AIYIMA A07 TPA3255 Review (Amplifier)

[AdamG]

Just…. wow

I just translated it. I didn’t make it logical or clear. He is new so he gets some wiggle room. Not a lot but some. Also, translations can get context and intent confused and inaccurate. If he continues to post in any language other than English. We won’t be as accommodating. Benifit of the doubt for new members is what everyone said we need to do better.

 

[xschop]

Well with an isolation transformer on the SDA circuit, this amp runs even cooler at very loud levels....
The details coming forth are even better, along with the huge SDA sound stage...

 

[carlmart]

Well with an isolation transformer on the SDA circuit, this amp runs even cooler at very loud levels....
The details coming forth are even better, along with the huge SDA sound stage...

How do you connect this transformer exactly and what are its specs?

 

[Talisman]

Well with an isolation transformer on the SDA circuit, this amp runs even cooler at very loud levels....
The details coming forth are even better, along with the huge SDA sound stage...

 

[xschop]

 

[xschop]

Here's the crossovers I used for the SDA conversion. Immense soundstage improvement...

To expound: this A07 Class D amp is adequate for running Polk SDA's with an isolation transformer as the interconnect cable.

 

[MediumRare]

Here's the crossovers I used for the SDA conversion. Immense soundstage improvement...

To expound: this A07 Class D amp is adequate for running Polk SDA's with an isolation transformer as the interconnect cable.


View attachment 365268

Can you explain what SDA means and briefly what the circuit does electronically and qualitatively?

 

[xschop]

Polk SDA is their method of interaural cross-talk cancellation via a crossover network that sends an inverted signal to either side speaker's "stereo dimensional driver".

Polk Audio SDA Speakers: 1985 Review of SDA-SRS

 

[Natal]

I have Dali Spektor 2 speakers driven by the Aiyima 07 amplifier. I listen at low "conversational" levels but find one speaker is louder than the other. Is the problem that the Aiyima is incapable driving inefficient speakers (84 db) at a low level and I need much more powerful amp to drive the 2 speakers equally at a low level? Would a higher efficiency speaker solve the problem?

 

[saberger0357]

Has nothing to do with the efficiency of the speakers. Could be connection issue, could be amp issue, could be speaker issue. I would start by disconnecting and reconnecting everything and go from there.

 

[antcollinet]

I have Dali Spektor 2 speakers driven by the Aiyima 07 amplifier. I listen at low "conversational" levels but find one speaker is louder than the other. Is the problem that the Aiyima is incapable driving inefficient speakers (84 db) at a low level and I need much more powerful amp to drive the 2 speakers equally at a low level? Would a higher efficiency speaker solve the problem?

No, that would likely make things worse. The problem is the unbalance of the volume pot when turned down. Higher efficiency speakers would need you to turn it down further.

Try turning down the source digitally (if digital) further up the chain - then you can set the amp to a higher level.

 

[wave]

The Aiyima 07 amp is powerful enough to drive Dali Spektor 2.

How I know? I have the amp and the Dali Spektor 2 and it can drive them really loud without distortion

 

[Natal]

Thanks for the tips guys. I've determined it was my iPhone. With my TV and CD player as sources it's fine - the sound is balanced. The thing that's really odd is that I get the same problem with 2 different iphones - 14 pro and 6s using bluetooth and a direct connection via the headphone jack. It defies logic but I'm not going to worry about it as the CD player is much better sounding.

 

[antcollinet]

Most likely your ipones are outputting a lower level, allowing you to turn up the level on the amp.

 

[Talisman]

Most likely your ipones are outputting a lower level, allowing you to turn up the level on the amp.

Considering that the problem only occurs with iPhones this makes no sense, if they emitted a lower level and you had to raise the volume more the problem would not exist.
On the contrary, they could have a higher level and therefore have to hold the amp knob at the beginning of the rotation

 

[antcollinet]

Considering that the problem only occurs with iPhones this makes no sense, if they emitted a lower level and you had to raise the volume more the problem would not exist.
On the contrary, they could have a higher level and therefore have to hold the amp knob at the beginning of the rotation

Yup - skim read, got it wrong.

