Fosi Audio V3 Amplifier Review

[Zek]

I hear a small boom in the speakers

Maybe there is a DC offset on the Denon line out.
Sequence to turn on the system - always turn on the source first, then the Denon and finally the Fosi. To turn it off, the procedure is the opposite.

 

[musica]

Maybe there is a DC offset on the Denon line out.
Sequence to turn on the system - always turn on the source first, then the Denon and finally the Fosi. To turn it off, the procedure is the opposite.

what would happen if I don't perform this procedure, it's for convenience reasons I continue to turn everything on at the same time from the remote control
I would like to do this, because my infantile cerebral palsy limits my movements

 

[musica]

could this little boom be the fault of the miniDSP connected to the pre-out of the Denon and the analog input of the Fosi v3?

 

[gwing]

could this little boom be the fault of the miniDSP connected to the pre-out of the Denon and the analog input of the Fosi v3?

It could be the fault of any of the components in front of the V3. Most likely if it is sufficiently quiet that you had difficulty noticing it then you'll be fine to ignore normal power on sequence recommendations.

 

[musica]

If I wanted to use the recommended on/off sequence, do I have to turn the Fosi v3 on and off with the volume knob or can I remove the power supply from the Fosi without stressing the Fosi volume knob?

 

[gwing]

If I wanted to use the recommended on/off sequence, do I have to turn the Fosi v3 on and off with the volume knob or can I remove the power supply from the Fosi without stressing the Fosi volume knob?

Probably it will be OK. and I'd say it will likely be better to cut the power rather than use the volume knob unless Fosi have (very unlikely) built some sort of soft start into the volume knob/switch circuit which you would be bypassing. What do the operating instructions from Fosi say?

At the end of the day though the V3 is an inexpensive device so even if you do end up shortening it's life by a sub-optimal operating procedure it may not be the end of the world. If just chopping the power gives you significant benefits I'd just do it that way. In practice I doubt it is going to make a difference whichever approach you take here.

 

[musica]

important is to avoid the small boom in the speakers?
for me it is easier to remove the power supply to the Fosi just buy a power outlet with remote control or not?

 

[totti1965]

A new bargain out there: the specs are showing, that it‘s SINAD (-74 dB) is just 14 dB worse than that of the Fosi V3. And, well….. the price is 2.000 times as high as Fosi. But well, we are quite close, aren’t we?
So: consider please buying the GRYPHON instead of the Fosi V3 - and leave a comment on this gentlemen’s YouTube channel! The Gryphon specs are at 7.35 min!

 

[Doodski]

A new bargain out there: the specs are showing, that it‘s SINAD is just 14 dB worse than that of the Fosi V3. And, well….. the price is 2.000 times as high as Fosi. But well, we are quite close, aren’t we?
So: consider please buying the GRYPHON instead of the Fosi V3 - and leave a comment on this gentlemen’s YouTube channel! The Gryphon specs are at 7.35 min!

I have always gotten a sick kick out of this character with his "Lab" designation.

 

[musica]

do you say that the Fosi v3 is a good amplifier?

 

[gwing]

important is to avoid the small boom in the speakers?
for me it is easier to remove the power supply to the Fosi just buy a power outlet with remote control or not?

Annoying but not important.

 

[musica]

Annoying but not important.

so the small boom in the speakers can't damage them?

 

[musica]

where is the load dependence?

 

[antcollinet]

View attachment 388364where is the load dependence?

A bit difficult to know since you are not saying what the two lines in the chart are showing.

 

[musica]

View attachment 388364where is the load dependence?

this is the frequency response with the Fosi v3 at maximum and the Denon at 9.30 o'clock there are no increases in the high frequencies

 

[Zek]

this is the frequency response with the Fosi v3 at maximum and the denon at 9.30 o'clock

You mean the green line?
How was that measurement obtained - with a microphone or what?
What is the white line on the graph?

 

[KaeliKoo]

Hi,

Using the Fosi V3 for a desktop setup, I recently switched to the Fosi 32V power supply instead of the 48V that came with the V3. I decided this change because the Fosi V3 would get hotter than I would like it to with the 48V PSU and the low power required for a nearfield listening. Using a subwoofer (90 Hz crossover for both speakers and sub), there is not that much power demand.

Testing the setup while sending full range signal to the speakers, there is no change in measurement frequency reponse or perceived sound between the two PSU and my speakers (4" Wharfedale Diamond 12.0) show distorsion in low bass way before the amplifier. To be honest I did not hear any distorsion comming from the amplifier even at high desktop levels.

Now with the 32V PSU the V3 gets barely warm to the touch, while it would get warm with the 48V PSU. For nearfield use, I think that the 48V PSU is really overkill and would reduce the V3 reliability because of more the heat stress.

I've run my V3 Stereo amp with the 36V Aiyima power supply, it's only 24 watts less than the 48V specs (240w vs 216w) and the V3 gets mildly warm after several hours of use.

 

[musica]

You mean the green line?
How was that measurement obtained - with a microphone or what?
What is the white line on the graph?

yes, the green line, calibrated Umik-1 microphone

 

[antcollinet]

yes, the green line, calibrated Umik-1 microphone

So if in room - yo0u've no idea how much variation comes from speaker/room, and how much (if any) from amp. From the look of it, most of the variation is speaker room, almost certainly is swamping anything that might be coming from the amp. To see the amp response you'd need to measure electrically at the speaker terminals.

 

[musica]

So if in room - yo0u've no idea how much variation comes from speaker/room, and how much (if any) from amp. From the look of it, most of the variation is speaker room, almost certainly is swamping anything that might be coming from the amp. To see the amp response you'd need to measure electrically at the speaker terminals.

so in my environment the v3 would not cause problems?