Where is Thumper (aka BT68) when you need him?

[JPJ]

Ok, I am currently building this

[attachment=1:P_Hamm_V___Full.jpg]
[attachment=2:P_Hamm_V___Body.jpg]

a five string precision (mighty mite neck, custom body) which is going to be equipped with 2 x Bartolini 'J' pickups + 1x Bartolini 'P' pickups all going via a stock Fender five way switch to a custom East circuit (basically a BTB + MID Sweep pre-wired with vol, output socket and battery clip).
The switching options I want are;

1) Both J p'ups with a slight bias towards the bridge p'up for a jazz bass style finger style setting
2) Bass J p'up with P p'up
3) P pickup on its own
4) P p'up with Bridge J p'up
5) Both J p'ups full on

I can work out how to wire positions 2 to 5 but I am struggling with position 1. I was thinking of measuring the resistance of the pan pot in my J-Retro equipped Jazz bass at my 'stock' mix and bridging the No1 and No5 tabs on the switch with a resistor of equivalent value but then I thought that this will effect the number 5 position, as I was just going to put a jumper wire between 1 & 5 for the both pickups full on option. So now the exam questions;

a) is it possible to do what I want to do?

the five way switch appears to have two independent switch matrix's (ie either side). Should I wire all the signals to one side and the grounds to the other or do I just wire the signals and collect the grounds together (John E has helpfully attached two short wires to show me where the signal and grounds connect to his circuit)?

c) if its not possible to do what I want, any ideas what I can do with position 1?

All advice gratefully received!

[d-basser]

I cant help with how to do it but for c) if you cant just wire 1 as a kind of kill switch type off thingy like on the Mk1 Urge bass

[JPJ]

A kill switch?

What, you mean guaranteed opportunity to disconnect yourself from any sound at all mid-gig?

Believe me, after twenty odd years (actually make that twenty nine odd years ) of playing bass, I have found every possible way of disconnecting myself mid-song without ever needing a dedicated kill switch

Thanks for the input though!

[Steve_K]

I can't see that connecting a resistor between 1 and 5 would make any difference to the sound on 5, as 1 would not be connected and so the resistor would play no part in the signal path.

Unless I've misunderstood you, it's all grand.

[d-basser]

I suggested the killswitch because the Urge has it, i take your point that it may be a recipe for disaster.

[Steve_K]

Actually - a resistor between 1 and 5 *would* affect them both, so you'd need a diode in there too.

[JPJ]

I thought of the diode, but that's starting to get way beyond my electronics capabilities to specify the right parts. I guess I actually need two diodes, one for the 'both on' option and one for the both on but reduced neck p'up option?

[Steve_K]

Regarding the diode, something as standard as a 1N4001 would probably do the job.


[attachment=16:Here_we_go_again.jpg]

Top: Probably would work
Bottom: Extra diode, which could be added if the top didn't work properly.


Oh, and regarding the testing of resistance of the JE-Retro, just stick a variable into your circuit, find out what you like it at and change that to a fixed (or preset pot, which is still variable but it won't get changed sitting inside the cavity.)


Sorry for the woeful diagrams, but it's rather early and I have a hangover again

[franzbassist]

The Fender Roscoe Beck bass has the facility to reduce the neck output slightly as you want to. Roscoe says "a 27k resistor goes across the neck pickup to slightly reduce its output" when you pull up the volume knob. Does that help?

Monster looking bass btw (in a good way!)

Edited May 17, 2007 by walbassist

[JPJ]

Thanks for the help guy's, the 27k option is probably the one I'll go for as fitting a variable is probably a bit beyond my electrical abilities!

[Lfalex v1.1]

[quote name='JPJ' post='350' date='May 17 2007, 02:21 PM']Thanks for the help guy's, the 27k option is probably the one I'll go for as fitting a variable is probably a bit beyond my electrical abilities![/quote]

What about a dinky lil' trim pot instead? that'd be tweakble for exactly what you want.
Install it so that you can adjust it with a screwdriver through a small hole in the control cavity cover...

Just an idea. My Hohner has one, to match the active level to the passive level so you can go from active to passive or vice-versa without huge volume gains or drops.
Works a treat. Slightly different application here, but the idea seems good.

[Steve_K]

That's a preset variable, doesn't want to go down that road

[Kiwi]

you could maybe ask Oxblood or OBBM?

[Toasted]

JPJ I suggest you clutch at straws.

PM sent

Edited May 20, 2007 by Toasted

[Oxblood]

I suspect that Thumper is currently unable to get to his computer, having accidentally imprisoned himself inside an enormous Bill Fitzmaurice sub-woofer. That'll teach him to use 5 minute construction adhesive!

[Buzz]

[quote name='Oxblood' post='3318' date='May 21 2007, 04:42 AM']I suspect that Thumper is currently unable to get to his computer, having accidentally imprisoned himself inside an enormous Bill Fitzmaurice sub-woofer. That'll teach him to use 5 minute construction adhesive![/quote]


To yourself and to the OP:

Sadly Thumper is no longer with us due to disagrements, so will be pretty much on Finnbass

[url="http://basschat.co.uk/index.php?showtopic=261&view=findpost&p=2767"]http://basschat.co.uk/index.php?showtopic=...post&p=2767[/url]

[Oxblood]

Gosh, that's a surprise.
Righty ho then. Whatever Steve's reasons may be for not wanting to do his thing on dis hya forum, I'll respect them.