Eurorack Modular J3RK Mirror Core VCO in PLL configuration (sort of...)

Published on May 5, 2014 encrust1

Watch your volume levels on this one.

"Just a bit of fun...

My newly constructed J3RK Mirror Core VCO kit from Synthcube. (Not quite finished - a switch needs wiring in and a knob adding.)

The only external module doing anything relevant is a Doepfer LFO.

The left side VCO is producing a reference frequency which the right side should lock to - although this frequency is very low for much of the video. This would be a classic PLL (with divider on the right VCO output, phase comparator XOR gate, and integrator controlling the right VCO voltage input) except that the Lockhart folder is inserted in the PLL loop. This is configured as VCA + single fold. The control voltage for the VCA comes from the external LFO.

The result is that the loop never really 'locks' but meanders around a few attractors which are heavily based on the left VCO frequency. The video camera doesn't capture it well, but this set up produces a lot of bass at times.

I also have the FM input of the left VCO controlled by a second phase comparator output.

I am looking forward to completing the module and getting it into my main rack with filters.

Sorry for the shaky video."