Posted by tabbycat on URL: http://guitar-fx-layouts.238.s1.nabble.com/DBA-Echo-Dream-2-tp27402p30859.html
thanks for the reply and suggestion, sonus.
i have acquired that same general feeling re better going over value rather than under when the cap is being used as a battery, to store up a bit of power to smooth out supply spikes and have a little in reserve for headroom and high demand. i think a bit bigger is ok there. but as this is going to ground it’s not being used for battery properties.
as for decoupling caps, again, i think they are better bigger than smaller or they start eating into desirable frequencies. I think this is a decoupling cap of sorts, to trim higher frequencies out of the feedback loop coming from repeat pin 15 of the pt2399 to reduce recycling noise and self-oscillation.
caps for tone stacks I understand to be critical to be spot on (or max +/- 10%) as movement either way again is binning desirable frequencies to ground. which isn't to say you can’t create something 'desirable' in a freaky thin or scoopy way by using wrong values, but ‘desirable’ as in faithful to integrity of the original layout.
so a 'delay feedback loop decoupling filter' (i think, if that’s a thing). but beyond giving it a name I don’t know how to work out what value it needs to be to work. i’m only at that ‘recognition’ stage on the taxonomy of stomp science, ‘application’ al lot higher up.
anyway, rather than risk messing up one of my biggest builds for the sake of a cap, i decided to be strict with myself and leave it alone until i get the specified 680n film box.
and instead of soldering yesterday i spent the day in bed with a couple of freaky fassbinders and my german dictionary. i will learn german if it kills me, which is likely. and I’ve picked up some great chat up lines.
‘wurdest du mit ein kruppel schlafen wollen?’.
btw, as a fellow synthy fan with a taste for the odd, you might like this extract from 46m30s to 47m30s.