Fosi Audio ZA3 Amplifier Review

[Richard G]

PA5 II (plus) is not a lot more expensive

I don’t know that brand/ product … in what way/s is it better? (And what is the brand?)

 

[D_Swooz]

I’m kinda of stumped here and unfortunately Burson Audio is playing games. I have the soloist voyager headphone amp. When using XLR I’ve noticed an windy static noise in my right headphone. It comes and goes very inconsistent. When I use 6.35 connection, it’s perfectly silent. I’ve disconnected the amp from a source so all that’s plugged into the amp is the power cable and my headphones. What’s causing this? Thanks fellas!

 

[somebodyelse]

I don’t know that brand/ product … in what way/s is it better? (And what is the brand?)

https://www.audiosciencereview.com/...topping-pa5-ii-stereo-amplifier-review.47362/

 

[Bleib]

I don’t know that brand/ product … in what way/s is it better? (And what is the brand?)

Topping. Cleaner, better frequency response..it's been tested here at ASR

 

[Jon L]

Do note with ZA3 that the frequency response is load-dependent so switching between stereo and mono modes may yield a different frequency response (whether you can hear the difference at such high frequencies is debatable). Mono may sound darker/less airy. Or it might not (to you).

Interesting, since coincidentally some report the Fosi ZA3 in monoblock mode to sound "the most analogue" sounding of all these TPA3255 amps

 

[Deleted member 72219]

Yeah, so I gave my dad both my ZA3s once I got my V3 Monos, along with a pair of Aiyima’s GAN 48V/10A power supplies, to make sure that they definitely had enough power to drive his tougher-to-drive speakers (Magnepan LRS+). The very first day he had them, the RCA connector broke off (I only ever used those ZA3s with XLR input), so I had him send it back to me and Fosi graciously sent me a replacement amplifier board. When it came in, I swapped the boards to complete the warranty repair, and shipped the fixed unit back to my dad. He enjoyed it for another one day and then the repaired amp cut out and doesn’t make sound anymore. Just too many problems with that one unit, so I decided to take advantage of the 20% preorder coupon from Fosi and ordered another pair of V3 Monos without power supplies rather than order another ZA3. Once they come in next month, I will give them to dad and take back the ZA3s to try and diagnose the issue with the bad amp. If I have anything useful to report, I’ll advise back in here.

-Ed

 

[Jon L]

Yeah, so I gave my dad both my ZA3s once I got my V3 Monos

So do Fosi V3 Monos sound less dark and "analogue" than ZA3 Monos?

 

[Deleted member 72219]

So do Fosi V3 Monos sound less dark and "analogue" than ZA3 Monos?

Sorry, but the only thing I’m going to talk about anymore around here is pure functionality and that’s it. I’ll keep my opinions to myself and other forums from now on.

If you want to discuss subjective matters, I’m up for it on DM. I will not make posts that may be deemed as such.

-Ed

 

[Bleib]

So do Fosi V3 Monos sound less dark and "analogue" than ZA3 Monos?

Erin compared the mono to some amp, you might want to check out his video
"Sounds like an amp", or something similar as he said.. to me it sounded like he thinks it doesn't really have any sort of sound

 

[Graham849]

$150AUD on Amazon using $10zip coupon, I could not resist.

 

[r3uba6HBHa2Ye7F]

Is it possible to short the volume pot without affecting the power on functionality?

I want to use my preamp to control volume.

How better is the v3/v3 mono vs this one? Thanks

 

[Deleted member 72219]

Is it possible to short the volume pot without affecting the power on functionality?

I want to use my preamp to control volume.

How better is the v3/v3 mono vs this one? Thanks

Here are the standardized ASR responses to these questions:
You do not need to do this because, as per Amir’s testing, leaving the volume dial on the ZA3 at maximum will allow you to use the amplifier at its maximum SINAD. Many people use the ZA3 this way in conjunction with a separate preamp, myself (previously) included.

