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Message

VC EG (breadboard) -- new idea

2000-02-12 by JWBarlow@aol.com

Last week I was impressed with all the divergent concepts about how a VC EG 
should work. I have even more respect for Paul's ability to produce a good 
module -- to separate the wheat from the chaff, as they say. 

First, an aside, one thing that occurred to me was that some people wanted a 
VC Lag for a VC AD/AR, but I was intrigued with Hugo's concept of a Peak 
Duration knob (or VC). I thought that, from the users point of view, it might 
be possible to have one control, and a switch to apply the duration knob to 
either a Lag (i.e., preceding the ATTACK stage) or to the Peak portion of the 
envelope. If this module ever gets in to preliminary design, one might want 
to look into this.

Now then, I want a new type of VC EG:
I have a few working VC EGs based on the CEM 3310. I have them set up with 
only one VC input and a reversing attenuator (what else?) which 
simultaneously controls the A, D, R sections of the envelope -- no VC 
sustain. There are several reasons why I chose this arrangement, a 
significant one is panel space. While these are great to use I often find 
myself wanting something that I can't get. So here's my proposal to diy some 
better 3310 based VC EGs:

A MOTM 2U panel 
-- 7 knobs including the basic four A D S R, and three reversing attenuators 
-- VC A, VC D, VC R.
-- 8 jacks including the basic output, trigger, gate and four unattenuated VC 
A, VC D, VC S, VC R inputs as well as one (magical) VC A-D-R input.
-- one manual push button, and one LED to show the EG's output.

I believe I'd rarely use the individual VC inputs (just past experience -- 
too much to deal with). The reason I really like the magical VC A-D-R input 
is that I tend to use my VC EGs with either something like a velocity CV, the 
basic 1V/oct CV output from a keyboard,  or the keyboard pressure CV (from my 
Serge TKB). 

Examples:
With velocity sensitive envelopes, I imagine that I'd like to have the attack 
time decrease as velocity CV increases, but also have the decay time increase 
-- a percussive type use. I can also imagine having both the attack and decay 
times decrease as velocity CV increases -- more of a muted percussion type of 
use.

With the 1V/oct CV, I can imagine having the decay and release times decrease 
as higher notes are played on the keyboard while the attack time remains 
constant -- much like strings behave.

Several ideas come to mind for the TKB.


I thought I'd mention this since all the banter last week made me concentrate 
on what I'd really like to have a VC EG do, and how I could make such a 
device in a reasonable package. I've been waiting to find some project worthy 
of the beautiful MOTM breadboard, and this may be the one. I think Paul may 
have some 3310s available as well(?)

It's probably easier to build a VC EG, than install a radio in truck that 
never had one to begin with -- there's far more steel in a small truck than I 
would've imagined.
JB

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