AIYIMA A70 Stereo Amplifier Review

[Guddu]

Moast parts of the amp is 100°F now when I left it on, not playing any music. The part underneath close to the skrews are 105°F. I think it's kind of warm, but not much to worry about, but I might be totaly wrong, on this.
Guess it's not a big difference if it's playing anything or not, this seems to be as warm as it gets. I will keep an eye on this for sure, but I'm not that worried.

You are seeing idle losses, which then also remains unchanged upto certain spl output.
It’s totally similar to several other similar amplifiers.

 

[hampestampe]

You are seeing idle losses, which then also remains unchanged upto certain spl output.
It’s totally similar to several other similar amplifiers.

OK, if I understand you correctly it's normal? My opinion is that this isn't an issue, but like I said before, I might be wrong.
It's not in anyway hot it's just warm, I mean 105°F at the warmest spot of the chassi, does not get me to feel any worry.

 

[Ace123]

OK, if I understand you correctly it's normal? My opinion is that this isn't an issue, but like I said before, I might be wrong.
It's not in anyway hot it's just warm, I mean 105°F at the warmest spot of the chassi, does not get me to feel any worry.

 

[Ace123]

I also seem to have a hum. I'm using the RCA jacks. I don't hear it with music just when it's idle

 

[hampestampe]

I also seem to have a hum. I'm using the RCA jacks. I don't hear it with music just when it's idle

You mean you got a hum in the speakers, like a ground loop? Or do you get some mecanical hum from the unit itself?
I have not noticed such problem. I also use the RCA direcrly from a Wiim pro plus. I will look closer in it tommorow.

 

[Ace123]

Hum in the speakers

 

[hampestampe]

Hum in the speakers

Is it like 50 Hz or if you are in US 60 Hz? I mean if thats the case it's probably some grounding issue.
Do you connect source and amp to the same power socket and is it grounded or are you using branch outlet? What source do you hook up to the amp, does it use linear power supply?

 

[Ace123]

I'm going to look at the power cords tomorrow. I just run a windows pc as a source, through an Apple dongle to RCA jacks

 

[Guddu]

I see that Aiyima has recently developed a ceramic knob that improves the knob on the A07max, do you guys think it's necessary?

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Necessary? - nope
But why not if you like the looks of it.

 

[bramsat]

After 3 years A07 and 8 opamps....the best sounding opamp for me is the phillips NE5532.

https://nl.aliexpress.com/item/1005003071748273.html?spm=a2g0o.order_list.order_list_main.11.50b179d2aR4Ui7&gatewayAdapt=glo2nld

 

[AIYIMA]

OK, if I understand you correctly it's normal? My opinion is that this isn't an issue, but like I said before, I might be wrong.
It's not in anyway hot it's just warm, I mean 105°F at the warmest spot of the chassi, does not get me to feel any worry.

The temperature we measured is same as your test result.
We used a 48v10a power supply to play with the A70 for two hours.
The temperature of the power supply is 89°F, the top of the A70 is 104°F, and the bottom of the A70 is 109°F.
There is a temperature difference between the top and bottom of the A70, mainly because the bottom is the heat dissipation port of the chip, so the bottom temperature is higher.

 

[hampestampe]

I'm going to look at the power cords tomorrow. I just run a windows pc as a source, through an Apple dongle to RCA jacks

OK computers can be great but also the oposit. Since you have this hum, my guess would be that the hum is transfered from electrical ground loops or interference, transfered via the signal path, since it's not galvanic isolated.

 

[hampestampe]

Hum in the speakers

Mine is totaly, quiet even when set to maximum volume, with nothing playing on idle.

 

[Belle]

I got the 10A. I'm not feeling much heat from it but the amp itself is getting very warm and it's no where near the power supply

The A70 is already for sale on Amazon, paired with the 48V5A's sold together, but there is also a link to the A70 and DC48V10A power supplies sold separately, I purchased the one with the DC48V 5A, I'll share it as soon as I can!

 

[Schlippwhip68]

View attachment 354996

...that sounds like the grind to me, a flippant office philosophy that some buzz nerd pisses everyone off with eventually so don't take it as an absolute! I would rather do less with more in some circumstances...but in others not.

 

[Schlippwhip68]

I am glad coffee is not this complicated, or the kettle!

 

[Pausi]

I can report from contact with Aiyima on Aliexpress that they have fixed the power on pop sound in the new batch.

 

[hampestampe]

I can report from contact with Aiyima on Aliexpress that they have fixed the power on pop sound in the new batch.

Yes I've got no such problems with my unit. So I can confirm from real world testing, that there is no pop when turning on or off.

 

[Dorus]

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.

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

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Question about the power bricks for ChiFi and others.

Is there any advantage to wrapping/shielding and grounding power supplies?

 

[YesChickenNuggets]

For what it's worth. I can not take anybody speccing their amps at 10%THD seriously, why not 100%THD, you would get even more "watts" ....

I just can not convince myself to get excited about this amp - it is cheap - cool. Better than other cheap chip amps - great. So what.
looking beyond performance at 5W and 1kHz [which is respectable] it offers very little. E.g. this graph is just plain ugly, rising distortion in multiples with every kHz added, and I fail to understand the comment "unhappy above 1kHz, but otherwise very good performance". There is actually lot of music going above 1kHz. Combine it with some average DAC, that has SINAD 120, but also shows rising distortion at higher frequencies and I think you will get into audible issue territory,

View attachment 355534

I can see this amp being used as desktop with some smaller bookshelves speakers ans some budget DAC - and here, if you combine everything - you can get get much better value by buying some well-performing powered monitors.

Also "cheap" is very relative - 220USD is not exactly cheap, like "if I don't like, I just throw it away" and for not much more money you can get some normal HYPEX based amp.

Sometimes cheap is just not worth it.

I asked StaticV3 about this subject, he told me that that graph doesn't matter and if it's 95 Sinad, it's 95 Sinad. He said when the power is reduced, the noise stays the same, so the Sinad goes down graphically.

I believe StaticV3, but in the back of my mind, if my credos as an ASR member is to deflect judgement of my feeble masculinity by possession of BIG SINAD amplifiers, then like yourself, I am also very bothered by these graphs. Maybe someone else can explain it more indepth. I didn't want to take up too much of StaticV3's time, since he seems like a busy guy.