Fosi Audio ZA3 Amplifier Review

[JimBean]

I'm very happy with my ZA3, after waiting a while for it to get here from China. I did get 15% off when I ordered it from Fosi's website. Seems to pair well with my 4 ohm Monoprice Encore T6 towers. I have the volume set to max on the amp and use my Schiit Magnius as my preamp.I will probably order a second and try them out as monoblocks. To be fair, my listening area is small, and I do listen pretty close, about 5-6 feet away.

 

[natna]

Finally! Thank you @amirm for your hard work!
I thought you skipped the ZA3.
Well I am just ok with the stereo SINAD, but disappointed with the mono mode.
Like many members here, I was anxious to find out, what the performance as bridged monoblocks would be. Using my SMSL D6s as a Preamp/ volume control of the system, I wanted to have a nice Crosstalk mark...
I also wanted to compare it with the 3E / Sylph solutions. (ok, it's a higher tier choice...)
The Stereo mode performance of ZA3 left the users very satisfied with the overall sound and driving ability. They say it's better than V3, even with upgraded OPAMPs. That's the general impression on Fosi's FB page.

Anyway, now I'm considering a pricier solution like the Topping PA5 II/ II plus, taking a reliability risk . Or one of the medium priced DIY LM3886 dual mono setups, since I don't need all that power.

 

[Talisman]

The Stereo mode performance of ZA3 left the users very satisfied with the overall sound and driving ability. They say it's better than V3, even with upgraded OPAMPs. That's the general impression on Fosi's FB page.

This is yet another demonstration of how a more premium casing and a higher quality aesthetic perception affects the perception of sound. From an audio point of view, the two products are exactly equivalent, with a minimal greater instrumental quality in favor of the V3.
The fact that many are convinced that the ZA3 sounds better is the best explanation for the audiophile phenomena of collective self-conviction.

 

[razamanaz]

Yes, it's coming soon!

with low GAIN?

 

[Steve Dallas]

What's astonishing exactly? A chip amp, in a tiny aluminium can, with an off-the-shelf SMPS. I don't see anything remotely astonishing about it. Personally, I think it's way overpriced for what it is (or isn't)

How grown men can get excited about an "amplifier" lacking pretty much everything that makes an amplifier remotely useful is beyond me.

One set of speakers- not switchable
No headphone socket
No tone controls
No filters
No loudness
No tone defeat
No signal routing options
No processor loops
No remote control
No muting
No phono stage
Only two inputs- LOL what a joke.

All of these things (except remote) were standard on ~USD$100 integrated amplifiers in the 70s/80s/90s and into the 2000s.

I cannot say I am excited about it, but I can say I am interested. This stripped down little amp has its use cases, including desktop use, the front pair in a home theater, a little lifestyle system in a spare room, home recording studio, etc.

$100 was a lot more money in the 70s through the 2000s than $150 is today.

Let's take my home office, where I am considering replacing an expensive integrated and pocketing the change. My current setup is a MOTU M4 interface into an unbalanced Peachtree Nova 300 in HTB mode into a pair of KEF R3s. Considering I am using the amp simply as a dumb power amp, it would not hurt my feelings to replace it with something simple with balanced connections. Feature by feature:

One set of speakers- not switchable - I have only one set of speakers
No headphone socket - My DAC has a headphone jack that I rarely use
No tone controls - Not wanted as I use DRC
No filters- Not wanted as I use DRC
No loudness- I have a loudness curve in DRC
No tone defeat- Not wanted as I use DRC
No signal routing options - Not needed in my simple setup
No processor loops - Not wanted nor needed
No remote control - Nice to have, but I tend to leave it set in the same place
No muting - Nice to have but not strictly necessary
No phono stage - I gave up on vinyl in the 80s and am never going back
Only two inputs- LOL what a joke. - Only one input needed

Not everything needs to be fully featured. Something like this has nearly everything I need and not much I don't need.

I wonder if there is a way to get a black knob? I really don't care to have the orange one staring at me all the time...

 

[Kevinfc]

Can anyone answer the following question; what is the detectable threshold level of SINAD for amplifiers?

 

[Toni Mas]

Still fine, but compares to V3, It looks that the added features degrade somewhat the overall performance. I clearly prefer the cheaper V3.

 

[Zaphod]

Can anyone answer the following question; what is the detectable threshold level of SINAD for amplifiers?

