Looking at the Green Bean docs, apparently I bought parts using the BOM from before 2014. That was when I expected to etch my own board. But I went ahead and bought a 2014 Bean board and now I'm seeing that the Drive pot is changed from a 500kB to a 500kA. Significance? I'm trying to learn and understand why, unless one was just a typo.
If I remember correctly, the drive pot is A500k for a stock Tube Screamer. Some guys like to use A1M. The Volume pot is the weird one. Ibanez uses B100k, but A100k works much more nicely.
The difference between the 500kA (logarithmic or audio taper) and 500kB (linear taper) is just in how the levels of gain are distributed across the sweep of the pot. The linear taper will get gainier quicker in the sweep (from 9:00 to 12:00 or so) while the log or audio taper will more gradually increase the gain - bunching more of it up past Noon on the dial. Log/Audio taper almost always works best for volume controls, but it's a personal preference for drive/gain controls - just depends on whether you like the gain spectrum bunched up more at the beginning or end of the dial.
Ok, that makes sense. I knew that A = Audio = Log, and B = Linear, (and C = Rev. Audio/Log, and W = something different) but I haven't been at this long enough to be able to test out the differences for my ears yet. What I'm understanding then is that the 500kB that I already have on hand should work without any problems and with the higher drive/gain hitting earlier in the sweep, but I can swap it to a 500kA if I want the drive/gain to be more tapered over the entire sweep of the pot. Basically correct?
Yep, you've got it :)
Awesome, thanks for the quick reply!