Fosi Audio ZA3 Amplifier Review

[SoySalsaPicante]

I have no experience with the WiiM Pro+.
But from what I've read, the output can be set to 2 V, 1 V, 800 mV, or 500 mV.
Personally, I'd keep it at 0.5 V, even lowering the WiiM's SINAD (well below the audible threshold), but ensuring it remains within ideal operating range with the ZA3.

[WiiM Pro Plus]
Line Out Revel
2 Vrms - SINAD 111.7
1 Vrms - SINAD 109.4
0.8 Vrms - SINAD 107.6
0.5 Vrms - SINAD 103.8

@Pep2020 Yes, I concur with this assessment by yallkok, although I would suggest maybe start with 1V. It didn't occur to me that you had adjustable output voltage at your source. This will allow you to raise your digital volume cap and make better use of your volume adjustment range.

 

[yallkok]

@Pep2020 Yes, I concur with this assessment by yallkok, although I would suggest maybe start with 1V. It didn't occur to me that you had adjustable output voltage at your source. This will allow you to raise your digital volume cap and make better use of your volume adjustment range.

1V is close to the clipping limit.
Why go so far out of spec?
They're usually very generous, too...

 

[Pep2020]

Set it at 800mV. Volume limit at 90%.

Sounds great. I think it allows me to use volume range better. Thank you both

 

[Witterings]

Anybody else running a pair as mono blocks and if so do you find there's quite a difference in output volume for each of them?

 

[kawal]

Got a ZA3 from Aliexpress and even with RCA it measures better than in the original review .
SNR 92.6dB and 0.0013% THD at 5W / 8 Ohm load

 

[kawal]

Multi tone is very clean as well - this is at 8 ohm at 5W.

 

[yallkok]

Got a ZA3 from Aliexpress and even with RCA it measures better than in the original review .
SNR 92.6dB and 0.0013% THD at 5W / 8 Ohm load

How many volts did your test source have at its output?

 

[kawal]

How many volts did your test source have at its output?

I do not recall the voltage - but the volume adjust was at max. Looking back at the screenshot actually shows that the voltage was 214mV RMS input to get the 5W output.

 

[yallkok]

I do not recall the voltage - but the volume adjust was at max. Looking back at the screenshot actually shows that the voltage was 214mV RMS input to get the 5W output.

You're right, I hadn't looked at the graph properly.
It's all clear.

 

[kawal]

You're right, I hadn't looked at the graph properly.
It's all clear.

I bought to amp to gift to my son but wanted to test it prior to gifting it. I was not sure if the Aliexpress one will be legit so I figured I would test it. The price on Aliexpress with coupons was way better than refurb from vendor directly.

BTW the QA403 is a pretty nice tool. Not without its own issues but pretty good overall. The automated tests are the best thing. Just setup and let it rip. For the higher output amps I do have to use external attenuators. But up to 200W the QA403 can measure without external attenuators.

 

[kawal]

Yallkok .

While I haven't tested 2V input I can confirm that 1V will achieve max power as the measured gain from RCA input is 29dB or 28.183X . I haven't measured gain from XLR at this time. Will this matter for music - probably not as music is not the same as test tones and music level vary even from album to album unless normalized. And who listens to the music turned all the way up? Either way if your DAC has no volume adjust you will have the ZA3 turned down a lot . If you do have Volume adjust on a DAC that will be turned down to normal levels so either way no problem. In case you need every dB of dynamic range you will not be using these toy amps.

Power at different input levels RCA

 

[kawal]

Gain measured from XLR inputs in my unit is 37dB . That is very high . Turning the volume knob from max to the 3 O'clock position reduced the gain to 27dB. Channel mismatch at this setting is good (0.2dB )

 

[peng]

I bought to amp to gift to my son but wanted to test it prior to gifting it. I was not sure if the Aliexpress one will be legit so I figured I would test it. The price on Aliexpress with coupons was way better than refurb from vendor directly.

BTW the QA403 is a pretty nice tool. Not without its own issues but pretty good overall. The automated tests are the best thing. Just setup and let it rip. For the higher output amps I do have to use external attenuators. But up to 200W the QA403 can measure without external attenuators.

Does the QA403 come with any measuring probes? I am interested in one for measuring preamp, dacs only, are the necessary probes of good quality available on Amazon? Thank you.

