Understanding Fixed Voltage Pads on Charge Pump

A

aechcutt

New member
I've been studying the layout of the charge pump PCB, as well as this thread on how to wire it up. I'm very confused by the fixed voltage pads at the bottom. The +18v seems to make enough sense, but the -/+9v pads are throwing me off. What is the context one would use those pads instead?
 
This board does 2 things: you can make the 9v/18v switchable (seen on the right that goes to the upper right side of the board) or you can put a wire into the fixed pads to save some real estate inside and not have a switch. IMO I don't see the need for the +9v fixed pad since that is the input voltage to the board itself. The -9v (classic fuzz face) or 18v (more headroom) I totally get.
 
Ah, nice. I didn't know that a classic Fuzz Face had -9v. That explains it, I suppose. I guess if your circuit was biased in such a way that you needed -9v to clip correctly?
 
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