http://catalinbread.com/
Versatile fuzz factory for guitar or bass
The core of the Catalinbread Giygas is a Muff-style circuit with some tweaked component values to give it a distinctive voicing. Inside, you'll find a trim pot and a slider switch. The trim pot boosts or cuts 40Hz (cutting can help bassists clean up low-end mud and tighten your tone), while the slider shifts the center frequency for the mid boost and tilt EQ from 900Hz to 250Hz — this optimizes the tone controls for bass. Careful with the 40Hz control — if you boost it, then use the tilt EQ to boost bass, you're adding a ton of low-end content to your signal.