Fosi Audio V3 Mono Amplifier Review

[mike70]

I have some years on this hobby (since 70s) and i never (never) saw any offer in this audio world of brand new monoblocks with 100 wats in 8 ohms / 200 watts in 4 ohms at this level of performance and features (balanced / auto power on) at 300 USD per pair.

Done.

I'm really grateful to today audio tech, that allow us to get the "hiend" sound at peanuts prices considering what we have to pay for in the "consagrated" brand names.
Also consider the power and quality of the pricier offerings (purify / hypex) ... they're also peanuts prices against accuphase, mcintosh, whatever.

And i think that's the great moral behind this amps. Enjoy music, now you can have the electronics performance you dream without a CEO position at your work.

... and wait for speakers ... is the next victim.

 

[rsqt]

Sinad is a point at 1kHz only. Looking at 5-15kHz the V3 mono is not really better than an Aiyima A07 regarding THD+N. This is not good and not high fidelity.
I have several V3 mono but max up to 500Hz/24dB. Up to that point it sounds really great and at 2kHz it is down 48dBs when THD+N risis.

 

[Old_School_Brad]

Sinad is a point at 1kHz only. Looking at 5-15kHz the V3 mono is not really better than an Aiyima A07 regarding THD+N. This is not good and not high fidelity.
I have several V3 mono but max up to 500Hz/24dB. Up to that point it sounds really great and at 2kHz it is down 48dBs when THD+N risis.

And here is a Yamaha A-S701.

 

[rsqt]

I run the four V3 monos at 2 ohms and from 500Hz I have something as LA90.

Yamaha is not really a gamechanger. Not much better than A07. I do not know if you can clearly hear a difference in a non "damped" room.
But everybody can buy what he "needs".

For bass (esp. at 2 Ohms it is a hammer) and mids for this low price it is perfect.

 

[mike70]

our ears are less sensible to distortion at high and low frequencies ... that's one of the secret keys about "magical" properties in amplifiers, even tube ones, generally the objectively worst amplifiers by far.

 

[transformer-coupled]

This is a review and detailed measurements of the Fosi Audio V3 Mono class D amplifier. It was sent to me by the company. The price with the power supply I tested is US $139.99.
View attachment 360697
I must say the concept of a "monoblock" amplifier in such a small size runs foul of any expectation a longtime audiophile would have! But monblock it is even though it is a very small block. Controls are on/off/trigger audio and selection of XLR vs RCA inputs -- just like the big boys! I am not showing the sides of the amp but there are very large holes with attractive orange color grid showing through. Nice. Back panel is again a bit of a shock to the system seeing XLR input:
View attachment 360698

The power supply as noted, is quite beefy with 48 volts at 5 amps on tap (240 watts). The amplifier is stated to have PFFB implementation which for a class D amplifier means it should have no load dependency together with lower distortion. Let's see if we get these with our measurements.

Fosi Audio V3 Mono Amplifier Measurements
Let's start with XLR input:
View attachment 360699
Wow, I did not expect this class of amplifier to break through the 100 dB SINAD barrier but the V3 Mono does exactly that, placing it in our prestigious category of "excellent:
View attachment 360700
View attachment 360701

RCA input costs you some performance but I was relieved to not see any mains interference:
View attachment 360702

Distortion is still at provably inaudible -115 dB. I like that the gain is nominal 25 which is my new recommendation for amplifiers.

Noise performance is excellent and at full power, darn near approaches sate of the art:
View attachment 360703

Now the all important frequency response and load dependency test:
View attachment 360704

There is essentially no impact up to 20 kHz between the 4 and 8 ohm indicating very low output impedance, albeit with a bit of peaking. Compare that to non-PFFB amps such as Fosi Audio V3 stereo Amp:

Above we have 2 dB differential at 20 kHz.

Distortion is very low and only increases with frequency:
View attachment 360706

View attachment 360707

Let's see how much power we can get out of this little box:

View attachment 360709

View attachment 360710
Efficiency must be quite high as we get essentially the power we put in (the power supply likely has some headroom).

There is decent amount of power even with 8 ohm and with very low noise:
View attachment 360712

As note though, distortion does rise at higher frequencies:
View attachment 360713

Fortunately it is good where our hearing is very sensitive (below 5 kHz).

I also threw my suite of my punishing reactive loads at it:
View attachment 360717

Translating into watts:

View attachment 360716

Amazing that this little amplifier can handle even 2 ohm load! Note that these are short term power ratings.

There may be a bit of power on noise:
View attachment 360718

Conclusions
All I can say is wow! It is incredible how far these small amplifiers have come. It is the result of a manufacturer listening to our needs, implementing features such as balanced and trigger inputs, and proper feedback mechanism to essentially eliminate load dependency. I can't imagine asking for more from Fosi when it comes to such an amplifier. Everything is as good as you could possibly want.

It is my pleasure to recommend Fosi Audio V3 Mono amplifier.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Great perfect review as always Amirm, my friends says it sounds amazing, wish the competitors @3eaudio would make for next model a true audiophile monoblock no fake mono stereo with volume for use our personal taste line stage, no always on auto off that make it suddenly blackout at low volume night late listening, just like the great this V3 Mono blocks by Fosi with its high current real monoblock no-autooff no-volume... but with the higher THD performance of @3eaudio , wish some engineer at @3eaudio listen our prays for next version

 

[mike70]

Audible distortion? Easy, go to

Listening Test

www.klippel.de

When I took the test I was surprised, I can bear much more distortion than I thought. And I think is the general case ... and one of the hidden reasons behind "hiend" audio.

