MOTM

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