Fosi ZA3 Amplifier Deep Dive Review (with Data)

Written review/data can be found here:
(coming soon)

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[ErinsAudioCorner]

Re: Audible differences in amps, opamps, etc

My personal take is this: Can differences be heard? Absolutely. Do measurements-only matter? Nope. Am I skeptical of claims of audibility? Yep.
Now, let me explain...

As someone who does have a bit of a following (albeit, quite small) I will always default to not talking about hearing things that I can't at least point to evidence with. It's not "just about measurements". It isn't. It's about being able to back up a claim. Whether that be providing measurements or results of a proper blind test. Either is acceptable to me as proof. The last thing I want to do here is to fool my audience into believing things that may not be true.


None of this means that differences can't be a) heard and b) measured. In fact, I think there very well can be differences heard. But are those differences real or are they some form of sighted listening bias? In the case of Fosi ZA3 amp I have shown that its load dependency can effect the response of the speaker and that may very well be audible.

The key is this: If someone can so easily hear differences in amplifiers, opamps, etc then it really should be easy to prove via a simple blind listening comparison. You don't have to have hardware or measurement experience. You just have to do a proper blind listening test with the help of a friend or friends. No one is doing that, though. At least not in the review space that I'm aware of.

None of the above makes me a "non-believer". It just means that I take a reserved stance and am cynical of claims of audibility without some sort of evidence. I think that's a pretty reasonable approach to take. Especially when it comes to spending money based on claims. And, in my specific case, especially when I'm helping people decide if they want to part with their money on a product. I wouldn't feel good telling a friend to drop $300 on something I wouldn't buy. I am not going to tell my audience to do that, either. 👍

I prefer to report on things that I can prove or at the very least have some sort of pointer to. Whether that be from a blind listening test or measurements, doesn't matter to me. I just need to feel confident in telling you all that what I am reporting is accurate and not just words I used to fill space.

I'm not saying any of this to get anyone to agree with me. I'm saying it so you understand where I'm coming from. Hopefully you can respect that.

- Erin

[richh]

I have watched over a dozen of the ZA3 amp reviews and your review is the best review by far. You actually understand how to test and then associate that with how it really sounds and preforms. Your efforts are MUCH appreciated as you have become my go-to reviewer!!!

[litzy]

After watching other reviews on this amp, my biggest question was how much power does it really have. And I knew if I were to ask in the comments they would just feed me the vague garbage that was provided by the manufacturer. But Erin came thru with the real measurements I wanted to see! I was impressed. Thanks you very much Erin.

[JosephTongret]

This isn't really about the amp, but I'd LOVE to see you get in one of the Minidsp models (Flex/SHD/2x4) and do a few videos covering procedures to improve system performance. Time align, fir, crossovers, etc. There's a lot of guides already out there, but the way you explain what's happening and why ALWAYS leaves me with a better understanding than what I initially had. You have a way of making complicated topics so much easier to digest than most sources. Thanks for the content Erin, you're an invaluable source!

[HunterMikeWI]

Fosi is working on LPF and HPF filters for the next gen models. They are deciding on fixed or variable frequency.

[slam]

Subwoofer issue: I am very happy that the sub is not attenuated. With proper tuning on your sub the overall presentation is beautiful. I am glad Fosi did what they did.

[xgzzqsq]

I have a geology degree here. It's about as useful as a roll of toilet paper. But I can say that sand is classified under different diameters, usually under 30mm (max range). But salt crystals can grow larger.

[Clobercow]

Late or not, I'd rather hear it from you than most of those jokers out there.

[tugbars]

Checking the frequency response of the amp with a reactive load is a genius idea.

[markalot]

Thanks for an actual review, much appreciated. As an old guy getting back into amplifiers "hifi" I was surprised to see many golden ear reviews but few if any actual objective reviews. I probably shouldn't have been surprised. Soundstage, imaging, lol, different op amps, oh my! I've got the WiiM amp, very happy with it for what it is.

