Fosi Audio V3 Mono Amplifier Review

[ocinn]

Amazing, however still handily beat by the 3E audio boards as measured.

Wonder what the 3E guys know that fosi does not yet.

 

[Petevid]

Very impressive amp, if only it had a trigger in and out capability. A pair of these and a Wiim Pro plus with the Wiim remote to power up, control volume and select inputs would be a sweet combination.

Edit: Just noticed the auto option on the power on/off switch on the front panel. Does this auto detect an incoming signal and switch on and switch off again if no signal is present?

 

[SMen]

Amazing, however still handily beat by the 3E audio boards as measured.

Wonder what the 3E guys know that fosi does not yet.

I think probably difference in gain, and the provision of DIP8 makes the difference - or substantially explains it.

 

[Bachemar]

I would like a gain control like e.g. the Topping P5 has. Using them in a active system, a volume knob is useful. Otherwise, awsome .

Historically it was not uncommon to include gain control on power amps, often pr. channel, like my old Kenwood L-1000M. This is useful for gain staging and when running them as part of active system. Agreed not all has, but the Topping PA3/5/7 does, which is a main competitor. Also when used with a DAC without volume control, a knob on the front here would expand it's usefulness.

In a monoblock amp? How would you manage channel imbalance?

 

[ocinn]

I think probably difference in gain, and the provision of DIP8 makes the difference - or substantially explains it.

Essentially the same gain (0.64db more on the Fosi).

Must be something else. 3E has much better load dependency, multitone, two tone multi, significantly better power:THD-N behavior, much better freqower plot, and better reactive load performance. If only they offered them in a pre-built plug-n-play enclosure.

 

[dagfinn]

In a monoblock amp? How would you manage channel imbalance?

Using two. Several ways to handle balance.

 

[SMen]

Essentially the same gain (0.64db more on the Fosi).

Must be something else. 3E has much better load dependency, multitone, two tone multi, significantly better power:THD-N behavior, much better freqower plot, and better reactive load performance. If only they offered them in a pre-built plug-n-play enclosure.

Yes ... in ones like Fosi's ... or bigger with power supplies ... or if someone like audiophonics would offer the pre-drilled kit at a decent price...

I wonder though if switchable RCA / balanced option affects the measurements too.

 

[JSmith]

Seriously?

JSmith

 

[Ze Frog]

Seriously?

View attachment 361058


JSmith

Likely people angered by buying something far more expensive that offers nothing over this, or in many cases is put to shame by it. The kind of cultist's who will defend a purchase with more vigor than their own kids. Lol, we need a reboot of the Taken franchise where Liam Neeson play's an audiophile.

 

[somebodyelse]

Seriously?

View attachment 361058


JSmith

You've been around long enough to know that there are always a few - just like those voting 'great' for the expensive things that measure badly.

 

[TonyJZX]

Seriously?

View attachment 361058


JSmith

this is the guy who built his own TPA3255 amp and bolted it to an old cookie tin and operates it with an xbox 360 controller and reckons everyone else should do the same

i think in reality this thing has the market by itself... granted the market for monoblock tpa3255s isnt big but also... $250 isnt a whole lot of money...

i didnt blink spending many multiples of this for amps that didnt perform as well, nor did it have the reliability... looking at you Marantz...

 

[Kimbrough Xu]

Something to do with the browser flavour - Chrome fails to display the Fosi home page and other pages correctly (at least on this laptop!); Firefox + its derivatives seem to show all pages correctly but still missing the early bird discount link !!

However, using Firefox on an Android tablet both the "early bird discount form" and the "support us on Kickstarter (Pending)" tabs were showing. Not confident that the discount form was actually sent, or maybe sent several times.

Obviously a difference between mobile and PC web pages but please sort out these software bugs!!

Looks like Fosi changed the page, just one button to subscribe now. https://fosiaudio.com/pages/monoblock-power-amplifier-v3-mono

 

[Kimbrough Xu]

No doubt there will be one or equivalent going forward, great leaps in quality seem to be what these companies do so well. In 10 years time, imagine, manafacturers are really going to have to kick it up a notch.

What amazes me is how a company like Fosi Audio actually listens to customer feedback and implements high quality parts that big companies charging big money wouldn't bother with. I was skeptical to a degree, but after seeing this review and heading to their website I was actually quite impressed.

