Re: Boss CS 3 question
Generally, the "attack" control on a compressor controls how fast the compression circuit takes affect on th incoming signal. So, a slow attack, would allow the signal to maintain its initial dynamics, or "punch", then be throttled back by your settings. You should be able to get some interesting affects by playing with it.
Try hitting a power chord fairly hard as you vary the control. That should show you how it works.
Oh yeah . . . and start with a fair amount of compression. That way, you can easily hear the affect as the compression circuit comes into play.