[sdiy] Re: Moog ADSR

[jhaible at t-online.de]

Hi Gene, and list,

> If I were you Juergen, I'd add a switch!! 

Well, the effect I have is quite different from what you describe about
the Minimmog. (But you make me curious to do some close analysis on 
what's 
going on in the Mini envelopes, for sure !)
What I have is a temporary rise of the -6V "floor" when both envelopes
are triggered at the same time, and with short attack time. One of the
side effects is that it can become stuck without decay phase, but the
effect is too dramatic to be good: The Modular has 12V supply, so there 
is 
a lot of "headroom" for overshooting. So I get something like 5 octaves
more than intended - not good. (I guess the situation in the Mini is
different, with its 10V supply.)

The *nice* side effect is a different one:
When the two envelopes are carefully set such that the overshoot does 
just 
not happen, but attack and decay times are still rather short, I get
a loose coupling of both envelopes. (They share one faulty -6V rail.)
With a steady sequencer clock applied to both envelope triggers, 
rhythmic patterns of shifting ENV amount and decay times are produced. 
To preserve this function by adding a switch it is way to unstable.
In that mode, envelope peak is 4V rather than 6V, and when suddenly
something gets stuck, it runs to nearly 12V. Too dangerous ! (;>)

But even when I'm going to fix this flaw (of my version, mind you. The
original Moog is perfectly ok !), I will think of other, more 
controlled 
ways of "envelope interaction". It's a bit like soft sync in a way.
Much food for further experiments.


> I've actually 
> patched an ARP 2600 
> to do the same thing - I used the sample and hold gated 
> by the keyboard gate 
> to sample the tail end of the decay from the ADSR and add 
> it to the filter 
> Fc. Worked great!

Great idea !

JH.