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Subject: Re: [motm] Using an Envelope Follower

From: jwbarlow@...
Date: 2000-07-22

In a message dated 7/20/2000 6:22:39 PM, ceres@... writes:

>I guess this is the part where I speak up and add that I'm one of the few
>people in the world who ∗really, really∗ likes the external signal
>processor on the MS-20 (and finds its' pitch->CV converter perfectly
>adequate for tracking a bass guitar).

Hi Doug,

I think this module may have a rather impassioned fanclub -- I seem to
remember hearing good things about the external input before. I don't know
the instrument at all.

Which has both a gate output and
>LED's to indicate A) input signal clipping/peaking, and B) gate status.
>For a MOTM Envelope Follower, I would really like to see those functions
>with a Trigger output in addition to the Gate, where a trigger signal would
>be generated every time a gate starts AND every time the input signal
>amplitude has a positive-going crossing of the trigger threshold level,
>which is set by a front panel knob whose 'zero' level is determined by
>the
>gate threshold level knob. Even better would be an additional hysteresis
>knob that would set a threshold level above the gate threshold, but below
>the trigger threshold, so that re-triggers would only occur if the input
>signal amplitude had passed below the hysteresis threshold before
>re-crossing the trigger threshold.
>
>Hmm ... so with all that, we'd need knobs at least for:
>1) Input amplitude (preamp)
>2) Gate On (rise) threshold level
>3) Gate Off (fall) threshold level (must be < Gate On level unless there's
>also a setting for Gate hysteresis)
>4) Re-Trigger threshold level (must be > Gate Off level)
>5) Re-Trigger hysteresis level (must be > Gate On level, < Re-Trigger
>threshold level)
>
>Plus one or two LED's ...

WOW! That's a lot of knobs! And I (of course) would like to see two
additional knobs:
A) EF Voltage Rise Rate
B) EF Voltage Fall Rate

BTW, I realized that I really only use my EFs in one of two ways: 1) to a lag
processor then to a VCF CV (or similar), 2) to a comparator (to generate a
gate signal) to an EG. That's why I'd like to see these built in. Does anyone
use an EF without a LP or an EG?

My initial thoughts about your ideas are:
1) Input Amplitude -- Unfortunately, I'm pretty sure the preamp is a separate
module, but you're right about needing some general EF attenuator.
2) Gate On Level -- I like this!
3) Gate Off Level -- good idea.
4) & 5) Trigger level/ Hysteresis -- OK, I'm not a big fan of triggers in
general -- though I know real keyboard players are. I like the way a gate
keyboard allows a single patch to have two different "personalities" by
merely playing a line legato or staccato (is there a more keyboardy term to
explain this?). I also don't like the way my ARP keyboard can be made (albeit
by my inept keyboard technique) to trigger and not gate (or vice versa -- I
forget which). In any event, I do like the idea of having these trigger
levels independent to allow the kind of playing I described above. This might
be a bit too deluxe for MOTM (???!!!!!), but if it wasn't on the LP module
I'd like to see it available somehow on some general housekeeping processor
module.

Thanks Doug and Ken!
JB