[mathumphreys]

I'm even later to the party, but I'm just glad to be here. I bought this amp after watching your review, so thanks for taking the time to put together a really useful practical review. In relation to the amp, I'm using it in a studio environment to power (secondary) monitors so I needed balanced inputs, flat response and silent. The performance is just brilliant for me - no fuss, does the job, run at around 75% all day and barely get warm and is transparent. Having the RCA inputs is a bonus because it has given me a couple of auxiliary inputs that I can flick when I want. I love this little thing.

[ck]

I own one of Fosi's 2.1 board amplifiers and I agree that some of their design choices are baffling. Mine suffers from exactly the same problem and with the small Paradigm Titans I paired it with, I ended up with noticeable low-end distortion from the Titan's at higher volumes.
Now here's what I found most interesting about that Fosi product. I checked Texas Instrument's page for the amplifier chip Fosi chose and found that Fosi copied Texas Instrument's very basic example design schematic and just called it a day. Granted, this is one way to save money since there's no need to hire someone to design an amplifier if you can just crib TI's example.
At the end of the day, the amplifier board was cheap, far more powerful than I expected it would actually be and I'm happy enough with the performance for what I paid for it. I picked it up as a neat toy to play with and I absolutely enjoyed it as a toy.
With just a little bit more work on Fosi's part, it could be more than just a toy but at the end of the day, that's really all their product's are; cheap toys. Nothing wrong with that as long as reviewers make that clear like you have done. Glad to see this review after doubting some other reviews I've seen recently on this product.
Keep up the great work Erin! You are a breath of fresh air in this space.

[michaelsparrow]

I agree 100% on everything you describe. Suggestion: You mention multiple times that a high-pass would unload the speaker. I'm sure you know that it also would/should unload the amplifier, but unless stated explicitly, some newbies may not perceive this. Cheers!

[ItsElvis]

An absolutely amazing video, Erin. I will be holding onto my Schiit Rekkr for my desktop setting. Almost 50k! Should be way over 100k at this quality.

[MrBonger]

I really like that you show us your testing methodology in detail. Thank you

[JukeboxAlley]

I have to say, after many years in the hobby and after probably 300+ amps and receivers, i got 2 of these and a decent preamp and i love em (the right preamp is always the key component to separates, remember that). Keep in mind this is compared to old legends (but often a little noisy in the background due to age, power supply, blah blah blah) adcom gfa-555, nakamichi pa-5 class A, emotiva xpa2, and many more, and i liked these better and had just as much to give in any area as the others and are silent, zero noise. Also you dont need to see a chiropractor after moving them around, i think their the best for the money that one can ask for. Thats just me, you hobbyists gotta do whatever works for you but i will say this, when 2 of these are running together on a decent preamp, they are certainly no joke and tonally great. Also on a 4 ohm load driving the flagship polk sda srs 1.2 (6 ft tall and 180 pds each) and did a VERY good job with plenty of headroom and kept their composure even at 115-120 db levels and on 10, 15 and 20 hz sweeps, no problems for me. Sounded as good or better as nearly anything else ive tried, including "claimed" bigger and badder amps and of different classes, they work for me just fine and id buy a dozen more for backups if i could afford to have them around, anyway, to each their own its just my opinion.

[JoseFerreira-zbwh]

You should try the smsl a300. Seems like good competition for this. It can be used as monoblocks, has a remote, tone controls and eq presets and a high pass filter (100hz is the only option though) so at least from a feature/ functionality point of view, it kills this.

[Blewis-Diarrheo]

I found this channel because of the whole speaker controversy. I subbed because the content is really good, and the subject matter is very interesting and very informative.

[BobbyBass-xi]

Erin thanks for your measurements and explanation of what they mean. Very helpful. Keep up the great work!

[Static_Age]

You’re not late. You just took the time to do it right.