Fosi Audio ZA3 Amplifier Review

[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.

 

[FanatNsk]

can your preamp or DAC control volume?

Doesn't reducing the volume of the DAC reduce the dynamic range? Let's say at maximum volume of the DAC you had a range of 100 dB, you reduced the volume by 50 dB and you have only 50 dB left for playing music? Of course, not everyone has DSD recordings with a SNR of 120 dB, but still, reducing the volume is a deterioration in the accuracy of reproduction, quieter nuances will be less distinguishable.

 

[Guddu]

Doesn't reducing the volume of the DAC reduce the dynamic range? Let's say at maximum volume of the DAC you had a range of 100 dB, you reduced the volume by 50 dB and you have only 50 dB left for playing music? Of course, not everyone has DSD recordings with a SNR of 120 dB, but still, reducing the volume is a deterioration in the accuracy of reproduction, quieter nuances will be less distinguishable.

Don’t know if you are kidding or serious!

 

[EddNog]

Don’t know if you are kidding or serious!

We’re not all experts—that’s a legitimate question. I don’t have the answer—I’m assuming you do?

-Ed

 

[Guddu]

We’re not all experts—that’s a legitimate question. I don’t have the answer—I’m assuming you do?

-Ed

Simply put - It should be fine controlling volume on a DAC in general, best if DAC can output full 2v (in general) or amplifier doen't need 2v to provide its full gain/output.

 

[TonyJZX]

so the implication is that in some cases perhaps run the V3 at close to max vol and use the DAC vol. knob as the main controller?

i mean its a 'solution' i guess but then Fosi and Aiyima should just make power amps then in that case....

 

[Guddu]

so the implication is that in some cases perhaps run the V3 at close to max vol and use the DAC vol. knob as the main controller?

i mean its a 'solution' i guess but then Fosi and Aiyima should just make power amps then in that case....

or do it like pros…. have a volume bypass like Topping PA7.
It depends on target audience in general, but a desktop amplifier would have a volume control in 99% cases.

 

[40 Inferno]

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.

That's what I did when I had a similar issue with a Dayton Audio HTA100's potentiometer. I set the source gain (my PC) to 20% and the amp's knob to 50%, that completely solved the problem. Increased floor noise, though, but that could be because it just wasn't a good amp.

 

[staticV3]

Doesn't reducing the volume of the DAC reduce the dynamic range? Let's say at maximum volume of the DAC you had a range of 100 dB, you reduced the volume by 50 dB and you have only 50 dB left for playing music? Of course, not everyone has DSD recordings with a SNR of 120 dB, but still, reducing the volume is a deterioration in the accuracy of reproduction, quieter nuances will be less distinguishable.

The only way in which reduced dynamic range can rear its head in the the form of noise/hiss.

If you can't hear the DAC's noise floor as hiss coming from your speakers, then it doesn't matter how heavily you use its volume control and reduce its dynamic range; the limiting factor will be elsewhere.

 

[EddNog]

Simply put - It should be fine controlling volume on a DAC in general, best if DAC can output full 2v (in general) or amplifier doen't need 2v to provide its full gain/output.

The only way in which reduced dynamic range can rear its head in the the form of noise/hiss.

If you can't hear the DAC's noise floor as hiss coming from your speakers, then it doesn't matter how heavily you use its volume control and reduce its dynamic range; the limiting factor will be elsewhere.

Does it matter whether the DAC in question is controlling volume in the digital domain versus if it’s controlling volume in the analog domain?

I see what you guys saying being true for DACs that have analog volume attenuators, but I was unclear on digital domain volume control. Does half volume mean half the available resolution?

-Ed

 

[TonyJZX]

a good dac should have a vol. control that has more bits than the chipset inside can do so you should not being losing any resoltuion on a good dac

 

[staticV3]

Does it matter whether the DAC in question is controlling volume in the digital domain versus if it’s controlling volume in the analog domain?

If you can't hear hiss, then it doesn't matter.

If you can hear hiss, and it's coming from the DAC, then adding an analog attenuators between DAC and Amp may get rid of it.

