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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: Re: A lot of people don't understand dither posted by Werner on March 6, 2007 at 23:24:36:
*** Best I ever got was a PCM1804, which after having discarded
any structural noise left me at -108dB rms. ***Care to show us a graph of your results?
I checked the data sheet for the PCM1804, and the noise curves on page 11 and 12 (Figures 8-15) clearly show that in PCM mode for single rate and dual rate, the noise levels are close to -140dB apart from a few spikes (which are not ditherable, but these spikes lower the dynamic range to 112dB). In DSD mode, the noise levels are just under -120dB. Even in quad rate mode, the noise levels are around -140dB below 48kHz.
For the PCM4202, the corresponding figures are on page 9-10 of it's data sheet, and show underlying noise to be very similar, just under -140dB. The main difference between the two chips are the lack of harmonic spikes on the PCM4202 (as it's a higher quality ADC), which results in better SNR and THD measurements.
This is consistent with my own measurements of similar ADCs. The laws of physics don't change for different ADCs.
If your results are wildly different, it either means what you are measuring is broken, or there's something screwy with your measurement method.
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Follow Ups
- Re: A lot of people don't understand dither - Christine Tham 15:39:06 03/07/07 (2)
- Re: A lot of people don't understand dither - Werner 23:57:08 03/07/07 (1)
- Great, now that you've finally had a chance to show some of your "knowledge" ... - Christine Tham 01:01:50 03/08/07 (0)
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