Not being an experienced electronics guy I'd appreciate some sort of bare bones tutorial that explains the key specs at play in the selection of op amps, diodes, caps, etc. and how substitutions and experimentation is not to be feared. I've always heard about forward voltage being a key in diodes . . . tried to read a spec sheet once, but to no avail. If somebody put it as simply as you just did that would be great. I heard something on a DIY site the other day about polarized vs non-polarized electrolytic caps. The guy was saying something like 'use non-polarized in the signal chain, but polarized in the power supply circuit' . . . don't really remember. BUT, my understanding is that polarization is immaterial (other than installing it properly). In order build a larger value cap, but keep it physically smaller in size the design required a specific direction of electron flow. Otherwise it's just another cap. Did I get that right? Some real basic 'how to's" like this could really broaden PPCB's market. I started out as a guy who could replace pickups, modify/rewire his guitars and build his own chords, etc. Now I'm saving hundreds of dollars on pedals (at least that's what I tell my wife).