I'm currently in the process of working on a no-budget instrumental album (I'm a guitarist) for mostly my own enjoyment, and seeing as it's a no-budget project, I'm using Garageband. Anyway, the problem is that whenever I'm recording something over three measures at a time and I have the distortion pedal turned on, the recording steadily decreases in volume. The end of the recording is noticeably quieter than the beginning. This happens no matter what volume I'm recording at, but it doesn't happen if I'm recording my acoustic or my electric on clean. Why is this happening and how can I stop it from happening?