I put a Delay filter on some audio. Ever since then FCP blasts painfully loud static noise randomly while the timeline is in playback. I know that it is random because it doesn't come from the same place twice. This is FCP 7.0.3 on a Mac Pro OSX 10.6.6

I trashed the prefs and hid the layer that has the audio delay filter. I turned the computer volume as low as possible, and tried speakers as well as headphones. It still makes a terrible noise at random.

Next I'm going to try to get rid of the clip with the filter completely, but I'm taking a break because the noise is so loud it hurts my ears. Any thought on avoiding this? I should record it, because it's pretty terrible.

This sounds like a hardware/rendering issue. Is the original audio track with the delay filter in the standard 48khz AIF/ACA format that FCP likes, or is it a WAV/MP3 or something else that requires pre-rendering? That might hold the key.

But, if the original audio file is in the correct format AND plays normally without the filter being applied it could very well be that there's a hardware issue - main-board specifically - when it tries to render core audio components.

Try playing the original audio track in QT standalone player first. Use the AV Controls window and play with the playback speed. If you get the horrible noise when you force QT to either slow down or ramp up the speed then it's a hardware rendering issue. If not, there's something else amiss.

Let us know.

This also happened to me, but only once, and I never found out why.
Scared the heck out of me.
Same version specs as you on my 2010 Mac Pro.

Mac Pro's have had a somewhat glitchy history with audio codecs and Apple Core Audio components, which Apple addressed in Firmware updates for specific machines. At worst, some machines had their main-boards replaced under warranty because Apple couldn't find a software solution.

I'd like to see what happens after Aric applies the troubleshooting I suggested - so keep us updated, Aric!

This happens to every member of my team on every type of Mac with every version of FCP. It happens at random and without any filters or advanced techniques being applied. It scares me so bad when it happens.

Same here, got me while I was up at like 3am editing. Scared me to death. Happens every so often.

I've copied all the clips in the timeline and pasted it into a new timeline, leaving out the clip with the audio filter. This has given me a clean slate, and I haven't heard the sound since. I'm just going to never use an audio filter again in FCP, I'll leave that up to the sound guy. I was using an aif by the way, because I've noticed when I use an mp3 in FCP I hear a bit of static.

Also, when there is no sound coming from this computer, I can hear like a beep or hissing sound, which completely goes away anytime music or sounds begin playing. I don't know what's up that.

Aric,

That beep or hissing is called "floor noise" and is most likely nearby RF interference caused by FireWire/USB drives that are connected to your system or other devices that naturally cause electronic noise when they operate.

If you are pushing out audio to your speakers from the 1/8"-inch stereo mini plug then you'll be susceptible to all kinds of RF in your audio. However if you use a USB or FW audio interface (there are about 2 dozen to choose from) to go out to a mixer or directly to your speakers this will eliminate that problem.

And for what it's worth FCP does NOT handle audio plug-ins very well; Soundtrack Pro seems to have mixed success from various users however it's been my experience that any audio tweaking/sweetening should be done externally from FCP and in a dedicated audio editor such as Peak, Deck, Audition, Logic etc.