Fosi Audio V3 Mono Amplifier Review

[anphex]

Nice little amp. But what about thermals? I don't see any vents in there. Is the body full metal?

Also this is probably me being picky but doesn't this amp bring along all old Class D child ilnesses we have fixed in this day and age?

 

[timiambeing]

I get the discount box and I'm UK based.

Just found out why, the iPad shows a different version of the page concerned, there are problems with layout and some sections are missing - loaded on the Mac and everything was there… something to check @Fosi Audio ?

 

[Yorkshire Mouth]

Nice little amp. But what about thermals? I don't see any vents in there. Is the body full metal?

Also this is probably me being picky but doesn't this amp bring along all old Class D child ilnesses we have fixed in this day and age?

Vents on the sides.

 

[Zek]

I don't see any vents in there.

They are located on the sides.

 

[JeremyFife]

Really nice looking (measuring) wee amp, and tremendous value. Looking forward to seeing how it performs in the wild, in real use.

One question: what's the thinking on stacking these? @amirm has commented that they are stackable and some of the promotional pictures show that too. Any concerns about overheating (appreciate that there's no practical experience possible yet)

I keep an eye on this end of the market for the time when my PA5 (original, repaired, doing very well now) finally dies. It's an odd choice now between Hypex, or these.
Hugely interested that @restorer-john has commented a couple of times without calling these 'toys' . It's looking good.

 

[Doodski]

Also this is probably me being picky but doesn't this amp bring along all old Class D child ilnesses we have fixed in this day and age?

Like what?

 

[PlasticDoc]

The V3 Mono is our first amp with PFFB implementation.

Good design (it closely follows the 10 principles of Good Design by Dieter Rams), good build, very good price.

You have a winner.

Waiting for the stereo version. I know that it will be harder, but not impossible.

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.

Regarding the TI PFFB implementation, it seems that most implementers read the 2018 TI paper SLAA788A.pdf (mostly by Dan Kisling) and forget to read the original 2016 paper SLAA702.pdf (mostly by Matthew Beardsworth), which has some valuable tuning insights regarding IMD, Gain Compensation and Zobel network (loudspeaker impedance issues).
It seems that 3e Audio has not missed out on either paper.
Fosi seems to be a fast learner.

 

[anphex]

Like what?

Load dependency and high frequency distortion

 

[Golf]

We must not forget the most important question:

When flipping down both front panel switches at the same time, will the backside of the device keep residing at the table?

 

[Yorkshire Mouth]

How do 2 of these compare with stereo balanced amplifier, Topping PA5 II (about US$250 now)?

In other words, which is the better option, for which use case.

Thanks.

I have a feeling that commentary will be moved outside of the review thread. So wanna start a new thread?

Here you go:

New Fosi Audio V3 Mono vs Topping PA5 II vs Topping PA7 (inc. 'Plus' versions)...and Aiyima A70

Someone in the new Fosi thread said a new thread would appear to compare models, so here it is. Links to Amir's reviews of the three: Fosi Audio V3 Mono Topping PA5 II Topping PA7 Aiyima A70 Prices are V3 Mono $260 (pair), PA5 II Plus $290, PA7 Plus $550, Aiyima A70 $220. Does the V3 match...

www.audiosciencereview.com

 

[daniboun]

I guess. I'd prefer 2 power bricks, as increased load in one channel can affect the other channel performance, not quite mono-block anymore.

Yep. And guys keep in mind that a real dual Mono amp has its own PSU per block. Splitting the 48/10A PSU is not a good idea for me....

 

[MCH]

Thanks for the review.
@amirm have you had the chance to experiment with the audio sense feature? Is it sensitive enough?
Monoblock without trigger input, if the auto on doesn't work properly it would be a cosmic fail. But if it does, this little amp is perfect!

 

[Doodski]

Load dependency and high frequency distortion

You must read the review! LoL... Naughty!

 

[Doodski]

Yep. And guys keep in mind that a real dual Mono amp has its own PSU per block. Splitting the 48/10A PSU is not a good idea for me....

I agree from a purist viewpoint. Perhaps @Fosi Audio has some words of wisdom to contribute<?>

 

[daniboun]

Good design (it closely follows the 10 principles of Good Design by Dieter Rams), good build, very good price.

You have a winner.

Waiting for the stereo version. I know that it will be harder, but not impossible.

Stereo version should be promising )
Now, to be honest I would wait for the O-NOORUS D1 PFFB Stereo amp with :
- PRE OUT
- Subwoofer
- Volume Control Potentiometer / Bypass mode
- Tone Control (bass / treble) / Tone bypass
- Remote control
- Digital front panel display


The TPA3255 PFFB amp war has been launched)

 

[somebodyelse]

Load dependency and high frequency distortion

@Doodski already addressed the load dependence, although it seems fosi have improved it further - good in that it's improved, but bad in that the review is no longer representative of the production amp. The HF distortion seems to be a general TPA3255 problem as others like the 3E behave similarly. I'm not too worried by that though - the harmonics are mostly ultrasonic by the time the levels start to rise.

 

[Toku]

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.

The PFFB technology used by Fosi has been around for a long time. However, due to patents, this technology could only be used by certain manufacturers. Therefore, even TI, which developed the TPA3255 chip, was not allowed to provide technology using PFFB.
However, that patent expired about three years ago(?), and anyone can now use PFFB. However, each company had been manufacturing products without PFFB for a long time, and it was difficult to incorporate PFFB right away.
I have been proposing to various companies to adopt PFFB because even after the patent for PFFB expired, no products using PFFB were released. As a result, Fosi's first product is the V3 Mono.
Even though the technology was well-established, it was still unknown to the company, and it must have been difficult to incorporate it into their products for the first time. However, the number of products that use PFFB should increase in the future.

 

[Hiten]

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.

If it was fine tuning inductor and component values, shouldn't it be done in the first place already ? Can you please share technical details how this was improved ? What are the chances of re-reviewing final version ?
thanks and regards.

 

[Multicore]

Mono input? So I have to use a separate 2:1 summing mixer?

 

[staticV3]

Mono input? So I have to use a separate 2:1 summing mixer?

Usually, you'd buy two Mono blocks, one for each channel.

If you want to listen in Mono only, then a single V3 Mono would suffice, and in that case, downmixing to mono would be a smart thing to do.