[sdiy] Delayed LFO fade-in time

Kenji Garland kenjigarland at gmail.com
Tue Mar 15 23:27:13 CET 2016

Just to chime in, I think there's really no set rule or "right" way to do
it, nor should there be. The Ensoniq ESQ-1, one of my favorite polysynths,
lets you route a (delayed) LFO to modulate anything you want, and
apparently unlike the Juno, it even has separate LFOs per voice – meaning
that not only can they be delayed separately, but the separate LFOs can be
in or out of phase with one another or even slightly detuned from one

Since you say "programming," I'm guessing you're working in software, where
of course you'll need to limit the choices available to the user to some
extent, but I'd be wary of limiting things too much where you don't have to.


On Tue, Mar 15, 2016 at 5:57 PM, Quincas Moreira <quincas at gmail.com> wrote:

> Richie, first, the assertion that LFO delay should only work for pitch
> modulation is purely a matter of taste and/or intention.  I've made
> patches with delayed LFO modulating the VCF and totally love the
> result.  Also, the way I know how to introduce such delay is to run
> the LFO through a VCA before the destination, and trigger the VCA with
> a slow EG, so the EG attack rate is responsible for the LFO delay
> time.  If you want that to be variable you need to use a VC-EG.  As
> for polyphonic implementation, checking with my juno MKS50, the delay
> is global, meaning once the LFO has started, if you play a new note it
> will already be affected by the LFO.  This leads me to think it is a
> single dedicated VCA/EG combo under the hood running the LFO delay.
> Hope this helps
> Cheers!
> Quincas
> On Tue, Mar 15, 2016 at 2:52 PM, Richie Burnett
> <rburnett at richieburnett.co.uk> wrote:
> > When programming LFO delay to implement delayed vibrato is there any
> > convention as to how the "fade-in" time is determined?
> >
> > For instance, I know that if the LFO delay is set to zero then there is
> no
> > delay and pitch modulation occurs immediately at full depth on all synths
> > I've tried.  However, if I select some LFO delay, then there is no pitch
> > modulation for some time, and then it is introduced *gradually*.  Should
> the
> > "fade-in" time for the pitch modulation be proportional to the delay
> time?
> > Or maybe it should always be a fixed amount of time?  ...or maybe even a
> > fixed number of LFO cycles at whatever the LFO rate is?
> >
> > Also, I believe that LFO delay should only work on pitch modulation of
> the
> > VCO, and not actually delay the introduction of VCF modulation or
> > pulse-width modulation?  Is this other people's understanding too?
> >
> > For a polysynth LFO delay will be polyphonic?  So that's one LFO
> oscillator
> > to implement in-phase vibrato across all voices, but 8 separate
> mono-stable
> > timers for the LFO delays in an 8 voice synth?
> >
> > Many thanks,
> >
> > -Richie,
> > _______________________________________________
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> > Synth-diy at dropmix.xs4all.nl
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> --
> Quincas Moreira
> Test Pilot at VBrazil Modular
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