Understanding (or not) clocks/converters

  • Thread starter Thread starter ryanformato
  • Start date Start date
R

ryanformato

New member
Can someone clear some information up for me?

Right now I have an EMU-1820m, a great river pre, a SP T3 mic, a behringer ada8000, a pod xtpro, a toft ATC-2 (As well as some other gear) and am making some awesome recordings.

I always hear a "Big Ben" or lucid clocks being talked about as well as higher end converters. Can anyone explain what a clock is and how it would help me or is it even necessary? The EMU-1820m already seems to have a wordclock setup but I don't have anything plugged into it.

Thanks,
Ryan
 
ryanformato said:
Can someone clear some information up for me?

Right now I have an EMU-1820m, a great river pre, a SP T3 mic, a behringer ada8000, a pod xtpro, a toft ATC-2 (As well as some other gear) and am making some awesome recordings.

I always hear a "Big Ben" or lucid clocks being talked about as well as higher end converters. Can anyone explain what a clock is and how it would help me or is it even necessary? The EMU-1820m already seems to have a wordclock setup but I don't have anything plugged into it.

Thanks,
Ryan
Click to expand...

A/D conversion happens at a sampling rate. I.E. the voltage of a signal is recorded x amount of times per second, say 44,100 times a second. All A/D converters need a clock source to determine when to sample, most have some sort of built in clock, like your EMU interface. The thing a dedicated clock can improve is the jitter of the EMU clock. Jitter is basically the error of the clock, a clock spec'd for 44.1kHz (44,100 times a second) may be for example 44.099kHz at some points or 44101kHz at other points. When you play the digital file back and the D/A convertor also runs off a clock. The jitter of the A/D clock and D/A clock results in a reconstructed signal that isn't exactly the same as the one originally sampled. It may be stretched out in some parts or compressed in others. A clock like the Big Ben has extremely low jitter, so this distortion is minimized. In the grand scheme of things the improvement this has on the sound is probably less noticable than the difference between a good mic/pre and bad mic/pre, but for some people the A/D and/or clock become the weaklest link.
 
reshp1 said:
A/D conversion happens at a sampling rate. I.E. the voltage of a signal is recorded x amount of times per second, say 44,100 times a second. All A/D converters need a clock source to determine when to sample, most have some sort of built in clock, like your EMU interface. The thing a dedicated clock can improve is the jitter of the EMU clock. Jitter is basically the error of the clock, a clock spec'd for 44.1kHz (44,100 times a second) may be for example 44.099kHz at some points or 44101kHz at other points. When you play the digital file back and the D/A convertor also runs off a clock. The jitter of the A/D clock and D/A clock results in a reconstructed signal that isn't exactly the same as the one originally sampled. It may be stretched out in some parts or compressed in others. A clock like the Big Ben has extremely low jitter, so this distortion is minimized. In the grand scheme of things the improvement this has on the sound is probably less noticable than the difference between a good mic/pre and bad mic/pre, but for some people the A/D and/or clock become the weaklest link.
Click to expand...
That's a great explanation, it's something I wasn't certain about tbh.
 
The other thing a dedicated clock is used for is to have a master clock that everything runs by. With all of you equipment cycling to the same clock, you will not get clicks and pops.
 
I think the jitter is responsible for reduction in stereo width.
 
The best way to describe the difference jitter makes is like that claritin commercial. Where everything starts out kind of washed out looking then they say 'claritin clear' and all of a sudden everything is more vivid. It's that kind of difference. It really isn't something you notice until you A/B between the two.
 
Well too many experts answered the question already so there is no need for my "craptacular" answer.

But I do have a question for Farview.. you can use one of your "other" pieces of gear as the master clock like his soundcard for example and set everything else to be a slave correct?
 
bigwillz24 said:
Well too many experts answered the question already so there is no need for my "craptacular" answer.

But I do have a question for Farview.. you can use one of your "other" pieces of gear as the master clock like his soundcard for example and set everything else to be a slave correct?
Click to expand...
Yes. That works just fine. Both spdif and AES carry clock signal, so you can set the recieving piece to slave to the input. Once you get a more complicated setup with tons of digital outboard, or when you are chaining things together, one after another, after another, it becomes necessary to use an outboard clock so everything cycles at the same time.
 
Yeah having one device don't spend the bucks. Most of the converter designers will tell you that any device of any decent quality is best left alone with its internal clock when not connecting to other digital devices (I think Dan Lavry talks about this on his forum).

War
 
reshp1 gave a fantastic answer--very thorough and concise!

the only thing i have to add is that while every digital soundcard will have a basic clock inside them, a dedicated clock will generally be a *better* clock than the onboard one.

many people have noted a marked improvement by clocking, say, an m-audio delta 1010 (which has a pretty decent internal clock) or a motu 2408 with, say, a clock like a Lucid GenX. usually this improvement is observed in stereo imaging and depth, as Falken and Farview have noted.....and a clock like that will run you only about the same price as a mid-level "prosumer" preamp, and many people state it as about the best "low priced" improvement that you can make to your setup.

you want more on clocking, jitter, etc? check out Mastering Digital Audio by Bob Katz (i think that's the name--it's sitting on my shelf at home right now--could be "Mastering Audio"). what a KICKASS book, and Bob Katz leaves no stone unturned.


cheers,
wade
 
You must log in or register to reply here.
Back
Top