Fosi Audio V3 Amplifier Review

[Fosi Audio]

When I took the amplifier out of the package, I noticed something rattling in there. Fearing the worst, I took the unit apart. Turns out one of the two large power supply caps had lost its adhesion to the PCB. The putty used is to keep the cap glued to the PCB was too flexible and had broken loose. No harm though as the cap is laying on its side and can't go anywhere. The sound I was hearing was it moving just a hair up and down and hitting the top of the case. Suggest company use a different material to fix this.

Yes, the adhesion between the caps and PCB is not steady enough. We had noticed the problem and had taken measures to fix this.

 

[Maiu95]

"In English, this means that depending on which speaker you use, the sound may be a bit bright or a bit dull if your hearing extends to 20 kHz."

How would it work with DBR62? (6ohm and 86db)
Because I didn't like A07, it sounded harsh to me.

 

[Talisman]

"In English, this means that depending on which speaker you use, the sound may be a bit bright or a bit dull if your hearing extends to 20 kHz."

How would it work with DBR62? (6ohm and 86db)
Because I didn't like A07, it sounded harsh to me.

You will probably have the same feeling, the problem with load dependence, as amir explained, is that it is not equalizable because the impedance curve of the speakers is not a straight line and varies according to the frequencies, consequently also the response of the amplifier will vary with frequency, so EQ that works for one frequency may ruin another.

I guess you could EQ if you had electrostatic panels... Lol

@fosi will we ever solve this load dependency with your products? It's the only thing that separates you from an outstanding product

 

[Maiu95]

You will probably have the same feeling, the problem with load dependence, as amir explained, is that it is not equalizable because the impedance curve of the speakers is not a straight line and varies according to the frequencies, consequently also the response of the amplifier will vary with frequency, so EQ that works for one frequency may ruin another.

I guess you could EQ if you had electrostatic panels... Lol

@fosi will we ever solve this load dependency with your products? It's the only thing that separates you from an outstanding product

So this amplifiers perform best with easy-to-drive speakers, with others will sound like zzzzzzz?

 

[KenA]

Yeah, I don’t know.
I kinda feel down in that price range you really are going to get what you paid for. Yes, nice enough specs. But quality? Will it last? Will you use it and have a smile on your dial? Doubtful.
I know, I know, someone will say ‘smile all the way to the bank’ I’m sure.

 

[Rubberducky]

I currently have Q Acoustics 3030i speakers, are these "easy to drive" with an amp like this? Or will the load dependence influence the sound too much?

 

[GWolfman]

Some of you have been aiming at creating more work for me by asking for for efficiency tests. I developed a test that is semi-automatic and provides reasonable accuracy (within 5%):

Great to see a new edition to the tests!

 

[Talisman]

I currently have Q Acoustics 3030i speakers, are these "easy to drive" with an amp like this? Or will the load dependence influence the sound too much?

It's not a question of easy or difficult.

this is the answer of the 3020i (I didn't find the 3030i), up to about 10khz there are no big problems. Between 10 and 20khz it goes from about 5ohms to about 7ohms, so I don't think it's very audible as a problem. That 24 ohm peak at about 1.5khz would be a problem, but at that frequency the load dependence is fortunately minimal or non-existent.
Eventually in most cases the problem will be barely noticeable, but it would be nice not to have it

 

[AdamG]

Bargain hunters Rejoice!!! All this for a hunski. Hot damn, get two and give one to a friend. Thanks for the Review Amir

 

[Talisman]

How would it work with DBR62? (6ohm and 86db)
Because I didn't like A07, it sounded harsh to me.

Actually, your situation may not be that bad

Yes, between 10khz and 20khz the impedance is around 10ohm, so surely you would hear some zzzz, but the impedance response is almost completely stable, you should be able to equalize and have a pretty good result applying a curve opposite, then gradually removing more decibels from 5khz to 20khz and measuring to get the flattest response

 

[sarumbear]

I have one on order. Amir have you tried remeasuring after Opamp rolling? On this or any similar amp?

There is never a reason why op-amp rolling will make any difference to the measured response of a unit.

 

[sarumbear]

...between 10khz and 20khz the impedance is around 10ohm, so surely you would hear some zzzz...

How does that sound then?

 

[Multicore]

Some of you have been aiming at creating more work for me by asking for for efficiency tests. I developed a test that is semi-automatic and provides reasonable accuracy (within 5%):

Wonderful! Thank you, Amir.

I have often though about asking for an efficiency test, because efficiency matters a lot to me, but never did.

 

[mctron]

141w! You love to see it

 

[Triliza]

Thank you for the review and the extra work. I think this is a decent amp (acknowledging the issues it has) for the price, and there is a need for well engineered products in this price range to exist when the budget doesn't allow something else.

 

[alvigg]

There is never a reason why op-amp rolling will make any difference to the measured response of a unit.

Thanks. That seems pretty definitive.

 

[sarumbear]

Thanks. That seems pretty definitive.

You are welcome, as it is. Op-amps are very high gain devices and their gain is controlled by high levels of feedback. This means any deviations in their design is cancelled by feedback.

 

[badspeakerdesigner]

Load dependency always means poor rating for me. I don't think it's an acceptable issue to have in these little budget amps anymore.

 

[ModDIY]

A or B Taper volume pot?? Thanks for the review!!

Type A

 

[Toku]

I would like to highly appreciate that Fosi Audio V3 has seriously tackled and improved some of the problems that have been pointed out in Chinese amplifiers.

Adoption of taper A volume pot
Adoption of 63V withstand voltage capacitor
Improvement of heat dissipation structure of amplifier IC
Improved part quality

There are still points to be improved, such as the adoption of PFFB, but I expect further improvements in the future.