MOTM

:)

Okay, just to be a wise-guy...

How about instead of VC of Sustain level, you have VC of sustain "leakage"
(obviously one would come up with a nicer name). At 0v to the CV input,
Sustain stays high forever (as long as the gate is high), just as with any
normal ADSR. But with more voltage applied, the sustain starts to droop, to
simulate natural loss-of-energy in some physical systems more closely.

Maybe you would reverse the CV so that low is high droop, I don't know. That
might make more sense.

I've always thought this to be a natural idea, but haven't seen it on any
commercial ADSR. In fact, I only ever saw this type of "drooping" on one
design a while ago, and it may have been one of JH's brain-children...can't
remember right now.


Mr. T

-----Original Message-----
From: jwbarlow@...
To: motm@yahoogroups.com
Sent: 3/30/01 11:01 PM
Subject: Re: [motm] Super VC DADSR EG


...I seem to recall Mr. T and I going round and round on this one due to my
being somewhat dismissive of need for a VC Sustain attenuator. I ain't
backin down now either!!!

Said bravely at a distance of close to 3000 miles from Mr. T's present 
location.
JB

In a message dated 3/31/2001 12:14:29 PM, ken.tkacs@... writes:

>How about instead of VC of Sustain level, you have VC of sustain "leakage"
>(obviously one would come up with a nicer name). At 0v to the CV input,
>Sustain stays high forever (as long as the gate is high), just as with
>any
>normal ADSR. But with more voltage applied, the sustain starts to droop,
>to
>simulate natural loss-of-energy in some physical systems more closely.
>
>Maybe you would reverse the CV so that low is high droop, I don't know.
>That
>might make more sense.
>
>I've always thought this to be a natural idea, but haven't seen it on any
>commercial ADSR. In fact, I only ever saw this type of "drooping" on one
>design a while ago, and it may have been one of JH's brain-children...can't
>remember right now.
>

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). I know the old Digisound (it just occurred to me how strange that 
name sounds -- "the sound of digital, with the affordability of analog!") 
line had a CEM 3310 based EG (or was it a dual EG) that had a couple of 
different modes. One of those modes involved a second VC Decay stage which 
decayed to the sustain level. I remember this as having a fair number of 
components even with the 3310. I could snail you a copy of the schematic and 
docs if it ain't already up somewhere.

Good idea, Ken!
JB

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@...
To: motm@yahoogroups.com
Sent: 3/31/01 8:14 PM
Subject: Re: [motm] Super VC DADSR EG

jwbarlow@... 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

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

ken.tkacs@... writes:

>>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.<<

Well I don't particularly find voltage control of sustain level or release 
time to be all that useful anyway, but I'm just thinking that sustain should 
be kept sustain and not a second decay.  Attaching sustain level to velocity 
would allow a person to change from a percussive type sound to a sustained 
type sound while playing.  Maybe not all that useful, but it's something that 
might come in handy once in a while.  I guess what I'm saying is that an ADSR 
is supposed to be an ADSR and not something that is specific to "dissipated 
energy in a natural system".  And I always apply more modules to get the 
complex sounds I want, which would include multiple EG's which you also 
mentioned.

BTW:  The Access Virus has 5 stage envelopes.  The the sustain section also 
has a rise/fall time knob.

-Elhardt