[sdiy] ADSR sustain question

[Colin f]

> And which 
> bit of the Sustain pot is causing the problem? In centre I've 
> got 5K toward Vdd, and 5K to ground. Which of these 5Ks 
> alters the Decay setting and why doesn't the other one affect it too?

Actually you've got 4k7 above the pot too.
Even if you didn't, 5k to Vdd and 5k to ground is equivalent to 2.5k to
(Vdd+0)/2
In effect, the pot has an output impedance.

Cheers,
Colin f