OUCH! There is no, one single, answer to that question, as it depends greatly on several things:

1) The speakers used. Most speakers exhibit pretty high levels of distortion, which might mask THD in preceding products in the chain. There are several speakers from a few manufacturers (Quad, KEF, B&W, et al) who quote THD at various levels and frequencies. Typically, the lowest distortion from a quality speaker might lie in the 0.1% area, depending on level and frequency.
2) The hearing acuity of the listener. This is pretty obvious, as some listeners can perceive much lower levels of distortion than others. My own experience tells me this. I've visited clients' homes where the complaint has been that there is distortion present. I've been unable to hear any problem, but, on taking the amp back to my bench and measuring the distortion, I find that the the client is correct. Often-times, a simple bias adjustment is the problem. In one instance, I found that the distortion in the complained about product was around 0.2%.
3) The type of music played. Obviously, much modern music is so much electronically altered, that added distortion is barely, if all, noticeable.

Anyway, it is generally regarded that approximately 0.1% THD is the limit of human hearing.

 

[dixter]

@ Fosi Audio .... I have been testing the ZA3 for several weeks with the purpose being end use of a headphone Amp mainly for hard to drive headphones like the Susvara, HE6seV2 and Modhouse Tungsten and others.. I purchased two of the ZA3 amps and I built 2 interface cables, one cable has a 4 pin XLR/banana and the other cable has banana/banana connection... for the first test I connected a Hifiman HE Adapter Box that presents the ZA3 amp with the following.. ( hifiman source )
Specifications:
Input: Speaker Connector
Output: 4 pin XLR
Resistors in Parallel: 10 Ohm
Resistors in Series: 25 Ohm

The configuration presents the amp output stage with a 10ohm shunt.. and the 4pin XLR connection to the headphones.. The amps are setup for Mono with one amp driving the left and the other amp driving the right headphone drivers... Both amps with the volume knob fully to the clockwise position ( full amp drive ) for the source I used two methods... a dual 3 pin XLR to 4.4mm balanced cable from ifi Audio used for balanced input to the amps and 4.4mm to a fiio BTR7 and for direct balanced connection I utilized the M15s via balanced 4.4mm LO (variable) ... with the BTR7 being wireless I can use an Iphone or the M15s ... the advantage device is the M15s as it has capable EQ so the sound quality can be fine tuned to personal preferences... and it can be connected via cable or wireless... in wirless its like the ZA3 setup has a remote control... so its nice to have that option... another connection option is the USB input on the BTR7..

For the two ZA3 amps I swapped out the left/right op amps with Sparkos op amps... the result is an airier sound but still well balanced FR from bass to treble...

The Headphone used to test this configuration was mainly the Hifiman HE6se V2 ..... sound quality is very nice, full FR from bass thru treble.. nice sound stage and instrument separation... couldn't ask for much more and at the price it is actually fantastic...

I also tested this configuration with a single ZA3 with the results pretty much the same.. I doubt a A/B test would allow someone to pick out the different setups... and there is plenty of power from a single ZA3 or a dual/mono ZA3... more than enough headroom..

For those concerned about the fact that the amps exhibit a Frequency response load impedance dependency where the FR can be presented at an elevated power on frequencies above human hearing...

If you examine the Frequency Response graph its noted that with a 4 ohm load the FR is " nice and flat " and with the 8ohm load " overshoot " "This means depending on your speaker impedance, high frequencies may be exaggerated a bit."

So I decided to utilize a different cable to interface the headphones... this cable has banana to 4 pin XLR but at the amp output posts I put a 5 ohm shunt resistor across the positive - negative posts and the cables banana plugs into the amp output posts... so the amps output is now presented with a 5 ohm shunt and no resistors in line to the headphones... again this setup sounds absolutely great

To the Fosi Engineers... you have the capability to create a purpose built headphone amplifier as I demonstrated with my interface cables... an opportunity is present for another product line...

 

[CedarX]

Not in my book, but it could be I guess. It would require a few relays in the amp, to disconnect and reconnect the outputs from each channel to a common pair. Notice the output is just one set, not two.

I'd lay my money on them simply shorting the input to one channel and calling the whole thing "mono". Look at the specs, they are hardly changed.

And parallel BTL is a misnomer.

There is a picture of the internals here:

https://audiosciencereview.com/foru...ode-balanced-amplifier-za3.48552/post-1762896

It does have relays… And Fosi confirmed the “mono” mode is actually PBTL (the TI term for this parallel bridge-tied load mode):

https://audiosciencereview.com/foru...ode-balanced-amplifier-za3.48552/post-1789801

 

[pseudoid]

Thank you @amirm for the (much anticipated) review.

I was kind of embarrassed to have replaced a 5-Channel Rotel PowerAmp for this diminutive ZA3 but it stows well out of sight, without any temper tantrums in the last month that it has been on 24/7 active duty.
I was not trying to go for the 'affordability' of the ZA3 but for how low one can get to the knee-of-the-curve between performance and price… without taking too many hits.

RE: Volume knob: I also don't like having 'double' the volume controls in separates rigs.
So, I was a bit apprehensive that the ZA3 at max. volume setting may cause other problems but my ears could not prove any. I was also worried that max. volume may cause additional heating issues but it has been not much higher than slightly warm to the touch.

