More about 3310 and envelopes

[Tony Allgood]

Hi all,

A while ago JH reported that one version of the Oberheim OB-8 used the
attack and asymptote to control the amplitude of the ADSR being sent to
the VCA/VCF for modulation depth. At the Synth do around Paul's at the
weekend, we tried to find this on the schematics to no avail. Although
there was a distinct lack of the 3080 used to control ADSR envelope
depth found in the older versions of the same synth, OB-Sx, Xa etc.
Perhaps they thought they would hide their little secret.

I have tried this on a more traditional ADSR, and it works well, but for
one important thing. I wanted to use this method of amplitude control to
adjust the modulation for different velocities. If you set the ADSR to
have a long release, and press one note again and again at different
velocities, you get a major problem. If the cap is still charged up to a
higher level than the new incoming attack peak, all hell breaks lose.
The decay phase never gets initiated and the envelope itself doesn't
sound natural. Does the OB suffer from this, or does the velocity not
control the modulation depth direct. If the depth is only changed at the
patch level, then this wouldn't be a problem.

Any ideas?

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan