Fosi Audio ZA3 Amplifier Review

[patrick1112]

literally this

using rca cables to 'neutralise and calm the disorder' (???) from opamp abuse is i cant begin to even parse what this is

Sorry Tony, just sharing my experience arround Fosi ZA3 with Sparkos opamp for those who wish to bridge the gap between technical aspects and audiophile concerns.
"Music hath charms to soothe the savage breast".

 

[Overseas]

Never know what a new cable will do, improve the soundstage, compensate for change of opamp or just take off the veil. Endless possibilities. Hifi a la Forrest Gump and his chocolate box. Engineers probably left the factories and now wizards build cables and amps.

 

[Sonhires]

Cet amplificateur, surtout double mono, est vraiment génial pour le prix et plus.
I replace thé amp op by 2 pairs of 1612 and it's better. Thé muses01 seem to be a good choice too.

 

[bboris77]

I have a very specific question for anyone that may be using both rca and balanced inputs and is connecting a subwoofer: Do you need to readjust the volume level on your subwoofer whenever you switch from
balanced to unbalanced input on your ZA3? I’m planning to use both inputs and it would be a deal breaker for me if this were the case.

A bonus question: Does this unit use an analog or a digital low pass filter for the subwoofer out? If it is in digital domain, I am hoping that it leaves the main signal untouched and only digitizes the sub out signal before rolling off the highs.

 

[pseudo]

Interested in this amp combined with a svb powered sub.
Could someone explain to me in simple terms the problem/issue that I've seen mentioned a few times about the sub out being filtered?
What does this mean in practice?
Thanks

 

[EddNog]

Interested in this amp combined with a svb powered sub.
Could someone explain to me in simple terms the problem/issue that I've seen mentioned a few times about the sub out being filtered?
What does this mean in practice?
Thanks

The subwoofer output on the ZA3 has a high-pass filter. This is a generally useless feature because virtually all active subwoofers (especially SVS) already have their own integrated.

That being said, I’ve found that my SVS SB-3000 sounds better hooked up to the single-ended outputs of my preamp than to the sub outs on my ZA3s.

-Ed

 

[Guddu]

Interested in this amp combined with a svb powered sub.
Could someone explain to me in simple terms the problem/issue that I've seen mentioned a few times about the sub out being filtered?
What does this mean in practice?
Thanks

If you have powered sub with frequency controls then there shouldn’t be an issue from sub prospective.
Only this to consider is that your main speakers will still get full frequency signal.

 

[EddNog]

If you have powered sub with frequency controls then there shouldn’t be an issue from sub prospective.
Only this to consider is that your main speakers will still get full frequency signal.

@pseudo exactly, having a high-pass filter for the main loudspeakers would’ve been a truly high-value feature. I’ve had to rely on in-line active crossover filters attached between the amp and the speakers in the past for this, a huge hassle.

-Ed

 

[pseudo]

If you have powered sub with frequency controls then there shouldn’t be an issue from sub prospective.
Only this to consider is that your main speakers will still get full frequency signal.

Hmm so is this not a good choice for my use case? How much of an issue is the main speakers low end combining with the sub's?
Is this the case with all these amps with sub outs in this price range?

 

[EddNog]

Hmm so is this not a good choice for my use case? How much of an issue is the main speakers low end combining with the sub's?
Is this the case with all these amps with sub outs in this price range?

It should be mostly fine for your use case, but there’s a lot of factors to take into account beyond just the amp. You’d have to consider what speakers you’re matching to (what their bottom-end extension and room frequency response are) and overall room response to the entire system.

I needed to take the drastic measure of high-pass filtering my main loudspeakers because my room had a MASSIVE bass hump at 43hz and no matter how much negative gain I set in the SB-3000’s DSP at 43hz, it was still too much bass there, so I needed to completely roll off my main speakers starting at 80hz in order to dumb down the total system at 43hz enough for a flat response. However, this difficult scenario was very much specific to my own situation/room.

