I would recommend the Source Audio Bass Envelope Filter Pro.
Sneak Preview of the Soundblox Pro Bass Envelope Filter It just came out, and has rocked my world since I got it. It has 6 programmable presets and an ungodly number of sounds. It has an adjustable 8 band EQ, 23 settings from single peak to triple peak, from peak and notch to 2 pole and 4 pole low pass filters. It has emulations of some great filters. It has tap/tempo in LFO mode, has I believe 8 LFO shapes, and a backpage menu that allows one to control the LFO, the various ways to control modulation and LFO through an expression pedal, and perhaps most importantly, has Lo Retain, allowing you to still keep the lowest lows. For $219, it's the best deal on an envelope filter, IMO. Plus, all my relations with the company have been super positive, and I will never sell this pedal. You can probably tell from my enthusiasm how much I dig this pedal.
