• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 8 1.5%
  • 2. Not terrible (postman panther)

    Votes: 15 2.8%
  • 3. Fine (happy panther)

    Votes: 108 19.9%
  • 4. Great (golfing panther)

    Votes: 413 75.9%

  • Total voters
    544
This OPamp rolling to going totally through the sky in this thread, how can one make any sense out if it!
The sole value of this things is their cost.Nothing else.Nada.Zero.
Load them with stuff with absolutely no merit as op-amps/fancy cables/whatever and say a long good-bye to this value.
Or say good buy to the amps themselves when they fall into oscillation,cause every circuit is not designed around 4987938759 op-amps,but just one.

Have money to spare?Get a nicer amp and that's it.
 
I think it lets down the rest of their approach which is so constructive, listening to customers etc. One where four are needed (or two depending on interpretation) seems quite cynical.
Yep, they make no claims for any benefits from swapping op amps, no doubt because they can measure the results and haven’t detected any. However they are keen to sell a few to the sort of hifi customer who falls for power purifiers and directional interconnects.

The more that you pay, the more it is worth.
 
The sole value of this things is their cost.Nothing else.Nada.Zero.
Load them with stuff with absolutely no merit as op-amps/fancy cables/whatever and say a long good-bye to this value.
Or say good buy to the amps themselves when they fall into oscillation,cause every circuit is not designed around 4987938759 op-amps,but just one.

Have money to spare?Get a nicer amp and that's it.
I think the reason why we are interested in these 3255 based amps, is because of how much more you have to spend to get a 'nicer amp' (not getting into what qualifies as 'nicer').
 
The sole value of this things is their cost.Nothing else.Nada.Zero.
Load them with stuff with absolutely no merit as op-amps/fancy cables/whatever and say a long good-bye to this value.
Or say good buy to the amps themselves when they fall into oscillation,cause every circuit is not designed around 4987938759 op-amps,but just one.

Have money to spare?Get a nicer amp and that's it.
Totally 100%
 
Last edited:
I think the reason why we are interested in these 3255 based amps, is because of how much more you have to spend to get a 'nicer amp' (
How much?
Value proposition goes out of the window the moment you look to change components, specially something like opamps.

The amplifier which most of us here would qualify as ‘nicer’ amp doesn’t even use any fancy opamps!!!

not getting into what qualifies as 'nicer').
But you still used the ‘term’ ;)
 
How much?
Value proposition goes out of the window the moment you look to change components, specially something like opamps.

The amplifier which most of us here would qualify as ‘nicer’ amp doesn’t even use any fancy opamps!!!


But you still used the ‘term’ ;)
Probably something that measures just as high but has more functionality (bass management, tone control, equalization, etc.).

-Ed
 
How much?
Value proposition goes out of the window the moment you look to change components, specially something like opamps.

The amplifier which most of us here would qualify as ‘nicer’ amp doesn’t even use any fancy opamps!!!


But you still used the ‘term’ ;)

I think I am being "miss-quoted" a bit here ... I quoted the term "nicer" which is why I put it in inverted commas "" ...

I'm going to quote again though and use "most of us here" from yours :D

@Guddu I think you have an owners thread started over here ... https://www.audiosciencereview.com/...v3-mono-user-impressions-owners-thread.54043/ ;)

Let's have fun over there when the rest of us get some of these ourselves!
 
Probably something that measures just as high but has more functionality (bass management, tone control, equalization, etc.).

-Ed
I hear you….
But comparison always loose its meaning if we compare a power amplifier with an integrated amplifier.

Back to the topic of the thread,
Amir measured the amplifier as it comes from the store, who can tell what change opamp rolling may bring without a repeat measurement.
And whatever data is available so far (with other amps), it shows no benefits, not at least measured one.
 
I think the reason why we are interested in these 3255 based amps, is because of how much more you have to spend to get a 'nicer amp' (not getting into what qualifies as 'nicer').
I'm not going to write what I consider as nicer but in general and close to price something like this:

Fosi Audio Mono V2 amplifier Multitone measurement.png vs AUDIOPHONICS MPA-S250NC Class D Ncore Stereo Amplifier Multitone Distortion Measurement.png

Fosi Audio Mono V3 amplifier power 4 ohm vs frequency vs distortion measurement.png vs AUDIOPHONICS MPA-S250NC Class D Ncore Stereo Amplifier Power 4 ohm vs frequency Measurement.png

(link)

That's two of the most meaningful measurements.
Add better thermals,on board PSU,western certifications,longer warranty,ease of return/repair,etc.
 
