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In Reply to: RE: Wenzel 10M oscillator with 50 ohm SMA(f) as Master Clock posted by bssk on July 08, 2015 at 17:22:39
Hi,
> Can I use an ultra low noise oscillator such as
> Wenzel 10 MHz - SC Blue Top Ultra Low Noise Oscillator
> (http://www.wenzel.com/wp-content/parts/501-28227.pdf)
> with 50 ohm BNC/SMA(f) outputs as a master clock to Mutec
> MC-3+ (http://www.mutec-net.com/product_mc-3-plus.php)
> which has a 75 ohm BNC WLCK IN.
No. Wordclock in requires 44.1kHz or similar audio clocks.
It seems the Mutec Clock can accept 10MHz via the same input though.
> Does connecting a 50 ohm BNC clock output to a 75 ohm WLCK IN
> cause reflections, this adding jitter?
Yes it will. Though I would not loose sleep, you can always add an attenuator (50 Ohm) which will correctly terminate the cable.
I rather doubt that you will gain any real benefit from doing this, even if this Clock can re-clock the incoming Data-stream and re-output it (which I cannot quite work out from the webpages). The key limitation is the SPDIF/AES-EBU input circuitry in your DAC.
Ciao T
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?
Follow Ups:
Hi Thorsten,
Thank you for your response. I started exploring the 10M ultra low phase noise clocks after reading some forums where members are experiencing significant improvement in transient definition and imaging spatiality while using 10M clocks. Here are some links:
http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/mutec-mc-3-a-17300/
http://www.computeraudiophile.com/f10-music-servers/reclocking-19326/
http://www.thinksrs.com/products/PERF10.htm
http://www.antelopeaudio.com/en/products/10M-atomic-clock (I have heard an audio system with this as the master clock and it was one of the best digital systems I have heard. However this clock is very expensive. I came across Wenzel while looking for lower cost and possibly better alternatives)
Some reviewers and forum members are also experiencing significant improvements with re-clocking:
http://www.mutec-net.com/artikel.php?id=1388254422
http://www.aktives-hoeren.de/viewtopic.php?p=68452
http://www.mutec-net.com/downloads/pdf/MUTEC_press_03-2015-1_ED.pdf
Most of these users are using NAD M51 DAC and I am using the same DAC. The NAD M51 DAC has a very good AES-EBU input (much better than its USB input).
I could not find whether connecting a 50 ohm BNC clock output to a 75 ohm WLCK IN cause reflections, thus adding jitter. Hence I posted on this forum. Based on your answer, it looks like I should be fine if I use a 50ohm attenuator near the WCLK IN of Mutec MC-3+.
Thanks,
Satish
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.
Ciao T
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?
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