Tascam US-1641 Playback distortion

[a-train]

I've got a recently purchased US-1641 running attached to a MacBook running Logic Pro 7 (and Garageband). The unit seems to work great for recording, but I can't play back more than 3-4 tracks at once without horrible 'crackling' and distortion. The individual tracks are not distorted, playing them one at a time sounds fine. Switching to the built in output for playback works just fine.
I've called Tascam's (notoriously unresponsive) Tech Support, they told me my unit was defective. So I sent it back (bought it online). Got the new one and it has same problem.

I've tried all available sample rates, I've tried two different macs, one running Tiger, one running Leopard, I can't understand it.

Does anyone else have one of these? Any ideas?

[rivilee]

Well, I've been using the interface for several months and the only problem I've had is it sometimes drops out right when I hit record. Kinda irritating.

My setup's with a pc so if it's a particular hardware/computer problem I'm no help. The only thought I can come up with is maybe it's an additive issue in your software. If I use several tracks in my Gigastudio software I have to make sure that the master output is low enough to give headroom for each additional track.

Right now I'm mixing a project with close to 50 tracks on it and the 1641 does great. With our band we've had several sessions of recording 13 tracks simultaneously and I've been impressed with the quality for the money.

Forgive my ignorance but I'm not sure what you mean by "Switching to the built in output for playback works just fine."

[a-train]

Thanks the reply! I'll check and see, maybe I'm somehow overloading the master output.

You're right, my original post wasn't clear--when I said "built in output" I'm referring to my Mac's built in speakers/headphone jack. When I'm using Logic (or Garageband) and I try and play back the same set of tracks through Mac's built in speakers or headphone jack, there's no distortion at all. I'm just saying that it has something to do with the 1641's ability to play back versus a problem with a particular project.

As always, audio things are sometimes tough to describe with words. Let me know if you have any more ideas, I'll try some more testing in the morning. I'm just glad to hear it works well for someone else.

[a-train]

rivilee, kudos to you. I had never touched the master output in Logic, only adjusted each track volume and then used the knobs on the 1641 for volume adjustment. Turning down the master output just played back 12 tracks flawlessly for me. I just did a quick test during lunch, more to follow tonight, but i'm already excited. Many Thanks!

[rivilee]

Cool! It's nice when something turns out to be an easy fix!