Fosi Audio V3 Amplifier Review

[PlasticDoc]

Looks like there is a new V3 (Mono) coming soon with PFFB support !!

Amplifier - V3 Monoblock with PFFB Implementation is Coming!

We know many of our fans are waiting for this monoblock! We'll post updates about this amazing amp in this thread. Jan 25 Update: Let's take a glance at some measurements first PFFB technology was implemented and load Independence was achieved! SINAD March 21 Update: April 1 Update...

community.fosiaudio.com

And a SINAD score > 100
Mono block support first - then a new V3 stereo model

"Efficiency is doing the thing right. Effectiveness is doing the right thing." - Peter Drucker

It looks like Fosi Audio is finally entering the "Effectiveness Phase". Hats off to Fosi.

But, and this is a big but, the model to look for will be the Fosi V3 PFFB STEREO.

Two notes:
a) SINAD: a SINAD of 100dB, even with XLR inputs only, will be very difficult to achieve; with RCA inputs it would already be very good to have values higher than 94dB.
b) Total power (watts RMS): it's to be expected that the V3 PFFB STEREO will be slightly less powerful than the normal V3, but this is perfectly acceptable given the price/performance ratio.

 

[PlasticDoc]

I can already imagine this V3 PFFB matchbox shaking the Larsen 4.3 speakers down to its almost 20Hz bass.

 

[mike70]

I like the monoblock for a very simple and (I think) very important reason: no volume potentiometer. Why?

Because really good analog volume potentiometers are very expensive and when you look at the price tag and read some opinions: "i hear imbalance in channels", "some noise moving the volume", etc etc. Cheap potentiometers lowering SQ.

So, we remove the analog potentiometer and we can have a hell of amplifier at that price.

My opinion.

 

[guy48065]

I'm content just keeping the V3 volume knob at 100% so the signal doesn't go thru that low-spec resistive element.

 

[mike70]

I'm content just keeping the V3 volume knob at 100% so the signal doesn't go thru that low-spec resistive element.

It doesn't go? ... I understand 100% volume is better than at the 20% ... but, the best is no potentiometer at all, in other way the signal isn't bypassed internally.

The mono doesn't have that problem and stereo needs the volume bypass (as Aiyima implementation).

 

[guy48065]

It doesn't go? ... I understand 100% volume is better than at the 20% ... but, the best is no potentiometer at all, in other way the signal isn't bypassed internally.

The mono doesn't have that problem and stereo needs the volume bypass (as Aiyima implementation).

Correct--doesn't go. At 0 & 100% the pot wiper rests on the solid pads at the end of the resistive arc.
True--it IS another connection that will eventually get dirty and start to sound scratchy. 10 years or more. At that point if I'm still using it (not likely) I'll solder a jumper across the pot.
Then it'll be just a power switch.

 

[grogi.giant]

It doesn't go? ... I understand 100% volume is better than at the 20% ... but, the best is no potentiometer at all, in other way the signal isn't bypassed internally.

The mono doesn't have that problem and stereo needs the volume bypass (as Aiyima implementation).

The audio signal does not go through a potentiometer. Potentiometer is used to control analogue (op-amps or transistors) or digital (exp. NJW1194) volume control circuitry.

 

[guy48065]

The audio signal does not go through a potentiometer. Potentiometer is used to control analogue (op-amps or transistors) or digital (exp. NJW1194) volume control circuitry.

Everything is behind the volume pot. There are no buffers on the inputs. It is impossible to overdrive the input.

I took this to mean the analog signal goes from the RCA inputs straight to the volume pot, then to the op-amps.

 

[mike70]

The audio signal does not go through a potentiometer. Potentiometer is used to control analogue (op-amps or transistors) or digital (exp. NJW1194) volume control circuitry.

sometimes we're too much technical ... change what i said for "volume control device", i'm not an electronic engineer, but i know that analog volume control is costly to do it right ... and if you have an entire amplifier at 100 usd, maybe your volume control isn't one of the very good ones.

Maybe is more clear in that way, if not, it's ok, we can go ahead with the thread.

 

[TurtlePaul]

There is a teardown of the V3 on the front page. The signal very much goes through a 2-gang pot. Where is there a digital volume control IC? I don’t see it.

 

[TurtlePaul]

I took this to mean the analog signal goes from the RCA inputs straight to the volume pot, then to the op-amps.

I am fairly confident that what grogi said is not true.

 

[grogi.giant]

I am fairly confident that what grogi said is not true.

You're right, I was wrong.

 

[colombiamgold]

Hi forum

I just want to know...if the pre/sub out its been used to connect to a sub....the mains out of the amplifier continue to provide a full range signal to the speakers?

if the sub have a variable loss pass filter that can be adjust from lets said 40hz to 300hz..the other 2 channels continues to receive the full 20-20.000 signal? or its just adjust to the frequency that the pre/sub outputs setups and get its from 300hz up??

thanks

 

[grogi.giant]

I just want to know...if the pre/sub out its been used to connect to a sub....the mains out of the amplifier continue to provide a full range signal to the speakers?

Yes

if the sub have a variable loss pass filter that can be adjust from lets said 40hz to 300hz..the other 2 channels continues to receive the full 20-20.000 signal?

You will need to set the crossover frequency on the sub in a way that it kicks in when the speakers stop playing. Let's say your mains have -3dB at 42Hz - you set the sub crossover to 42Hz...

 

[carlo]

Interested to this V3 for an old pair of Mission 760 still working fine but needing an amp. As I would like to have bluetooth functionality which V3 doesn't have, I've seen that the model BT20A pro is based on the same chip. Are they comparable sound wise or - should the V3 be considered definitely better - is it possible to add an external bluetooth module to it?

 

[Zek]

Look reviews, and compare

 

[Talisman]

Interested to this V3 for an old pair of Mission 760 still working fine but needing an amp. As I would like to have bluetooth functionality which V3 doesn't have, I've seen that the model BT20A pro is based on the same chip. Are they comparable sound wise or - should the V3 be considered definitely better - is it possible to add an external bluetooth module to it?

From the amplifier's point of view it is extremely unlikely that you will be able to hear any kind of difference.
It should be noted, however, that the Bluetooth of the bta20pro does not have LDAC, so you could also think of a V3 combo with LDAC receiver (for now LDAC receivers are around 40/50 euros)
Make your own assessments. But whichever of these solutions you choose there will be no day/night difference

 

[Tio]

I have Wharfedale Diamond SX subwoofer which has speaker level and line level input and output.

Is it safe to connect the speaker out from Fosi V3 to the subwoofer speaker in and then from the subwoofer out into my stereo speaker? I read somewhere that is it not safe to do that if using class D amplifier. Thanks.

 

[carlo]

From the amplifier's point of view it is extremely unlikely that you will be able to hear any kind of difference.
It should be noted, however, that the Bluetooth of the bta20pro does not have LDAC, so you could also think of a V3 combo with LDAC receiver (for now LDAC receivers are around 40/50 euros)
Make your own assessments. But whichever of these solutions you choose there will be no day/night difference

Thank you for your suggestion. I didn’t know about the existence of Ldacs…. Is there a dac inside? I just need to connect one of them to the amp via rca? Thanks

 

[IndieSynth]

I'm curious how much load dependency could be impacting my system. My V3 feeds a pair of Diamond 12.2, which I think would be impacted to some extent. Is there a way of compensating for load dependency with EQ to see if I can tell the difference?