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Aiyima A07 Max Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 32 14.2%
  • 2. Not terrible (postman panther)

    Votes: 113 50.2%
  • 3. Fine (happy panther)

    Votes: 65 28.9%
  • 4. Great (golfing panther)

    Votes: 15 6.7%

  • Total voters
    225

amirm

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This is a review and detailed measurements of the Aiyima A07 Max stereo class D amplifier. It was sent to me by the company and sells for (I think) $85 with the included power supply:
AIYIMA A07 MAX stereo amplifier class-d desktop review.jpg

I like the little design touches and the much heavier enclosure (made out of steel?). I really appreciate the larger and staggered speaker binding terminals:

IMG_0016.jpg

As you see, the power supply is rated at 36 volts @ 6 amps. It has no branding though so not sure about the safety marks. There are vent holes underneath and during the testing, the case stayed quite cool.

Let's see how it measures. If you are unfamiliar with what is about to follow, please watch my video tutorial:

Aiyima A07 Max Measurements
As usual we start with our dashboard:
AIYIMA A07 MAX stereo amplifier measurement.png

I had a hard time setting the output to 5 watts due to fairly large channel mismatch. I did feed each channel independent (not shown) to get them both at 5 watts and results were similar. As is, performance is very good:
best cheap stereo amplifier review.png

Zooming in:
best cheap stereo amplifier review zoomed.png


Noise performance is good:
AIYIMA A07 MAX stereo amplifier SNR measurement.png

Multitone shows increasing distortion at high frequencies (fairly typical):
AIYIMA A07 MAX stereo amplifier multitone measurement.png


Which winds up hurting 19+20 kHz more:
AIYIMA A07 MAX stereo amplifier 19 20 Khz IMD distortion measurement.png


Frequency response shows the class load dependency in budget class D amplifiers but also the channel balance issue:
AIYIMA A07 MAX stereo amplifier frequency response measurement.png


Crosstalk is pretty good:
AIYIMA A07 MAX stereo amplifier Crosstalk measurement.png


Let's see how much power we have:
AIYIMA A07 MAX stereo amplifier Power 4 ohm measurement.png

AIYIMA A07 MAX stereo amplifier Max and Peak Power 4 ohm measurement.png

AIYIMA A07 MAX stereo amplifier Power 8 ohm measurement.png


Pretty good amount but one channel shows that rising distortion above a few watts which we also saw in the dashboard.

There is some frequency dependency as we would expect in this class of amplification:
AIYIMA A07 MAX stereo amplifier Power 4 ohm vs frequency measurement.png


Amplifier is stable on power up:
AIYIMA A07 MAX stereo amplifier warm up measurement.png


The volume control is also the on/off switch. So I can't test the on/off pop the usual way as that would be at minimum level compared to other amps with separate power switch that are at full gain. So while not practical, I turned the amp on/off using the AC plug:
AIYIMA A07 MAX stereo amplifier power on off noise pop crack measurement.png


Edit: Bridge Mode Measurements
I put the amplifier in bridge mode (mono) and measured at 4 ohm:
AIYIMA A07 MAX stereo amplifier Power 4 ohm Bridged measurement.png

Surprising that you don't get much more power. The unevenness in the response is smoothed out though. We get a bit more power if we allow 1% THD:
AIYIMA A07 MAX stereo amplifier max and peak Power 4 ohm Bridged measurement.png


I was told the amp was rated down to 2 ohm in bridged mode which is very unusual. So I gave it a try and it worked to produce a lot more power:
AIYIMA A07 MAX stereo amplifier Power 2 ohm Bridged measurement.png


Note that majority of speakers I test have their lowest impedance between 3.5 and 4 ohm.

