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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: Wenzel 10M oscillator with 50 ohm SMA(f) as Master Clock posted by bssk on July 10, 2015 at 10:36:31:
Hi,
I do not know these products in detail.
Personally I found designing a SPDIF/AES-EBU Input (at the core SPDIF and AES-EBU are the same, except AES-EBU uses connectors even more inapproriate to high frequency signals than the much maligned RCA socket) that can match a competent asynchronous USB input quite a challenge (I love challenges though).
Honestly, if a AES-EBU input equals or betters async USB it should reject any jitter strongly.
I have elsewhere shown this diagram before:
The upper (red) trace shows a conventional SPDIF receiver when faced with a J-Test signal that had intentionally 50,000pS of 200Hz square-wave jitter added (using the "add jitter" function of the Audio Precision 2).
The lower trace is the same using my design of circuitry, which uses a memory buffer and low jitter clock synthesiser.
To the chagrin of some we named this principle "Zero Jitter", it does of course have some residual jitter generated within the device, but it completely locks out source jitter up to the point where it unlocks and mutes.
Incidentally the same device tested above also has a USB input to (using the same memory buffer and clock) and it measures (and sounds) essentially identical.
I do tend to be suspicious of claims of "lower jitter" that are not accompanied by evidence of the objective kind. It may very well sound different and sometimes the difference is preferable. But turning this into definite claims of quantity XXX has been changed and lowered seems unwarranted.
You may wish to check the actual clock output from the Wenzel clock, it may be a 1V sinewave, which may not allow any reduction in level for that reclocker towork correctly.
It certainly is a much better choice as master clock than anything that says "Rubidium" - rubidium clocks themselves have high short term variability (aka "jitter") they are generally used to control a crystal clock to produce a usable output.
As Audio Band phase-noise is what we are interested in, the rubidium part is of questionable value, it needs to have a quartz clock. You may find this article quite revealing:
http://www.ke5fx.com/rb.htm
Anyway, you may want to be careful with system integration in your case. In liew of an attenuator, just keep the cable extremely short, reflections can only occur if there is appreciable delay. Any cable short enough not to allow for transmission line effects will do fine.
It is important to understand the system and what the problems are t solve them, just randomly plugging stuff together is unlikely to work past the power of self suggestion.
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: Wenzel 10M oscillator with 50 ohm SMA(f) as Master Clock - Thorsten 09:57:40 07/12/15 (0)
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