What use are the Audio Unit Effects?

The AU effects are often quite powerful and flexible effects, and require some knowledge to apply effectively. Try using the presets from the drop down menu at the top of the write dialogue.

These effects are appropriate regardless of the instrument you are applying them to, but you should always have a good reason before applying an effect, i.e. a problem with the sound that needs fixing, or a particular sound that you wish to obtain.

For advice on the proper use of studio effects you can browse the forums at Sound on Sound.

If you are talking about the guitar distortions, etc. then the obvious thing is to not use distortion on your amp and then distort it some more using the effects. The sound will be bad. The au's require a clean sound coming in.

For the final mix learn about compression and EQ and reverb. They are vital to getting the final mix done well.

Kurt

I use the basic Overdrive effect sometimes if I need some extra grit to a guitar. And on one I also used the distortion. But I don't think those are AUs, at least they are not in the AU list, but rather the GB effects list. I get great results adding a bit more overdrive to what I got from my amp and a mic. I have NOT had good results if I try to use one of the amp sims after recording my amp, though.

I have used the limiter a few times if I had a guitar note that seemed to keep getting me an over. I have also used the AU reverb and delays, but most of the other stuff, I don't use on guitar at all.

My confusion was over the Audiounit effects which can be found beneath the Garageband effects in the drop-down menu eg AUBandpass, AUHipass, AUPeakLimiter.

These effects are emulations of studio outboard processors, rather than the sound effect type fx you mention (phaser, etc.): as such they are mainly problem solvers. In other words, if something is awry with the recorded sound, these may be able to put it right (in the right hands).