Xotic BB preamp switch question

[Endless Mike]

Howdy all,

I'm building the Xotic BB layout here, and really don't want to drill the only enclosure I have for the switch. I'm wondering id there's a reasonably simple way to work around this. I thought it would be as simple as somehow inserting between the Sw1-5 and Drive 1 by some means or another. If I'm mistaken, please let me know.

If there is one way of doing this that would be better than another, I'd really appreciate knowing that as well.

Alternatively, if drilling for a switch is the best way, the only toggle switches I have on hand are DPDT on/on switches. Could that be used instead?

Thank you

[Marbles]

Hey Mike,

It depends. I'm at work, and terrible at making graphics, so I hope this noodling is clear (and correct, since I'm not an exprt).

This basically explains how the signal is routed through the switch:

Switch down, switch in the middle, switch up:




As you can see, the On/Off/On gives you 3 options: Switch down routes the signal through a diode configuration, switch in the middel just sends it straight through without diodes, and the switch up sends it through another diode configuration.


So to answer your question about  the On/On switch: It it possible, but you would only have the 1st and 3rd option in my drawing. You have to choose 2 options out of the 3 there are now. Like no diodes in the bottom position and diodes in the top. Or only diodes, etc.



I'm not sure, but I think originally there were no diodes in the pedal?

If the above makes any sense, it should answer your question about omitting the switch. If you choose no diodes (the middle position) the switch doesn't do anything, it just passes the signal. So you can just see it as one wire, and connect the 2 as if there was no switch in between them.

[nocentelli]

The original version has only a single pair of diodes. If you've already cut the vero to size (so you can't extend the board by a couple of columns), you could use a tiny scrap of vero to make a daughterboard to hold the single diode pair, or even just wire them directly across the lugs of the drive pot. Alternatively, if you wire your on-on dpdt exactly like the one in the vero picture, you'll get both diode clipping options, but will lose the "no diodes"/"opamp-clipping only" option (the "off" position is literally that - no connection between any pins).

[Endless Mike]

That's great, thanks. I had to order another enclosure as the 1590B is too much of a squeeze, so I had it drilled for a toggle and will use the on/on switch. I really didn't want the diode lift option.

Thanks to both of you, I really appreciate the help.