AIYIMA A70 Stereo Amplifier Review

[AIYIMA]

Purchased one of these about a week ago and am very pleased with its performance -- an excellent buy for the money. I don't play music particularly loudly so went with the 48V/5A power supply (still has more power than my prior amp.) My only complaint is that the Amazon info as to what's included isn't quite as clear as it could be. I bought the amp during Amazon Prime Sale days and thought I was getting an even better than normal price only to discover the low price was because NO power supply was included. So the amp sat unused for a couple of days waiting for the subsequently ordered power supply to show up, with the total cost the same as if I'd bought both at once before the "sale." But, I notice that from time to time with Chinese goods where it would behoove them to have a native English speaker take a look at the wording used in their Amazon ads.

Thanks for the like. Do you have any suggestions for our Amazon ads?

 

[mlsstl]

Thanks for the like. Do you have any suggestions for our Amazon ads?

As noted previously, the Amazon Prime Day sale ad I purchased from did not make it clear that the power supply was not included.

 

[magreen]

I understand you can’t use high level subwoofer inputs from the speaker outs of this chip amp (and tbf others like it) because it operates in bridged mode. Do I have that right?

If so, that makes the subwoofer output much more important than usual. Can someone confirm that the subwoofer output works as it should—properly sums both channels, no strange effects on the amp’s input signal, no channel mixing when the SW out is in use?

 

[somebodyelse]

I understand you can’t use high level subwoofer inputs from the speaker outs of this chip amp (and tbf others like it) because it operates in bridged mode. Do I have that right?

It depends on the subwoofer - some high level inputs work with bridged amps and others don't. You should check the manual, or ask the manufacturer if the manual doesn't say.

 

[magreen]

Thanks. I have three subwoofers that accept high level input. None of the manuals say. Some of the makers aren’t in business anymore. So to be safe, I have to assume it won't work. That’s why I’m asking about the SW out.

 

[Jukka]

Thanks. I have three subwoofers that accept high level input. None of the manuals say. Some of the makers aren’t in business anymore. So to be safe, I have to assume it won't work. That’s why I’m asking about the SW out.

In my experience, a proper subwoofer integration requires a DSP unit. You need high-pass for mains and low-pass for subs and also you most likely need delay.

If adding subs without a proper processor, you aren't going to get high fidelity system and all else is more or less in vain.

 

[dayronch]

This is a review and detailed measurements of the AIYIMA A70 stereo class D amplifier. It was sent to me by the company and costs US $190 with 48v @ 5 amp supply. As tested with 48v 10amp GaN supply, it costs US $220.
View attachment 354921
As you see, the A70 comes in vertical desktop configuration. Controls are easy: push the button for power up and again to cycle between XLR and RCA inputs. Hold it for a few seconds and it goes into standby. Back panel shows nice inclusion of balanced XLR inputs:
View attachment 354922
Yes, that 10 amp brick is the mother of all external power supplies! At 480 watts, any heat dissipation would be challenging given the sealed box. Use of GaN transistors seems to have enabled high efficiency as it hardly warmed up during the testing. The amp's heat source is on the bottom. I wish the feet were taller to allow better convection cooling. Fortunately that area didn't get too hot in testing.

Nice to see trigger input to allow one button power up of the audio chain from the source. We also have a sub output wit variable filter output (yes, it is controlled by the volume setting).

Diagonal speaker terminals help some to fit beefier speaker wire termination.

There is a switch to add 3 dB of gain to RCA input. I didn't realize this until after testing. It is a smart move as the gain otherwise may be a bit low for some people.

The A70 is one of the few TI TPA3255 chip based amplification utilizing post filter feedback loop (PFFB). This should get rid of load dependency and improve linearity by dialing out the distortion from the output stage. Let's see if that is the case.

AIYIMA A70 Amplifier Measurements
Let's start with setting the volume to max using XLR input (all testing with 10 amp supply):
View attachment 354923
We see a nice boost in SINAD as predicted, landing the amplifier essentially in our "excellent" category:
View attachment 354924
View attachment 354925
RCA input has fair bit lower performance but still above average:
View attachment 354926
Note that I adjusted the volume down to 25 dB per my recent standard of testing amps (used to use 29 dB).

