[sdiy] Simple (?) sequencer mod for syncopation

[Jerry Gray-Eskue]

<<Also, it would be hard to change the counter settings on the fly in a
meaningful way, because changing one count would change the beat length of
the entire sequence.>>

Yep that would be a bear to deal with.

Now I understand what you are doing with the PWM, That would be very nice. A
musician could get very expressive with that type of control.

-----Original Message-----
From: David G. Dixon [mailto:dixon at interchange.ubc.ca]
Sent: Thursday, June 04, 2009 3:47 PM
To: 'Jerry Gray-Eskue'; synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Simple (?) sequencer mod for syncopation


I guess that would work, and that would give one the option of doing triplet
patterns as well (16 notes --> 48 events), among others.  It reminds me of
the Arturia emulation of the Moog 24-step sequencer in Moog Modular V.

However, this would require presetting the down counter's starting point
into each step, and this seems hardware-intensive (Thumbwheel?  Rotary
switch?), and I imagine it would require a fair bit of additional logic
circuitry as well.  Remember, I'm thinking about this as a "simple" mod for
Ray Wilson's 16-step sequencer.

Also, it would be hard to change the counter settings on the fly in a
meaningful way, because changing one count would change the beat length of
the entire sequence.  With my technique, each note has just the one
additional switch which can actually be changed on the fly for interesting
rhythmic effects, and one would still get whatever number of steps one would
normally get from the sequencer (by turning the step gating switches on or
off) regardless of the R/I trigger settings.  Also, the down-counter
technique precludes asymmetric beats for "swing" which would be dead easy
with my technique, simply by putting a bit of PWM on the clock wave.

Also, I forgot to mention it in the original post (mostly because I hadn't
thought of it), but if the switch were of the DPDT On-On-On variety (soon to
be available at a reasonable price from Small Bear, I'm led to understand),
then the middle setting could be R+I, such that both triggers would trigger
the step.  This could also be pretty useful.

Finally, if there were a single routing switch whereby one could switch the
positions-in-time of the rectus and inversus triggers (i.e., all the
downbeats would become upbeats, and vice versa), then this could also have
some fairly interesting musical effects.  This could be achieved simply by
inverting the incoming clock signal prior to rectification!  These are the
kind of mods I like: very simple things which have potentially dramatic
musical effects.

> <<a sequence of 12 notes.  However, the sequence would require a
> 32-step sequencer clocked in the normal way, because the sequence is over
> two bars, and those bars each must be subdivided into 16th-notes to
> capture
> the funky rhythm of the sequence.>>
>
> It sounds like you may be going about it the hard way.
>
> How about you feed the sequencer a 16th note clock and a user set down
> counter for each step.
> The down counters decrement for each 16th note clock and at 0 the next
> stage
> becomes active.
> The down counters automatically reload the user setting as the next stage
> becomes active.
> That way you can have each step last a user selected number of 16th notes
> before the next step.
>
> for this sequence
>
> /--/--/---/-/-/-/--/--/---/-/-/-
>
> you set the down counters at 3,3,4,2,2,2,3,3,4,2,2,2
>
> Of course the Clock would not have to be 16th notes and you could use any
> size of down counters.
>
> -Jerry
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of David G. Dixon
> Sent: Thursday, June 04, 2009 1:48 PM
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] Simple (?) sequencer mod for syncopation
>
>
> I thought it might be nice to have a little break from the physics of
> sigmoid waves, so here's something musical and synthy to consider.
>
> I'm in the process of beginning to organize a 16-step sequencer for my
> ever-growing modular, based on Ray Wilson's famous circuit with Thomas
> White's brilliant circular front panel layout (only mine will have a panel
> board to eliminate a whole bunch of wiring).
>
> Coupled with this activity, I've been listening to various synth-based
> music
> in my car, including Herbie Hancock's classic "Headhunters" album.  The
> opening of the famous first track "Chameleon" (many of you probably know
> it)
> involves a sequence of 12 notes.  However, the sequence would require a
> 32-step sequencer clocked in the normal way, because the sequence is over
> two bars, and those bars each must be subdivided into 16th-notes to
> capture
> the funky rhythm of the sequence.
>
> Now, coupled with these thoughts, I have just been reading Allen Strange's
> book, "Electronic Music: Systems, Techniques, and Controls (1972 ed.)."
> In
> the excellent Chapter 6 on "Gating" (page 44) he talks about something
> called "pulsed mixing."  In this technique, one takes a pulse wave,
> isolates
> the positive and negative parts, and uses them separately to gate two VCAs
> processing different signals, causing anything from a jarring "ping pong"
> effect to a seamless blending of the two.  I find this very intriguing.
>
> This got me to thinking: Why not "pulsed triggering?"  One could take a
> standard 16-step sequencer and feed it with two clock signals, both
> derived
> from the same pulse wave.  One signal would consist of rectified pulses
> from
> the clock wave, and the other signal would consist of rectified pulses
> from
> the inverted clock wave.  Hence, one would have 32 triggering pulses at
> ones
> disposal.  Each step of the sequencer would be provided with an extra
> switch
> for selecting whether that step is triggered by the (first) "rectus" pulse
> or the (second) "inversus" pulse.
>
> Now, going back to Herbie Hancock's "Chameleon" sequence, starting at the
> downbeat (i.e., the fourth note of the opening), here is the succession of
> notes (/) and rests (-) over the two bars:
>
> /--/--/---/-/-/-/--/--/---/-/-/-
>
> As you can see, there are 32 events here, but only 12 notes.  If each pair
> of events corresponds to a single step of a 16-step sequencer, then here
> is
> the sequence of pulse selections for all 16 steps (R = rectus, I =
> inversus,
> X = don't care (no note on that step):
>
> R I X R X R R R R I X R X R R R
>
> So the 16-step sequencer has been tricked into becoming a virtual 32-step
> sequencer (albeit with only 16 notes).  The only caveat is that one could
> not have three notes in a row without at least a 16th beat rest between
> two
> of them.  However, within this limitation, the funky possibilities are
> nearly endless.
>
> Finally, pulse width modulation of the clock wave gives "swing" as well as
> syncopation (Thomas White has already done something like this, bless
> him!)
>
> Discuss!
>
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