 

[kawal]

QA403 comes with no probes or cables included . It comes just with the unit and nothing else. The inputs and outputs are BNC so you can make your own cables or use 1x oscilloscope probes. You want a probe that can be switched to 1x do not use probes with 10x as it will change the response curve of the system. The cheap $10 probes work just fine as they are designed for above 1Mhz work. I purchased a few probes and a few RCA to BNC adapters. I made my own RCA to XLR cables.

 

[scruffy1]

so, amazon had a special on the fosi za3 for $199.99 delivered overnight (with 48v supply) - arrived thursday, in time for a good friday

i'd been reading a lot about it, and having become accustomed to the klipsch promedia 2.1thx in the study (with smsl dl100 and eq'd with peace) the wharfedales in the living room just didn't "sing" with the old nad d3020v1with quite the same authority

added a pair of tekera xlr cables in the order, and cleaned up the system (and the living room)

so currently - old school htpc in the antec nsk2480 case > topping e70 pushing matched 5v signal to the fosi, driving my pair of wharfedale 10.1 and the 10.gx active sub, and.... wow ! loving it ! the nad was a good thing in its day, but 30w mean vs 120+ is no contest, and the wharfedales at 6ohm with a sensitivity of 86db have suddenly taken a deep breath...

the e70 is at -3db, and with the za3 at 10 o'clock it is plenty loud in a 5x7m room - using the software as my remote volume, with flac at native 44100/16bit

there's a sneaky akliam dd2 bluetooth also, as the topping bt died and their repair options are non-existent; it can receive flac files from the nas using neutron on my re-purposed oneplus 5T on a dedicated 5g wifi channel at home > ldac , for "casual" convenience, but without actively listening it sounds pretty much as good

i'm rating it as good, but my experiences with amps is limited to the nad, and previously my luxman L2 that needed more work than i could do

 

[JRiv]

Hello ASR staff and members, first time logging here even though following this site for years as my one-stop preferred site for reviews on budget Amps and DAC's.
I really apology if I posted in the wrong sub-forum between.

Long story short:
I've been owning, messing and modifying Class AB amps for ages and currently owning several old Pro "Heavy-Iron" amplifiers raging from 170, 500, 700, 2000 and 5000W for my home audio setup, yup I like "power, dynamics, headroom" but in my current "near-field" setup they are becoming overkill plus the relatively high-idle power consumption.

That being said, due to the overwhelmingly high recommendations on the Fosi Audio ZA3 around the net, I just pulled the trigger after reading Amir's review and ordered two ZA3 amplifiers without power supply(more on this later), between I'm a Class AB Heavy-Iron with discrete outputs fanboy here but I think its time to enter and test the Class D amplifiers on my near-field DIY efficient monitors in horizontal bi-amping.

Since this is the first time entering the Class D for near-field monitoring, I have a question/concerns about my planed "power setup" for this little amplifiers, so I hope others here in this forum have done the same or similar setup as I will do as described below.

The power supply to be used is a Delta IMA-S1000-48-YYPLI 1000W 48V, I picked this power supply due its power and features, including galvanic isolation, dual MOPP, PMBus, voltage range from 38~56V etc., so this will power the two Fosi ZA3 initially, possibly more if I like the setup.

Back to the question:
I plan to install this power supply in a closet(preferred) with additional electrical/computer stuff, including a Solar Lithium battery, Raspberry PI, WiFi/Gigabit AP, CCTV-DVR, 2U Server/Hypervisor etc., so I'm concerned about possible noise(EMI/RFI) pickup on the power cables as there will be about ~18 feet DC run to the amplifiers, also possible damping factor degradation.

So the first question, is this 18' 48V DC run ok with just 10AWG twisted-pair from the power supply to the near-field DC power outlet with an LC filter, or should I use 2-conductor shielded power cable which is rather expensive?

PS The ZA3 amplifiers will be driving a pair of efficient bookshelf speakers fully active with the following drivers: FaitalPro HF10AK Tweeters and the PRV 6MB550FT for Midbass.

Regards

 

[RandomEar]

Hello ASR staff and members, first time logging here even though following this site for years as my one-stop preferred site for reviews on budget Amps and DAC's.
I really apology if I posted in the wrong sub-forum between.

Long story short:
I've been owning, messing and modifying Class AB amps for ages and currently owning several old Pro "Heavy-Iron" amplifiers raging from 170, 500, 700, 2000 and 5000W for my home audio setup, yup I like "power, dynamics, headroom" but in my current "near-field" setup they are becoming overkill plus the relatively high-idle power consumption.

