I have wondered for a while what these generic Chinese DAC boards found on ebay are actually like. On face value can they really be that bad?
First one is a ES9028Q2M based board. It has single ended, balanced and headphone outputs. Audio and digital sections appear to have separate power supplies driven from a 2x 15V and 1x 9V transformer. This board only accepts I2S input but there are a plethora of xmos based boards that will do the job of conversion from USB. It comes with a short ribbon cable for connection. Note there is no onboard clock with this board, MCLK has to be provided from the USB to i2s board.
I bought this from Audiophonics simply due to the massive and rather random delivery times from Chinese Ebay vendors (not to mention Cinese New Year delay) where it can be found much cheaper.
https://www.audiophonics.fr/en/diy-...alanced-dsd-1x-lt1963-regulators-p-12355.html
Single Ended Outputs
0dBFS - Output is low at 1.44V rms. 2nd and 3rd harmonics are fairly high.
-6dBFS - harmonic distortion drops significantly
-60dbFS - Noise floor drops revealing a spread of harmonics, but these are at a low level
-90.31dBFS (24BIT)- Quite a noisy waveform with low frequency (probably 50Hz mains) modulation
24 Bit J-Test - Not the cleanest but no significant jitter
IMD SMPTE - Again not the cleanest
FR and imaging
Linearity - Not good, bombs after -115dB
Overall conclusion from the single ended output is its unimpressive, but not that bad. Considering I have seen this for as low as $30 US on ebay then you have to put it in perspective.
I will test the balanced later and see if that offers improvement.
First one is a ES9028Q2M based board. It has single ended, balanced and headphone outputs. Audio and digital sections appear to have separate power supplies driven from a 2x 15V and 1x 9V transformer. This board only accepts I2S input but there are a plethora of xmos based boards that will do the job of conversion from USB. It comes with a short ribbon cable for connection. Note there is no onboard clock with this board, MCLK has to be provided from the USB to i2s board.
I bought this from Audiophonics simply due to the massive and rather random delivery times from Chinese Ebay vendors (not to mention Cinese New Year delay) where it can be found much cheaper.
https://www.audiophonics.fr/en/diy-...alanced-dsd-1x-lt1963-regulators-p-12355.html
Single Ended Outputs
0dBFS - Output is low at 1.44V rms. 2nd and 3rd harmonics are fairly high.
-6dBFS - harmonic distortion drops significantly
-60dbFS - Noise floor drops revealing a spread of harmonics, but these are at a low level
-90.31dBFS (24BIT)- Quite a noisy waveform with low frequency (probably 50Hz mains) modulation
24 Bit J-Test - Not the cleanest but no significant jitter
IMD SMPTE - Again not the cleanest
FR and imaging
Linearity - Not good, bombs after -115dB
Overall conclusion from the single ended output is its unimpressive, but not that bad. Considering I have seen this for as low as $30 US on ebay then you have to put it in perspective.
I will test the balanced later and see if that offers improvement.
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