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korz
12-16-2005, 01:28 PM
I'm building a brand new system. I just got the PC up and running and have gotten the primary interface installed (hw & drivers).

I've got an EMU 1820M as my primary interface and then I want to connect a Behringer ADA8000 (essentially, it's just an 8channel-analogue-to-ADAT and ADAT-to-8channel-analogue unit) and an ART DI/O 2channel tube preamp with digital output unit.

They all have BNC word clock connectors. The EMU has both in and out, the Behringer has a switchable single BNC (actually, it says "WC slave," "ADAT slave," "44.1k master," and "48k master."), and the ART has just a BNC word clock input.

Now, I've read where if you connect two units together via ADAT, you can use the ADAT clock as your sync. That explains the "ADAT slave" position on the Behringer.

My questions:

1. I would suspect that the EMU would have the most accurate clock because the other two units are a fraction of the price, but I'm not going to take that as a given. I'm going to measure the accuracy of the Behringer and the EMU clocks with a scope I brought home from work. But let's say the EMU's turns out to be the most solid clock. I can then use the word clock to connect all three units, run two ADAT optical links between the Behringer and the EMU and run S/PDIF from the ART to the EMU. Voila! 18 channels of synced input and 16 channels of synced output. Am I missing something?

2. Alternatively, I suppose I could use the ADAT clock to sync the EMU and Behringer and the EMU literature says that the word clock transmits all the time, regardless of what you've selected as your sync source, so I would imagine I could sync the ART to the other two using the word clock. Is this likely to be better or worse than solution 1? If I choose the EMU to be the master and use ADAT to sync the Behringer and EMU, is it correct to assume that the EMU's word clock would be synced to the ADAT also and I could use it to sync the ART? In other words, when the EMU is the master, are all the clocks in the EMU (ADAT and word clock) internally synced?

3. The Behringer can only go as high as 48k, even if it is not the master clock. The ART will go as high as 96k and the EMU 192k, but at the higher frequencies, the EMU can do less and less channels simultaneously. I think that 48k is enough for what I'm doing, but if I use solution #2, presuming it works, it would be easier for me to pull the Behringer out of the system and use the ART and EMU together for 10 channels of 96k... actually, I have two ART DI/O's, so I could connect one via S/PDIF and one via ADAT and run 12 channels at 96k. Do you think that being able to to go that route would make solution #2 any more desirable?

Any other thoughts?

Thanks.

Al.

MrM
12-17-2005, 06:32 AM
I think most people here will use 44.1 rather then anythinh higher.
But you are free to use 48 or higher if you prefer.
Is 48 or higher a big must for you?

korz
12-17-2005, 04:02 PM
It's not like we're currently recording for DVD soundtracks or anything like that, but eventually, we may. Sonar 5 has a very high quality sample rate conversion tool, so even though the end product will probably be 44.1, we will probably try higher sample rates just to see if we can tell the difference.

Al.

jmail
12-17-2005, 06:17 PM
Korz, I'm not certain, fer certain, but, I think S/PDIF does it's own "syncing" in the stream, also... If you're talking about doing a whole band "live" and using all 18 inputs on the 1820, no problem with the 1820 as "Master" and the others "slaved" to it. 48kHz is nice, if you've got the hard drive space, but that extra bandwidth becomes a liability to the computer trying to process it... Be sure you do a test recording of sufficient length before you jump... It might be that you can do 6 minutes of 48k with 18 tracks "live" before you start getting drift, maybe 15, maybe 30... find out before you do the "gig" (or you'll get "gigged"). Be sure you defrag the hard drive before you start the project, also, and cold boot the computer just before doing it, also, in order to "clear" the Windows cobwebs... Me, myself and I all prefer the sound of recording at 48kHz, 24 bits for the benefit of future processing. The 24 bit part is more important than the 48kHz part.

korz
12-18-2005, 12:36 AM
So, perhaps syncing is only important if you are using two or more independent PCI (or USB or firewire) interfaces, but is not an issue when you are feeding digital data to one of the interfaces from other interfaces (via ADAT and/or S/PDIF)?

I know that I would have designed it that way, and I think I had heard that you can use ADAT or S/PDIF for sync, but just wanted to make sure.

I don't expect to record 18 tracks at once too often, but my keyboardist/drummer, the other half of the writing team, likes to invite some musicians over for a jam every now and then, so it will be really cool to be able to record the whole mess live on individual tracks. In the past, it was a few vocal mics, kick, snare and then two room mics. Not as easy to mix down as having 18 tracks with a lot of direct-ins.

Thanks.

Al.