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Why have separate, special clocks

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Why have separate, special clocks

Postby RCapes » Tue May 03, 2011 4:58 pm

Dear Forum,

When all soundcards have clocks in them, what is the purpose of these very expensive, separate clocks?

Thanks for any answers
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Re: Why have separate, special clocks

Postby desmond » Tue May 03, 2011 5:05 pm

If you have three watches that are all good but all tell different times, which you you use to get the accurate time from?

The purpose of having one good clock is to a) have a *good* clock, and b) so you can clock *everything* else from it, locking it all to the one good clock.
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Re: Why have separate, special clocks

Postby Hugh Robjohns » Tue May 03, 2011 5:28 pm

RCapes wrote:When all soundcards have clocks in them, what is the purpose of these very expensive, separate clocks?

The clocks in sound cards can't always be synchronised to some types of external reference, such as video sync, which is often necessary in audio-visual applications for example.

Also, it is sometimes more practical to use a master clock to drive everything from a central point, rather than chain the clock from a soundcard around a complex system.

For most small digital systems the clock in the soundcard is entirely adequate and can be distributed to the few units that need it without much problem.

And from a techniacl point of view, it is always better to run the main A-D from its internal clock. With only one or two exceptions, running an A-D from an external clock degrades its technical performance, sometimes quite significantly.

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Re: Why have separate, special clocks

Postby . . . Delete This User . . . » Tue May 03, 2011 5:29 pm

separate clocks are only really useful in complex digital systems where multiple devices need to be synchronised together... for example, if you have a protools rig, and logic rig, and a hardware recorder, and some digital FX, and a couple of digital 2 track recorders (like we do) then you need to get everything sync'ed together from one master clock, and doing so in parallel form a clock with multiple dedicated outputs is far more reliably stable than daisy chaining them all .

especially if some of the clocks use different formats, like Protools does, a master clock capable of generating all the different formats is essential.
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Re: Why have separate, special clocks

Postby RCapes » Wed May 04, 2011 4:18 pm

Many thanks to those who answered. I now understand!

cheers
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Re: Why have separate, special clocks

Postby Mixedup » Thu May 05, 2011 8:33 pm

Hugh seems too modest to mention his authoritative article on this issue... so I'll post the link here for him
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