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Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 7 1.5%
  • 2. Not terrible (postman panther)

    Votes: 11 2.3%
  • 3. Fine (happy panther)

    Votes: 95 19.9%
  • 4. Great (golfing panther)

    Votes: 364 76.3%

  • Total voters
    477

EddNog

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Looks like the GAIN switcher only works for RCA input, the XLR has fixed gain.
Accurate.

I actually like that the XLR has lower gain than either RCA setting; allows me more room to play with source gain, preamp buffer mode selection (I have a Schiit Freya+) and volume adjustment granularity.

-Ed
 

GabrielPhoto

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Just out of curiosity, why use such an advanced and high-performance power amplifier for shakers? I think we need something very powerful and less sophisticated instead.
A professional Behringer amplifier for example or simply a Sabaj A20A 2022 which puts out 350watts when bridged. Any old Yamaha p1500/3500 power amplifier would do the job much better and can be found used for less than 150 euros
I was using the V3 stereo as an example of what I tested. Based on the tests here showing enough power in stereo mode to drive both to more than enough performance, I was disappointed to find out the tests here did not reflect real life performance in a situation like this. So it was a simple test for a much smaller and quiter amp vs getting a pro amp of which I already have several for all my TR devices.
Luckily in bridge mode the 07 max (and I assume the ZA3) work fine but its interesting to see that even measurements as we got here do not always tell the story for all possible uses
That Sabaj A20A 2022 looks like a nice compact one to try.
 
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GabrielPhoto

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Same curiosity here,why struggle with it and don't get a used pro-audio nice and light little beast who can throw you out of your chair?
Sound has nothing to do with it.
It has nothing to do with "struggle". Read my previous reply....
 

Sokel

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It has nothing to do with "struggle". Read my previous reply....
I see.
I believe at some point on this thread or on the stereo one I did mention the limitations i guessed are there given the small heat dissipation area in comparison with the specs and TI's heat dissipation plot.
So...
 

GabrielPhoto

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I see.
I believe at some point on this thread or on the stereo one I did mention the limitations i guessed are there given the small heat dissipation area in comparison with the specs and TI's heat dissipation plot.
So...
I do keep a fan on them and it seems to keep cooler with the 48v 5A than the stock psu but still same results in stereo. I was just surprised how the measurements didnt deliver for this particular case.
At the end of the day I will probably just grab an XLS1002 or so.
 
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brunes

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So I don't neeeeed these monoblocks but.. I'd like to hear them... would be cool to have a set that we could send around for those that are curious...like an amp library.
 

Sokel

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I do keep a fan on them and it seems to keep cooler with the 48v 5A than the stock psu but still same results in stereo. I was just surprised how the measurements didnt deliver for this particular case.
Measurements deliver what is there but in a very short time frame (VERY short) .
What you experienced would need a more continuous test which is debatable as not all amps have protections and most of them are on loan.

But one can guess what's going on under the hood (or looking at the hood) to some extent.Specially about thermals,one can easily calculate as data is there (TI's data sheet) and calculating some simple stuff here:


(It's as a really good read plus it describes how one can easily calculate )
 

Trasam Audio

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Accurate.

I actually like that the XLR has lower gain than either RCA setting; allows me more room to play with source gain, preamp buffer mode selection (I have a Schiit Freya+) and volume adjustment granularity.

-Ed
It seems the gain of XLR is 20dB, is it what you want?
 

EddNog

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It seems the gain of XLR is 20dB, is it what you want?
I don’t think I have a very specific gain that I’m looking for, but that will work better for me than 25 or 31.

-Ed
 

Ze Frog

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I was using the V3 stereo as an example of what I tested. Based on the tests here showing enough power in stereo mode to drive both to more than enough performance, I was disappointed to find out the tests here did not reflect real life performance in a situation like this. So it was a simple test for a much smaller and quiter amp vs getting a pro amp of which I already have several for all my TR devices.
Luckily in bridge mode the 07 max (and I assume the ZA3) work fine but its interesting to see that even measurements as we got here do not always tell the story for all possible uses
That Sabaj A20A 2022 looks like a nice compact one to try.
I'd be slightly weary of the Sabaj A20A. I looked at these but going by some customer reviews these seem to be unreliable, especially when used as monoblocks.
 

antcollinet

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Yes, we'll provide that option too. The campaign will launch on April 20.:)
Earlier you offered a signup for a discount, and sent me vouchers for this.

Do these vouchers give discount priority, or do I just have to join the kickstarter race like everyone else?
 

antcollinet

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TPA3255 PBTL Mono won't gain anything (significant or useful) from 48v 5a to 10a, no benefit.
Not so sure about this.

According to the data sheet, in PBTL mono, it can do about 250W at 48V into 4ohm. This would require about 8amps.

Further, it can do more than 400W into 2ohm (say speaker impedance dips). This would need 14A.

I'd certainly like to see the power measured with a 10A supply feeding a single amp.


(EDIT - although I note that the measurements here show similar power with the 5A supply. This suggests that supply has significant short term headroom)
 

Guddu

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Not so sure about this.

According to the data sheet, in PBTL mono, it can do about 250W at 48V into 4ohm. This would require about 8amps.

Further, it can do more than 400W into 2ohm (say speaker impedance dips). This would need 14A.

I'd certainly like to see the power measured with a 10A supply feeding a single amp.


(EDIT - although I note that the measurements here show similar power with the 5A supply. This suggests that supply has significant short term headroom)
Thanks
 

sikahr

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Jul 20, 2021
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Regardless of datasheet data and short term tests/measurements, what is not tested with this class of little D amps is long term continous power behavior. Anyone knows for such test?

@Fosi Audio , do you test/measure your amps at some defined power for prolonged time? Of course not every manufactured amp( ala quality control), only test samples amps.
 
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jvdburgt

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Apr 17, 2024
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Hi there, new here and also looking forward to get my hands on some of these V3 mono's, to replace my Yahama AX-892 that I currently use as amp for my fronts.

@Fosi Audio : My question is whether these blocks will only be sold in pairs, or also individually? Other than a pair of these for my fronts, I would like to get an extra (single) one for my center speaker as well.
 

Guddu

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Hi there, new here and also looking forward to get my hands on some of these V3 mono's, to replace my Yahama AX-892 that I currently use as amp for my fronts.

@Fosi Audio : My question is whether these blocks will only be sold in pairs, or also individually? Other than a pair of these for my fronts, I would like to get an extra (single) one for my center speaker as well.
They are priced per amplifier, and then there are bundle deals.
You can buy as many as you like.
 
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