Fosi Audio ZA3 Amplifier Review

[FanatNsk]

Have you measured your 2.24V signals in loopback (without the amplifier, just DAC out directly to ADC) to check out all is good?

The message about the clipping is given by the REW generator; there is no clipping at the sound card input.

Here is a loopback measurement of my sound card 2.24V

 

[FanatNsk]

I found another problem with Fosi ZA3, at very low volume the left channel is quiet, the right one is audible. Perhaps this is a defect of my amplifier, can someone check it for themselves, smoothly reduce the volume to zero and compare the volume of the left and right channels.

 

[EddNog]

I found another problem with Fosi ZA3, at very low volume the left channel is quiet, the right one is audible. Perhaps this is a defect of my amplifier, can someone check it for themselves, smoothly reduce the volume to zero and compare the volume of the left and right channels.

Cheap volume attenuator (potentiometer). They have to cut costs somewhere.

-Ed

 

[staticV3]

I found another problem with Fosi ZA3, at very low volume the left channel is quiet, the right one is audible. Perhaps this is a defect of my amplifier, can someone check it for themselves, smoothly reduce the volume to zero and compare the volume of the left and right channels.

Common issue of all potentiometer-based volume controls.

To fix it, turn down the audio source device and turn up the Fosi to compensate.

 

[FanatNsk]

Common issue of all potentiometer-based volume controls.

To fix it, turn down the audio source device and turn up the Fosi to compensate.

I had cheaper amplifiers, on TPA3116 (Aiyiama B01, Aiyiama A03), TPA3255 (BRZHiFi X21, O-noorud D3, Fosi V3, ZK-AS21) also amplifiers on TAS (O-noorus DA10, Aiyiama D05) - none of these amplifiers had problems with the volume control at low volume, Fosi ZA3 is a fiasco!

 

[somebodyelse]

I had cheaper amplifiers, on TPA3116 (Aiyiama B01, Aiyiama A03), TPA3255 (BRZHiFi X21, O-noorud D3, Fosi V3, ZK-AS21) also amplifiers on TAS (O-noorus DA10, Aiyiama D05) - none of these amplifiers had problems with the volume control at low volume, Fosi ZA3 is a fiasco!

That's more a matter of luck than design. Potentiometers have a specified range of matching for the two channels. Most fall nearer the middle of the range (good matching) while some fall nearer the limit. Unfortunately you've got one of those this time. Manufacturers can buy potentiometers with tighter tolerances, or test them all before use to reject the worse ones, but those add to the cost.

 

[FanatNsk]

That's more a matter of luck than design. Potentiometers have a specified range of matching for the two channels.

I agree, there are often regulators with an imbalance of 1-2 dB, but in this case the difference is 10 dB.

 

[somebodyelse]

I agree, there are often regulators with an imbalance of 1-2 dB, but in this case the difference is 10 dB.

View attachment 392744

What range of volume control does this apply over? And you're sure you didn't accidentally enable the pad on one of the inputs?

 

[FanatNsk]

What range of volume control does this apply over? And you're sure you didn't accidentally enable the pad on one of the inputs?

The channel imbalance is audible at low volume of the speaker system, about <50 dB, at higher volume everything is fine, it is usable, but unpleasant, sometimes I listen to music at night at low volume.

 

[Power Pop 23]

Fosi Audio is discounting the price (ranging in price from $87.99 to $107.99) of new samples of the ZA3 amplifier in select configurations - with or without a 32 or 48 volt power supply unit - on Ebay:

Fosi Audio ZA3 TPA3255 Balance Stereo Amplifier Home Audio Mono Subwoofer AMP | eBay

Audiophile-Grade Components: The ZA3 features the TPA3255 high-end Class-D amp chip and utilizes premium Japanese NCC, ELNA, and German WIMA capacitors, and Japanese Sumida inductors for exceptional audio quality.

www.ebay.com

 

[Miiksuli]

Front op-amps are for RCA input?

 

[Spiky]

Hello!

I'll ask here too

I have a Fosi V3 2024 stereo amplifier, on which a t.amp amplifier is connected to the preout, which drives the subs.
My question is, would it make sense to replace it with a ZA3 that has a separate sub output?

 

[KR500]

The channel imbalance is audible at low volume of the speaker system, about <50 dB, at higher volume everything is fine, it is usable, but unpleasant, sometimes I listen to music at night at low volume.

Maybe try contacting Fosi Audio about this to see what they say.
It appears they listen to feedback from the community and might address issues in further production ?
The JDS Labs Atom 2 amp I use has a really good potentiometer gain knob with excellent channel balance and operation.
So, it is doable at this price point if attention is paid to securing the right part and implementing it

 

[burkm]

It depends, because the ZA3 has the same amp chip (TPA3255) as the V3 Stereo (and the V3 Mono), but the (passive) subwoofer out is somewhat different, if I remember correctly.
The "new" V3 (2024 Version. sold out ?) has a volume controlled output for a 2nd amp, but it can't handle a passive subwoofer without an additional amp, just an active one. It doesn't have a "subwoofer out", so you would need some kind of a low pass filter in front of the active subwoofer and the amp section (full bandwidth) is (almost) the same as for the ZA3.
Ususally You have at least a low pass filter for the (active) "Subwoofer out" and a high pass filter for the (passive) main speakers.
The (normal) V3 stereo version doesn't have PFFB correction either, which the V3 Monos have.
As already suggested, try to communicate with the Fosi Audio support about Your question...

 

[FanatNsk]

Maybe try contacting Fosi Audio about this to see what they say.

They said it was normal.

 

[40 Inferno]

They said it was normal.
View attachment 396855

I recently bought a ZA3 to replace my Dayton Audio HTA100, which had a similar problem with channel imbalance at low volume. I bypassed it by lowering source gain and turning up amp volume, and that helped but increased noise floor. The Fosi actually works fine but this does seem to be an issue with cheap amps. The customer support at Parts Express was better though (they acknowledged that it's a problem and offered to replace the amp).

 

[chomi]

I just want to confirm if the fosi v3 with a 48v psu runs warm to touch when just idle?

 

[EddNog]

I just want to confirm if the fosi v3 with a 48v psu runs warm to touch when just idle?

Yes.

-Ed

 

[dedede223]

Ok so, i'll make my ZA3 go back to amazon, the left chanel dropout regularly even after having check all the solder and replace the thermal past. it's not an overheating issue and doesn't seems to be a bad solder, maybe one OPamp is bad somewhere but i don't have the patience to test all of them and thing. I think i'll replace it with a V3. I would love to buy two V3 mono but it's a little bit too expensive for me.

So i sent back my Fosi ZA3 a few week ago and bought a Aiyimia A07 MAX, i have the exact same issue with both speaker and it's always the right chanel that drop, i also found that when crancking up the volume a little bit each time it does that allows me to have the signal back a few moments.
It seems the amp chip really doesn't like the Bowers & Wilkins Matrix 2 S1, my old topping PA3s never had any issue like that.

 

[Guddu]

So i sent back my Fosi ZA3 a few week ago and bought a Aiyimia A07 MAX, i have the exact same issue with both speaker and it's always the right chanel that drop, i also found that when crancking up the volume a little bit each time it does that allows me to have the signal back a few moments.
It seems the amp chip really doesn't like the Bowers & Wilkins Matrix 2 S1, my old topping PA3s never had any issue like that.

can your preamp or DAC control volume?
Probably worth trying setting amp vol max in such case to eliminate potentiometer if it has anything to do with it…. but seems unlikely with 2 different amps.
Don’t know if you already isolated it.