A07 Max Measurements with 48volt/5a Power Supply
Worrying that the power supply may be the limiting factor, I swapped out the 36v/6 amp one for a 48v/5amp unit I had on hand. Let's do a sweep in stereo first:
AIYIMA A07 MAX stereo amplifier Power 4 ohm Bridged 48 volt power supply stereo sweep measurem...png


That is nearly 60 watts more power than with the 36 volt power supply. This test is current limited so the extra voltage shouldn't have helped much. It seems to point to the stock power supply not having the 6 amp current it claims. Let's test in stereo where the extra voltage does help:
AIYIMA A07 MAX stereo amplifier Power 8 ohm Bridged 48 volt power supply stereo sweep measurem...png


Indeed we get a lot more power (nearly double).

Now let's test in bridged mode:
AIYIMA A07 MAX stereo amplifier Power 4 ohm Bridged 48 volt power supply sweep measurement.png

We get more power than with the other power supply but still not what a bridged mode should do. There is also some noise penalty which may be due to different power supply or higher voltage. Here are the 1% THD max and peak powers:

AIYIMA A07 MAX stereo amplifier Power 4 ohm Bridged 48 volt power supply measurement.png

This again is far more power than the stock 36 volt one.

EDIT2: Here is the measurement of the included 36v/6amp power supply. First, at rated 6 amp:
AIYIMA 07 MAX Power Supply at 6 amps.jpg


Fully 6 amps is provided however voltage drops by about 1.2 volts. So instead of ideal 216 watts, we are getting 209 watts.

The power supply was quite robust, allowing me to max out my electronic load's capability of 250 watts:
AIYIMA 07 MAX Power Supply at 9 amps.jpg


Note that there is further voltage drop so not good for high impedance speaker loads. But for low impedance, we have as much as 7.3 amps out of output without the supply shutting down.

EDIT 3:
AIYIMA A07 Max Listening Tests
I connected the A07 Max, don't laugh, to my $23,000 Revel Salon 2 speakers as requested by a member. I must say, I was not remotely prepared for what I heard. This little amp with its 36 volt/6amp power supply had no trouble driving the Revels to incredible dynamics! Resolution and detail was superb. Deep, sub-bass was produced with no sign of amp straining or wanting to turn off. I am still listening to it as I type this and can't believe what I am hearing. The binding posts on the speakers probably weigh as much as this amp!

Granted, I am scared of turning it up to max volume as to risk damaging my speakers should something go wrong. But so far, even at very elevated listening levels, the amp is performing beautifully. It defies one's or at least my intuition. Feed this amp well recorded music and pair it with great speakers and you are set.

Note that if you have less sensitive speakers, you may run out of power.

Conclusions
Aiyima has made good strides in the mechanical and outside design of the amplifier with heavier chassis with venting. The look is simpler and cleaner. And bind posts are now quite proper. Electrically, performance is similar to their other offerings which is to say it is very good. The only thing I didn't like here compared to others I have tested is channel imbalance. This is strange as I had the volume control fairly up high (as you see in the review picture) so not at the lower levels where channel imbalance usually comes up. This would cause the stereo image to shift to one side some. The sample you get may be the same, worse or better. At this price, I guess we can't expect hand picked pots but I was hoping for better.

For above reasons, the Aiyima A07 Max is not something I would buy. But your conclusion may be different.

------------
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/
 
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amirm

amirm

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Manufacturer Specifications:

A07 MAX TPA3255 Power Amplifier

Stereo Max Output Power(switch stereo mode):300Wx2 / 4Ω(48V/12A)

Mono Max Output Power(switch mono mode):600W/ 2Ω(48V/12A)
(R+ connect to speaker +, L+ connect to speaker -)

Working Voltage:DC24-48V,5A or more

Replaceable Op-Amp Chips:OPA2604AP, OPA2134, MUSEO1/02/03, LME49720NA, LM4562, AD827AQ, etc

AUX OUT: active nsubwoofer or power amplifier

3.5mm AUX OUT as output connect to next amplifier without volume control

THD:0.007%

SNR:≥110dB

Input sensitivity:1V

AUX Maximum Output level:1V

Frequency response 20Hz-20KHz(±1dB)

IMG_0514.jpeg
 
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TheWalkman

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Thanks for the teardown photo.