 

[surroundman]

Not impressed at all. If it was about 25% cheaper it would have been a "fine" vote, but at this point I find "not terrible" to be more accurate for the product.

 

[Bruce Morgen]

FYI - for those members who already own a performant power supply unit.......


Fosi Audio offers the option of ordering a ZA3 amplifier without a power supply unit for $109.99

Fosi Audio ZA3 Balanced Stereo Amplifier Home Audio 2CH Mono Amp with TPA3255 Chip

This new generation mini amplifier offers both stereo and mono modes, adapts flexibly to your diverse needs, allowing seamless mode switching.

fosiaudio.com

That's over double the price of an Aiyima A07. I guess if you need balanced inputs, more power, and/or the mono mode the extra $$ are worth it. For my application -- the four ambience/surround speakers in my 7.1 system -- there's no ROI to speak of in replacing my trusty A07s with ZA3s, but for a 2.0 or 2.1 system such a swap might make sense, especially if the speakers are particularly power hungry.

 

[Mikig]

Not impressed at all. If it was about 25% cheaper it would have been a "fine" vote, but at this point I find "not terrible" to be more accurate for the product.

everyone has their own perception, I'm not arguing, but if you read the conclusion of Amirm's review, there are at least 3 good reasons that justify this price.

Price Which I remember being equal to a “good” dinner for 2 people or in Europe to a full tank of fuel...

nowadays, moreover, if you keep in mind the provision of good quality internal components, I read Elna etc, the possibility to customize the op-amps, a well-made box, distribution, shipping, etc.,
objectively it becomes difficult to ask for more…

 

[iLoveCats]

*Edit* I have been informed that Fosi has posted purchase orders for genuine op amps somewhere in this forum. So I guess my experiment will just be rolling Burr Brown OPA2604's in. *Edit*

Somewhere along the way I read the op amps included may be clone NE5532's and somebody replaced them with real 5532's and it was better. I just bought some, hopefully, genuine Texas Instruments NE5532's and Burr Brown OPA2604's off eBay and I'm going to find out. I've got about $40 into this experiment.

 

[surroundman]

everyone has their own perception, I'm not arguing, but if you read the conclusion of Amirm's review, there are at least 3 good reasons that justify this price.

Price Which I remember being equal to a “good” dinner for 2 people or in Europe to a full tank of fuel...

nowadays, moreover, if you keep in mind the provision of good quality internal components, I read Elna etc, the possibility to customize the op-amps, a well-made box, distribution, shipping, etc.,
objectively it becomes difficult to ask for more…

I did read the review post, why would you suggest that I haven't? Saying that you are not arguing does not mean you actually are not doing so. When we talk about price we may completely disagree and there is nothing wrong with that. If I feel like an item is expensive, can I not simply state that opinion of mine without having to reason myself? Yes, I do believe that the price of $149.99 before taxes is too much. Why? Right now, I can buy an Aiyima A07 Max 48v for $82.52 AFTER taxes (or a Fosi V3 for $88.87) (with the current coupons/discounts from Aliexpress). The ZA3 at $149.99 is about double that price. Do you value the extra features enough to justify the extra price? If you do so, that is completely fine. However, like I mentioned in the post you quoted, to ME alone this isn't worth it. And not everyone dines in restaurants.

 

[DanTheMan]

Someone mentioned using this as a sub amp, but I would think that for the money you'd be better off with THIS. Of course it's speculation because that's never been measured that I'm aware of, but I'd still look to put my money there.

 

[Guddu]

Thanks Amir, as always for your efforts.
It felt a bit strange though, to read that the review was held because of “not-so-good” measurements of the 1st unit. Many FMs have bought that version and they would have wanted to see their version reviewed.
You probably could have done v1 (pre Jan24) and v2 (post Jan24) way which you have done with some other products, guessing you already have had spent time measuring the 1st one.

OTOH, don’t know how would a buyer find out now if they are buying low gain version.

 

[audioje]

So... if one has a dac with only rca out, za3 has not much advantage over v3 as a stereo amp?

 

[GNK]

What's astonishing exactly? A chip amp, in a tiny aluminium can, with an off-the-shelf SMPS. I don't see anything remotely astonishing about it. Personally, I think it's way overpriced for what it is (or isn't)

How grown men can get excited about an "amplifier" lacking pretty much everything that makes an amplifier remotely useful is beyond me.

One set of speakers- not switchable
No headphone socket
No tone controls
No filters
No loudness
No tone defeat
No signal routing options
No processor loops
No remote control
No muting
No phono stage
Only two inputs- LOL what a joke.

All of these things (except remote) were standard on ~USD$100 integrated amplifiers in the 70s/80s/90s and into the 2000s.

Big Mac was $0.65 in 70s