 

[xschop]

I have Dali Spektor 2 speakers driven by the Aiyima 07 amplifier. I listen at low "conversational" levels but find one speaker is louder than the other. Is the problem that the Aiyima is incapable driving inefficient speakers (84 db) at a low level and I need much more powerful amp to drive the 2 speakers equally at a low level? Would a higher efficiency speaker solve the problem?

The volume pots from factory have this issue I've found, even on the Aiyima A04. I remedied the A04 by using Deoxit on the pot switch, but swapping the A07's pot with ALPS 50KAX2 permanently mitigated the issue.

 

[18000rpm]

Considering that the problem only occurs with iPhones this makes no sense,

Yes, especially because it also happens when you use Bluetooth. It's a digital signal - it's impossible to be unbalanced.

 

[Mark Lawless]

This is a review and detailed measurements of the AIYIMA A07 desktop amplifier based on TPA3255 class D amplifier chip. It was kindly purchased new by a member and drop shipped to me. The cost is US $72 on Amazon including prime shipping. And as of this shipping, it also included a 32 volt, 5 amp switching power supply. Member also purchased and sent me a 48 volt/3 amp power supply which I also tested.

The case is standard budget audio affair:
View attachment 102785

The volume control feels cheep but does the job. The back panel terminals were way too small for my binding posts:

View attachment 102786

The DC input socket was quite stiff especially with the 48 volt power supply. Tightness is not a bad thing as far as power transfer is concerned but this was a bit too stiff. Here are the two power supplies:

View attachment 102787

They both feel kind of cheap as they would be at these prices ($21 for the 48 volt one). Personally I would not leave these plugged in permanently if I am not around. The included power supply has a two-pronged AC cable that was not polarized. Rotating it around made a small difference in mains leakage.

AIYIMA A07 Measurements
Let's start with our usual dashboard of 5 watts into 4 ohms:
View attachment 102788

As you see in the FFT display, there is considerable amount of mains leakage at 60 Hz. This tends to be a function of switching power supplies. I played with grounding and improved it a lot in one channel but not in the other (not shown). SINAD did not get impacted since it is bound by distortion harmonics. As it is, performance is above average:
View attachment 102789

Signal to noise ratio is not great due to the mains hum:
View attachment 102790

Frequency response is well behaved, albeit with a slight droop at 20 kHz:

View attachment 102791

Crosstalk is good and well above bargain basement desktop amps:
View attachment 102792

Power is everything in a small amp so let's see how we do with 4 ohm load:

View attachment 102793

As expected, with low impedance of 4 ohm we are current limited so the 5 amp stock power supply does better, turning in 77 watts. Yes, the 300 watt rating is a fantasy but maybe it can do better with momentary peaks. Alas, its aggressive protection circuit would shut it down and not let me test max and peak power.

Naturally the higher voltage power supply does better with 8 ohm load where we become voltage limited:
View attachment 102794

Sweeping power vs frequency and distortion shows a very well behaved class D amplifier:
View attachment 102795

Conclusions
Traditionally these desktop amplifiers have produced really poor performance in the form of noise and distortion. Not so anymore. These TPA3255 based amps seem to have good bones in them, producing above average performance for peanuts. Alas, you are saddled with two boxes and cheap and potentially non-safety compliant parts. For desktop use, these are probably acceptable compromises.

I am going to recommend the AIYIMA A07 based on its performance.

And with this, our last review of 2020 comes to an end! Nice that it is ending on a happy note.

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I bought one of these amps just for fun. Right now it is running my high-end speakers, some B&W801D4s sounds crazy but they also sound very good. I think I upgraded the little amp by changing out the op-amps in them to some Burr Brown. It was very easy to do and I did research the op-amps to find some that had better specs. It was easy to do and I do think the sound improved. I can say that they make my speakers sound fantastic as they should. I would certainly recommend this little amp for anyone that has speakers that are not power hungry.

 

[375HP2482]

^ An op-amp running at low gain re the OG NE5534 will not exhibit audible differences in the A07.

A much lower S/N power amplifier than the A07 unit might reveal some tiny increase in noise.