MOTM

> Hold before seems to be no more than a gate delay.

Just the opposite. Gate isn't delayed, it's "held". It's like a monoflop,
only that the
hold time starts when the gate is removed (not applied), so the resulting
internal gate signal is the sum of the time you hold the key and the
(voltage controlled)
Hold parameter.
Hold before the ADSR, as the MS-20 has it, and as it's part of my VC-HADSR
design,
allows you to trigger a long envelope, even with long attack, by just
sending a very short
gate signal. I use this a lot when I make complex soundscapes "live in the
studio": Trigger
the JH-720 (where this env in implemented) for a long self-evolving sound,
and then
quickly go on playing other synths. Combinations of different H, A and D
times create
different contour shapes (very much unlike the also self-completing AD shape
of
some other classic EGs).

JH.