build docs for v5.3
the current top pcb version 5.4 requires six 10k resistors
BOM for VnIcursal version 5.3/5.4
build docs for entire version iv.1 Vnicursal mother board.
version iv.1 subtracts six 47k resistors and adds six 75k resistors for unity gain with 5v in the cv input. also this new rev brings back the two 10uf caps but these have to be small ones. the mouser # for them is under the diy tab.
There are a couple changes to the version iv vca.
- And most importantly the 2 caps listed 0.0047uf are mislabeled. They should both be 10pf.
- The IC orientations are flipped (mirrored)on this version from version iii. This means that the ICs are on the same side as all the other components now(between the sandwich) the notch orientation is also flipped so follow the silkscreen.
- There are no more AC/dc coupling jumpers. Meaning there are 6 less 3 pin male headers as well the 6 shunts associated with them.
- There are no more 10 uf caps
- Now there are 6 additional 270k resistors as well as 6 100k trims for dialing in 0v~ offset so every vca can have a consistent gain range.
- Also trim 6 sits a little close to trims 4 and 5 so make sure trim 6’s legs aren’t touching any other trim legs.
Other than that the board is really close to v iii. And the pics below will still mostly apply to the resistor locations. Besides the 270k.
Since the ICs now go between the pcb sandwich it might be necessary to cut all the “metal” tabs poking through the solder joints like pot chassis and legs of jacks on the bottom of the control board so they aren’t too close to the ICs on the mother board.
For trimming you can get all scientific on it and measure the db I guess. But I just put something like a saw in the input with the panel control at full ccw(counter clockwise)and plug the out to whatever mixer/amp chain you work with and then turn the trim on the pcb to the left/ccw until the vca is silent. If your vca is silent from the get go then good and move on and repeat for each channel.
But keep in mind this could be adding negative offset into the gain structure if you trim too much. Resulting in a sort of strange slope/gain when injecting positive cv.
So I guess you can also experiment with different configurations of offset for + or – voltage as now there are pcb and panel controls doing relatively the same thing.
68k added(keep in mind this is leaving out the led resistors)