I used to have long termer's MXR M288 Bass Octave Deluxe and an MXR M82 Bass Envelope Filter on my pedal board. I replaced both of these pedals with a single Source Audio C4, which adds a lot more than what either / both of these could offer me. The Source Audio Spectrum Intelligent Filter covers the same ground, slightly cheaper without the synth and step sequencer options of the C4. In my opinion the C4/Spectrum are the most versatile and accessible filters / octaver pedals on the market. It can do your quack down filter no problems at all...and a lot more. Last week, I created a patch that pretty much nails the Meridian Funkulator V1 sounds and controls...so that's another no longer needed pedal going on ebay....