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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: High frequency jitter in an over $400 DAC posted by dave789 on May 16, 2015 at 12:01:34:
Hi,
I have no interest to comment on the specific products you mention, however given that the CS8416 seems to crop up a fair bit, I thought it is worthwhile mentioning that it has some peculiar "Features" (as in "it's not Bug/Bugfix, it's a feature").
You can read Cirrus Logic's own take on this here:
http://www.cirrus.com/en/pubs/appNote/AN339REV1.pdf
A more indepth discussion is here:
http://www.diyhifi.org/forums/viewtopic.php?f=2&t=1879
The upshot is simple.
The CS8416 has a operation mode where it emulates in effect the CS8414, including the limitation of the sample rate to 96kHz. In this mode the random noise-like jitter from the CS8416 VCO itself is suppressed very well (by an action that is in effect negative feedback), but any jitter from the source passes through to the DAC unattenuated, unless it is above the audio band.
This is the classic SPDIF receiver behaviour and is replicated by earlier Cirrus Logic, AKM etc. parts. It is the cause for much of the stories of digital transports and digital cables making huge audible differences, well, because they did, measured as well as audibly.
The second mode of the CS8416 is needed for > 96kHz sample rates and is one of those things that "seemed a good idea at the time". It is in effect capable of rejecting all source jitter that does not cause the receiver to unlock (I tested that using AP2 jitter generation feature).
The downside, it does very little to attenuate the noiselike jitter generated by the CS8416 VCO. And the levels of this noiselike jitter are directly linked to the sample rate, the lower the samplerate the more of this jitter. And there is a lot of it, enough to FUBAR the noise floor of most DAC Chip's.
So, you choose, massive sensitivity to source jitter or massive noise jitter. I am sure there is a lesson in this for the wisdom of using the CS8416 in high end audio products, to me the lesson was "use something else"...
Thor
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?
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Follow Ups
- RE: High frequency jitter in an over $400 DAC - Thorsten 05:20:51 05/18/15 (0)
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