two soundcards at once

[macca166]

Hey guys...

I've been working on transferring some tracks over from a roland mixer. I'm using SMTPE/MTC ( in which I'm having a problem but thats for another day). I'm looking to send four inputs at a time into my computer because I have a good number of tracks to copy over. I have two sound cards plugged in, so I am using the left and right of each.

I've been running some tests. What I did was I played a CD into all four of my inputs and recorded into cool edit pro. The two sound cards are obviously out of sync, because I am getting a very slow flange between the two tracks.

I'm not too familiar with recording with more than one soundcard. What should I do? I believe this has something to do with latency ... if so, is there a way I can figure out what latency value I need to add to the problem sound card? Thanks in advance.

 

[AlChuck]

It's not latency. The two sound cards each have their own physical clock reference and it's virtually impossible they will be precisely the same.

There are a few conditions under which you can get more than one sound card to work together in the same PC.

One way is if they are both the same type of card that has been engineered to work in synch with others of the same card in the same PC (for example, the M-Audio Delta cards). Since they are the same card, a single card's clock can control them all if they designed that way.

Another way is if the cards (same or different) support an external timing reference via a digital port (S/PDIF) or something called word clock.

So basically there's nothing you can do to make this work reliably unless the cards you have are capable of being locked together via the methods I mentioned.

 

[macca166]

Okay thanks for the explanation...that made much more sense. So I guess with my current setup I'm limited to transferring over only 2 tracks (one left and one right) at a time.

While we are at it, maybe you can help me with my other problem. I setup SMTPE/MTC to control the time. I was running Cool Edit Pro on my computer which was the master SMTPE and I was getting tracks from a roland VS-1680 workstation. Basically I'm looking to transfer over a few songs of about 14 tracks each.

I successfully got Cool edit to control the roland. When I would hit record on cool edit, the roland would play the appropriate tracks in sync and everything lined up perfectly.

Although, there was a major problem. During the recording of a track into the computer, every once in a while there would be a major pitch bend all of a sudden... the pitch would suddenly drop and then increase back up, almost like the sound of a tape slowing down and speeding up to catch up. In a 4:30 song it happened about 3 or 4 times per track. Unfortunately it was way too noticeable to overlook.

Is this a general problem with using SMTPE/MTC? I'm assuming that I'm having some kind of problem...like the values setup in Cool Edit or the workstation (I left pretty much everything to default) are inappropriate. I'm hoping that SMTPE/MTC isn't like that all the time, because I need to go back later this week and try again.

And I don't think my computer is the problem. It is 600Mhz with 256MB of RAM running windows XP. Cool edit pro was the only thing running (including in the background....except for basic windows services) and there was no load whatsoever on the computer. It wasn't having any problems recording the tracks... but for some reason the quick pitch bends were happening.

Does anyone know what I can do?

 

[AlChuck]

Sorry, I've never heard of that happening before. It's certainly not a general problem with using SMTPE/MTC...