Err, pardon me, but isn't it a fact that there is NO sustain level in
the struck bar scenario you mention below? Sustain by nature is, well
sustain. Sounds like what you want is ADDR or something.
Moe
--- In motm@y..., "Tkacs, Ken" <ken.tkacs@j...> wrote:
>
> But would you really want velocity to simply control sustain level?
It's
> easiest to implement electronically, sure, and nice & neat on the
front
> panel, but is it the best way to create envelopes? This wouldn't
simulate
> the way energy is introduced & dissipated in natural systems.
That's all I'm
> saying.
>
> Lets say you whack "something" with a mallet.
>
> Now let's say you whack it harder.
>
> Using the simplified "Ussachevsky-esque" ADSR metrics of the
envelope, what
> has happened on the second strike isn't just a rise in the sustain
level. As
> far as the ear is concerned, that's the least of it.
>
> What typically happens (and this is a gross generalization of
course, and of
> a percussive sound per the example) is that the attack is faster,
the attack
> peak is higher, decay rate is sharper, the ratio between the
overall peak
> and sustain level actually ∗increases∗ (even though all levels are
higher),
> and the length of time it takes for the steady-state energy to
dissipate is
> longer, but it does eventually dissipate.
>
> (In addition, chaotic frequecy modulation is increased in the
attack, etc.,
> but we're just talking amplitude envelopes here.)
>
> Only in a system (such as a pipe organ) where energy is continually
fed into
> the system does the sustain level remain somewhat constant. For
this, the
> standard ADSR is perfect. Which is why, as has been said, most
synthesizer
> work tends to degenerate into quasi-organ character.
>
> (The excellent UEG, as mentioned, is great for complex envelopes,
but the
> stages aren't VC-able, which is why I hadn't mentioned it in this
outing.)
>
> The way the typical synthesizer patch simulates the above is to use
two EGs,
> and while the VCA EG's sustain is holding firm, an EG controlling
the Fc of
> a VCLPF is using a long Decay stage to slowly filter more & more
high
> frequency content away during the envelope's Sustain portion.
> Psychoacoustically, this roughly simulates (for a while) energy
being
> dissipated in a natural system, but it's a real finger-painting
approach
> compared to actually simulating the amplitude envelope properly.
>
> If you just want velocity data to control loudness in a simple way,
than the
> easy thing to do is to set up a simple ADSR for the rough
characteristic
> envelope and then feed the final sound through a VC AR for final
amplitude
> shaping. And add that VCF EG too. This takes care of the initial
velocity CV
> of which you speak.
>
> Anyway, this is all just waxing poetic. In the world of
synthesizers, VC
> envelope control is a strange rarity. ∗Anything∗ is an improvement,
so I'm
> just thinking out loud about these variations. The amplitude
envelope is the
> single most distinguishing charteristic of a sound, yet most of us
spend
> more time thinking about VCOs & VCFs. This is why a Korg MS-10 does
a
> simple, but decent (for what it is) job imitating natural sounds!
(And I'm
> not besmirching VCOs... I happen to be a VCO-head, myself.)
>
> But envelopes are everything!
>
> Sorry, I just love envelope generators. You just cannot have too
many.
>
> OT: has everyone been watching the "April Fool's Weekend" Monty
Python
> festival on BBC America? That's why I'm a bit punchy right now. DST
folks,
> don't forget to set your clocks ahead.
>
>
>
>
> -----Original Message-----
> From: elhardt@a...
> To: motm@y...
> Sent: 3/31/01 8:14 PM
> Subject: Re: [motm] Super VC DADSR EG
>
> jwbarlow@a... writes:
>
> >>I have to admit, I find this idea much more interesting than a
basic
> VC
> sustain level (since I can see little use for increasing the sustain
> level
> over time).<<
>
> VC sustain doesn't necessarily mean you are changing its level over
> time. It
> could mean you are giving it an initial control voltage everytime
you
> strike
> a key. Keyboard velocity could determine its level every note, or
a key
>
> triggered S/H for a random sustain level every note. I'd hate to
see it
> get
> too confusing or move too far away from what a VC-DADSR is supposed
to
> be
> with it replacing sustain with "leakage". There is always the UEG
for
> more
> complex decay curves.
>
> -Elhardt