Fosi Audio V3 Mono Amplifier Review

[DavidM1]

@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.

 

[DavidM1]

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:

 

[Brian Hall]

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.

 

[rvsixer]

Sorry to hear, best in getting it resolved.

 

[Brian Hall]

Amazon is going to have a replacement for the bad one here Monday as well as having UPS pick up my return item the same day. Good customer service.

 

[Endibol]

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.

 

[Endibol]

If a Chinese chipamp doesn't have enough power, get a proper Hypex or Purifi based amp. No surprises here.

Nonsense, power is power independent of the “nationality”.

 

[Brian Hall]

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.

 

[Doodski]

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. Play the long game on this stuff. Long being days...

 

[Sokel]

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. )

 

[antcollinet]

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.

 

[burkm]

Just a quick bystep: How is the thermal paste on the V3 Mono to be changed or (re-)applied without smearing it all over the place (inside) ? I checked on the internet, but nobody, who did it, seem to explain - in detail, how he actually did it ???
Anyone with experience wants to answer this question ?

 

[Doodski]

Just a quick bystep: How is the thermal paste on the V3 Mono to be changed or (re-)applied without smearing it all over the place (inside) ? I checked on the internet, but nobody, who did it, seem to explain - in detai- l, how he actually did it ???
Anyone with experience wants to answer this question ?

Use a tissue wet with isopropyl alcohol and Q-Tips.

 

[Endibol]

I've had a few Class D amps and have always found them harsh/clinical for my taste. How would you sum up the Fosi Audio V3 Mono sound.

The sound is perfectly neutral like any other modern class D-amp lacking load dependency that probably caused the so-called “harsh” sound of previous generations low cost designs.

 

[burkm]

Use a tissue wet with isopropyl alcohol and Q-Tips.

This signals to me, that the thermal paste should be applied to the chip or to be exact, to its alu heatsink, and not to the bottom of the alu casing marked by the two screw positions.
Should the thermal paste be - thinly - covering the chips complete heat sink ?
The needed slide-in of the 4-layer PCB with its attached components does not (at least partially) remove or damage the layer of the rather thin thermal paste covering the alu heatsink during its movement ?

 

[Endibol]

iI don't remember well but you might want to read minidsp instructions or their forum. iirc, if you use Dirac live, they recommend max of -10dB.

Correct, if you don’t do that you are likely to hear distortion (crackling sound) in the base (in case Dirac is cranking up the base) .

 

[Tell]

Just a quick bystep: How is the thermal paste on the V3 Mono to be changed or (re-)applied without smearing it all over the place (inside) ? I checked on the internet, but nobody, who did it, seem to explain - in detail, how he actually did it ???
Anyone with experience wants to answer this question ?

Why would you need to know how to change the thermal paste? Are they applying bad or too little of it at the factory giving subpar cooling? Or is this just another trend after opamp rolling or something?

 

[burkm]

Why would you need to know how to change the thermal paste? Are they applying bad or too little of it at the factory giving subpar cooling? Or is this just another trend after opamp rolling or something?

I have several of them already delivered in two charges and don't know, if thermal paste has been applied during production or not. Thus I will have to unmantle them looking for that thermal paste. They seem to be getting rather warm or "hot", as stated by most of the users, who got them already and thermal paste improves coupling temperaturwise

 

[iLoveCats]

I have several of them already delivered in two charges and don't know, if thermal paste has been applied during production. thus I will have to unmantel them looking for that thermal paste. They seem to be getting rather warm or "hot", as stated by all users, who got them already

I would say that is an indication the paste is applied. It's transferring heat to the case.

 

[burkm]

I would say that is an indication the paste is applied. It's transferring heat to the case.

How do You know wihout looking at them opened? Some have received units without or had it only partially applied...