Noise performance is excellent:
View attachment 354927
Despite its lower gain with XLR input, you can still reach full power at 3.3 volts which is well below nominal 4 volts we see out of majority of DACs. So I am good with that.

Let's jump into frequency response as that is the other big deal:
View attachment 354928
Nice! We see a bit of frequency dependency but it is outside of our hearing range.

I set the subwoofer output frequency to the lowest and measured this:
View attachment 354940
I don't know how this is useful for anyone....

Crosstalk is extremely good:
View attachment 354929

Good performance numbers give way as you go up in higher frequencies in multitone and especially in 19+20 kHz IMD:
View attachment 354930
View attachment 354931

Let's see how much power we have:
View attachment 354932
View attachment 354933

That's a lot coming out of this little box. We are talking nearly 360 watts total. 8 ohm output is naturally lower:
View attachment 354935

Edit: as noted, performance does degrade above certain frequency:
View attachment 354941

My reactive load doesn't like these bridged amps. The issue seems to be in one channel so I left that disconnected and drove only one:
View attachment 354936
The amplifier is specified down to only 4 ohm but seemed robust enough to even handle 2 ohms, albeit with a good bit of voltage drop. Translating the above into watts we get:
View attachment 354937
For those of who want to use these amps in mono, you now have that information as well.

There is likelihood of a turn on "pop" but turn off noise is completely eliminated:
View attachment 354938

Finally, amplifier was essentially ready to go on power up:
View attachment 354939

Conclusions
What a journey to have watched in these "chip amps." We have gone from $30 to $40 amplifiers with horrible performance to above average in less than $100. Load dependency remained though and so many of us pointing it out, we finally have a solution to that as well. Alas, cost has increased so we are not talking about a fast food meal but one at a nice restaurant. You have to decide now if the extra performance is worth it. It is to me as an amplifier doesn't obsolete so might as well get a good one and sleep easy.

I am happy to recommend the AIYIMA A70 stereo amplifier.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

I would like to find this kind f info for the Fosi Audio V1.0b

 

[Zoli64]

Hello! Has anyone measured how many Watts of quiescent power the A70 consumes? By the way, is it not possible to reduce idle power consumption and idle heating even more with some technical trick or conversion?

 

[Guddu]

Hello! Has anyone measured how many Watts of quiescent power the A70 consumes?

See this post, it has idle power consumption snapshot:

Aiyima A70 [TPA3255 PFFB Stereo] - User Impressions | Owner's Thread

Dear FMs, [ Contents: A70 Amplifier unit, 48v 5a GAN PSU and user manual/docs. > A70 amplifier unit has brick shape and non-metallic smooth finish which prevents finger prints and dust. Ventilation holes on sides and bottom of the case should help a bit with heat transfer. > TPA3255 chip is...

audiosciencereview.com

By the way, is it not possible to reduce idle power consumption and idle heating even more with some technical trick or conversion?

You can add some active cooling but no way to reduce idle power.
However Triggered input works well on this amplifier, you might look to use it to plan turn-off through DAC/AVR or any kind of triggered output switch.

 

[Zoli64]

See this post, it has idle power consumption snapshot:

Aiyima A70 [TPA3255 PFFB Stereo] - User Impressions | Owner's Thread

Dear FMs, [ Contents: A70 Amplifier unit, 48v 5a GAN PSU and user manual/docs. > A70 amplifier unit has brick shape and non-metallic smooth finish which prevents finger prints and dust. Ventilation holes on sides and bottom of the case should help a bit with heat transfer. > TPA3255 chip is...

audiosciencereview.com

You can add some active cooling but no way to reduce idle power.
However Triggered input works well on this amplifier, you might look to use it to plan turn-off through DAC/AVR or any kind of triggered output switch.

Thank you. So there are no electronic modifications that reduce idle consumption or are difficult to solve.

 

[mlsstl]

Besides the 12 volt trigger option, you could also use a "smart" power strip that turns associated equipment on and off based on whether a main unit is drawing power. I use one of these in a secondary system to control my Gjallarhorn power amp when the preamp is turned on or off. (For the main system I'm using the WiiM Ultra's 12 volt trigger to control the A70.)

