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Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 13 2.0%
  • 2. Not terrible (postman panther)

    Votes: 21 3.2%
  • 3. Fine (happy panther)

    Votes: 128 19.3%
  • 4. Great (golfing panther)

    Votes: 501 75.6%

  • Total voters
    663
I'm not sure if i'm understanding the issue correctly, but am i going to be affected by it if i want to use two monos for, say, SMSL D6s acting as a pre-amp/dac in conjunction with ELAC DBR62s? Using RCA cables and banana plugs.
Consider using just XLR though as the amp performs better in this mode
 
Can't comment much on it. I was expecting more.
Did you already have some other TPA3255 amps before you are comparing to Fosi V3 Monos? I don't think people were expecting noticeable subjective SQ improvement with the new V3 monos, were they?
 
Mine arrived yesterday and are also hot - and they seem hotter than my PA7 - warming them up now and will use my trusty COVID surface temperature thermometer. I will compare to PA7 and share findings.
I have seen some people just remove that orange-colored strip from the sides of the chassis for better ventilation, which sounds like a good idea, especially during these super hot summer months.
FosiV3Mono.PNG
 
I have seen some people just remove that orange-colored strip from the sides of the chassis for better ventilation, which sounds like a good idea, especially during these super hot summer months.
View attachment 382593
I don't have one, but the holes seem quite big in the picture. I wonder if dust could become an issue.
 
I got these from AE:

IMG_8990.png


Got 5 V3M’s lined up next to each other, and these holders put them at a nice angled position for better airflow (mine are in a cabinet with active ventilators, so looks are not an issue)
 
Consider using just XLR though as the amp performs better in this mode
Thank you for this suggestion, so i've read - may i ask how do i do that in aforementioned setup? I've never used XLR cables really, i'm still learning :/

Edit: nevermind, i think i got it :) going with the XLR then.
 
Last edited:
It is difficult to get my head around this type of performance is such a small and inexpensive package. I have been looking to add an amplifier to my Onkyo RZ50 to drive my front speakers-ML Vistas (4 Ohm). I have no complaints with the RZ50, but the V3 Mono Blocks appear to perform better on the bench. I would be interested if people think that there would be a noticeable difference (Better or Worse) in sound quality.
In my case the Fosi sound clearly worse than my old Marantz SR6009 using the same streamer and DAC.
 
I don't have one, but the holes seem quite big in the picture. I wonder if dust could become an issue.
I'd be more concerned with metallic objects getting into the amp and killing it.


A great way to replace a non problem (amp temperature) with a real problem (broken amp)
 
My V3s have also arrived ;)
But they get very hot and I wonder when hot is too hot....

I have now ordered an infrared thermometer.

Edit:
Do they perhaps get so hot because I use 10A power supply units? Is it better to use a splitter cable and only one power supply?
I really wouldn't worry. Amps give off heat, it's one of their charms. Fosi has posted a video on the V3 monos and they point out that the entire case is a heat sink and it's going to be warm to touch. Not a problem and a good sized heat sink is a wonderful thing.
 
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Ok. Got this information/ confirmation through Fosi
"Hello There,
Our R&D team has confirmed that the V3 MONO is a single-channel unit without positive and negative phases. Its circuit design differs from conventional designs: it operates positively when paired with another V3 MONO. When one V3 MONO paired with other models, it may result in a reverse phase. In such cases, simply swap the positive and negative output lines of the V3 MONO. This unique product design aims to achieve superior performance parameters."
 
Any ideas about this thing? It arrived with my V3 monos.View attachment 382672
Someone in the factory must be searching for it's screwdriver now :facepalm:
Ok. Got this information/ confirmation through Fosi
"Hello There,
Our R&D team has confirmed that the V3 MONO is a single-channel unit without positive and negative phases. Its circuit design differs from conventional designs: it operates positively when paired with another V3 MONO. When one V3 MONO paired with other models, it may result in a reverse phase. In such cases, simply swap the positive and negative output lines of the V3 MONO. This unique product design aims to achieve superior performance parameters."

:facepalm:²
 
I agree. I think the simplest fix for this perceived heat issue is for people to stop touching their amps.

Yes, you can do it like that ...
But Fosi talks about (I think) 33 degrees in the video.
Mine are getting hotter, but I haven't been able to measure it yet because the thermometer hasn't been delivered yet.

What happens when they reach 60 degrees (Celsius ;))?
Just don't touch them and don't think about it?
 
Ok. Got this information/ confirmation through Fosi
"Hello There,
Our R&D team has confirmed that the V3 MONO is a single-channel unit without positive and negative phases. Its circuit design differs from conventional designs: it operates positively when paired with another V3 MONO. When one V3 MONO paired with other models, it may result in a reverse phase. In such cases, simply swap the positive and negative output lines of the V3 MONO. This unique product design aims to achieve superior performance parameters."
Well that is a bunch of nonsense, other than confirming the phase inversion, but without the specific information confirming RCA, XLR, or both.

Specifically, phase inversion has nothing to do with:
This unique product design aims to achieve superior performance parameters."

Which I'm assuming to be about the PFFB.

@Fosi Audio please can you get some valid and accurate technical information into this topic, and leave out the marketing spin. It doesn't wash here.

Thanks.
 
Well that is a bunch of nonsense, other than confirming the phase inversion, but without the specific information confirming RCA, XLR, or both.

Specifically, phase inversion has nothing to do with:


Which I'm assuming to be about the PFFB.

@Fosi Audio please can you get some valid and accurate technical information into this topic, and leave out the marketing spin. It doesn't wash here.

Thanks.
This should be stated in the technical specification online and in the paper included in the box.
 
This should be stated in the technical specification online and in the paper included in the box.
I agree it would be a good thing to see in specs, but I don't remember ever seeing it from any manufacturer. From time to time a manufacturer will make a point of preserving absolute phase in marketing material, but that's the exception rather than the rule.
 
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