Your owners thread I keep referencing here is excellent! :) I'm looking forward to posting my own highly subjective impressions :D
:D:D:D
Please do, I am looking forward to have participation there.
 
I'm not going to write what I consider as nicer but in general and close to price something like this:

View attachment 371116 vs View attachment 371115

View attachment 371117 vs View attachment 371118

That's two of the most meaningful measurements.
Add better thermals,on board PSU,western certifications,longer warranty,ease of return/repair,etc.
Yes okay. But again these 325* class D's are what have "upended" the market in my view. Really challenging how much we need to pay more to hear better.

And yes I am looking forward to participating.
 
Yes okay. But again these 325* class D's are what have "upended" the market in my view. Really challenging how much we need to pay more to hear better.

And yes I am looking forward to participating.
The one I posted (Hypex) costs $444.
I hope is now clear why one should not reach close or exceed this price.
 
The one I posted (Hypex) costs $444.
I hope is now clear why one should not reach close or exceed this price.
Yes - I understand your point of view and kind of agree. The game changing element is that the "price cap" for improved performance is getting lower - I wonder if we don't need to go better than the hypex you mention for a "really audible" improvement.

Even with measurements, I'd still like to listen to a Hypex. You see, my journey to this web forum, ASR was AFTER buying and listening to the little Aiyima A07, and deciding to look up why it might sound pretty good (which it did). And so I found Amir's review in my lookup.

From my point of view, even going to monos (for my efficient speakers) is overkill. I reckon that a higher performance balanced stereo unit for less, must surely be just around the corner. So audibly as good in most use case scenarios for $150. I don't like all the opamps in the Fosi ZA3. Nearly went down the DIY route with a Sylph.

I will see (listen / hear} in a couple of weeks!

Yes looking at your charts again referencing AUDIOPHONICS MPA-S250NC - keeping perspective on these add ons with things like opamps needed. I like the fact that the frequency response rolls off above 10khz too (from the review link)... and a single box! Need a balanced version because I'm using balanced phono pre... Cool!
 
Last edited:
I like the fact that the frequency response rolls off above 10khz too (from the review link)
Yes,that's another one,Hypex rolls off 0.5dB (most class D amps do,even Purifi) at 20Khz,Fosi has the opposite,a peak of 0.5 dB.

The most important thing though is as seen at the chart Hypex is completely load independent and Fosi has some dependency out of the audible range.
Fosi stated that improved that after the review but only measurements will tell us.

Measurements about op-amps was done here with the best conditions possible,a Purifi.
Even the slightest improvement would show if it was there.But it wasn't,it's so faint as much we can consider it measurement variation.
So...
 
I suppose internally balanced design is a good thing, but this means full potential is realized when feeding the amp true balanced signal. If using RCA input, one needs to upgrade THREE op-amps per mono. Six discrete op-amps, we are looking at around $500-600!
Just to try and rebalance this thread a little.

No, you don't need to replace (not upgrade) three op amps per mono.

Because you don't need to replace ANY opamps. As has been said many times here - especially on the op amp rolling thread, it is a pointless exercise offering nothing of any value for audio quality - almost certainly nothing even audible for anyone.
 
Last edited:
This is indeed a well done FAQ.

The answer to: "How are you synchronizing the TPA3255 oscillator between the monoblocks in order to avoid Class D "Beat Tones" ? " ,
should have been a simple and honest: "We don't.".

This is another reason why the Fosi V3 Stereo PFFB will be a superior value proposition for the average consumer in comparison to the Fosi V3 Mono.
@PlasticDoc

1. Are these "beat tones" present in all Class D mono-blocks?

2. Is the audibility of these beat tones theoretical or empirically verified?

3. If audible, what coloration would be introduced (if a generalization is possible)?

Thanks.
 
Last edited:
Sokel mentions - better thermals, yes - heat dissipation is easy to achieve but hardly any commercial or even DIY amps ever really deal effectively with what is a very important aspect. I understand Commercial resistance to dealing with this because it would drastically lengthen the life of components.

Internal PSU - why on earth would you want to put this inside the same chassis and risk interference with the circuit components?

Layout, component quality with ample operating headroom and good thermal dissipation negate the need for a longer warranty. Same reasons re. return and repair.

As someone who has always modded a lot of gear, especially caps and resistors in the signal path, some manufacturers make this 'possibly' deliberately difficult.

The fact that these monos have no volume control is a good thing. How often do you see manufacturers boasting about using an Alps Blue, as standard it seriously sits upon the sound, shunted with the right resistors it mostly disappears which is good thing.
 
Back
Top Bottom