env shapes

Christopher_List at Sonymusic.Com Christopher_List at Sonymusic.Com
Thu Oct 24 20:27:43 CEST 1996

  On Thu, 24 Oct 1996, Haible_Juergen#Tel2743 wrote:

  > >  I personally find this to be a feature, and, therefore, prefer envelope
  > >  generators with linear slopes  - as it allows for;
  > Are you sure? I mean almost every analogue synth I know has RC-shaped
  > slopes. I use a Slew limiter (=AR envelope with linear slopes) in my
  > Modular from time to time, but for general use I highly prefer the
  > *traditional* shape.

  Yes, I was thinking of just AD and AR type envelopes. If you run the
  output of an ADSR into the time CV for both decay and release, the shape
  of those sections will change based on the sustain level - hmmm, hadn't
  thought of that :).

  Still, with AD / AR types, with linear *control inputs*, and with fixed
  range of 0-5v, couldn't you get very close to the RC shape just by
  adjusting the amount of feedback to the CV inputs? I've played with this
  a little with expo control inputs, but not linear. Which brings me to
  another topic, but I'll put that in another post...

  > With very strong feedback you can achieve almost linear slopes
  > (by overdriving the OTA and using its input stage as a comparator),
  > or perfect RC-type slopes (if you make sure that your feedback path
  > doesn't overdrive the OTA). And of course everything in between.

  How would this apply your linear 13600 AR circuit? Could you run the
  output straight to the (-) inputs on the OTAs and get RC curves (instead
  of connecting the - inputs to ground)? The current out of the OTA is
  based on the difference of the inputs, so this would make sense - bigger
  difference = more current = faster change...

  Am I off target here?

  - CList

More information about the Synth-diy mailing list