AIYIMA A70 Stereo Amplifier Review

[tomtoo]

That subout frequences are hehehe.

Was the engineer drunk?
Was the complete team on a lets kiff weekend?

Did someone add a 0 where it not should be?

Please aima give us a answer what you thought (or more possible not thought)

Hehehe sub out at 800Hz is for me one zero to much.

 

[daniboun]

GaN semiconductors, e.g. diodes and transistors, are significantly more efficient. This allows smaller, cooler and more powerful switching power supplies to be built, but above all more efficient ones. This can improve the efficiency by 5-10%, which would also be the measurable difference.
Information about gallium nitride / GaN semiconductors can be found online.

This is exactly what I am pointing.. Read this

Aiyima’s TPA3255 PFFB based amplifier, coming soon

Nice, looking forward to see the review ) AIYIMA A70 PFFB pre-measurements (36V / 48V PSU) 4R Load 3E Audio 260-2-29A PFFB (48V PSU) 4R Load Do not forget to look at the Y-axis. Values are different (even though not much).

audiosciencereview.com

 

[tmtomh]

Ask yourself why Aiyima asked Amir not to test the 48/5A that they ship to him ?
Check the Fosi V3 ASR test with 2 different PSUs and make your conclusion.....

Yes, because a baseless conspiracy theory is just what we like to see here at ASR.

 

[Sokel]

Check the Fosi V3 ASR test with 2 different PSUs and make your conclusion.....

You have to take different gain into consideration,between the two amps but also between the different gain of the same amp.

 

[dtaylo1066]

Yikes! What more could ask for for 220 bucks?

 

[daniboun]

You have to take different gain into consideration,between the two amps but also between the different gain of the same amp.

Hummmmm
The Fosi V3 with no PFFB / RCA has a better Sinad than the Aiyima A70 with PFFB / RCA @ almost same gain..... The same goes for the ZA3 with no PFFB....

 

[GiBo61]

Most of us would like to see measurements with the stock 48/5A psu please ) as discussed below. Aiyima did not specify their test condition so you will help everybody here by doing it. You did it for the Fosi V3 should be fair to do it for the A70 as well ....

Aiyima’s TPA3255 PFFB based amplifier, coming soon

Nice, looking forward to see the review ) AIYIMA A70 PFFB pre-measurements (36V / 48V PSU) 4R Load 3E Audio 260-2-29A PFFB (48V PSU) 4R Load Do not forget to look at the Y-axis. Values are different (even though not much).

audiosciencereview.com

See atrached file for what Aiyima claimed

I understand your point and I would also be happy to see the measurements with the stock 48/5A PSU.
However, for a variety of reasons, Amir may be unable or unwilling to perform such testing (I'm sure he has a long waiting list for other devices to try). We are all grateful to Amir for what he does and if we are on this forum it's because we believe in the maximum transparency of what is published.
Anyone interested in purchasing an AIYIMA A70 at this point knows what to expect with a 48V/10A PSU, while if they decide for the version with a 48V/5A PSU they must be aware that - in the absence of instrumental measurements - the test results could be less satisfactory and therefore consider alternative brands/models in the same price range already tested in ASR.

 

[surroundman]

I vote great, for this is almost perfect. High pass filter and a more reasonable sub frequency adjuster will be the next needed improvement.

 

[Mikig]

Thanks Amirm for the review!

Nice product, versatile, and with good performance.
These chips are now practically a guarantee. Well done Aiyima who raises the bar with every release.

The recent history of DACs is also repeating itself in amplifications... good chip, a bit of copy and paste, and every 3 months a "new" product... oops an improved clone of the previous one.
But that's okay, this approach is leading to a series of devices with top performance and a bargain price, okay, it will be useful to everyone.

In my opinion, but only in my opinion, it is a question of taste, I prefer slightly larger devices: I would probably go for a Yamaha AS201 for the same amount, or rather I would invest 70 euros more and go for the AS301, with remote control , digital in, sub out, and phono.

 

[peniku8]

Sub Out: 20Hz~150Hz/600Hz(-3dB) (adjustable output cutoff frequency)

I'm a bit confused honestly

Interesting, in Amir's picture, the label looks like it reads 200-800Hz, but the measurement is -3 at 150Hz as the new(?) labels would suggest. Still utterly unusable, including the fact that it does not cut bass frequencies from the mains either.
I'd personally rather buy that product without the 'sub out' even if it costs the same. I guess you could say I'd pay to not have 'broken' features in otherwise perfectly good devices

 

[daniboun]

I understand your point and I would also be happy to see the measurements with the stock 48/5A PSU.
However, for a variety of reasons, Amir may be unable or unwilling to perform such testing (I'm sure he has a long waiting list for other devices to try). We are all grateful to Amir for what he does and if we are on this forum it's because we believe in the maximum transparency of what is published.
Anyone interested in purchasing an AIYIMA A70 at this point knows what to expect with a 48V/10A PSU, while if they decide for the version with a 48V/5A PSU they must be aware that - in the absence of instrumental measurements - the test results could be less satisfactory and therefore consider alternative brands/models in the same price range already tested in ASR.

