Jitter ? Word Clock ? ADDA Converters

  • Thread starter Thread starter PapillonIrl
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PapillonIrl

PapillonIrl

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Okay, I've just been looking at the Lucid converters.

Pretty sexy, but could someone address these dumb questions:


Q1 Could you explain the term Jitter ?

Q2 Word Clock ?

Q3 Say I bought one of these (which won't happen yet 'cos I don't understand what they do fully) would my Delta 44 have to be disconnected or would it have a place in my signal path along with the lucid converter ?


I know these have been addressed before by Sjoko and others, I have searched and the threads concerned seem to explain the benefits better than they explain the terms, and I think this thread would be of use to someone searching for info on the above terms.

Thanks,

pAp.
 
When digital audio is clocked such that the sample slope doesn't occur at the same time as the when the original signal was recorded, you get distortion of the timing of the digital signal called jitter.

Word clock is the timing reference used by the converter.

Digital recording and playback depends on a very precise timing being made available to all digital devices. It is better to control a digital devices by a single clock source so all digital signals being apssed around receive the EXACT same timing reference.

Jitter, sample time-based distortion, of the signal can significantly degrade the sound quality of a digital signal, since - at its worst - it can completely throw off what the converter considers a leading or trailing edge of the signal - meaning whether the sample is interpreted as a 1 or 0 at that time, is corrupt!

Bruce
 
Thanks a million. That makes a whole heap of sense.

I take it that that it my delta would be rendered useless if I purchased such a gizmo ?

Would your PC see it as a soundcard device ?

Thanks again,

pAp.
 
The device you want to use with it would require a word clock input -- usually a BNC connector.

It has nothing directly to do with sound so I doubt the comp would see it as a sound source, if it even needs to see it at all.

I should think it's the soundcard itself that would have the connection and connecting a clock there would simply disable the soundcard's internal clock.

Bruce
 
Jitter. All analog to digital converters have a clock in them that governs the frequency at which they sample (44.1kHz, 48kHz etc). This is generaly crystal controlled. The quality of this clock is expressed as jitter (how precise and stable the frequency of the clock is). The better the clock, the lower the jitter. This also translates to better analog to digital conversion.
Word clock (or super clock, in the case of digidesign), in the context of your question, is an external clock source that can do a couple of things, be a higher quality, very stable low jitter clock that replaces the internal, lower quality clock and also can be a master clock source, syncronizing multiple digital devices to each other (providing of course they have a word clock input, that is).
Does your sound card have a word clock input and a digital input?
 
M-Audio Schpiel....

Delta 44 Specifications:
• 4x4 24-bit/96kHz full-duplex recording interface.
• PCI Host card with external audio break-out box.
• 4x4 analog break-out box accepts balanced or unbalanced connections on
• 1/4" TRS jacks.
• Analog I/O configurable for +4dB and -10dB signal levels.
• Measured D/A specs: 103dB (A-weighted) dynamic range, 0.0015% THD @ 0dBFS.
• Measured A/D specs: 99dB (A-weighted) dynamic range, 0.0023% THD @ 0dBFS.
• All data paths support up to 24-bit/96kHz performance
• Powerful digital mixing, routing and monitoring capabilities.
• Drivers for Mac, Windows, NT, Linux, and more

There is no other inputs apart from the four balanced TRS inputs, but I get the idea...to upgrade to a better clock, I also need to upgrade to a card with a input to accept instructions from it, and a digital input.

Much appreciated Bruce and Track Rat,


pAp
 
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