i use an auto-wah, and i can't get the exact effects like jerry ever did. don't get me wrong, i love my A-Wah, but an envelope filter would give ya a better sound. i think an a-wah sounds like the soundwaves are waving out, and an envelope filter sounds like the sound waves are waving back into the amp, like a reverse wah, or a-wah, just my opinion though... peace, michael