[sdiy] Vactrols subbed for dual-gang pot

[Tom Wiltshire]

On 9 Jul 2010, at 18:23, Dave Kendall wrote:

> By hand-selecting LED/LDR pairs, I can match the off resistance of the home-rolled vactrols to within a few ohms, and limit the max resistance fairly easily, but between those points, I suspect the LDRs may "drift apart" due to different response curves to incoming CV. How would this affect the BPF circuit? Does it even matter?

I agree with Paul - I don't think it matters either. You're talking about differences of linearity in components that are usually given 20% tolerances. Exact matching of responses and values will increase the cutoff slope and the Q, but I don't think that's exactly the point here. After all, if you wanted a precision instrument, you wouldn't be building it with vactrols, right? It'll sound funky as it is.

Build it, don't stress about getting everything exactly matched, and call it "analogue character"!

T.