[sdiy] Delayed LFO fade-in time

Quincas Moreira quincas at gmail.com
Tue Mar 15 22:57:21 CET 2016

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



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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Quincas Moreira
Test Pilot at VBrazil Modular

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