I understand your point and I would also be happy to see the measurements with the stock 48/5A PSU.
However, for a variety of reasons, Amir may be unable or unwilling to perform such testing (I'm sure he has a long waiting list for other devices to try). We are all grateful to Amir for what he does and if we are on this forum it's because we believe in the maximum transparency of what is published.
Anyone interested in purchasing an AIYIMA A70 at this point knows what to expect with a 48V/10A PSU, while if they decide for the version with a 48V/5A PSU they must be aware that - in the absence of instrumental measurements - the test results could be less satisfactory and therefore consider alternative brands/models in the same price range already tested in ASR.

What if we let him answer for you? I would be surprised if the problem came from Amir. He did it for many other TPA325X amps....

 

[ROOSKIE]

I vote great, for this is almost perfect. High pass filter and a more reasonable sub frequency adjuster will be the next needed improvement.

I voted fine.
The sub out frequency makes absolutely zero sense.
I can see wanting to bypass it but otherwise use a range of 40-150hrz.
The fact they chose what they did makes me suspicious of the entire project.
Someone is nuts. Honestly it is straight up stupid as what they have here is entirely useless.

Otherwise this is very decent but I think for $220 it isn't a steal if a deal but rather about market price now give or take a few %. I'd be zero excited to buy one but I guess that is true of many amps that do the required job well enough.

 

[daniboun]

Yes, because a baseless conspiracy theory is just what we like to see here at ASR.

Transparency matters for members and consumers.

 

[GiBo61]

What if we let him answer for you? I would be surprised if the problem came from Amir. He did it for many other TPA325X amps....

Just my 2 cents

 

[oldandintheway]

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/

So this seems like progress, the load dependency is mostly gone. My remaining question about these TI chip amps is: is the rising distortion at high frequencies something that is built into the chip, or can it also be cured with external circuitry? I want good behavior, not "good for class".

 

[NTK]

I don't understand at all. What is a bridged amp? How is the DUT a bridged amp? What does it mean that a load doesn't like bridged amps? What relevance does this load's likes and dislikes have to me and other consumers?

TL;DR version:
It is a limitation of Amir's reactive load box, and it prevents the reactive load testing on some amplifiers due to the design of these amplifiers. This limitation is not relevant to the vast majority (99%+) of passive loudspeakers, which are what these amplifiers intended to drive.

More detailed version (will need some basic understanding of electrical circuits):
The TI class-D amplifier chip that does the majority of the work in this amplifier can operate in 3 different modes:

The TI TPA 3255 chip used by the A70 has 4 amplifier sections. It can drive 4 speakers in its SE (single-ended) mode; 2 speakers in its BTL (bridge-tied load) mode, or simply bridged mode; and 1 speaker in its PBTL (parallel bridge-tied load) mode. The A70 is configured to operate in the BTL mode.

In the SE mode, one side of the speaker (usually the negative terminal), is connected to electrical ground inside the amplifier. In the BTL mode, Output B is configured to have its output at the reversed polarity of Output A (similar for outputs C & D). The combined output of OUT A and OUT B doubles the voltage output to the speaker. By "bridging" together outputs A & B, the amplifier can double its output voltage capacity without having to increase the power supply voltage as in the SE mode (i.e. use the same power supply). The output current limit of the BTL mode remains the same as SE mode, and since 2 amplifier sections are together driving the speaker, the "apparent load impedance as seen" by each amplifier section is half that of the speaker. That's why for bridged amplifiers, the rated minimum speaker impedance is usually twice that when they operate in the single ended mode.

To counter the output current limitation, in the PBTL mode the amplifier is configured to 2 BTL sections in parallel (each providing half the demanded output current), thereby doubling the current output capacity. The minimum required speaker impedance in the PBTL mode is the same as in the SE mode, but with output power is increased by ~4X.

The issue with Amir's complex load is that it expects the negative output of the amplifier to be connected to the electrical ground. Since this is not the case with the BTL or PBTL modes, the complex load box doesn't work all the time for bridged amplifiers. This is not a problem with the vast majority of passive speakers as they don't need nor expect the negative amplifier output to be at electrical ground. Exceptions may include some electrostatic speakers and the older Polk SDA (don't know about the current ones).

 

[tmtomh]

Transparency matters for members and consumers.

Drawing unwarranted conclusions is not necessary to promote transparency.

 

[amirm]

What if we let him answer for you? I would be surprised if the problem came from Amir. He did it for many other TPA325X amps....

I gave the answer. It makes little sense to get the half power supply just to save $30.

 

[TonyJZX]

i have no issue with the device itself... except for creeping costs

lets see how fosi responds

however I'm confused about whatever they're doing with the sub out

150-800hz doesnt look normal at all

should be like 50 60 70 80 up to 200? no?

so in that regard i would ignore this and rely on whatever you got upstream

 

[gfx_1]

150-800hz doesnt look normal at all

should be like 50 60 70 80 up to 200? no?

Subwoofers have settings for frequency range and relative volume. It works fine.
The stereo output gets the full range.