Envelope filters

[alanp]

The state variable filter seems to be the go-to filter from what I've seen, maybe because that way you get LP/BP/HP from one circuit. Or more likely because I've never bothered building a Nurse Quacky or anything other than the Nautilus and Meatball.

Has anyone tried adapting a diode ladder or transistor ladder filter to a pedal envelope filter pedal? Only low pass, but I suspect it could be glorious with bass.

[blearyeyes]

alanp,
Even though I am a newbie EE person, I am very interested in Envelope Generators for guitar pedals. I have used a plug-in within Native instruments Guitar Rig that I really like. I like the ability to trigger an envelope generator from the input using a threshold setting. There is a top and bottom threshold which enables you to have the "stuck wah" effect with the attack, decay, sustain, release adjusted to your liking. I love the sound and wish it wasn't digital. So I want to build this...  Are there any ADSR circuits out there?  Wish I had started in EE years ago...

Dan S.   

[Strategy]

Alanp, the Moog Moogerfooger 101, the Lowpass Filter, is the Moog filter implemented as a guitar (or whatever) envelope filter. Awesome pedal, love the envelope (use one on rhodes piano in my band, belongs to a bandmate). One thing I've observed is that lowpass filtering can be quite severe on guitar as far as really cutting out a lot of sound. Guitar is a pretty mid range instrument generally so bandpass works well for a kind of conventionally "wah-ish" sound. The Moog sounds great on guitar but I prefer it for bass keyboards etc. I would imagine this is the case with many of the filter types you mention, just a little less tonal flexibility

[raulduke]

I imagine it also comes down to cost. State variable filters are considerably cheaper to build than ladder filters. They also take require less calibration, parts matching etc.

I always wonder why more envelope pedals don't feature an fx loop after the envelope detector circuit.

That way you can put a distortion/fuzz in the signal chain after the envelope detection circuit, but before the filter.

Can get some crazy synth like sounds using that method.