jitter


I am pretty sure I understand jitter generated by streamers and/or DACs. My question  is, when a digital recording is created, can there already be jitter in the digital data itself from the ADC? If so, can this ever be corrected during playback, either by the streamer or DAC?

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Showing 3 responses by yage

@jw944ts

Sampling clock jitter is inherent to the digitization process so it can't be removed by anything in the playback chain. Here's a good overview from Texas Instruments on how sampling clock jitter affects ADC performance - https://www.ti.com/lit/an/slyt338/slyt338.pdf?ts=1698696178966&ref_url=https%253A%252F%252Fwww.google.com%252F

 

Practically speaking, given today's ADC performance, clock accuracy and the relatively low input frequencies of audio vs. sampling a signal at radio frequencies, this type of jitter can most likely be considered inaudible.

 

For example in the paper linked above, the 'average' jitter is calculated at 26 ps which equates to spurious frequency components that are ~100 dB below the RF carrier frequency. If we translated this to an example at audio frequencies, even with music playing at rock concert levels (110 dB), the jitter would still be quieter than a whisper (~10 dB). If we also account for the fact that we now have sampling clocks with femtosecond accuracy (as in the case of RME's SteadyClock technology), the jitter components will be below the threshold of perception in virtually all cases.

In the other thread you mentioned that you were going to try a different a streamer. I also suggested trying a different digital input on the DAC. Did you ever test those situations?

 

Finally, can you tell if the ’glitchy’ DAC actually loses connection due to jitter? For example, on the Benchmark DAC3 B, the input light will flash if sync is lost. Does the other DAC give you some sort of indication that the connection is bad?

Hopefully that fixes things. Given what you've posted, I think most signs are pointing to something going wrong on the DAC since replacing it with another DAC solves the issue.