easy envelope swell

[Hal]

how hard would it be to convert an envelope filter to envelope swell?  I suppose the easiest way to do this would be to replace the notch filter with a low pass filter, that would begin out of a guitar's range, then sweep into it.  Are there any other easy ways to do something like this?

[smoguzbenjamin]

Use the nurse Q envelope detector and use that FET to ground to change the gain of an opamp. Should work just fine