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:
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:
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:
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:
Zooming in:
Noise performance is good:
Multitone shows increasing distortion at high frequencies (fairly typical):
Which winds up hurting 19+20 kHz more:
Frequency response shows the class load dependency in budget class D amplifiers but also the channel balance issue:
Crosstalk is pretty good:
Let's see how much power we have:
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:
Amplifier is stable on power up:
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:
Edit: Bridge Mode Measurements
I put the amplifier in bridge mode (mono) and measured at 4 ohm:
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:
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:
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:
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:
Indeed we get a lot more power (nearly double).
Now let's test in bridged mode:
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:
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:
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:
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/
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:
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:
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:
Zooming in:
Noise performance is good:
Multitone shows increasing distortion at high frequencies (fairly typical):
Which winds up hurting 19+20 kHz more:
Frequency response shows the class load dependency in budget class D amplifiers but also the channel balance issue:
Crosstalk is pretty good:
Let's see how much power we have:
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:
Amplifier is stable on power up:
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:
Edit: Bridge Mode Measurements
I put the amplifier in bridge mode (mono) and measured at 4 ohm:
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:
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:
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:
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:
Indeed we get a lot more power (nearly double).
Now let's test in bridged mode:
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:
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:
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:
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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