- Thread Starter
- #21
Here is an interesting data point. I looked up the measurements of the Analog Devices AD5547 which Schiit Multibit uses: https://www.analog.com/media/en/technical-documentation/data-sheets/AD5547_5557.pdf
There, they show an FFT of THD similar to mine. Here is how their measurements compare to actual implementation in Schiit Multibit:
Notice the far, far better performance Analog Devices is showing in their measurements versus Modi Multibit. Their worst case distortion is around -110 dB or 25 dB better than Modi Multibit! That massive second harmonic peak seen in Modi Multibit is simply not there in Analog Device's measurements of the same chip in their bench implementation.
So we are really back to what I said in the review: people seem to sweep clear engineering problems away. They don't verify their designs properly and leave clearly engineering mistakes in there. Done correctly, the AD5547 would have been much closer to classic Delta-Sigma implementations. Until recently, Schiit did not take this seriously. They needed to have.
There, they show an FFT of THD similar to mine. Here is how their measurements compare to actual implementation in Schiit Multibit:
Notice the far, far better performance Analog Devices is showing in their measurements versus Modi Multibit. Their worst case distortion is around -110 dB or 25 dB better than Modi Multibit! That massive second harmonic peak seen in Modi Multibit is simply not there in Analog Device's measurements of the same chip in their bench implementation.
So we are really back to what I said in the review: people seem to sweep clear engineering problems away. They don't verify their designs properly and leave clearly engineering mistakes in there. Done correctly, the AD5547 would have been much closer to classic Delta-Sigma implementations. Until recently, Schiit did not take this seriously. They needed to have.