Yes, few companies want to talk to their customers nowadays, I bought lots of products from many brands, but I have never talked to them so close.

 

[DanielT]

Essentially the same gain (0.64db more on the Fosi).

Must be something else. 3E has much better load dependency, multitone, two tone multi, significantly better power:THD-N behavior, much better freqower plot, and better reactive load performance. If only they offered them in a pre-built plug-n-play enclosure.

But it seems that Fosi is still developing the V3 Mono, see #14 of this thread:

The V3 Mono is our first amp with PFFB implementation. 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.


That in itself is good but it can also be potentially bad. The desire and ambition on Fosi's part to improve is of course good. The potentially bad thing is if you buy an amp that seems to be in the development stage does the durability test, on the amp iteration you buy, really been tested under tough and long-term conditions?
I haven't read all the posts in the thread so this aspect may have already been covered?

Anyway, it made me think of my father's advice: Never buy the first year model of a new car because they can have childhood diseases.
(with a new amp, the first few months of a new amp model?)

In any case Fosi Audio V3 Mono is very good amp for the money I must add though. You can assemble 3E yourself. Not everyone wants to do that.

Audiophonics assembled ready to use 3E amps with built-in power supply that they sell for €499.00 tax incl. To compare with 2 x US $139.99 + external power supply that the Fosi Audio V3 costs.

AUDIOPHONICS AP300-S2503E Power Amplifier 3E AUDIO 260-2-29A PFFB

The Audiophonics AP300-S2503E is a stereo power amplifier featuring a 3e Audio PFFB amplifier module. This enables it to develop 2x250W of power under 4Ω while delivering exceptional sound quality, combining precision and dynamics.

www.audiophonics.fr

 

[Golf]

Seriously?

View attachment 361058

Well, there may be people how who know better about that device than reading this thread only.

 

[Ze Frog]

Yes, few companies want to talk to their customers nowadays, I bought lots of products from many brands, but I have never talked to them so close.

Yeah, this is definitely something that companies like Fosi and WIIM excell at, there's not many companies in this world that are so customer focussed. Let's just hope as they grow they maintain this and don't fall into the standard set by others.

It's incredible, the kind of customer service and feedback with these companies is something you would have gotten from a few boutique brands usually selling rather pricey equipment, I think that's part of the magic of these companies really.

 

[CedarX]

Edit: Just noticed the auto option on the power on/off switch on the front panel. Does this auto detect an incoming signal and switch on and switch off again if no signal is present?

I believe that’s how it works and although it is totally irrelevant for the performance aspects, it can be important functionally: my experience with these auto-power is that they tend to turn the amp off during quiet music passages, which is (very!) irritating… It’s a fine balance between setting the right thresholds (what is “no (analog) signal”? Is the “on” threshold the same as the “off” threshold?) and right timers (do you power “on” immediately? How many ms is “immediately”? How long do you wait with “no signal” before powering “off”: 1, 5, 10mn ?)

A 12V trigger is much more reliable, but brings other complications…. Or you leave it on most/all the time, which becomes more and more environmentally incorrect (even if largely inconsequential for a class-D amp).

Anyway, Fosi gives you the choice to use that feature or not, which is always good!

 

[Overseas]

Not clear to me what power source is included in the FOSI standard package, whatever the price ?
Or is it separate option and cost ?

 

[jooc]

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.

-----------
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/

Do people usually use monoblocks with a pre-amps of some sort where they actually adjust volume?

I imagine people usually set both monoblock amps at top volume, and then actually adjust the volume via a remote control streamer/pre-amp? Or how do you make sure volume is equalized on both channels?

Thanks, sorry for the dumb question.

 

[Guddu]

Do people usually use monoblocks with a pre-amps of some sort where they actually adjust volume?

I imagine people usually set both monoblock amps at top volume, and then actually adjust the volume via a remote control streamer/pre-amp? Or how do you make sure volume is equalized on both channels?

Thanks, sorry for the dumb question.

A pre-amp, DAC with Volume Control, AVR (pre-outs) or even source can be used to control volume in case of any power amplifiers (monoblock or stereo) with or without volume control (you can set the volume knob to max and leave, if the amp has one).