Clock in RME AD/DA 1nS Jitter! - diyAudio
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Old 22nd May 2004, 08:20 AM   #1
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Default Clock in RME AD/DA 1nS Jitter!

RME is highly respected and used in music production. Below is an extract from the manual of their latest AD/DA, the ADI-2.

*low jitter design: <1 nS in PLL mode, all inputs

*Internal Clock: 800 pS jitter, random spread spectrum

RME claims in general that the sound of jitter has been eliminated in their hardware.

How does this tally with our discssions here on clock jitter? Do we expect 1nS or even 800 pS jitter embedded in professional recording gear?
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Old 23rd May 2004, 01:47 PM   #2
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The manual of my 2 RME DIGI8/96 PAD says that the output jitter of the cards is less than 2ns ! Nano not pico. However, they sound pretty good. Anyway, replaced the crystal with LC XO3. Some perceived improvement definately.

Regards,
Joe Ling
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Old 28th May 2004, 05:02 PM   #3
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Hey...

I want to use the clock and adat i/o from my RME HDSP9652 to feed some alesis opto/recgens that will inturn be used with some dacs and adcs I've knocked up...

The HDSP has a wordclock i/o module with 2 bnc connectors. Could i just take the LRCK direct from the bnc to feed the opto/recgen/adc/dac's? Is it just a simple case of takin the signal direct from the connector?

Cheers.
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Old 28th May 2004, 05:17 PM   #4
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Default RE: RME

Interesting, Lynx Two has 20ps peak jitter in 400Hz-22kHz range, measured with AP ...
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Old 28th May 2004, 06:42 PM   #5
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Default Re: RE: RME

Quote:
Originally posted by Gordon McGregor
Interesting, Lynx Two has 20ps peak jitter in 400Hz-22kHz range, measured with AP ...
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Lynx is much more expensive. All the RME stuff seem to have nS jitter but are regarded as high qualitym even by Stereophile!
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Old 30th May 2004, 09:13 PM   #6
Giorgio is offline Giorgio  Italy
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I am not completely sure the figures about RME cards are correct at all. If I remember the jitter spectrum from Stereophile was far better; I am a little afraid it is just some snobbish idea of understating their own product...

By the way I am working on jitter measurements with a far less expensive and older Terratec EWX 24/96, and I have recently measured a 120pS jitter with a Weiss Medea DAC.... which should in my view not possible if the receiving ADC jitter were really bad, unless the jitter is at very very low frequency.

But I would really like to have your opinion about this. Jitter measurements seem to be so delicate (apart when an object like a Medea is inthe loop...) that anything apparently can have an effect on them, and I am always afraid of making wrong assumptions.

Kind regards
Giorgio
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Old 31st May 2004, 07:09 AM   #7
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[QUOTE]Originally posted by Giorgio
[B]I am not completely sure the figures about RME cards are correct at all. If I remember the jitter spectrum from Stereophile was far better; I am a little afraid it is just some snobbish idea of understating their own product...

By the way I am working on jitter measurements with a far less expensive and older Terratec EWX 24/96, and I have recently measured a 120pS jitter with a Weiss Medea DAC.... which should in my view not possible if the receiving ADC jitter were really bad, unless the jitter is at very very low frequency.

But I would really like to have your opinion about this. Jitter measurements seem to be so delicate (apart when an object like a Medea is inthe loop...) that anything apparently can have an effect on them, and I am always afraid of making wrong assumptions.

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Yes, the cable and connectors as well as power supply can induce jitter. 120 pS is possible on many units these days, even lower.

Unfortunately, it costs quite a bit to set up reliable jitter measuring kit.

The Terratec is a good card. The WDM driver sometimes fail to load on switch on (WHY) but a major improvement will be to get rid of the 4558 opamps and short out the coupling caps. There was no significant dc on my unit. Unfortunately the opamps are of the very samll footprint type. I rate the card in sonic terms as mid fi.
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Old 31st May 2004, 08:45 PM   #8
Giorgio is offline Giorgio  Italy
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Well, I cannot give any rating from the sonic point of view... in facts I have never listened to music converted through the card with any serious system, I use it for measuring only.

And while possibly there is some more distortion at higher levels than I would like (around -90+dB, in any case, and I am not so sure, it is not so simple to find something that is more precise than a 24bit sound card at human price levels...) and some 0.1-0.2dB raise in frequency response at 20K (which in my view is scarcely significant in terme of measures, but can make the difference in terms of sonic character of the unit), for the rest it is a really nice card. With proper dither you have any trace of distortion at -90dB hidden in the ground floor...

It has RCA audio connectors, it is very easy to add digital electric connectors, and most important, you can find it for far less then RME and Lynx cards on eBay....

Kind regards
Giorgio
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