That being said, due to the overwhelmingly high recommendations on the Fosi Audio ZA3 around the net, I just pulled the trigger after reading Amir's review and ordered two ZA3 amplifiers without power supply(more on this later), between I'm a Class AB Heavy-Iron with discrete outputs fanboy here but I think its time to enter and test the Class D amplifiers on my near-field DIY efficient monitors in horizontal bi-amping.

Since this is the first time entering the Class D for near-field monitoring, I have a question/concerns about my planed "power setup" for this little amplifiers, so I hope others here in this forum have done the same or similar setup as I will do as described below.

The power supply to be used is a Delta IMA-S1000-48-YYPLI 1000W 48V, I picked this power supply due its power and features, including galvanic isolation, dual MOPP, PMBus, voltage range from 38~56V etc., so this will power the two Fosi ZA3 initially, possibly more if I like the setup.

Back to the question:
I plan to install this power supply in a closet(preferred) with additional electrical/computer stuff, including a Solar Lithium battery, Raspberry PI, WiFi/Gigabit AP, CCTV-DVR, 2U Server/Hypervisor etc., so I'm concerned about possible noise(EMI/RFI) pickup on the power cables as there will be about ~18 feet DC run to the amplifiers, also possible damping factor degradation.

So the first question, is this 18' 48V DC run ok with just 10AWG twisted-pair from the power supply to the near-field DC power outlet with an LC filter, or should I use 2-conductor shielded power cable which is rather expensive?

PS The ZA3 amplifiers will be driving a pair of efficient bookshelf speakers fully active with the following drivers: FaitalPro HF10AK Tweeters and the PRV 6MB550FT for Midbass.

Regards

Honest answer: Use the default supplies sold with the amps. Your selected PSU is certainly high quality and may outlive any cheap brick, but driving two class D amps from the same DC source can lead to weird interactions. You can search for the Fosi V3 mono thread: The manufacturer had to include a "power filter" box between the single PSU and the two amps in the set due to noise popping up. And even with the filter, you get some noise when one of the amps enters standby.

You can test your setup and if you're lucky this doesn't affect the combination of components you selected. But using two PSUs with separate AC-DC converters is the safer choice. This would also avoid any of those LC filter, shielded cable and whatnot solutions, which you very likely won't need anyway - even with the setup you are currently planning to use. Don't make it more complicated than it has to be!

 

[JRiv]

Honest answer: Use the default supplies sold with the amps. Your selected PSU is certainly high quality and may outlive any cheap brick, but driving two class D amps from the same DC source can lead to weird interactions. You can search for the Fosi V3 mono thread: The manufacturer had to include a "power filter" box between the single PSU and the two amps in the set due to noise popping up. And even with the filter, you get some noise when one of the amps enters standby.

You can test your setup and if you're lucky this doesn't affect the combination of components you selected. But using two PSUs with separate AC-DC converters is the safer choice. This would also avoid any of those LC filter, shielded cable and whatnot solutions, which you very likely won't need anyway - even with the setup you are currently planning to use. Don't make it more complicated than it has to be!

Hi @RandomEar thanks for the quick reply.
Yeah I did read somewhere as well about the noise on the Fosi amps when two are powered from a single power brick with a Y cable, then I saw the Fosi video that supposedly addressed the issue with their "Power Filter" but dint ordered those.

Since I'm that kind of guy who like to DIY basic electronic stuff for fun I think going to experiment myself with this setup first as you said, maybe I may have some luck as this amps will always be triggered-on/off both at the same time.

I'm planning to test first with just the twisted pair for the DC run and see how it goes with and without LC filtering then report back, otherwise I had to order two power bricks istead.

Regards

 

[scruffy1]

i have a single amp, and put a ferrite choke on the power cord near the insertion point; no idea if it made it cleaner (other than technically) because it was placed there before first use, and there is NO noise

 

[JRiv]

i have a single amp, and put a ferrite choke on the power cord near the insertion point; no idea if it made it cleaner (other than technically) because it was placed there before first use, and there is NO noise

Hi, yes I have several of those split ferrite cores as well, we use those occasionally on HAM radio stuff too to reduce noise pickup from older noisy SMPS.

I really hope for minor to no issues with my rather unusual power supply location.

Regards