Jazz bass control options - help please Weirdy !

[wokkaboy]

Hi Weirdy, I've just started an ash jazz bass build and am looking at wiring options. I've ordered one of these 2 band active eq units Pablo recommended.
http://www.ebay.com.au/itm/like/4003...2F400368322849

There are 3 control knobs on the plate but was going to drill a jack hole in the side of the body and use the jack hole for a 4th pot which the active EQ has 4 pots.

How hard is it to put a mini toggle switch and have an active/passive switch to change the setting to active and passive ?

I could always use a concentric pot to control treble/bass and would maybe like to add a tone control to a concentric pot for volume.

think there is enough room on the plate to drill a mini toggle switch for active/passive.

I'm almost ready to stain the body so not keen on routing a battery box cavity so I may route out more space under the pickguard for the battery box.

cheers in advance Weirdy !

Also Ponch is interested as he is building a jazz bass and is looking at options !

[WeirdBits]

The pot values make things tricky. Active circuits tend to use smaller value pots (25/50/100K), while passive uses higher values (250/500K). From what I can see the EQ-B2T has two 25K pots, a B500K pot and an MN500K balance pot. It appears the pickups connect to the balance pot and that then has a hot and ground connecting to the rest circuit.

Just spit-balling...

If you could find a concentric 25K pot you could merge the active's two 25K pots into a single unit, that would free up space for a concentric vol/tone 250K pot for the passive side. A 4-pole mini-toggle could use one pole to control power to the active unit (the stereo jack would turn it on whenever a lead is plugged in), another two poles switching the balance pot's connections from the active circuit to the passive vol/tone (500K would work for passive balance too) and the last pole could switch the jack's hot from the active circuit to the passive vol/tone. That *may* work.. but it would all depend on finding a 25K concentric pot.

Even if the above all worked out you'd still have the issue of a potential 'thump' going through to your amp if you ever switch from passive to active while everything is cranked.

[wokkaboy]

ah ok thanks for the reply Weirdy. It sounds all too hard to have an active and passive switch. I'll stick with the active system and drill a jack hole on the side and have the 4 pots on the control plate.

[Simon Barden]

Though you could come straight off the volume pot to a passive/active selector switch and go straight to the output from there. The volume pot appears to be an A500k pot which would leave the sound a tad brighter than normal (but you'll probably get a different tone anyway with the active circuit in place). You wouldn't have any tone control, but you've still got that balance pot to change the sound. Better than nothing if the battery fails during a gig.

You could expand on that and swap a tone pot for a dual-gang pot (so still only one knob) with A25k and A250k pots and add a capacitor to act like a standard tone control. Even if a 25k/250k dual-gang pot (i.e. common shaft, not-dual concentric) is hard to find, tapping off after the volume control still gives you a passive option.

You'd probably want to take the disconnected path to ground via a resistor to avoid unconnected wires acting as aerials and picking up noise, but you should be able to do that with a selector switch with the right number of poles.

[Brendan]

Go Ricky style - 2 jacks - active and passive.