Filter enveloppe mod filter enveloppe decay ? What's the trick ?

[slashy]

Hi,
I need to understand when in Mod Path, the Filter enveloppe modulate the Filter enveloppe decay.
I like a sound of a kick, and i try to understand how it is built.
This patch, essentially done by resonance (127), audio mod (20), try to simulate a sine wave in auto oscillation.
I understand the concept for all parameters, but not 2:
Why the Filter enveloppe modulate the filter enveloppe decay ? what's happen in term of synthesis ?
Why the Lp Keys is on 24 ?

[muleskinner]

Have a look at page 27 of your manual 

[John the Savage]

The real answer to the modulation question has less to do with music and more to do with mathematics, so I'll spare you the boring algebra.  All you need to know is that the curve of the envelope (which is logarithmic, blah, blah) can be changed by modulating it with itself.  What this means in practice is, if you were to, say, use the amp envelope to modulate its own decay, a positive modulation amount would cause the decay portion of the envelope to bow downward, creating a snappier sound; and a negative modulation amount would cause the decay portion of the envelope to bulge upward, creating a rounder, boomier sound.  But since the sound in question is a resonant filter kick, this same principle is being applied to the filter envelope to shape the pitch-sweep of the resulting sign wave.

The key-tracking, on the other hand, is being applied, presumably, so that the kick can be played (to some extent) in 16 Tunings mode: i.e. the filter cutoff in this case is determining the fundamental pitch of the kick, and key-tracking sets the degree to which the filter will open as higher notes are played, in turn raising the pitch of the kick.

Cheers!

[slashy]

thank you so much.
Because it was a problem for me (to understand).
I come to "rock" music, and i very interested about electronic sound.My tempest become time after time, my favorite instrument to create some "Breakbeats" beats.