I work in live audio, don’t record often, but lately I’ve had a couple artists ask me to record and have discovered a frustrating problem…
MacMini 5,2 (2011)
OS X 10.6 (Snow Leopard)
Audacity 2.0.6 (I know, just realized it was out of date tonight.)
Audio interface is a MOTU 828mkII
Audio source is a Yamaha M7, line level analog
I’ve been doing live mono mix-downs and recording them in Audacity as mono single tracks. 44.1KHz on both MOTU and Audacity.
I don’t run any other programs in the background, this is strictly a production machine.
There is no clipping anywhere in the signal path.
The mac is set to never sleep / hibernate / powersave.
Sometimes this set up works just fine. I’ve recorded tracks more than 45 minutes long without incident. Sometimes… not so much. Suddenly, and seemingly without warning, the audio starts to “crackle”, and continues to do so until the end of the track. (File and screen shot of a couple seconds around the start of the crackle attached.) Crackle persists when exported as WAV and played elsewhere.
One time it started about 5 minutes into a recording, tonight it started about 27 minutes in. I don’t recall the circumstances of previous incidents, but I do know that tonight I recorded the soundcheck (45min, crystal clear), saved and closed the project, then started a new project and started the new recording.
I brought the project files home with me and loaded them up on my personal machine (Macmini 7,1; 10.10.3, 2.1.0) and had the same problem in the same place at playback. After scouring the forums for a while, I started experimenting with the “Audio to Buffer” setting, trying it from 0 all the way up to 150 in increments of 10 with no positive effect on the playback. (0 made it way worse, everything else sounded pretty much the same.)
Being so intermittent has made it hard for me to troubleshoot, especially since I can’t stop, playback and listen during a live event. Any fix suggestions welcome.
I realize this is probably a shot in the dark, but is there a chance I could salvage the recording? It was a fantastic concert and I would love to be able to give the artists something useful.