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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
There are people who are doing, “instrumented,” testing using Audessy (SIC?) and finding that the XLR was correct and the RCA was wrong in original units, and now RCA is right and XLR is wrong on updated units.

-Ed
Yes, I think that this is the point that needs answered (still).
 
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...

IMG_E4358 (net).jpg
IMG_E4359 (net).jpg
 
Yes, but then switch to the other input. Will it be inverted and therefore your sub integration is wrong again?

That is the question at hand. They build in this great feature where you can switch between sources, but if it ruins sub integration that’s just a gross error that should never have gone out the door.
Yes, not ideal. I expect Fosi will have a pffb stereo amp before too long so if it causes you issues then that might be a solution.

Has anyone listened to see if they hear phase differences between xlr and rca with a sub? I never use one.
 
Yes, not ideal. I expect Fosi will have a pffb stereo amp before too long so if it causes you issues then that might be a solution.

Has anyone listened to see if they hear phase differences between xlr and rca with a sub? I never use one.
That’s remarkably difficult to hear. It definitely requires basic instrumental testing. With the wrong phase, you’ll find that bass will cancel out itself in certain frequencies that are within the crossover range of the sub and speakers. Much easier to do with fixed test frequencies and some sort of decibel meter.

-Ed
 
Has anyone listened to see if they hear phase differences between xlr and rca with a sub? I never use one.
If I had Fosi’s in hand, would easily be seen in a quick measurement. By ear would be inconclusive for the reasons @EddNog alluded too (though I’d personally use a mic/REW to do it with certainty).
 
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I’m not sure you understand the issue. The same thing could happen on an incorrectly implemented RCA/XLR source input switch on a stereo amp as well.
It’s not hard to understand. Fosi says xlr and rca are the same. Some people here doubt it, which is why I asked if anyone had tried a listening test. When they bring out their next stereo integrated amp it’s unlikely to have any issues with polarity.
 
Video posted at #3096 post shows that polarity is the same for both RCA and XLR.
Assuming that all that fosi changed are the speaker wires they should both have the same and correct polarity in the revised version.

Older version requires opposite connection for speaker wires by the user.
This soldering may be beginner "my first soldering iron" level but at least shows that is all they have changed so the older amps are too have RCA and XLR same polarity,only reversed.

Ok,one could curse to the heavens for such a mess but there is a small excuse such half-baked products have,after all is a kickstart item,child diseases is the norm to it.
 
Ok, I’ve just done the mod. Even though I’m listening in stereo to 2 x V3m and it makes no difference, I’ve reversed my speaker connections. Now the signal is correct polarity and all is right with the world. Cheaper than buying a high end power cable for my DAC.
 
It looks to me, if those soldering connections have been done by someone, who is new to the soldering technique.
But if thats all there has to be done and it's valid for both inputs, then someone shouldn't have to sent his amps back to China just for that....
Even a simple exchange of the plugin positions (polarity inverted) of the speaker cables would be OK (some sticker for this is required, if some one else or You lateron is doing this).
Note: There are simple (and cheap) professional instruments available, which show the phase/polarity of each unit, Some even might have it already at home....
 
Ok, I’ve just done the mod. Even though I’m listening in stereo to 2 x V3m and it makes no difference, I’ve reversed my speaker connections. Now the signal is correct polarity and all is right with the world. Cheaper than buying a high end power cable for my DAC.
It only makes a difference, if You are mixing it with some other (non-inverting) amps or an active subwoofer, because than phase inversion (polarity change) does some "strange" things...
The combination might not even been hearable tp someone, if an automated room-measuring software, i.e Audyssey/YPAO/MCACC (?) etc. is taking care of any polarity/phase errors already (the distances might change).
 
It looks to me, if those soldering connections have been done by someone, who is new to the soldering technique.

It's hard to make a modification like that look good. At least the joints don't look cold.

A thick wire soldered to a big lump of metal takes a lot of heat, and the insulation on the wires won't be happy about going through a second big thermal cycle, no matter that you do.

They should probably have replaced the wires with fresh ones, and smothered the terminal ends with gel flux before reflowing. But... time and money.
 
It - too - looks, as if done in a hurry.
I don't know, if Fosi Audio ordered an external company doing this "conversion", but to me this modification still looks rather "badly" done.
Delivering this to someone who bought those amps a few days ago is a rather "ugly"... I would redo it with a shrink tubing at least to cover that "misshape".
I will have to open mine (several new units), just to see, what I got...
 
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At least the joints don't look cold.
I'm not so sure about the red wire,if not cold it's definitely not in contact with the post's metal,it's only the solder in between that keeps them together.
I would return that.

Some heatshrink would also make the wire not looking like it was in some kind of flame-thrower conflict.

Edit:also the plastic of the posts have seen better days,magnifying them show signs of prolonged heat (probably by the absence of the gel you mentioned that would make a nice quick job if used)
 
It's not been a terribly productive evening so far.
I've already posted a screenshot of measurements which is a clearer indication than this video IMO but learning how to make this video was a very effective way of avoiding paperwork duties.
As I've previously said, I backed the kickstarter and received my two units a few weeks ago before Fosi would have made any modifications. RCA and XLR are matched and inverted in my units.

This ends the argument. Both inputs result in reversed polarity. Thank you.
 
After seeing the soldering my two Fosi Audio V3 Mono's are going back to Amazon UK for a refund.

Im not sold on the sound quality and now seeing this it's the excuse I needed. I've had a few Class d amps and each and everyone makes my ears bleed.
 
It - too - looks, as if done in a hurry.

I will almost guarantee you it was done in a hurry. We're talking about a product with a $140 retail price. Fosi's own margin goes into the red really fast if they don't do these modifications at blistering speed.
 
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