I always scratch my head and wonder why these chip amp manufacturers cut corners and save a few cents by using 50V capacitors rather than 63V.

I understand what price point design is all about but it still seems very shortsighted to me.
 

Toku

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I'm testing two A07 Max units and I believe the difference in R/L gain in the amirm measurements is due to a defective volume pot. There is no such difference on my A07 Max.
Also, there is no pop noise when the power is turned on/off.
There is no pop noise at all whether you turn it on/off with the volume knob or on/off the AC line.
Are these differences due to manufacturing variations?
 
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Toku

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Thanks for the teardown photo.

I always scratch my head and wonder why these chip amp manufacturers cut corners and save a few cents by using 50V capacitors rather than 63V.

I understand what price point design is all about but it still seems very shortsighted to me.
AIYMA staff never listens no matter how many times I point this out.
Many members of ASR have not pointed out anything about this until now.
 

Joe Smith

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I believe they have stated that latest production models have the 63v caps...

Weird about the channel imbalance. Likely that is variation due to the volume pot, right? I have not noticed any channel imbalance in mine.

Now I need to go back and see how these results compare to the original A07 as measured by Amir...

Overall, kinda disappointing as seems like lower performance than the Fosi V3.


Edit: Went back and looked at the December 2020 A07 review. Most interesting spec comparison to me was that Amir got more power for 8 ohms with the original A07 with the 32v power brick (48 watts) than the new MAX at 8 ohms with the 36v power brick (40 watts).
 
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amirm

amirm

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Also, there is no pop noise at all when the power is turned on/off. Is it due to product variations?
I tested that as I noted by plugging/unplugging the AC cable. Is that how you tested it? What it does is likely dependent on power supply as well.
 

Guddu

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I tested that as I noted by plugging/unplugging the AC cable. Is that how you tested it? What it does is likely dependent on power supply as well.
There isn’t any pop out noise with my unit if I use on/off using volume pot, however there is faint pop out noise with ac adapter on/off.

P.E. I also didn’t get any channel imbalances, tested with windows L/R to spl meter app on iPhone.
 
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amirm

amirm

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P.E. I also didn’t get any channel imbalances, tested with windows L/R to spl meter app on iPhone.
SPL meter may not accurate enough to find such differences. You need to use a volt meter.
 
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amirm

amirm

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There isn’t any pop out noise with my unit if I use on/off using volume pot, however there is faint pop out noise with ac adapter on/off.
That's right. I explained this in the review. That the fact that the volume control is also power switch, kind of nullifies the standard test. My testing then was just with AC cord.
 

Guddu

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@amirm
Would you have recommended this amplifier if CH2 imbalanced wouldn’t have been an issue and SINAD would have landed between 88-89 bB?
 

Toku

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I will correct my previous post.

The A07 MAx capacitor that arrived from China's AIYIMA Store yesterday had been changed to a 63V withstand voltage.
If you shine an LED light through the heat dissipation hole on the side of the case, you can see the words 63V 2200uF.
The A07 Max I purchased a month ago has a 50V 2200uF installed.
AIYIMA seems to have adopted a 63V capacitor for the latest lot A07 MAx.
 
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TheWalkman

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I will correct my previous post.

The A07 MAx capacitor that arrived from China's AIYIMA Store yesterday had been changed to a 63V withstand voltage.
AIYIMA seems to have adopted a 63V capacitor for the latest lot A07 MAx.
I stand corrected. (So where did @JSmith Get the photo shown above, post #7?)
 
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amirm

amirm

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@amirm
Would you have recommended this amplifier if CH2 imbalanced wouldn’t have been an issue and SINAD would have landed between 88-89 bB?
Yes. Even with current SINAD it would be fine for this price category.
 
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