This is measurements of the HIRESFI AMPER502 Full Digital Amplifier. It was kindly sent by a member in EU and costs €116.16 (including tax).
As you see, this is clearly hobbyist level packaging. Inside though, it boast an ARM processor which is used to provide some level of signal processing. Alas, the equalization is at fixed frequencies so not very useful for speaker/room correction but can be used to do bass management and such. Core amplification is based on ST Micro STA350BW single chip "digital" amplifier IC.
Upon powering up the sample, the amplifier section turned off as soon as I pushed it above 3 watts (the processor was alive and well). It did that no matter if I drove one or both channels. It stayed up a bit longer with 8 ohm but still would shut down at 5 or so watts. Owner had it shut down also but when playing loud so had supplied me with a beefy 24 volt switching supply. I wanted to test with another but could not find a barrel connector that fit it. Whether this is a design flaw or fault of this specific sample, I can't be sure. This being an interesting topology of converting digital samples directly to high power output, I thought we test it anyway.
HIRESFI AMPER502 Amplifier Measurements
I got the amp close enough to 5 watts and took a snapshot before it shut down:
High level of distortion places the amplifier well below average of all amplifiers tested (SINAD of 85 dB). Company specs 100 dB SNR but I don't know at what power level. Using the 4.x watts above, we only get 86 dB:
Frequency response is disappointing:
It is unfortunate that I can't push the amplifier to its full 50 watts but even at 3 or so watts, we can see the trends:
Those are very elevated noise and distortion levels.
Conclusions
Admittedly, our hands are tied with the sample we have in hand. Still, we can see that the amplifier has quite high distortion and it is not anything special in noise department either. Frequency errors may be due to poor DSP implementation or filtering. Either way, it does not make a good showing and I can't see that being due to anything broken.
The concept of "power DAC" has always been appealing in the way it seems to bypass a number of audio stages. But so far, I have not seen any implementation that performs very well. Some things are not intuitive and this is one of them!
I haven't give this test a "review" title and won't include a poll due to specific sample perhaps being broken. Just some data to look at and discuss.
------------
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/
As you see, this is clearly hobbyist level packaging. Inside though, it boast an ARM processor which is used to provide some level of signal processing. Alas, the equalization is at fixed frequencies so not very useful for speaker/room correction but can be used to do bass management and such. Core amplification is based on ST Micro STA350BW single chip "digital" amplifier IC.
Upon powering up the sample, the amplifier section turned off as soon as I pushed it above 3 watts (the processor was alive and well). It did that no matter if I drove one or both channels. It stayed up a bit longer with 8 ohm but still would shut down at 5 or so watts. Owner had it shut down also but when playing loud so had supplied me with a beefy 24 volt switching supply. I wanted to test with another but could not find a barrel connector that fit it. Whether this is a design flaw or fault of this specific sample, I can't be sure. This being an interesting topology of converting digital samples directly to high power output, I thought we test it anyway.
HIRESFI AMPER502 Amplifier Measurements
I got the amp close enough to 5 watts and took a snapshot before it shut down:
High level of distortion places the amplifier well below average of all amplifiers tested (SINAD of 85 dB). Company specs 100 dB SNR but I don't know at what power level. Using the 4.x watts above, we only get 86 dB:
Frequency response is disappointing:
It is unfortunate that I can't push the amplifier to its full 50 watts but even at 3 or so watts, we can see the trends:
Those are very elevated noise and distortion levels.
Conclusions
Admittedly, our hands are tied with the sample we have in hand. Still, we can see that the amplifier has quite high distortion and it is not anything special in noise department either. Frequency errors may be due to poor DSP implementation or filtering. Either way, it does not make a good showing and I can't see that being due to anything broken.
The concept of "power DAC" has always been appealing in the way it seems to bypass a number of audio stages. But so far, I have not seen any implementation that performs very well. Some things are not intuitive and this is one of them!
I haven't give this test a "review" title and won't include a poll due to specific sample perhaps being broken. Just some data to look at and discuss.
------------
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/
