Dual audio blend knob and three way switch?

[GabeOfTheSpring]

Hello! I am currently building a bass and I am in the wiring stage.

I have two pickups on the bass and would like to use a three way selector switch to switch between them since the idea for the tone came from the Gibson Ripper basses which used rotary switches to switch between pickups. I ordered an Aguilar preamp with a bypass switch to put in the bass for maximum tonal options and versatility since I really enjoyed the Anaconda bass I demoed at NAMM with this feature.

However, the tone pot on the preamp is a dual audio tone pot designed for the pickups to be wired to it individually, it has six tabs to wire to instead of three. But the wiring diagrams I had been looking at are based off wiring the pickups to the selector switch. I would like to find a way to wire the selector switch to the tone knob. Any advice?

My current idea is to use a capacitor in place of where the pickups would be wired to the tone knob but I am not sure if that would work? Any help would be very much appreciated!!!! Thank you!!!

Here are the links to the wiring diagrams I've been looking at: http://www.aguilaramp.com/wp-content/uploads/wiring-diagram-obp-3-v2.pdf
http://www.aguilaramp.com/wp-content/uploads/wiring-diagram-obp-3-v2.pdf

 

[sikamikanico]

That's not the tone pot, that's the blend pot. If you're using a switch, skip the blend pot, and wire directly to the volume pot. If you want passive tone controls, add your own tone pot (with specs of your choosing).

But if you're using a 3-way switch, which settings will you use? If neck-parallel-bridge, then you might as well skip the switch and use the provided blend pot...

 

[GabeOfTheSpring]

Ok thank you, as I research more this is starting to make more sense to me. Follow up question that is probably dumb: lets say I use the 3 way switch and replace the blend knob with a tone pot so it now has a standard three way switch, one volume, one tone schematic. Would adjusting the tone knob when the switch is in the parallel position blend the tone of the two pickups together (and do it well)? If so, what value capacitor and pot should I get? I have a spare 500k tone pot with a capacitor already attached to it but all the other pots on the preamp are 250k. However, I am using two humbucker pickups and have read that 500k pots are better for them. Thank you again!

 

[sikamikanico]

Follow up question that is probably dumb: lets say I use the 3 way switch and replace the blend knob with a tone pot so it now has a standard three way switch, one volume, one tone schematic. Would adjusting the tone knob when the switch is in the parallel position blend the tone of the two pickups together (and do it well)?

I'm not sure what exactly you mean with "blending the tone of the two pickups together", but all the "blending" you will be doing is with the switch in the middle position where both pickups are at full volume (in parallel with each other). That's equivalent to having the blend knob in the middle, minus the resistance loading of the pot (so a switch sounds slightly brighter than a balance pot). That then goes to the tone control, which cuts the treble of the combined signal. This type of circuit is common and works well (think jazz bass).

If so, what value capacitor and pot should I get? I have a spare 500k tone pot with a capacitor already attached to it but all the other pots on the preamp are 250k. However, I am using two humbucker pickups and have read that 500k pots are better for them. Thank you again!

This is mostly preference, and I highly suggest experimenting. Passive electronics are cheap...and if you want to skip soldering a lot, use alligator leads to quickly swap components. Read around here for more info, but in a nutshell: the higher the resistance value of the pot, the brighter the sound when the pot is fully open. 1M pots are almost as bright as direct wiring. But the higher the value, the less granular your control is. And this applies to both volume and tone controls. I think 500K for both works well, with a nice balance of brightness and control (full disclosure: I like brighter tones, and don't fiddle with knobs that much). But you can easily mix and match pots to your preference. Note that pot taper also highly affects the granularity of the control, but generally most people prefer audio taper for tone controls; opinions for the volume control taper are more divided (between audio and linear tapers).

For caps, same story: experiment! Higher value caps sound darker. Typically you'll see them between .1uF (gives a dubby tone), and .033 uF the highest (more middy tone). Note that the effect of cap value only comes in when the tone pot is at about 25% or less (the first 75% of the action comes from changing the resistance).

Or, if you don't want to experiment (yet), just use what you have and see how you like it. Frankly, most differences are subtle, and matter more for passive basses. With a 3-band pre, you can do your tweaks actively.

 

[GabeOfTheSpring]

Thank you very much!!! You guys have been so helpful!!! Since my band is going on tour soon and i am trying to finish the bass before then I may stick with the blench knob for now and skip the 3 way switch but I’ll definitely experiment with it and may change it later!!! Thank you again for all the help!!! I am a rookie at this stuff (as I’m sure you can tell lol) but I really want to get more into building my own instruments and I want this first one to really be something special!! Thank you x1 million I cannot wait to finish this project over the next week!!!