Fosi Audio V3 Amplifier Review

[musica]

What I would do:

1 - Turn your V3 down to zero.
2 - SLOWLY Turn your Denon up to max.
3 - Now SLOWLY raise the volume of the V3 so it is a little bit louder than you will ever want to listen to. This is the volume you should leave the V3 at. Mark it with a small bit of tape or similar.
4 - Now you can control the volume DOWN from there using the Denon volume control. With the Denon volume control at the higher end of the range, and the gain in the amp minimised, you will optimise SNR.

if I do this, the sound distorts immediately even with minimum SPL

 

[musica]

between the denon and the fosi there is also the miniDSP

 

[Sokel]

View attachment 389056
between the denon and the fosi there is also the miniDSP

As far as I remember 2x4 has a jumper to choose between .9 or 2V input voltage.
You should choose the 2V one.
I'm also not sure about how Denon performs in max as a pre,some measurements I saw it's performance starts to flatten after the -10dB mark.

 

[juliangst]

I'm in the process of selling my Denon integrated and replacing it with one of those small Fosi Amps for my desk setup.

Will the V3 with the included 32V PSU have enough power for LS50 (in near field)?

With roughly 64W into 4 Ohms, the LS50 should theoretically reach about 100dB@1m which is way more than I would need at the desk (including headroom)

 

[antcollinet]

if I do this, the sound distorts immediately even with minimum SPL

In that case it sounds like the Denon is clipping the pre outs. Are you able to turn the amps of on the denon so only the pres are in operation? This might help.

If not, then instead of max, with low volume on the fosi, turn the denon up as far as you can without distortion - instead of max.

 

[antcollinet]

View attachment 389056
between the denon and the fosi there is also the miniDSP

Ah - ok then it gets more complex. You also have to avoid overvolting the MiniDSP inputs. You could turn the denon up until the RMS meter shown gets near max. Or alternatively you could reduce the gain setting (I think)

 

[musica]

Are you able to turn the amps of on the denon so only the pres are in operation?

sorry, but I didn't understand

 

[musica]

ou will optimise SNR.

how you perceive a better SNR when listening?

 

[ninetylol]

I may sound a bit silly, but do I actually need more than the 32v supply if volume is adequate?

Or would Sound quality improve?

 

[Bleib]

I may sound a bit silly, but do I actually need more than the 32v supply if volume is adequate?

Or would Sound quality improve?

No need to upgrade.

 

[antcollinet]

how you perceive a better SNR when listening?

Reduced noise.

The method I described will optimise SNR - but whether it is audible or not is definitely system and listener dependent. In most cases it will probably not be.

However it does have one other non sound quality related advantage. If the Fosi volume is limited to max wanted volume at max source volume, then no matter what happens up the chain, the volume cannot get dangerously loud (either for your speakers or your ears).

 

[antcollinet]

sorry, but I didn't understand

I don't know what denon you have. If it is a pure preamp, then my question doesnt apply. If it is an amp or avr, and you are using as a pre-amp with pre-outs into the FOSI, then turning off the internal amplicification can (with some devices) improve the behaviour of the pre-outs.

 

[antcollinet]

I may sound a bit silly, but do I actually need more than the 32v supply if volume is adequate?

Or would Sound quality improve?

No, and no. As long as you are not clipping on musical peaks.

 

[ninetylol]

No, and no. As long as you are not clipping on musical peaks.

I see. Since you never actually know if you are clipping some dynamic peaks, I guess you could use a bigger power supply for peace of mind though

 

[ninetylol]

Another question for sciences sake, would the V3 profit from a 48v10a supply over the standard 48v5a or would that be out of its working limits?

 

[musica]

I don't know what denon you have. If it is a pure preamp, then my question doesnt apply. If it is an amp or avr, and you are using as a pre-amp with pre-outs into the FOSI, then turning off the internal amplicification can (with some devices) improve the behaviour of the pre-outs.

my Denon is a PMA 700AE stereo integrated with pre-out. It has a direct source button and a button to exclude the power circuit to the speakers
connections:
Denon pre-out --- miniDSP input ------- miniDSP out ------- Fosi v3 input -----speakers

 

[Jimbob54]

my Denon is a PMA 700AE stereo integrated with pre-out. It has a direct source button and a button to exclude the power circuit to the speakers
connections:
Denon pre-out --- miniDSP input ------- miniDSP out ------- Fosi v3 input -----speakers

And for the benefit of new readers, just remind us why you can't go :

Source(s) - minidsp- denon - speaker and just use that as the sole amp?

Or even sources-minidsp-fosi-speakers?

 

[antcollinet]

I see. Since you never actually know if you are clipping some dynamic peaks, I guess you could use a bigger power supply for peace of mind though

You could. Or you could just ask "can I hear any distortion at my highest listening volume" and if the answer is no, get your much lower cost peace of mind that way.

 

[musica]

And for the benefit of new readers, just remind us why you can't go :

Source(s) - minidsp- denon - speaker and just use that as the sole amp?

Or even sources-minidsp-fosi-speakers?

no, I want to use the Denon as a preamp and the Fosi as a power amp. Is that really not possible?

 

[Jimbob54]

no, I want to use the Denon as a preamp and the Fosi as a power amp. Is that really not possible?

Yes, but you are having difficulty with gain staging. Life is a lot easier with only one amp.