Add the placebo effect with jewelry to the eyes and you can buy a 10 k USD component as "magical" sound.

 

[RickS]

Trolling a review thread has ramifications for all…

Help avoid a mass cleanup effort for the staff and report offenses early and often. Post deletions and a thread ban have been issued.

Thanks in advance!

 

[NeLey169]

Does the Fosi v3 mono overheat like the reviewers say? I'm afraid it will affect the durability of the amp.

 

[antcollinet]

Does the Fosi v3 mono overheat like the reviewers say? I'm afraid it will affect the durability of the amp.

No - it has an operating temperature of around 40 to 45C (this is what people are saying is "overheating")

Probably much lower than your average class AB amp, and well within the operating temperature range of internal components.

 

[Mr_RGB]

For those obsessed with heat dissipation, I wonder if anyone has tried flipping the amps upside down and attaching an external heatsink directly on top of the case where the heat transfer plate presses against the case? I'm not saying this is needed, but this seems better than attaching a passive heatsink on the top of the case on the opposite side from where the heat plate interfaces with the case.

 

[arancano]

For people like us, we like the fact that we can roll different op-amps and experiment with the sound. It’s like ordering a custom-tailored suit rather than just buying off-the-rack. Same reason I love my Schiit Freya+, because I was able to tune the distortion to my liking by rolling tubes.

-Ed

I would like statements to the effect that op amps don't make a difference to end with whether subjective listening was done or not, and the op amps were Sparkos, and op amps 2 and 3 were both replaced. Amir's impeccable reviews were flawed in this case in that, so far as I can tell, he replaced only one op amp, albeit on Fosi's recommendation. I think that, in this particular case, following his guidance is not warranted.

I have the monos with Sparkos op amps in positions 2 and 3. Only 2 out of the 17 individuals in my audio club could not tell a difference, subjectively of course. On blind listening, the average value for the amp they were listening to was $1,700. Two amps @ $280 plus four Sparkos @ $60 adds up to $520. I'd say that the V3 monos are a great deal against the perceived value of the amps based on sonics. At least, a reasonable case can be made for it.

 

[Owis]

I have the monos with Sparkos op amps in positions 2 and 3. Only 2 out of the 17 individuals in my audio club could not tell a difference, subjectively of course. On blind listening, the average value for the amp they were listening to was $1,700. Two amps @ $280 plus four Sparkos @ $60 adds up to $520. I'd say that the V3 monos are a great deal against the perceived value of the amps based on sonics. At least, a reasonable case can be made for it.

Are you saying the blind listening was between 2 x V3 Mono with Sparkos op amps versus 2 x V3 Mono with stock amps

Or between

2 x V3 Mono with Sparkos op amps versus an amp with average value of $1700?

 

[Lux_ury]

What happened to Ed?
Anyhoot I'm in discussions with fosi getting a new dc filter. They want proof on there promise to me ! Back in September 2024. Let's see what decisions they make?
Rolling amps still a thing LOL.

 

[JohnnyNG]

RCA is 25kΩ, and for XLR, it is 5kΩ.

https://support.fosiaudio.com/hc/en-us/articles/33330075531161-What-is-the-input-impedance-of-the-V3-Mono

Link is dead now and I can't find the info on the Fosi site. Has anyone measured this?

 

[saberger0357]

Link is dead now and I can't find the info on the Fosi site. Has anyone measured this?

https://audiosciencereview.com/foru...o-v3-mono-amplifier-review.53474/post-1945385

 

[JohnnyNG]

https://audiosciencereview.com/foru...o-v3-mono-amplifier-review.53474/post-1945385

Thanks. I saw they’d mentioned it in this thread early on but since they removed it from their FAQ I wondered if it had changed or been tested.

 

[Xenio]

Hello,

I'm looking for a power amp that can handle without any problems a 2 Ohms load. My power requirements are not that high, I just need something reliable that handle such annoying load.

So this Fosi v3 mono looks good, but I did see a *lot* of people having reliability issues with their mono v3 and even Fosi aknowledging it. And knowing that 2 Ohms load are more "hard" on amplifier due to higher current output ...

Is it fixed ? It would be great, because it's twice cheaper than buying a NC502MP-based power amp which is the next cheapest good power amp that handle 2 Ohms without problems I've found yet, but I'd rather shell out more money and have peace of mind.

 

[Roland68]

Hello,

I'm looking for a power amp that can handle without any problems a 2 Ohms load. My power requirements are not that high, I just need something reliable that handle such annoying load.

So this Fosi v3 mono looks good, but I did see a *lot* of people having reliability issues with their mono v3 and even Fosi aknowledging it. And knowing that 2 Ohms load are more "hard" on amplifier due to higher current output ...

Is it fixed ? It would be great, because it's twice cheaper than buying a NC502MP-based power amp which is the next cheapest good power amp that handle 2 Ohms without problems I've found yet, but I'd rather shell out more money and have peace of mind.

3e Audio A5, A7 and A7 Mono are 2 ohm stable, A5se and A7se only go up to 4 ohm.

 

[Audionaut]

looking for a power amp that can handle without any problems a 2 Ohms load

If it is to be a power amplifier based on TPA3255, you just have to make sure that it uses one TPA3255 for each channel, then they are load-stable up to 2 ohms.

Otherwise, buy a good PA amplifier.