 

[Zoli64]

I would like to ask at what switching frequency the A70 operates and what is the output carrier frequency residual at the output. Does anyone have this data? Also, can the switching carrier frequency of these final stages be increased somehow? Thanks for the help, please explain.

 

[MCH]

I would like to ask at what switching frequency the A70 operates and what is the output carrier frequency residual at the output. Does anyone have this data? Also, can the switching carrier frequency of these final stages be increased somehow? Thanks for the help, please explain.

Typically 600, 500 or 450 kHz. To know which one, check the value of the resistor that goes to pin 8 (or measure the resistance of pin 8 to ground if you already have the amp) and you can find the correlation in the datasheet. I believe you can change the frequency changing the resistor and no other modification, but I am not 100% sure (I had a tpa3251 amp with switches to do so).

 

[Zoli64]

Typically 600, 500 or 450 kHz. To know which one, check the value of the resistor that goes to pin 8 (or measure the resistance of pin 8 to ground if you already have the amp) and you can find the correlation in the datasheet. I believe you can change the frequency changing the resistor and no other modification, but I am not 100% sure (I had a tpa3251 amp with switches to do so).

Does anyone know the A70 specifically? and can it cause problems if, for example, it is 450 now, but I raise it to 600? Thank you

Ps: @AIYIMA , can you help me the A70 current switching frequency?

 

[Sylvia]

If I use the Aiyima A70 with a Wiim Pro Plus, what would be the difference between these 2 options?:

a) Using the Aiyimas RCA input

b) Using the Aiyimas XLR input (using a cable that goes from RCA to XLR)

Just curious, thanks a lot in advance

 

[JimBean]

I have a question with my A70. I noticed that the RCA is louder than the XLR when the gain switch is on and when it's off both output has the same audio output level which should be the XLR output should be louder than the RCA Output comparing with Fosi Audio ZA3. Is this an issue? Anyone has the same experience on their A70?

I just got the A70 with the 48v/10A power supply and I noticed I have to turn the volume up more on my preamp compared to the Fosi ZA3 with a 48v/5A power brick. Running XLR on both, thought the bigger power supply would give me more volume, not less.

 

[mlsstl]

I just got the A70 with the 48v/10A power supply and I noticed I have to turn the volume up more on my preamp compared to the Fosi ZA3 with a 48v/5A power brick. Running XLR on both, thought the bigger power supply would give me more volume, not less.\

You're comparing devices from two different manufacturers. The only thing a 10 amp power supply does compared to a 5 amp one is it allows more current, and therefore more maximum wattage, particularly at lower speaker impedances. The position of the volume control is not an indication of how much power is available or being delivered by the amp. Your Fosi amp either has more gain in its preamp section than the A70 or a volume control potentiometer that tracks differently. (I have an A70 with the 48V/5A supply and am very pleased with it.)

 

[JimBean]

You're comparing devices from two different manufacturers. The only thing a 10 amp power supply does compared to a 5 amp one is it allows more current, and therefore more maximum wattage, particularly at lower speaker impedances. The position of the volume control is not an indication of how much power is available or being delivered by the amp. Your Fosi amp either has more gain in its preamp section than the A70 or a volume control potentiometer that tracks differently. (I have an A70 with the 48V/5A supply and am very pleased with it.)

Fair enough. Definitely getting less usuable volume range with my Schiit Freya S preamp. Having to turn it up to closer to 3 o'clock with the A70 compared to noon-1o'clock with the Fosi for roughly the same lostening level. Both amps were at max level on the volume knob.

Edit - Even setting the Schiit Freya to the highest gain setting (4x) didn't really give a ton of range with the volume control

 

[Rover]

You gave a certificate for JYH38Z. On sale and in the review is a power supply unit under a different number JYH37Z. What is the difference? Is there a certificate for this?

In fact, as it turned out, just the same JYH38Z is on sale now.And the fact that Ali's pictures and other JYH37Z sites show this old photo.JYH38Z is now on sale and accordingly its certificate is posted correctly.

 

[Vlvvv]

hello! dear forum members, tell me, please, which one is better to choose an amplifier for acoustics Fosi za3 or aiyima a70? I am sincerely grateful in advance for your help