Dual gang pot sounds like the right way to go.
I've been doing this for years on active/passive basses. I thought I was on to something original until I found that Reggie Hamilton pot on ebay last year! Oh well... there's very little that's truly original in audio electronics I'm afraid...
I've always thought it's a bit of a compromise puting a volume pot before a preamp, just so it works when you go passive. There's heaps of discussions here about this. It's very misunderstood. You
do get treble loss when you turn down because you are drastically lowering the input Z of the pre. I use my volume control a lot with the sort of gigs I do so I like the volume after the pre in active mode. OTOH, if, like a lot of bassists, you play with the vol up most of the time, then it's really no biggy TBH.
As for the resistor, well, if you don't earth the blend, and don't have a volume pot before the pre, then there's often no earth reference for the input cap on the pre (although designs vary here), and the input cap can cause a pop when you switch. When you get your preamp, you can simply measure the DC resistance between the input lead and earth before you install it. If you don't get a reading (you may have to set your meter as high as its 20meg range) , then you'll probably need that resistor. I'd start with a 1Meg. You could even install a trimpot and tweak it to get the active treble response you like. Some preamps on the market these days have an input Z switch or whatever, this is the same sort of thing. I'm not a huge fan of soldering to pot casings, but you
could mount the resistor on the blend control. One end on one of the hot lugs, and the other earthed via the pot casing. OTOH, if you prefer the sound of your blend pot with its earth connections, then there's no need for the load resistor.
Also, now you have a dual gang volume pot, it means that you can't use a push-pull volume for active-passive. Without drilling for a toggle or something, you'll have to pick another pot, and the blend is also out of the equasion. There are a few dual gang push-pull pots out there, but none that I've seen have the right tapers/values for what we are talking about. You can get 50KB push-pulls too these days, so one of your active tone knobs could be the active-passive switch as well. But not with your stacked treb and bass though. And these days a lot of guys like a mid pot that switches centre frequency, so a push-pull here is usually for that. If you go with a passive tone pot, that could be the place for the active-passive push-pull I guess.
since its a dual bar humbucker design
Ah I get ya. Yeah, it depends more on how hot the coils are really, and whether you go with series or parallel. A typical single coil J is wound to 7.5K, and a typical MM humbucker in series mode is like 8K. The other day I had an early 90's ibanez on the bench. Its series humbuckers were wound to 16K!...
yep 10 guys, 10 different choices...
You really just have to try a few out for yourself and see what you like. It's a good learning experience anyway.
My wiring is a bit eccentric I guess, but I'm a gigging pro and bass teacher, and it works for me. On
one of my basses anyway!...