Once level matched, the difference in overall sound quality between ZA3 and V3 Mono should be essentially indistinguishable except potentially at the extreme highest frequencies due to the load level dependency of the frequency response curve of the ZA3, which is a condition Fosi eliminated on the V3 Monos by using a PFFB design. Whether or not you can hear that difference depends on the ability of your speakers to even reproduce frequencies that high accurately, whether your room/listening space allows the speakers to translate frequencies that high to your listening position, and whether you are still able to perceive and process frequencies that high.

-Ed

 

[r3uba6HBHa2Ye7F]

Does it make a difference (power wise) if using balanced input and in mono mode?

Thanks

 

[Deleted member 72219]

Does it make a difference (power wise) if using balanced input and in mono mode?

Thanks

Mono mode produces a >30% increase in power at the same THD versus Stereo mode, however Stereo mode has better SINAD than Mono mode. Additionally, there is likely a change in the high frequency response due to change in load effect on the amplifier between the two settings on ZA3 due to the lack of PFFB. The right choice to go with will depend on multiple factors included how hard your speakers are to push and whether or not you can actually hear that difference in SINAD. Arguably, one should use Stereo mode by default and only use Mono mode if your speakers are too hard to drive in Stereo mode.

-Ed

 

[r3uba6HBHa2Ye7F]

Mono mode produces a >30% increase in power at the same THD versus Stereo mode, however Stereo mode has better SINAD than Mono mode. Additionally, there is likely a change in the high frequency response due to change in load effect on the amplifier between the two settings on ZA3 due to the lack of PFFB. The right choice to go with will depend on multiple factors included how hard your speakers are to push and whether or not you can actually hear that difference in SINAD. Arguably, one should use Stereo mode by default and only use Mono mode if your speakers are too hard to drive in Stereo mode.

-Ed

Are your statements whether I use XLR or RCA?

 

[Deleted member 72219]

Are your statements whether I use XLR or RCA?

Choice of input does not affect maximum power, it affects gain. XLR has higher base SINAD, but the difference between Mono versus Stereo is the same.

-Ed

 

[Deleted member 72219]

Just wanted to report back with something odd. My pair of ZA3s that I gifted to my father after upgrading my chain to V3 Monos, he said the left ZA3 failed first and then the other one eventually went, after he attempted to hook his REL subwoofer up to them via high (speaker) level connection. He is returning the two seemingly dead amplifiers to me to check them out, but they don’t arrive until Monday. For now, he has begun rearranging his chain to utilize the low/line-level input for his subwoofer instead by hooking it up to the second output on his preamp.

I am curious if anyone else has had any opportunity to or success with hooking up a subwoofer via high level connection to a pair of ZA3s. Or even to a single ZA3 running in stereo?

-Ed

 

[ampguy]

Just wanted to report back with something odd. My pair of ZA3s that I gifted to my father after upgrading my chain to V3 Monos, he said the left ZA3 failed first and then the other one eventually went, after he attempted to hook his REL subwoofer up to them via high (speaker) level connection. He is returning the two seemingly dead amplifiers to me to check them out, but they don’t arrive until Monday. For now, he has begun rearranging his chain to utilize the low/line-level input for his subwoofer instead by hooking it up to the second output on his preamp.

I am curious if anyone else has had any opportunity to or success with hooking up a subwoofer via high level connection to a pair of ZA3s. Or even to a single ZA3 running in stereo?

-Ed

Check with Rel, using high level inputs from class d is different than from a/b amps. There is an explanation and alternative proposal on their site, maybe double check with Fosi as well.

 

[Zek]

maybe double check with Fosi as well.

Perhaps the problem is that the (-) output for speakers on the D-class must not be connected to the GND (-) input of active speakers.

 

[Deleted member 72219]

Got the amps back from my dad, swapped all of the stock op-amps back in, and swapped them into my chain in place of my V3 Monos to test them and they’re both working fine now. Guessing either their internal safeties got kicked and disconnecting them from power reset their safeties so they work again, and/or the aftermarket op-amps were fried (did not get to test them yet, but I really hope they are okay too!). Now I have…way too many amps. Hah!

(Please disregard the doorstops—they are just to weigh the amps down in case one of my cats trips the speaker cable with their luscious little bodies)

-Ed