Maxon CP101 Compressor Works perfectly with bass guitar, electric guitar, or acoustic/electrics Provides clean compression and minimal noise CP101 COMPRESSOR While it is on you will notice note-to-note levels that are smoother and more consistent, chords and arpeggios that are tighter and more focused, and when used with an overdriven amp, sustain that will last for days Best of all, you'll notice minimal coloration to your guitar signal and less of the note-attack alterations so common to other compressors At the heart of the CP101's circuit sits an HTV #P873 CdS (Cadmium Sulfur) Photocoupler