In the end I did away with the active crossover entirely and resorted to PEQ adjustment for the entire system, which has worked out even better since I am able to retrieve sub bass response back using a big low shelf at 30hz despite a big negative peak at 43hz. Also needed a boost around double that frequency to restore punch.

-Ed

 

[Guddu]

Hmm so is this not a good choice for my use case? How much of an issue is the main speakers low end combining with the sub's?
Is this the case with all these amps with sub outs in this price range?

What are you main speakers?
Most of the bookshelf & Floorstands might be okay as they have crossovers taking care of stuff.
If you are going to use some on-wall type small speakers then louder volume would have distortions and other issues.

 

[zziplex]

- removing all the opamp, expect the right channel, gave an additinal real step of improvement. All seems better, with the same tonality, but all better (precision, space, reality). At this point result is just astonishing, sound is so high quality, so real, giving me goosebumps.
- then I changed the original opamp with the SS3602 (around 200€ for 2). Additinal improvement is there, but more tricky. There is more precision, but it changes the tonality, giving more (too much ?) upper mi-range that gave me fatigue . I had to change RCA cable for a more nutral one to calm this disorder. And now I am happy

In my system, I found that using muses02+ SS3602 produced better results compared to using empty + SS3602 in a mono setup (not using opamps in other sockets).

 

[EddNog]

In my system, I found that using muses02+ SS3602 produced better results compared to using empty + SS3602 in a mono setup (not using opamps in other sockets).

Did you also consider trying leaving the stock op-amp in the left channel? And are you running single-ended RCA or are you running balanced XLR?

-Ed

 

[zziplex]

I've experimented with several opamps and found that, after comparing them, I rarely stick with the stock one. I don't use XLR DACs or cables.

Initially, I plugged in the Muses02 to the left channel for burn-in, but I ended up leaving it there because it sounds better to me. I accidentally ordered extra Muses02s ^^.

Currently, my setup consists of two Burson Audio V7 Classic opamps with one ZA3 amp.

 

[mike70]

I've experimented with several opamps and found that, after comparing them, I rarely stick with the stock one. I don't use XLR DACs or cables.

Initially, I plugged in the Muses02 to the left channel for burn-in, but I ended up leaving it there because it sounds better to me. I accidentally ordered extra Muses02s ^^.

Currently, my setup consists of two Burson Audio V7 Classic opamps with one ZA3 amp. Unfortunately, the RCA cap fell off the other ZA3 amp, and I'm still working with Fosi support, which has been disappointingly slow (one email per day).


View attachment 364691

That test was maded blindly / levelled gain or with a sight / uncontrolled approach?

 

[zziplex]

That test was maded blindly / levelled gain or with a sight / uncontrolled approach?

I hope this answers your question.

-Edit-

Hmm, this post seems a bit negative to Sparkos. I'm a big fan of the SS3602 OPAMP and Andrew Sparks.

 

[mike70]

I hope this answers your question.

Well, it seems is an uncontrolled sighted test. So, the results are (very) subjective to who maded the test. It's not a technical fact.

 

[gigantic]

In my system, I found that using muses02+ SS3602 produced better results compared to using empty + SS3602 in a mono setup (not using opamps in other sockets).

to be clear, are you using the MUSES02 and the differential op amp & the SS3602 in the driver socket or vice versa?

 

[zziplex]

to be clear, are you using the MUSES02 and the differential op amp & the SS3602 in the driver socket or vice versa?

"Well, it seems is an uncontrolled sighted test. So, the results are (very) subjective to who maded the test. It's not a technical fact."

 

[swiper1911]

I'm pleasantly surprised by the performance of this amp. Before I was powering my bookshelf speakers with the MC 101 by Fosi, which is no slouch. But the sound stage and presence that I'm getting with the ZA3 is next level. The mid range is fuller, and the sub out is much better at providing a signal to my sub amp. And as a result my subwoofers play louder, deeper, and much cleaner. I'm absolutely delighted by this amp.