Monday, 9 November 2009

PotD - The Organ Grinder

Featuring the Plan B Model 23 Analog Shift Register.

The Organ Grinder plays his merry tune. All is well until monkey and Schnapps get the better of him:

PotD - The Organ Grinder  by  navs

In this patch the M23 was used to shift a quantized sequence to a pair of detuned VCOs, the 'both' input of a Bananalogue/ Serge VCS and the CV input of a VC-LFO. The sequence was transposed by the stepped output of a Wogglebug. A sequential switch was used to alternate between a 'regular' and voltage controlled clock. The switch was triggered by a comparator reading the output of a second random source.


UPDATE: Patch details

I tried to keep the patch description as simple as possible, but for those of you who want to try this here is a patch chart.

The A-147 VC-LFO acts as the master clock and feeds the SQ8, which sends a gate to the VCS (or Maths).

The envelope generated by the VCS is patched to the output VCA. In my patch I fed the two VCOs to a separate mixer (VCA-4MX) before the final VCA (VCA-2P), but for simplicity I've shown an A-131 in this chart.

The sequence generated by the SQ8 goes to an A-156 quantizer, the CV goes to the ASR and the trigger output of the A-156 clocks the ASR. From there, output one goes to VCO1, output 2 to VCO2, output 3 to the second input of an A-151 switch and the last output feeds the 'both' input of the VCS.

The random elements:

the 'step1' output of the SQ8 clocks the Wogglebug. In turn, its clock output steps the S&H/ noise.

The Wogglebug's stepped out feeds the transpose input of the quantizer. At the beginning of the patch I kept the randomness to about 9 o'clock, towards the end I swept it up manually and then back to zero.

The SH-NZ output feeds an A-119, which I've used as a comparator. Depending on the gain & threshold settings you can generate an amplitude-dependent gate. As the A-151 feeds the CV-in of the VC-LFO, the gate toggles the switch between 'regular' and VC-clock. As an alternative, you could use a VCA to alter the amount of VC-clock or, indeed, alter the CV amount manually. If you don't have a comparator or A-119, you could use the burst output of the Wogglebug. I sometimes find this too frenetic, so I send the burst gate to a clock divider to calm it down a bit!


REwire said...

That's Great!

I have an M23, Wogglebug, Not a VCS but MATHS, VC-LFO, Switch and Sequencer. No comparater though. Can you sed me patch diagram?

leftbrain AT sbcglobal DOT net

Thanks! Dan

Navs said...

Thanks Dan!

I've updated the post with the patch details.

The comparator/ switch element is nice, but not essential. I don't have a standard comparator either, but 'abuse' the A-119 ext. input for this.

This is also a great way to generate random, but in-sync gates: use an LFO + clk div + SH-NZ/ A-119 combo to fire a gate when the sample exceeds the threshold set on the A-119.

This also allows you to imitate the WB's burst generator or even the Heisenberg's random meter output. The benefit of doing it this way is that the random gate is always an exact multiple or division of the master clock.