I've put together a new vero build without the ground plane.
I wanted to see if I could get a single sided PCB to work with no heterodyning, so I tried to made the vero follow the PCB layout that I have in mind.
It is NOT a good vero layout as there are way too many cuts and room for error and I wouldn't recommend it to anyone.
PicturesMark-up of front and back


Strip breaks and jumpers


Final view of top and bottom

Layout changes to previous buildThe two digital sections (VCOs+BBDs) are at opposite ends of the board.
The LFO section (orange and brown wires) and the audio section (all the other wires) are in the middle.
Surprisingly I only had two construction errors (shorts in the LFO section) and I found them quite quickly.
Circuit changes to previous (corrected) build:1) Star topology for supply and grounds.
2) BBD supplies are separate now (not using audio supply for BBDs).
3) There is only a simple 100k + 100pF LPF at each BBD input (and no Sallen-Key).
4) There is an active 2 pole LPF at the BBD output (instead of 3 pole), and the BBD output pins are not tied together.
I haven't put in the trim pots for separate BBD bias levels (its still a single bias via the audio path) or
for BBD output balance (it's just a pair of 4k7 resistors) but I made sure the layout
can allow for those options and the PCB layout will give the builder the option of adding them if they wish.
5) There are 10R resistors between the main (audio) ground and the grounds of the LFO and digital sections.
6) I haven't put any 100nF caps directly been IC power pins on the bottom of the board yet.
ResultIt flanges with no heterodyning whatsoever
ProblemsLFO ticking: I didn't have that before. It could be because I have really long wires in there at the moment.
The wires to the rate pot are close to the audio section too, and not on the edge of the board like before.
Reliably hitting zero without crossing it: With the previous build, I could make the sweep hit the zero point without crossing it for all Depth settings.
I now find that having a single zero point at maximum depth causes the zero to be crossed at lower values of Depth.
I am currently thinking it is either:
a) Something to do with those 10R resistors in the ground lines separating LFO ground from VCO ground.
The control voltages don't have a common reference point anymore.
b) When I took apart the old build and reassembled it, I may not have used the same components in the same places as before.
i.e. I previously fluked a situation that was trimable to a single zero point.
Investigation continues...