Fosi Audio V3 Mono Amplifier Review

[EddNog]

SMSL D6 or Topping E50 are amongst the lowest cost balanced output DACs

Do their volume controls work well? I had an SMSL DO100 a while back and the volume control wasn’t usable because of the insanely loud clicking/popping noises between tracks whenever sample rate changed if I tried using a straight power amp or setting volume to max on a power amp with adjustable volume/gain.

-Ed

 

[antcollinet]

Do their volume controls work well? I had an SMSL DO100 a while back and the volume control wasn’t usable because of the insanely loud clicking/popping noises between tracks whenever sample rate changed if I tried using a straight power amp or setting volume to max on a power amp with adjustable volume/gain.

-Ed

No idea - I don't have any of them. @vuittion should probably find some owners to ask.

 

[vuittion]

SMSL D0100 or D6 or Topping E50 are amongst the lowest cost balanced output DACs

At a little more there's also the Schiit modius - but with XLR outputs rather than TRS

Thank you

 

[EddNog]

Thank you

I recommend against DO100 due to the clicking/popping noises when changing sample rates. First hand ownership experience.

-Ed

 

[Miley_B]

My pair of Fosi V3 Mono were delivered just over a week ago. Sadly I haven't had much time to listen to them however when I measured them within my system, using the XLR input showed an inverted polarity.
I contacted Fosi and they asked me to check my wiring and the RCA input so I did a few mores tests (My RCA and XLR inputs have the same phase and polarity) and sent them some measurement data after which they sent me the same confusing reply that some other members on this forum received stating that the amplifier doesn't have positive or negative phases.
I'm very impressed with Fosi responsiveness to email but less impressed by the actual content of the replies as they clearly aren't resolving the confusion.
For me the inversion is not a big deal although I see no reason for the product to have been released with it this way when it's such a simple fix. But IMO if it is to be inverting then it must be stated somewhere in the literature or on the unit.
Someone earlier asked about some Topping units and I have measured the PA7 plus and the original PA5 both on XLR and found the polarity to be normal (positive).

No doubt my input will add to the confusion so I shall look forward to the next 100 pages of this review thread.

 

[DavidM1]

It seems the issue, if I’m following it correctly, is that by incorporating PFFB Fosi’s design has made balanced and single ended inputs opposite in polarity at the binding posts. Not a concern for anyone using only either balanced or single ended for stereo put possibly an issue with multiple amps, say, in home theatre.

It seems the solution is straightforward and easy to implement. Fosi should include a statement in the manual to say that in multi amp systems they recommend using either balanced or RCA connectors for all amps in the system to avoid the possibility of speakers being out of phase.

Warning customers that the polarity is reversed between the different inputs is pretty much all that’s needed.

 

[early rejecter]

Fosi should include a statement in the manual to say that in multi amp systems they recommend using either balanced or RCA connectors for all amps in the system to avoid the possibility of speakers being out of phase.

That advice only addresses the issue if all of the amps in the system are V3 Monos; it doesn’t account for common scenarios like a system that includes a subwoofer amplifier, or an AVR powering surrounds.

 

[Sokel]

Now wait,because @Miley_B reports that both XLR and RCA are the same and reversed.
That changes things and differs from other users experience.

Someone must measure this thing properly,on lab conditions.

 

[antcollinet]

Now wait,because @Miley_B reports that both XLR and RCA are the same and reversed.
That changes things and differs from other users experience.

Someone must measure this thing properly,on lab conditions.

Agreed (Perhaps not lab conditions - but at least with an oscilloscope looking at input compared with output for both inputs) . Confusion abounds.

 

[Hiten]

I contacted Fosi and they asked me to check my wiring and the RCA input so I did a few mores tests (My RCA and XLR inputs have the same phase and polarity) and sent them some measurement data

Can you share the measurement data ?
Thanks.

 

[Miley_B]

Can you share the measurement data ?
Thanks.

Edited to clarify that this is whole system phase response not the amplifiers in isolation.... just incase anyone couldn't tell!

 

[iLoveCats]

Fosi said in a Facebook post in one of the groups that both RCA and XLR are inverted.

 

[Sokel]

Fosi said in a Facebook post in one of the groups that both RCA and XLR are inverted.

If that's the case it's only a small mess and easy to fix,just reversing the speaker cables in both (XLR or RCA) cases.
The chart above your post also shows both to be inverted.

Now,considering that some users faced a different polarity between RCA and XLR a good sanity check would be to inspect their chains for any weird cables,previous (maybe) inverting amps or sources,etc.

That's too confusing.

 

[vuittion]

I've had a few Class D amps and have always found them harsh/clinical for my taste. How would you sum up the Fosi Audio V3 Mono sound.

 

[avdoc]

I've had a few Class D amps and have always found them harsh/clinical for my taste. How would you sum up the Fosi Audio V3 Mono sound.

My Magnepans are extremely revealing. Compared to the class D amps in my Pioneer SC-LX901 receiver, the V3M are much cleaner and smoother. There's no harsh digital "edge" to the sound like with the Pioneer. Also, the background is totally silent which is an improvement over the prior Fosi ZA3 I also own. The V3M are so revealing, that I'm currently auditioning new interconnects. I couldn't be happier with the V3Ms.

 

[DavidM1]

I've had a few Class D amps and have always found them harsh/clinical for my taste. How would you sum up the Fosi Audio V3 Mono sound.

I find it totally engaging… but I thoroughly enjoy detail.

 

[vuittion]

Thsnk you for your feedback.

 

[Borland]

The sound of my Fosis is neutral. No difference to other amps i use.

 

[antcollinet]

The V3M are so revealing, that I'm currently auditioning new interconnects.

Wow - that's peak...errr.... something.

Audiophillia perhaps.

 

[Stoutblock]

This was posted on FB by Fosi. Looks like the same statement posted here with the addition of the news that they will modify the polarity markings on the next production batch.


"Fosi Audio
3h ·
Official Statement Regarding the Inverted Phase of the V3 Mono
Dear V3 Mono Users,
Due to the implementation of the PFFB architecture, the phase inside the V3 Mono is inverted when the input signal is processed, which can help enhance the audio quality. The polarity markings on the V3 Mono's back panel align with the chip’s output and not the inverted phase. Normally, using two V3 Monos together won't cause any phase issues. However, if you integrate the V3 Mono with other equipment, please note that the phase might be inverted.
We apologize for any inconvenience this may have caused. This is indeed a shortcoming in our work, as we failed to clearly inform everyone about this design in advance. We will modify the V3 Mono and make the polarity markings match the phase in the next batch of production.
If you have any other questions or feedback regarding this statement or the V3 Mono, please feel free to contact [email protected]. Thank you for your attention and understanding.
Best Regards,
Fosi Audio Team"

I sure hope Fosi adds some sort of configuration ID between the inverted polarity and non-inverted polarity versions of the V3. If they don’t its going to be a huge opportunity to mess up a system if you have a mixture of both versions!