Persistent audio glitch using new computer

[benmcd]

I finally upgraded to an Intel Mac, and now every track I record has an audio glitch around 6 or 7 seconds into the track, with a fuzzy sound two or three times and a time shift (a lot of latency before the glitch, normal amount of latency after the glitch). I've attached one sample MP3 to this post, but keep in mind that it sounds a bit different each time. (And no cracks about my singing, please!)

I'm using the same mic and audio interface as I did with my previous Mac. Activity Monitor shows no issues with CPU, memory, or disk usage.

I've tried various settings for sample rate, sample format, and playthrough. I've tried Audacity 1.3.13.0, 1.3.14.0, and today's debug release of 2.0.0.0. The problem is always the same, but it never happens at exactly the same time (even with the same settings).

Mic: MXL VO: 1-A
Audio interface: CEntrance MicPort Pro
Computer: Mac mini, 2.3 GHz i5, 8 GB RAM, OS X 10.7.3

Any ideas?

Thanks,
Ben McDaniel

[kozikowski]

That's a cousin to the Shure X2U I reviewed. Did you upgrade to a USB hub because you ran out of connections? Stop that. Audio systems must have one single dedicated connection to the computer.

Koz

[benmcd]

I'm going straight into the back of the Mac.

[benmcd]

One other thing -- I did some recording in Melodyne today with no problems, and I always had problems with it on the old computer.

[steve]

As you can see in the middle of the highlighted area, there is a bit of data missing:

firsttrack000.png (10.84 KiB) Viewed 4079 times

For some reason your Mac is unable to keep up with the amount of audio data. Do you have any idea why that might be?
Is your hard drive busy doing something else?
Are you trying to record direct to a USB memory stick?
Are you trying to use a very high sample rate?
Are you using any other USB devices?
Do you still have the problem since you rebooted?

[benmcd]

For some reason your Mac is unable to keep up with the amount of audio data. Do you have any idea why that might be?
Is your hard drive busy doing something else?
Are you trying to record direct to a USB memory stick?
Are you trying to use a very high sample rate?
Are you using any other USB devices?
Do you still have the problem since you rebooted?

As I said before, Activity Monitor shows no issues with CPU, memory, or drive performance. And, as I also said before, I tried various sample rates. The answers to your questions are no, no, no, no, no, and yes.

[steve]

There's a list of suggestions on this page: http://wiki.audacityteam.org/wiki/Manag ... nd_Drivers
Many of them are more relevant to Windows, but as I'm not a Mac user you will have a better idea of which may apply than I do.
I believe this type of problem is unusual on a Mac and I don't see any obvious reason for the problem, so even if some of the suggestions seem highly unlikely, check them out anyway.

[benmcd]

Well, now I can't reproduce the problem. That's a little frustrating, but not nearly as frustrating as having the problem in the first place! I can't get it to have any glitches now even when I really push it -- have other programs open, record 96 kHz 32-bit float, etc., etc. This is how I expected the new computer to work, and now it is!

Maybe it was writing to Time Machine or search indexing or something before, but it happened over and over again and Activity Monitor didn't show anything. I thought I had restarted (as suggested above), but maybe I didn't and that was all that was needed.

I'm having other issues with Lion, though. It's almost bad enough to make me consider getting a (gasp!) PC.

Thanks for your help, guys. If it happens again, I'll try to figure out what's going on and report back so y'all will know what to do if someone else has this issue.

[steve]

Pleased to hear it's OK now. Let's hope it stays that way.

There's worse things than getting a PC, such as getting a Windows PC