Hi ja-ki
What you were after is as follows, yes?..
An envelope that has an adjustable hold level in the first portion of the drum hit followed by a envelope decay that's also ajustable.
Judging by your initial question I assume you want this envelope to tailor drum hits, so that you may create your own unique sounds.
A simple decay envelope might remove too much transient energy from the early part of a hit and still not be able to fade enough towards the tail end.
You might want to combine a few drum hits into a preset all mapped to the same key
Individually adjust volume
Individually adjust tuning
Individually adjust amp envelope settings
Individually adjust filter values & filter types
Individually alter delay offsets and sample start offsets
By combining sounds with different frequency characteristics you could create hybid drum hits that could be re-sampled to produce unique drum sounds.
You might use sounds from an existing library with top mid and bass frequencies such as...
clicky electro kick
mid sounding vinyl break kick
and perhaps a third sub bass TR808 long boom
Here's the envelope setting to create hold befor a decay.To shorten the hold time just reduce the value of Attack 2 rate
To shorten decay/release reduce their rate values.
If you have a keyboard or controller surface you can use the following cords to shape the sound in real time using controllers A & BYou can hear a demo of this setup here
https://soundcloud.com/jahfunk/drum-env-demoIf you want this you can download the preset below.