Power delivery is the reason for high jitter from even good master clocks. Power delivery includes:
1) power supply
2) cabling
3) decoupling caps
4) board design
5) regulator design
Steve N.
Empirical Audio
How can I tell if I need a better clock for my DAC?
I was interested in the responses to a related post by leemaze this week, saying that a Synchro Mesh was a good way to improve a DAC with subpar jitter. I have a Cambridge CXU, with an inboard DAC; how could I determine how much jitter it has?
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This Stereophile AES J-test includes a very high level signal mixed with a LSB (smallest signal) and is a great test for interface jitter and any modulation distortion. Ex 1. Benchmark DAC3 HGC, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 24-bit TosLink data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. https://www.stereophile.com/images/1117BDAC3fig11.jpg There is no jitter (spurious signal) visible above -150 dbfs noise floor on the analog output. This means there is excellent interface jitter rejection. —-&———————— Ex 2. Schiit Yggdrasil, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 24-bit USB data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. https://www.stereophile.com/images/217Schiitfig12.jpg There is jitter (lots of low level spurious signal at very specific tones).... probably inaudible but it is there. |
This DAC has no reclocker, just an AK4113 receiver. It would benefit greatly from an external reclocker like the Synchro-Mesh if the S/PDIF input is used. Are you certain that the j-test plot was using the S/PDIF input and not the USB input? The Benchmark 3 on the other hand does a good job of rejecting jitter compared to prior models. Reclocker not necessary, however you are stuck with the sound of the master clock in the DAC. If you like that, nothing more to do. Steve N. Empirical Audio |
In response to the OP, jitter never goes away; in the best DACs it is reduced to a minimum. The best way to keep jitter to a minimum is to see that your component has one of the high quality, high specification, clocks. If it doesn’t, sell it and buy one that has a great clock. At the moment the best clocks used in very high quality consumer units are referred to as a femtoclocks with about 80 femtoseconds of jitter.* At least one manufacturer, Wyred4Sound, makes a femtoclock available as an upgrade to existing DACs. Reports are that the clock change alone makes for better SQ. That being said, there seems to be little doubt that the quality of the incoming digital signal (jitter, noise) will affect the amount of correction the DAC has to do and so affects SQ. That’s why, for example, some disk players can sound better than others feeding the same DAC, and why some use reclockers in front of their DAC. As to whether you need a better clock, that's hard to say. Do you need better SQ? Will your associated equipment allow a better clock's effect to be heard? How critically do you listen? Can you afford? No one can answer for you. *There are more accurate clocks but they are used in the space and defense industries and are very, very expensive. |
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