[sdiy] MOTM-800 clicks. Arg!

[Czech Martin]

Right.

Well, I made this resonator thing digital. Just a 2nd order difference equation.
Pole radius and angle can be selected. A unit impulse will start it.
By calling this program several times (by shell script) you can
produce sinoid transients and later arrange them.

I noticed that giving a different pole radius for each note (i.e.
different resonance, thus different attack/decay) this makes more
interesting music than a fixed transient approach would do.

Voltage controlled envelopes...

Sometimes too much automation leads to boring structures...


m.c.

> -----Original Message-----
> From: jhaible at debitel.net [mailto:jhaible at debitel.net]
> Sent: Donnerstag, 16. Oktober 2003 14:58
> To: Czech Martin
> Cc: Aaron Day; synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] MOTM-800 clicks. Arg!
> 
> 
> > I have heard this fast attack problem on many synths, also digital.
> > I guess all such configurations show the same behaviour, if the
> > envelope is really fast enough.
> 
> Yes. It can be explained directly from signal theory, and would
> even occur in perfectly ideal modules.
> 
> 
> > Another question: we could ask what kind of thing this VCO-VCA-Env
> > thing is modelling. If you create sound by applying a impulse to 
> > a 2nd order resonator, you will see that the rise time depends
> > on frequency and resonance. Perhaps a very simple ideophon
> > model. It will never happen that the wave starts at 100%, the
> > differential equation will always start with 0 (given the initial
> > conditions say so). I've just done this for a composition
> > I'm going to present this Saturday or Sunday.
> > 
> > The usual synth circuits divide the action
> > of a resonator in two parts, frequency and time transient,
> > which are not correlated. Thus it is not surprising that things
> > do not work as supposed (in the sense of said modelling).
> 
> That's a very interesting way too see it - I never thought about that,
> but it makes perfect sense. Maybe that's also the reason why synth
> that only have a single envelope generator (shared by VCA and VCF)
> often produce a more "natural" behaviour. Of course that's a big 
> limiation as well - every time I played with a 1-ADSR synth, I wished 
> I had a second ADSR. But often, when I _have_ 2 ADSRs, I wish the
> 2nd would "follow" the first one somehow. Would be easy to implement
> with two VCADSRs: One set of knobs for common A. D, S, R values,
> second set of knobs for (relative) offset A, D, S, R values on the
> second EG.
> 
> 
> Linked parameters can often be very nice. I've been playing with
> VC ADSR parameters on the PolyKorg Clone a lot recently. I think
> with full polyphony available, the behaviour of release becomes
> even more important. (No need to model everything exactly, when
> the release is cut off 8 notes later, anyway.)
> I found that the usual prolonging of the Release time for
> a "damper pedal" effect can be much improoved if the Decay
> time is adjusted accordingly as well. But I disgress.
> 
> 
> Back to the Attack click problem. Many non-modular synths have
> a small time constant (RC-filter) built-into the VCA, in order
> to limit the transient speed of the EG. With a nonlinear VCA
> CV input, this would even be different from ordinary 
> filtering, and different from ordinary slew limiting as well.
> Just think of the famous Vactrol-based VCAs!
> On a modular, you want more degrees of freedom, and you want
> to _allow_ sound that sound unnatural. This can mean your
> emvelopes can be faster than you really want them for a certain
> application. Referring to Martin's example of a 2nd order resonator,
> no think of a "real" bass drum, for instance. If you hit the 
> base drum,
> the hitting may produce a transien that is faster than the damped
> oscillation after the impact, but _how_much_ faster can it possibly
> be? (on a real bass drum?). Will certainly depend on the strength
> of the impact, damping from the beater's material, and so on.
> But will it be as fast as the 1 ...2ms of a "good" synth ADSR?
> 1ms coresponds to a quarter-cycle (i.e. zero-to-maximum) of a 250Hz
> resonator. But this zero-to-maximum excitation will only happen
> when you really synth your VCO to the ADSR such that it starts with
> a zero-crossing. Think of it: If your ADSR strikes at the VCO
> wave _maximum_, whis coresponds to a drum membrane that is sort-of
> "plugged". If you have a 1ms transient, it's like plugging a
> membrane that's tuned to 250Hz (approximately).
> 
> 
> JH.
> 
> 
> -------------------------------------------------
> debitel.net Webmail
>