Onboard preamp with 4 knobs and 2 mini toggles?

[ColdEye]

Pics of the existing control layout may help. Unless you really need the Z modes, I'd go with a simpler config...few ideas:

* Volume - Blend - Mids - Stacked Treble / Bass. Use the mini-toggles spots for Mid-Freq switch and battery LED...no unused real estate!!

*If you don't care for stacked knobs: Enlarge one of the mini-toggle spots to accommodate an EQ pot. Volume - Blend - Bass - Mids - Treble...stick a 3 way Mid-Freq in the remaining switch spot.

Riis

Here is a pic. I actually now have an Aguilar OBP-2 that I am taking out of a bass I got. I might just use this. Looking at Aguilar website I can do Vol/Vol/B/T and add a switch for A/P. For now I don’t want to enlarge the hole for the switch.

 

[Zooberwerx]

Here is a pic. I actually now have an Aguilar OBP-2 that I am taking out of a bass I got. I might just use this. Looking at Aguilar website I can do Vol/Vol/B/T and add a switch for A/P. For now I don’t want to enlarge the hole for the switch.

View attachment 5360139

Well, that completely shakes things up. I liked my first suggestion as it uses up everything w/o modification. What do you have to add to the OBP-2 to make it "whole"?

It's gonna be a 2 band, no mids, but bonus points as you already have it on hand.

Riis

 

[factory presets]

Here is a pic. I actually now have an Aguilar OBP-2 that I am taking out of a bass I got. I might just use this. Looking at Aguilar website I can do Vol/Vol/B/T and add a switch for A/P. For now I don’t want to enlarge the hole for the switch.

View attachment 5360139

Doesn't look like there'd be a way to change switches for knobs, anyway.

I put a four knob East Uni Pre in an old Heartfield, and couldn't be happier with it. V/B, B/T, swept mids and A/P push/pull on a passive tone knob. I get a lot of use for passive mode with the tone control. Sweepable mids pull their weight and all.

Downside = it's not cheap. Mainly mentioned it for the 4 knob configuration if you were still looking to buy something.

The humbuckers give you plenty of options for your switches.

 

[jfiver]

Here is a pic. I actually now have an Aguilar OBP-2 that I am taking out of a bass I got. I might just use this. Looking at Aguilar website I can do Vol/Vol/B/T and add a switch for A/P. For now I don’t want to enlarge the hole for the switch.

View attachment 5360139

That's a tight spacing! I'm only eyeballing it, but looks to me that the switches that Underhill uses would fit, provided they were oriented towards–away from the strings.

And like @Zooberwerx said, the best pre is generally the one you have. But FWIW, I have absolutely zero regrets about pulling out an OPB-3 and replacing it with an Underhill. (BTW, another way to use the switches with an Underhill pre are as filter bypasses, which I reckon is great but it's a whole other topic.)

 

[bowthing]

That's a tight spacing! I'm only eyeballing it, but looks to me that the switches that Underhill uses would fit, provided they were oriented towards–away from the strings.

And like @Zooberwerx said, the best pre is generally the one you have. But FWIW, I have absolutely zero regrets about pulling out an OPB-3 and replacing it with an Underhill. (BTW, another way to use the switches with an Underhill pre are as filter bypasses, which I reckon is great but it's a whole other topic.)

The switch boards are the same width as the switch bodies, so the switches can go as close as about .475" (center to center).