Fosi Audio V3 Mono Amplifier Review

[mctron]

Very nice, would love to see a single box stereo version but one power brick for two amps is fine too I guess. Might be time to get all my vintage amps listed and out the door lol

 

[TonyJZX]

i keep thinking you want something like this

https://m.media-amazon.com/images/I/81uWsExXBXL._AC_SL1500_.jpg

so you can loose place two boxes on the front of your rack and have the CHONKY 48v 10a psu out the back

but yeah i'm guessing it'll come to a point where its $250 for 100w x 2

we now await their stereo one box solution... and the one coming from O-Noorus

 

[poodude]

I have a 2.1 setup for office use and would love to see a stereo version of this with a sub out and adjustable high pass filter out to the speakers. That would be killer as I don't think one exists in any sort of reasonable price or small form factor.

 

[Cal_Cobra]

I have a 2.1 setup for office use and would love to see a stereo version of this with a sub out and adjustable high pass filter out to the speakers. That would be killer as I don't think one exists in any sort of reasonable price or small form factor.

You mean like this?

Of there's this:

Personally I think they should all have some sort of bass management built-in.

 

[lxg208]

Fosi Audio V3 Mono Monoblock Power Amplifier

The V3 MONO is a monoblock high-power amplifier integrated with the Texas Instruments TPA3255 amplifier chip, suitable for speakers of 2Ω to 8Ω impedance. It implements Post-Filter Feedback (PFFB) technology, addressing the long-standing issue of load-dependency in Class-D amplifiers.

fosiaudio.com

look for:

View attachment 360762

Thanks, found it now. I zoomed the page and this part was hidden from me

 

[amirm]

These amps are so small that stacking them to get stereo is no big deal.

 

[JSmith]

If I didn’t know better I would think this is a well done April Fools joke. But Amir doesn’t joke!

Ah, but he does!

Sony Tapecorder 101 Review (Vintage Reel to Reel)

This is a review and detailed measurements of the Sony Tapecorder Model 101 vintage Reel to Reel tape recorder. My brother found it for me at a Goodwill store. The 101 was released in 1959 and retailed for 29,800 Japanese Yen (today's conversion and adjusted for inflation: $2,377). I must stay...

www.audiosciencereview.com

The V3 Mono is our first amp with PFFB implementation.

Good to see.

The V3 Mono is currently in production

So the unit Amir tested was a pre-production version?

Thanks to @amirm for testing this amp, it sure packs a punch for a small chip amp.

JSmith

 

[Mike-48]

During the period we sent the set to Amir for testing, our R&D team did not stop optimizing the V3 Mono, and we have now further improved its frequency response curve. Below is the chart for your reference.

I think that is a big improvement. My impression has been that treble peaks, even if outside but near the audible range, can harden the sound and cause more irritation. Do I have objective data? No. But I am delighted to see that Fosi has eliminated that as a possibility.

 

[Ismapics]

Just read this from the company in their message to me when the amp was sent:

"We'll provide a bundle including two V3 mono amps and a 48V/10A psu for no more than 260USD. That single 48V/10A psu can power the two sets of v3 mono simultaneously."

Hello: are the amps ever tested for power output using pink noise?

 

[poodude]

You mean like this?
View attachment 360763
Of there's this:
View attachment 360764

Personally I think they should all have some sort of bass management built-in.

Woah, why yes, just like the DTA-100ST. A Fosi bass management version would be amazing.

 

[JDS]

About 70 cents per watt for performance that is provably indistinguishable from the state of the art.

Glad I'm not in the high-end amplifier business.

 

[CedarX]

What I find surprising is that the key ingredient, the TPA3255 chip from TI, has been around for… 8 (more?) years. Why did it take so long for somebody to figure out the successful recipe?
Kudos to Fosi Audio for listening to the users, and applying good engineering rather than chasing some esoteric BS audio paradigm.

 

[Urib]

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/

Back in 2019, when I bought my amazing Topping D90 I wrote them few emails that this is what I and the market are looking for. Since than they repeatedly produced various similar DACS and desktop amps with no remote....

 

[Doodski]

Ah, but he does!

Sony Tapecorder 101 Review (Vintage Reel to Reel)

This is a review and detailed measurements of the Sony Tapecorder Model 101 vintage Reel to Reel tape recorder. My brother found it for me at a Goodwill store. The 101 was released in 1959 and retailed for 29,800 Japanese Yen (today's conversion and adjusted for inflation: $2,377). I must stay...

www.audiosciencereview.com

Good to see.

So the unit Amir tested was a pre-production version?

Thanks to @amirm for testing this amp, it sure packs a punch for a small chip amp.

View attachment 360766


JSmith

I gotta admit I'm baffled at the power handling of that IC!

 

[Doodski]

What I find surprising is that the key ingredient, the TPA3255 chip from TI, has been around for… 8 (more?) years. Why did it take so long for somebody to figure out the successful recipe?
Kudos to Fosi Audio for listening to the users, and applying good engineering rather than chasing some esoteric BS audio paradigm.

Maybe they finally provided the necessary heatsinking for this power output?

 

[Billy Budapest]

I see the opamps are swapable. However, it doesn’t look like there is enough space for the boutique discrete opamps that audiophiles believe influence sound quality. I wonder if any other conventional opamps would offer better measured performance?

 

[Doodski]

I see the opamps are swapable. However, it doesn’t look like there is enough space for the boutique discrete opamps that audiophiles believe influence sound quality. I wonder if any other conventional opamps would offer better measured performance?

If one imagines reallllly hard of course. LoL...

 

[Golf]

I am not showing the sides of the amp

I believe I can imagine why.

 

[dtaylo1066]

If I didn't have about 6 Hypex UCD 180 modules in my closet I would just by two or four of these.

 

[JSmith]

I believe I can imagine why.

Many holes... I gather cooling will not be an issue;

JSmith