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Fosi Audio V3 Mono Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 12 1.9%
  • 2. Not terrible (postman panther)

    Votes: 19 3.0%
  • 3. Fine (happy panther)

    Votes: 122 19.5%
  • 4. Great (golfing panther)

    Votes: 472 75.5%

  • Total voters
    625
Here is a photo from the Fosi FB group that shows new vs old.

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They just reversed the output wires to the speaker terminals. :facepalm:
Isn’t it more old vs new??? So old is the picture on top?
 
I just received my six V3M amps today and I can confirm they have all been updated (output wires switched). I had the cycle time for checking down to four minutes after doing it six times! I'm using the RCA inputs on my HT system, and I don't have a clue if they are in phase or out of phase but at least they are all the same. They sound just fine! Have to do some wire routing...

View attachment 386893View attachment 386894
Shockingly bad soldering quality though. Clearly modified by a person who has. no idea how to do it.
 
Got two of these delivered today and hooked them up in my office setup replacing a single Fosi ZA3.

I haven't done any proper testing, but it seems like everything sounds a bit better. It may just be expectation bias, but they sound great.

It is probably just be the power difference. I'm using a Wiim Ultra as a preamp (and streamer/DAC/headphone amp). With the single ZA3 in stereo mode (gain maxed out), I had to take the volume control on the Ultra to over 50 to get the same sound level as I get with 27 on the V3 monos.

I just ordered another pair for the stereo setup on my main system.

I've been measuring the temperature to see how hot they get. The temperature in this room is 72F. After running for about 3 hours, one is showing 104.0F and the other is 103.9F. I have them side by side with a gap of two inches between them.
 
Hang on. Fosi has said rca and xlr are the same and there was a post earlier where someone tested it and agreed. I don’t understand all the negativity. It was the same when there was a thread panic about heat.

Phase issues with speakers are typically easy to hear by a/b comparison. If it isn’t audible at all to the listener because one speaker is a sub then perhaps the polarity difference isn’t all that important.
@Stoutblock tested his old units (and that he would check his six new units as well). And AFAIK up till Fosi's latest testing post, we had no one else that had tested the new units (and no "I got my reworked units and they sound okay" does not count). Until I saw Fosi's confirmation of new unit actual measurements, I was simply seeking the truth, sorry you took this as negativity.

Also sorry a few posters here trying to explain proper sub integration to you is explained away by its an easy a/b comparison and perhaps it isn't that important, if one has dabbled in LF phase audibility and LF in rooms and shaping it via sub(s) one can see it is important indeed. Grimani has some excellent material on this if interested.
 
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There's literally a video demonstration by a member in this thread showing the phase is exactly the same on XLR and RCA inputs.
That was on old units, and he was going to test (6) new reworked units when he (@Stoutblock) got them. He has rec'd those, awaiting a non-Fosi confirmation on new units, that speaker polarity does not change with input selection.
 
But I am actually an Engineer and quite knowledgeable on how to set up a valid test…

Then I honestly don't understand why this is such a big deal to you.

Sure, it would look more professional if they hadn't just grabbed two units from different stages of the assembly line, but we can only assume that the PCBs themselves have both passed testing. The result will be the same from the setup you're suggesting, so I don't see what makes it more valid.

Fosi Audio would have zero reason to mess with their test setup in order to get a fake result.
 
@Stoutblock tested his old units (and that he would check his six new units as well). And AFAIK up till Fosi's latest testing post, we had no one else that had tested the new units (and no "I got my reworked units and they sound okay" does not count). Until I saw Fosi's confirmation of new unit actual measurements, I was simply seeking the truth, sorry you took this as negativity.

Also sorry a few posters here trying to explain proper sub integration to you is explained away by its an easy a/b comparison and perhaps it isn't that important, if one has dabbled in LF phase audibility and LF in rooms and shaping it via sub(s) one can see it is important indeed. Grimani has some excellent material on this if interested.
Fosi has said on more than one occasion that rca and xlr are the same polarity yet some posters have remained suspicious and that seems like unnecessary negativity to me. Perhaps it is a need for reassurance given that Fosi is at the more affordable end of the market and a new brand to many.

Clearly the phase of the monos and any subwoofer is important, even if difficult to hear, and I’m sure folks with worries about it will feel heartened to know the rca and xlr are the same.
 
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There was mention earlier of class D amps causing ears to bleed (nasty). Here is a vid on aural illusions that is well made and fascinating:

 
Bad news. One of the V3 monos seems to have died. No blue smoke or anything like that. I had everything turned off for a couple of hours. Came back in my office, turned everything on and the right channel had no sound. Made sure the balance L/R settings on the Ultra hadn't changed. Turned off the V3s and swapped them around. The problem moved to the left channel.

Both have indicator lights so are getting power. Swapped the power cords. Still no sound from one V3.

The switches and gain settings are the same on both.

This concerned me so I canceled my order for two more that I placed earlier for my other system. I've put the ZA3 back in place and it is working fine with audio from both channels.

I guess I'm going to return the defective one to Amazon for a replacement. Is it easy to open the unit without making it obvious that I opened it? I want to make sure nothing simple failed on the RCA inputs and check the solder.

It didn't overheat. Both were powered completely down. I did rerun the cables while they were off to neaten things up a bit so unplugged and replugged the RCA cables.
 
I received the 2 units a couple of weeks ago and the mains filter somewhat later. The top covers reach a temperature of about 40 degrees C even if there is no music playing.
 
If I shake the V3 mono that failed, I can hear something moving a bit inside. Not like a completely loose component, but more like a wire that is connected on one end and not the other. Could be that one of the solder repairs they did came loose when I disconnected and reconnected the RCA inputs. I'm tempted to open it up to see what it is, but since I already have the return set up for Monday, I am resisting that.
 
If I shake the V3 mono that failed, I can hear something moving a bit inside. Not like a completely loose component, but more like a wire that is connected on one end and not the other. Could be that one of the solder repairs they did came loose when I disconnected and reconnected the RCA inputs. I'm tempted to open it up to see what it is, but since I already have the return set up for Monday, I am resisting that.
Judging from the looks of some wiring solder joints that I have seen yes there could be a loose wire end floating inside. I think under the circumstances it would be prudent to return the unit without opening it. :D Play the long game on this stuff. Long being days...
 
If I shake the V3 mono that failed, I can hear something moving a bit inside. Not like a completely loose component, but more like a wire that is connected on one end and not the other. Could be that one of the solder repairs they did came loose when I disconnected and reconnected the RCA inputs. I'm tempted to open it up to see what it is, but since I already have the return set up for Monday, I am resisting that.
These were mend to be opened.
Unless there's a magical way to do the famous op-amp rolling (actually it would be nice,it would save users from bricked amps by putting it in reverse,with bend feet,etc. )
 
If Fosi wants to prove that the new amps have the same and correct phase for both XLR and RCA, why not show two identical production units with the only variable being RCA vs XLR input?
The picture is not intended to prove anything. It is simply provided to demonstrate how, and that, they have done the test.

We can give them the benefit of the doubt regarding the test being done accurately.


@Fosi Audio I've been one of the loudest complainers regarding information on this topic. Thanks for doing - and showing us - the test.
 
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