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A number of high-end manufacturers (dCS and Burmeister, perhaps others) offer transports and DACs that can be synced to one clock (in the DAC for both Burm. and dCS). I have also noted that a fair amount of professional digital gear has the provision for clock 'slaving' to an external unit, so that one master clock serves as clock for a bunch of components.How often are these master clocks typically employed in professional environments? And are the jitter-reduction and/or other sonic benefits of such a setup significant in the opinions of many engineers?
Thanks -
Mike
Follow Ups:
Know why people have been complaining about the sound of Pro Tools for so long? Simple: When using the USD's (Digidesign's Universal Slave Driver) internal clock as the master, you introduce jitter into the recording chain. Jitter is a form of distortion, and that's why stock Pro Tools "sounds bad," according to many. You get what you pay for, and the USD is a relatively inexpensive device with a crappy source clock.
However, you have a wonderful option in this setup: Get an outboard source clock, such as Rosendahl or Aardvark Aardsync, and hook it into the USD's word clock input. (Besides, you can't nix the USD since it's how Pro Tools interfaces clocking & timecode functions to the outside world.) Does anyone know if the clock is any better in the Pro Tools HD SYNC box?
Another option with Pro Tools or any other other DAW is to use converters that offer a better clock than the USD. Hell, you'll be hard-pressed to find anything worse! The most common alternative to the Digi 888|24 is the Apogee AD-8000 (stock or SE). The Apogee has a good clock, certainly world's better than the USD, and good quality converters. In the land of pro audio, there will always be better and worse options, depending on what your budget is. While that's a general rule, I've found it to be true every time.
My experience is that masterclocks are often employed in audio studios and always employed in any sort of sofisticated video system. In audio more and more people are syncing using a masterclock like the Genex or Aardsync. These provide a very stable low jitter clock. A lot of gear however uses the clock thats imbedded in the digital stream. this isnt as accurate but still very functional. At my home studio I use my RME converter as a master clock for protools using the lightpipe digital stream as the sync. I found a small benefit when using a Genex in this system. I think the RME clock is pretty good. however when I used my Genex in a studio with Digidesign 888 interfaces the 888's performed much better with the external clock.
Frost
How often are these master clocks typically employed in professional environments? And are the jitter-reduction and/or other sonic benefits of such a setup significant in the opinions of many engineers?Normally an ADC uses its own internal clock. If you force it to use an external clock, you're increasing jitter, not decreasing it.
How does that increase jitter? Or put another way, why would any of the ADC's come with clock-sync capability? I guess you're saying that it's best to make the ADC's internal clock the master, and make everything else slave to *that* clock...?Mike
How does that increase jitter?Well, you're sending the clock over a cable. It may not hurt a lot, but it certainly doesn't help.
Or put another way, why would any of the ADC's come with clock-sync capability?
One possible reason is if you need to use more than one ADC box at the same time and want to keep all channels in perfect sync. There are probably other uses.
I guess you're saying that it's best to make the ADC's internal clock the master, and make everything else slave to *that* clock...?
Definitely.
I respectfully disagree with some of what youve said. Clock sync was originally added for the purpose of keeping a whole system on one clock (necessary for video, and some audio such as multiple ADC uses) however since clocks have become much better in recent years, outboard clocks can improve the AD and DACs of lots of gear. You are right that performance is degraded over that same clock built into a piece of gear since it is going over wire but since that clock isnt imbedded in a digital stream it isnt so bad and since lots of clocks are terrible, outboard clocks can make a positive improvement. Heck, George Massenberg uses a genex with his dB technologies AD and DAC's which are fabled to have amazing clocks.My findings on this are backed up by noting that my RME converters (which have pretty good clocks) dont benefit much (but some) from the ultra low jitter genex clock but my digidesign 888 boxes do benefit a lot.
Frost
Adding a little more into all your arguments. Wether or not you are using multiple DA's or AD's isn't the point. All the different digital equipement in your chains must clock to a common clock!! In a DA situation, it is likely to be clocking to the input source working as a slave. Digidesign 888's are not in my opinion good AD or DA devices anyhow. Run Pro-tools, a DA 88, and a 02R desk and see the problems you get if you try to have more than one Master clock in the system.regards
Roland
In a professional enviroment it is absolutely imperative that there is only one master clock source, or you are asking for trouble. With the advent of digital desks, linked to computer digital outputs and then DAT machines and possible peripherals (reverbs, ect) the decision is usually based on the possible clock source. A lot of rubbish is talked about low jitter clocks, any manufacturer worth his salt uses low jitter devices. In the aforementioned scenario, it is likely that the Desk would have to be the master clock source, as some of the peripherals are unlikely to be connected direct. I've just bought a 24bit 96khz AD encoder from a firm called RME, not a cheap unit, but in professional terms at the lower end of the cost scale, and both the subjective performance, alongside the technical performance can match the best in the business. I'm not a lover of Prism converters, as the only recordings I've heard made on them sounded a little "brittle" but they have many advocates.Regards
Roland Clarke
I noticed that a lot of mastering pros seem to like Weiss digital gear, such as their EQ1 and their DS1 limiter/compressor, but these units do not have the capability to be clock-synced. Would digital EQ and compressors fall under the same umbrella as far as your post above is concerned...? Or are there scenarios where, in mastering studios, units like these could be installed in ways that syncing to one clock is not really necessary? (From your post, I'm guessing your answer would be that they would be better off to be synced to one clock under all scenarios, but I'm trying to make sure.)Thanks -
Mike
All gear "sync's" to digital clock. If its in the digital domain it has to. There is always something that is being seen as the master. Weiss gear is well considered, but there are plenty of other great pieces of mastering kit out there. Your question is really asked the wrong way round. If you don't have clock syncing you have major problems, that are definitely audible. In my studio, I have a Sadie mastering system, that I leave set to automatic. That way if it recieves master clocking it slaves, if not it acts as master. If you get clock problems it doesn't take much to hear it, usually starts with odd clicks then moves on to distortion. In the case of a CD player with a external DA convertor, I would expect your DA convertor to be the clock source, although it will probably be buffering the data anyway.Regards
Roland
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