 

[burkm]

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

Fosi Audio already provides a fan by now for those, who feel, that the V3 Mono is to warm to be handled without it. On Amazon you will find other options to do this for a lesser price (120mm 3 speed quiet USB fans with screens and silicone standoffs on both sides). They just fit between the footings of the cabinet...
For some unknown reason the classification of "warm" or "hot" crossly deviates between users. The real cause of discern would be, knowing the resulting "internal" temperatures of those components (electrolytic capacitor), which might change their life expectancy accordingly to the temperatures in the near surroundings.

 

[dedede223]

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.

so far i tested three amp (Topping PA3s, fosi ZA3 and Aiyimia A07 Max) the fosi and A07 both have the same issue with the right channel dropping, i didn't try to set the amp to max and control everything else, i'll test that for the days coming,
for a moment i though the crossover of one of my speaker was going bad but i switched my speaker (thinking the bad one was on the wrong shelf and not easily accessible) and got the "good" one at my right and got the same issue. Some crackling noises and the sound that cut and come back a few times, cracking up the volume settle it for a few days usually

i've jsut set the amp to max volume and will control the volum from my computer to see, but except that seems like the TPA3255 doesn't like my speaker xD

 

[FanatNsk]

Does it matter whether the DAC in question is controlling volume in the digital domain versus if it’s controlling volume in the analog domain?

I made measurements, the volume on the DAC is 100% at the output of the SNR 80 dB.

I reduced the volume on the DAC with a cheap analog regulator by -36 dB, the output of the SNR is 54 dB.

With digital volume control on the DAC, the volume is 100% at the output of the SNR 107 dB

With a decrease in volume -36 dB at the output of the SNR 73 dB.

So cheaper volume controls are not suitable for DACs. Topping uses precision LNRD (low noise regenerative divider) in their best DACs. Fosi's advice to turn down the volume on the DAC means I have to steal my SNR.

 

[EddNog]

I made measurements, the volume on the DAC is 100% at the output of the SNR 80 dB.

View attachment 401035

I reduced the volume on the DAC with a cheap analog regulator by -36 dB, the output of the SNR is 54 dB.
View attachment 401036

With digital volume control on the DAC, the volume is 100% at the output of the SNR 107 dB
View attachment 401037
With a decrease in volume -36 dB at the output of the SNR 73 dB.

View attachment 401038

So cheaper volume controls are not suitable for DACs. Topping uses precision LNRD (low noise regenerative divider) in their best DACs. Fosi's advice to turn down the volume on the DAC means I have to steal my SNR.

At risk of going even further off topic, do we know what type of volume control is on the Topping E70 Velvet when set to Pre mode?

-Ed

 

[staticV3]

At risk of going even further off topic, do we know what type of volume control is on the Topping E70 Velvet when set to Pre mode?

Digital volume attenuation applied by the AK4499EX

 

[Bene]

i've jsut set the amp to max volume and will control the volum from my computer to see, but except that seems like the TPA3255 doesn't like my speaker xD

I set the volume at 12 o'clock and after that I control the volume only from the PC...for me it sounds very loud...I can't imagine setting the amp. aka Za3 above 12 o'clock. I have a pair of Keff Q150 with only 85 db. rca to zen dac

 

[FLS3]

I made measurements, the volume on the DAC is 100% at the output of the SNR 80 dB.

View attachment 401035

I reduced the volume on the DAC with a cheap analog regulator by -36 dB, the output of the SNR is 54 dB.
View attachment 401036

With digital volume control on the DAC, the volume is 100% at the output of the SNR 107 dB
View attachment 401037
With a decrease in volume -36 dB at the output of the SNR 73 dB.

View attachment 401038

So cheaper volume controls are not suitable for DACs. Topping uses precision LNRD (low noise regenerative divider) in their best DACs. Fosi's advice to turn down the volume on the DAC means I have to steal my SNR.

I don't think that's correct, as it's a ratio. You lower the signal and the noise stays the same, obviously you get a different SNR. It doesn't mean the noise is going up, so it doesn't mean you're losing sq. You're just setting it at a below where SNR is measured for comparison's sake.

If I'm wrong I'd love to know!

 

[gpunique]

I like this amp a lot but wish it had a headphone jack. Is there any way to add one easily and not too pricey? I would like to be able to run headphones needing 300 ohms. Thanks.