AIYIMA A07 review

This test review was performed to comply with FTC: 16 CFR Part 432 (July 5, 2024) - Power Output Claims for Amplifiers Utilized in Home Entertainment Products

The Aiyima A07 is a small, affordable, 2-channel Class D amplifier. It embeds a TPA3255 amplifier chip. The inputs are in stereo RCA or on Jack 3.5mm. In addition, it is equipped with two upgraded LM4562 operational amplifiers with excellent performance.

1. Test conditions

The amplifier was tested with a 27Vdc SMPS power supply and 4ohm load. As per the manufacturer, output power depending on the power supply voltage should be as follows:

2. Pre-conditioning

First of all, the amplifier was pre-conditioned at 1/8 of the rated power. I estimated the rated power from the distortion measurement as 64W/4ohm. So, the pre-conditioning was at 2 x 8W/4ohm for one hour, as requested by the FCT document. At the end of the pre-conditioning period, the amplifier case was only mildly warm. The distortion in the beginning and in the end of the pre-conditioning is shown below.

3. Noise

Amplifier noise was measured with the volume pot turned full left. The output noise voltage was 224 uV (20Hz - 20kHz) and 176 uV(A).

4. Frequency response

Frequency response was measured at 6.6V output voltage into 4ohm, 10ohm, and simulated woofer speaker load.

One can see that frequency response shape is ld dependent. It is because of the amplifier output LC filter that is outside the feedback loop and the LC resonance is damped only by the load impedance. The filter is optimized for the 4ohm load, as can be seen from the plots.

5. Power frequency response measured at 64W/4ohm, to 45kHz

Power frequency response was estimated as 20Hz - 45kHz

6. Distortion was measured at gain setting by volume pot as G = 26dB

6.1. Distortion at 2W/4ohm (2.828 V)

6.2. Distortion at 10W/4ohm

6.3. THD vs. output voltage into 4ohm load at 50Hz, 1kHz, 10kHz with measurement bandwidth 90kHz

16V corresponds to 64W/4ohm, P = V^2/4

6.4. THD vs. frequency at 2W and 25W/4ohm

6.5. THD vs. frequency at rated power 64W with measurement bandwidth 90kHz

So, I am declaring the rated power over 20Hz - 20kHz band to be 64W at THD < 0.2%. The amplifier has passed 5 minute test at 64W/4ohm/1kHz.

Pavel Macura 11/23/2024