Fosi Audio ZA3 Amplifier Review

[CrypticSignal]

It could be --- can you turn auto off?

I don't think it's set to auto. The setting in the SVS app for "SUBWOOFER STANDBY" is set to "ON" rather than "Auto" (see attached screenshot) which I'm assuming means it's on all the time.

And I haven't had this issue when using the subwoofer with the Bluesound Powernode or WiiM amp, just with the Fosi.

Also, it shouldn't be going to standby during a song even if the subwoofer was set to auto, after a quick Google, it should only go into standby after 20 minutes.

 

[CrypticSignal]

I've done some more testing. There's definitely something wrong with the amp, I'm listening to music and it just stops outputting to the subwoofer at some point. There's no way my subwoofer is going to standby within minutes especially while I'm listening to music and it should be receiving a signal.

 

[Dennis_FL]

I've done some more testing. There's definitely something wrong with the amp, I'm listening to music and it just stops outputting to the subwoofer at some point. There's no way my subwoofer is going to standby within minutes especially while I'm listening to music and it should be receiving a signal.

I have the same amp. If you send the problem to [email protected] --- they get back very quickly

 

[CrypticSignal]

I have the same amp. If you send the problem to [email protected] --- they get back very quickly

I don't think there's anything that can be done from opening it and inspecting to see what might be the cause, or getting a replacement. I bought it from eBay and the seller is okay with me returning it and issuing a refund, so that's what I'm going to do. I think I'll stick with the WiiM Amp, it also has a subwoofer output which not only sets a LPF but also a HPF for the speakers, which is what I want.

 

[carlmart]

Is there any thread or place where we can see the "Rate this amplifier" list complete with users comparisons?

 

[EddNog]

While I see your point, the volume control here gives you variable gain settings. In my testing I just set it to max and ran all the tests.

Anybody know approximately where on the volume dial travel would be close to unity gain (zero gain)? Or how would it be possible for me to figure that out?

-Ed

 

[somebodyelse]

Anybody know approximately where on the volume dial travel would be close to unity gain (zero gain)? Or how would it be possible for me to figure that out?

-Ed

You can measure it with a multimeter. The cheap ones are usually ok up to ~400Hz on the AC setting. You need something to generate a sine wave signal - this could be software like REW. Set the frequency to somewhere between 50Hz and 400Hz - the exact frequency isn't important. First you should unplug the cable at the amp input and measure the signal level. With the amp powered off reconnect the cable to the amp, turn the volume down low then connect the meter leads to the amp output before turning on the amp. Now slowly turn up the volume until the meter shows the same as you measured for the input.

 

[Graham849]

Is there any thread or place where we can see the "Rate this amplifier" list complete with users comparisons?

Brian has a few posts before and after this

Fosi Audio V3 Mono Amplifier Review

Honest question here as I see people very happy about the phono input... First, I am not a vinyl guy, but why would you want digitize the beloved vinyl/analog output? Because analogue amplification is compromised, but most importantly you can't apply room correction, arguably even more...

www.audiosciencereview.com

 

[HDavidson]

Which entry is better in your opinion, RCA or XLR?

 

[Graham849]

Which entry is better in your opinion, RCA or XLR?

Xlr

 

[HDavidson]

There is a big difference in volume between RCA and XLR with Topping DX5. I read on one forum that the XLR Fosi input is more decorative. It is converted into an RCA input later. That is why I doubt using XLR.

 

[Graham849]

There is a big difference in volume between RCA and XLR with Topping DX5. I read on one forum that the XLR Fosi input is more decorative. It is converted into an RCA input later. That is why I doubt using XLR.

Did you read the review in post#1, and look at the measurements. Is the Topping DX5 measuring the same input level? Was the other forum commenting about the original release with gain issue? I have been using XLR out from DO100 and am very happy with the volume.

 

[FanatNsk]

Today I measured Fosi ZA3 in REW-RTA on 1 kHz sine wave and found that THD increases if the input signal exceeds 1.3 Vrms. I can't find any information about the characteristics of the input signals for RCA and TRS inputs on ZA3?

 

[LSPhil]

The Texas Instruments says in its catalogue that the maximum input voltage should be 4.0Vpp.
You can calculate your 1.3Vrms and the answer will be self-explanatory

 

[EddNog]

There is a big difference in volume between RCA and XLR with Topping DX5. I read on one forum that the XLR Fosi input is more decorative. It is converted into an RCA input later. That is why I doubt using XLR.

Did they state which model amplifier they were talking about? V3 Mono is balanced internally, so there is an op-amp performing a signal conversion for single-ended inputs on those. For ZA3, it is the reverse, where internally the amplifier is not balanced, so there is an op-amp performing a signal conversion for the balanced input, which means it DOES take advantage of fully balanced differential input signals, but it gets converted down to single-ended for amplification.

-Ed

 

[LSPhil]

The input for TPA3255 is always symmetrical. An RCA signal must be converted to symmetrical input for TPA.

 

[EddNog]

The input for TPA3255 is always symmetrical. An RCA signal must be converted to symmetrical input for TPA.

The chip itself is one thing, but the circuit they implement it in is another, no?

-Ed

 

[MCH]

The input for TPA3255 is always symmetrical. An RCA signal must be converted to symmetrical input for TPA.

Can accept SE signals as well. Not confirming that ZA3 does, which I don't know and seems a bit strange, but it is indeed possible.

 

[LSPhil]

Can accept SE signals as well. Not confirming that ZA3 does, which I don't know and seems a bit strange, but it is indeed possible.

In the SE configuration we have 4 amplifiers in which the input is asymmetric. TPA must be specially coded for this type and 470uF capacitors on the output.

 

[LSPhil]

The chip itself is one thing, but the circuit they implement it in is another, no?

-Ed

TPA ist Symmetrisch, and I don't know how it was solved at the input level, because I don't know the circuit diagram of the entire amplifier.