When I turn any of the upper 4 pots, their values affect each other, and (possibly) also the CV I/O values drift up or down depending on the pot positions.
Users have reported that in some cases (no pun intended) the -10V analog voltage reference (Test point AREF_-10) is not strong enough and will drift depending on the load.
If you suspect that your values are drifting, check the voltage on the test point “AREF_-10V”. It is on the Big Genes PCB but slightly hidden under the Ksoloti Core. If you measure anything other than 10.0x V (though 9.95V to 10.05V is perfectly fine) OR if you measure different voltages depending on where the upper 4 pots point, you may want to try one of the two fixes below.
There are two possible fixes to stabilize the voltage reference:
-
Solder a 1k resistor parallel across R72 to supply (about 2mA) more current to the LM4040 -10V reference.
R72 is 560 ohms but it seems we may have to go even lower. 560 and 1k in parallel would result in about 358 ohms, supplying up to 5.58mA to the LM4040. Well within specs still.
Disadvantage: the LM4040 might warm up more, which would slightly affect AREF-10 during warmup. You might get that vintage “it needs to warm up for 10-20 minutes” feel, numbers drifting towards stability, which may or may not not bother you on a digital module. -
Replace the upper 4 pots with higher resistance ones.
This will reduce the AREF-10 current flowing through them, increasing voltage stability. B25k or B50k is fine, maybe even B100k.
Disadvantage: Higher resistance pots might be noisier and exhibit more jitter.
