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Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 13 1.9%
  • 2. Not terrible (postman panther)

    Votes: 21 3.1%
  • 3. Fine (happy panther)

    Votes: 129 19.3%
  • 4. Great (golfing panther)

    Votes: 505 75.6%

  • Total voters
    668
I guess I am wondering if class a/b rated at 60 watts per channel is cleaner than class D at 100+ watts per channel especially at extreme volumes both soft and loud. The reviews seem to suggest listening at loud volume causes distortion above 85 db. Or is this a stupid question?
That would depend entirely on the SPL, speakers, listening distance and the music genre. :)
 
That would depend entirely on the SPL, speakers, listening distance and the music genre. :)
not sure how to find the SPL. My speakers are Totem Sttaf at least for now. I listen at a distance of about 12 feet away. I listen to almost everything. My room is small to medium in size. If I had to guess may be 15' x 15'.
 
not sure how to find the SPL. My speakers are Totem Sttaf at least for now. I listen at a distance of about 12 feet away. I listen to almost everything. My room is small to medium in size. If I had to guess may be 15' x 15'.
You can download the NIOSH app on your phone and use it to measure the sound levels at your listening position at the maximum volume you listen at to get an idea of the levels.
 
You can download the NIOSH app on your phone and use it to measure the sound levels at your listening position at the maximum volume you listen at to get an idea of the levels.
I got it up to 87 db before it was uncomfortable to listen. I didn't think it was too bad. I'll report back on the Cambridge gear later today.
 
Anyone have experience using the v3 with passive subs? I have been running a pair to power a pair of subs over the last week. They are each 4ohm dual 8inch units. Both mono's run pretty hot after a music session. Should I be worried about their longevity. I also get a pretty good "pop" when they kick on. I haven't seen that reported in any reviews.
 
Anyone have experience using the v3 with passive subs? I have been running a pair to power a pair of subs over the last week. They are each 4ohm dual 8inch units. Both mono's run pretty hot after a music session. Should I be worried about their longevity. I also get a pretty good "pop" when they kick on. I haven't seen that reported in any reviews.
I also get the pop out of the speakers when they power up. How are you connected to them XLR or RCA? I get of a pop with RCA.
 
I also get the pop out of the speakers when they power up. How are you connected to them XLR or RCA? I get of a pop with RCA.
In my case there's an amp pop with XLR and a faint one in the speakers too when turning off the mains. I use two Monos with SMSL D6s + ELAC DBR62.

Is the speaker faint pop actually harmful for them and should i refrain from disconnecting the power strip? the sound is not loud at all.

I do this using a remote so it's much more convenient than physically turning the monos off but if it harms the speakers in any way then i guess i have to stop doing this.
 
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In my case there's an amp pop with XLR and a faint one in the speakers too when turning off the mains. I use two Monos with SMSL D6s + ELAC DBR62.

Is the speaker faint pop actually harmful for them and should i refrain from disconnecting the power strip? the sound is not loud at all.

I do this using a remote so it's much more convenient than physically turning the monos off but if it harms the speakers in any way then i guess i have to stop doing this.
You will get a pop on switch on from the amp if your source is putting out any DC. It might have nothing to do with the amp. Try switching on/off without any input connected to check.
 
FWIW I have a CXA81 which I replaced with V3s and haven’t noticed any tonal difference (though I haven’t done a full blinded test)
 
FWIW I have a CXA81 which I replaced with V3s and haven’t noticed any tonal difference (though I haven’t done a full blinded test)
Not noticing is the FWIW (and interesting) bit, and a good reason not to bother with a blind test.
 
we can use a simplified model ...
what is sound? frequencies translated in the air
what is a tonal difference? a difference in that frequencies
if the amplifier have a flat frequency response, there will be no tonal difference with other flat frequency response amplifier

so, if you can hear a tonal difference, is everything else (acoustics, speakers, gain, ..., mental bias) than a real amplifier difference.

i think is very simple ... and we know based on measureaments that the Fosi and the Cambridge have a flat frequency response.
 
Interesting that you found them tonally different from the Fosi pair. Just not to your taste? I wonder what measurements would have revealed that?
In my opinion the CXA61/81's warmth sacrificed clarity. So the far the Fosi V3 mono's are working the best for me. I am going to audition the Topping B100 monoblocks in a few days.
 
I've been using the V3M XLR input (RCA to XLR cable) because my preamp (RCA out) has too much gain.
For me this solution sounds great and the question is:
- why does this work, feading the XLR with half the signal
- if it works, why is there an additional/3rd opamp (se to balanced)
- what could go/sound wrong (lower XLR input impedance)
 
No pop for me, but an individual V3 mono is significantly hotter than a ZA3 in stereo. Both with XLR and 48V/5A power supply from Fosi

V3 mono also a bit quieter than the ZA3 in identical setup (other than ZA3 being used in stereo)

Edit: just measured with my infrared thermometer, the top is at 53c when completely idle. The ZA3 at least had to be doing something to get a little warm. Concerning?
 
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