valve mic pre-amps? what does "texture" mean?

@lu74wn2002:  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

@Scrufboy:  There is more bad with the pass-through. Please test this yourself if you can.

First... The pass-through works both ways... You can input via the 3.5mm too. Then you would use the RCA as outputs. Just like the Aiyima A07. It is really only a Y cable. Not even a line out.

So here is the nail in the V3 coffin. I found out last night that the RCA and 3.5mm pass-through of the V3 are wired wrong and when another device is plugged into the V3, while conducting an isolated L-R stereo separation test, reveals the crossed signals. This error doesn't happen when you only use the RCA(or 3.5mm) input alone... But as soon as you plug something into the V3 for output... L-R tests reveal the cross-fed signals. When testing, the left channel will play and a reduced signal will play in the right channel too and vice versa. This should not happen. Fosi Audio obviously copied the original circuit layout of the Aiyima A07. The A07 also had this error in their first run... They did fix it... So they say...

For Shame Fosi! You will have to split your signal before your V3 and feed your secondary device that way. You cannot use the pass-through in the V3. The entire first run of this device is junk for anyone needing that pass-through to work as intended. Buyer Beware!

@Douglas_Blake_579 replies to @Scrufboy: It's not a cross feed ... the left and right channels are reversed.

@Scrufboy replies to @Scrufboy: @@Douglas_Blake_579 Actually, no... We have been testing alot lately and working with FOSI.

I took down my videos because they don't tell the whole story.

This effect only happens when you use one of these small subwoofer amps that sum the two channels for use as LFE sub out. It does not happen when you hook up. The 3.5mm to a subeeofers L & R channels.

But because the V3 does not have a true pre out, you get this crosstalk.

Other amplifiers like the A07 pro, when paired with a Fosi M-03 or an Aiyima A3001, they do not have this issue.

@Douglas_Blake_579 replies to @Scrufboy: @@Scrufboy
Largely because the Fosi and Aiyima pre-out are stereo jacks connected right across the RCA input jacks with no isolation whatsoever. If you plug in a mono cable you are effectively shorting the two channels together.

I rather suspect this started out as a secondary input, use one or the other, and someplace between design and marketing it got bastardized into being called an output.

@GK-vj9dz:  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.

@johnsealey5334:  Great review, checkout temple audio bantam/one for similar amps.

@christopherlawler3033:  I recently saw a dyno test & review of this amplifier on Williston Audio Lab's YouTube Channel . . .

It contains a single integrated circuit for its output topology. So I sincerely doubt that it will EVER achieve that kind of rated output power values regardless of speaker load/impedance. If you watch this video; you will notice that he could not even come near the rated maximum power output rating of 600W - even when using a 20 ampere laboratory-grade DC power supply set for 48V output... He was able to obtain actual power readings of about 93/91 watts RMS into 8-ohms, 108/105 (clipping/distortion) and 115/112 dynamic power (burst) into 8-ohms & 183/176 watts per channel RMS into 4-ohms @ 1%THD, 189/183 watts per channel driven to clipping/distortion and dynamic power (burst) of about 215/208 watts per channel into 4-ohms and even with that beefy lab-grade 20A power supply - it still only drew a measly 5 amperes of power consumption (probably due to internal current-limiting circuit protection).

@Douglas_Blake_579 replies to @christopherlawler3033: Search for "tpa3255 data sheet" ... the graphs and figures there are accurate and I can confirm from bench testing that it will do what they say.

@gershomg1537:  nailed it.

@Random-kq4pz:  Seems like there is no output speaker protection in this amp. If something goes bad in this amp will it output DC and fry the speakers? Ouch!

@poofygoof replies to @Random-kq4pz: won't the IC self-destruct long before hazardous power can be delivered to the speakers?

@Random-kq4pz replies to @Random-kq4pz: @@poofygoof No, the main power output stage of the amp can output dangerous voltage and current to the speaker if protection is not part of the amps design. No one seems to talk about this.

@Douglas_Blake_579 replies to @Random-kq4pz: The chip has built in protection.

Check the data sheet ... you'll see.

@stephenmcbride6359:  If you want a real hoot try a pair of Aiyinma A3001 200w mono blocks.I hadthe fosi V3 but wanted to dable (play) more. hence orgered the mono blocks on a lark.rated a 200 watts into 1 channel wirh a 32v, 5A power supply still means that it can only produce 160 watts, but that is only through one channel.This seems to take some of the load off and opens up for greater reolution and a larger soundstage(lol). Also with the flip of a second switch it becomes a dedicated subwoofer amp with controls going from 20-160 hz. This amp uses the same chips as the V3 and is priced at 89.00 Canadian or about 115.00 pouns for a pair. Try them out you will be pleasantly surprised. more so than with the V3.

@stephenmcbride6359 replies to @stephenmcbride6359: Hopefully this reply goes to the right place. You asked either how would I feed the mono blocks with only one audio signal, the answer being a y-adapter. I however have discrete outputs for each channel on my pre amp so this is not an issue. Cheers and I hope this helps.

@ianl.9271:  Some of my favourite opamps for audio in the order of preference.. OPA2228, OPA1612, LM4562, TL072, NE5532.

@ianl.9271:  The audiophile won't be able to stand the whine of the oscillator. Fortunately, I can't hear it.

@Douglas_Blake_579 replies to @ianl.9271: Nobody is going to hear 330,000 hz.

@cytowing3353:  Why do people add the wattage for each channel together and call that the total wattage. It is 300 watts per channel not 600 watts.

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Sunday October 29, 2023

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David Mellor

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Adventures In Audio.

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