More about 3310 and envelopes

[Hairy Harry]

Good points:

If you really want to hear something bad... try a sampled
cymbal crash, re-hit from loud to soft!

Very unnatural !

H^) harry


>From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
>To: Tony Allgood <oakley at techrepairs.freeserve.co.uk>,        DIY  
><synth-diy at node12b53.a2000.nl>
>Subject: RE: More about 3310 and envelopes
>Date: Wed, 15 Nov 2000 17:21:45 +0100
>
>	>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?
>
>The OB-8 has no velocity, so there is no such problem.
>
>But you're raising a most interesting question: How *should* the envelope
>of a retriggered voice behave when the new velocity value is lower than the
>"remaining" amplitude from the previous note ?
>
>Not easy !
>
>Consider the *same* note is struck again for that voice: Should the
>amplitude
>jump back abruptly to the new value, or should the maximum of both values
>be valid, or should the sustaining ("releasing") note dominate ? Or should
>the tiny amount of the low velocity note be *added* to the sustaining
>previous note ?
>When a vibrating Guitar String is plucked again, I guess it will stop
>vibrating
>as long as the finger touches the string. (?)
>When the reed of an electric piano is hit with the damper open, some
>of the newly applied energy might add to the sustaining note's energy
>I suppose. So there is no general solution.
>
>Now think of the new note assigned to that voice being different to the
>previous one. Say, the voice is sustaining at C with a momentary level of
>70,
>and a D# with an initial level of 30 (lower velocity) is bound to replace
>that C.
>I'd say the big question is not *how* that note should be replaced (in 
>terms
>of level), but *if* it should be replaced under these conditions at all !
>Replacing a loud note with a soft note abruptly is a striking event
>regardless
>how you do it.
>
>JH.
>

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