Fosi Audio V3 Mono Amplifier Review

[antcollinet]

and also distortion rising the closer you get to recording silence.

Where is this coming from?

 

[antcollinet]

The Loxjie has more apparent power than the ZA3 and V3 monos.

Don't mix up gain and power. Two different things.

 

[Bernard23]

That will be fine with the RCA input to the mono. Even on the lower gain setting it will most likely drive more volume than you can use. If you select the higher gain, then 2V is more than enough to drive the monos to full power.

Thanks. presumably for optimum SINAD I'd run the Ultra at highest output and the Fosi at lower gain setting?

 

[burkm]

I wasn't too concerned about the phase being off, but did a "test" for fun (non measured, and not blind).

Moved the Fosi LC30 amp/speaker switch to my office. Same speakers (Sony SSC-S5), but two amps. The older Fosi V3 stereo vs the V3 monos.

The V3 stereo was louder at the same preamp level on the Wiim Ultra. The V3 stereo seemed to have a tiny bit more treble, but the subwoofer bass sounded better.

I changed the phase switch on the subwoofer and now the bass sounds better with the V3 monos, so I guess I did receive a set with the reversed phase. Expected as each only has one QC sticker.

It doesn't seem right to me for the V3 stereo to be louder than the V3 monos since they have more power on paper, but it is. Other than the slightly increased treble, I do not hear any difference in sound quality. I guess the V3 stereo was actually better than I thought it was.

I recommend the LC30 to anyone that wants to do a simple, quick comparison of amps or speakers or have two setups like my main system (stereo and atmos).

Had to compare the V3 monos vs the ZA3 with the LC30. Again the ZA3 is louder as previously determined. The subwoofer sounded wrong with the ZA3 as expected since I changed the phase for the monos. Switching the phase back corrected that for the ZA3.

Did a compare between the V3 stereo vs the ZA3. ZA3 slightly louder at same preamp level. Not as much difference vs the V3 monos. V3 stereo still seemed to have more treble. Both sounded great. Subwoofer phase needs to be the same for the ZA3 and the V3 stereo. Needs to be switched for the V3 monos.

Knowing what I do now, it doesn't seem like there is really any advantage in my two setups to having the V3 monos vs the ZA3 Stereo or maybe even the V3 stereo. All of them sound great.

I've also "tested" all of them driving my new Klipsch Heresy IV speakers. All sounded equally great as did the Loxjie A40 which seems to have the most power of any of them. Still noticed a slight treble boost with the V3 stereo vs all the others.

My guess: Most V3 mono have only 1 QC sticker on the bottom, meaning they are still delivered "reverse phase", because delivery of the corrected version for many Fosi Audio partners might take some time to spred due to their existing inventory. All of mine had a reversed phase on the V3 mono amps, allthough I got them from Fosi Audio (German warehouse) directly, because of that inventory situation.
Phase reversal (polarity change) is quite simple, because you need only to reverse the speaker connections (no soldering needed: (+) => (-), (-) => (+)).
But You have to remember it...

PS.: This will change as soon, as all "reversed phase" units have been delivered, because new units are then already "fixed" during its production and therafter they will all have just 1 QC sticker again.

 

[galego100]

Dear Galego.
I am more than sure that Fosi Audio will eventually respond for this problem. I can attest that their customer service is of an excellence rarely seen. I am really convinced that they will try by all means to solve your problem, but what you describe is strange, to say the least.
I am from Argentina and my V3 mono They left Hangzhou (China) passing through Shanghai, Sennan (Japan), Anchorage (Alaska), Oakland San Francisco (USA), Campinhas (Brazil) and finally arrived in my country. Throughout this itinerary there was no problem since all of them are transit places and not destinations.
It is not appropriate for ANY customs in ANY country to retain your shipment. The control must be done by the customs of your country.
Therefore, I believe that the problem lies with the logistics service provider and not with Fosi, although I repeat, you can be sure that they will respond.
Greetings!

If Fosi have a warehouse in Spain, it´s normal spanish customs involved.

 

[Brian Hall]

They should sound fantastic. They are a modern class D amp with a good IC chip. What is the comparative expense for the various models you ran in this test?

The Loxjie A40 amp (also includes a pretty good dac and a phono preamp, and an HDMI ARC input) was $255. V3 stereo amp was $80 or $90. ZA3 stereo amp was $149. Paid $240 for the pair of V3 monos with separate 48v/5amp power supplies.

The Loxjie A40 is a nice unit with a functional remote.

The Fosi LC30 amp/speaker selector was $149.

 

[Brian Hall]

Don't mix up gain and power. Two different things.

Ok, it makes my speakers put out louder sound and can obviously go much louder than I would ever want to hear.

 

[Endibol]

I wasn't too concerned about the phase being off, but did a "test" for fun (non measured, and not blind).

Moved the Fosi LC30 amp/speaker switch to my office. Same speakers (Sony SSC-S5), but two amps. The older Fosi V3 stereo vs the V3 monos.

The V3 stereo was louder at the same preamp level on the Wiim Ultra. The V3 stereo seemed to have a tiny bit more treble, but the subwoofer bass sounded better.

I changed the phase switch on the subwoofer and now the bass sounds better with the V3 monos, so I guess I did receive a set with the reversed phase. Expected as each only has one QC sticker.

It doesn't seem right to me for the V3 stereo to be louder than the V3 monos since they have more power on paper, but it is. Other than the slightly increased treble, I do not hear any difference in sound quality. I guess the V3 stereo was actually better than I thought it was.

I recommend the LC30 to anyone that wants to do a simple, quick comparison of amps or speakers or have two setups like my main system (stereo and atmos).

Had to compare the V3 monos vs the ZA3 with the LC30. Again the ZA3 is louder as previously determined. The subwoofer sounded wrong with the ZA3 as expected since I changed the phase for the monos. Switching the phase back corrected that for the ZA3.

Did a compare between the V3 stereo vs the ZA3. ZA3 slightly louder at same preamp level. Not as much difference vs the V3 monos. V3 stereo still seemed to have more treble. Both sounded great. Subwoofer phase needs to be the same for the ZA3 and the V3 stereo. Needs to be switched for the V3 monos.

Knowing what I do now, it doesn't seem like there is really any advantage in my two setups to having the V3 monos vs the ZA3 Stereo or maybe even the V3 stereo. All of them sound great.

I've also "tested" all of them driving my new Klipsch Heresy IV speakers. All sounded equally great as did the Loxjie A40 which seems to have the most power of any of them. Still noticed a slight treble boost with the V3 stereo vs all the others.

The v3 mono’s don’t have the load dependency the others two models have. If your speakers have an impedance tending to be higher than 4 Ohm, the treble in both stereo units will be enhanced a bit.

 

[Freezak]

The v3 mono’s don’t have the load dependency the others two models have. If your speakers have an impedance tending to be higher than 4 Ohm, the treble in both stereo units will be enhanced a bit.

Lack of load dependency is honestly a big deal and this alone makes the Mono V3 model worth purchasing over any other Fosi amp.

 

[Bleib]

The v3 mono’s don’t have the load dependency the others two models have. If your speakers have an impedance tending to be higher than 4 Ohm, the treble in both stereo units will be enhanced a bit.

It's still not quite neutral

Erin's audio corner measurements
But sure, it's better than ZA3 for instance

 

[antcollinet]

Thanks. presumably for optimum SINAD I'd run the Ultra at highest output and the Fosi at lower gain setting?

Yes.

 

[antcollinet]

It's still not quite neutral
View attachment 389025
Erin's audio corner measurements
But sure, it's better than ZA3 for instance
View attachment 389026

What are the different lines in your chart?

 

[burkm]

Different speaker Ohms / Impedance.
The PFFB type V3 mono has less variability at higher frequencies than i.e. a ZA3 or other Non-PFFB class D amps. Distortion etc might be affected too.
It depends on Your hearing (and age) if that is hearable or not.
There is a White Paper from TI about the PFFB technique...

 

[EddNog]

It's still not quite neutral
View attachment 389025
Erin's audio corner measurements
But sure, it's better than ZA3 for instance
View attachment 389026

Is that graph in Stereo mode? Or is it in Mono mode? Would changing between Stereo and Mono modes change that graph?

-Ed

 

[Endibol]

It's still not quite neutral
View attachment 389025
Erin's audio corner measurements
But sure, it's better than ZA3 for instance
View attachment 389026

True, but practically inaudible I would say.

 

[burkm]

True, but practically inaudible I would say.

it is not known to me, if other consequences exist, because the judgement considering "sound quality etc." seems to be at least inconsequential ...

 

[Sokel]

Is that graph in Stereo mode? Or is it in Mono mode? Would changing between Stereo and Mono modes change that graph?

-Ed

Don't take the above chart as a law,this (really) small deviation with the simulated speaker (complex load) applies only to that particular load.
Other complex loads (speakers) may have none or a greater effect.

There's a thread about the load depended cousin,same calcs apply to this one or any other more or less load depended amp.

 

[Bernard23]

Mine arrived today, set them up worked fine, got a bit hot. They came with the DC filter but I noticed still a buzz if you turn off one of the pair and leave the other on
Ultimately didn't sound any different to my Yamaha so they're back in the box ready to be returned tomorrow.
It's been a fun ride.

 

[Freezak]

I'm just wondering what's the consensus on using fans (like 120mm AC Infinity) under these monos? I've read conflicting posts on whether the SINAD effect mentioned earlier would be audible or not in a normal daily music listening scenario.

 

[Sokel]

I'm just wondering what's the consensus on using fans (like 120mm AC Infinity) under these monos? I've read conflicting posts on whether the SINAD effect mentioned earlier would be audible or not in a normal daily music listening scenario.

As far as I have seen measuring various ones,the result can be measurable but it's highly unlikely to be audible.