Problem with left handed Jazz bass wiring

Hi folks,

Long time no visit since I've been off playing mostly guitar these days, but when bass beckons I heed the call. I just completed a total rewiring project (or so I thought) for my left handed Jazz bass, including a series/parallel switch. I didn't use a push-pull DPDT pot for the switch/tone control, because I couldn't find any such pots with a reverse log taper, but instead I have the usual VVT setup using CTS 250K lefty pots, and a separate toggle switch for which I drilled a hole in the control plate. All good you say? Well, was I surprised to find the tone control behaving exactly as I wanted, with a nice gradual sweep, but the volume controls behaving more like on-off switches. I want the change in volume to be gradual as well. Faulty pots or a wiring glitch on my part? I figured I couldn't go wrong with a mirror image of this:

 

Sure about that? I'm using CTS lefty not standard pots, so wiring them in reverse should have given me the volume taper I desired, as it is doing for the tone control. For reference I flipped the above and compared it to the Fender Standard Jazz Bass LH wiring diagram, and outside of the DPDT switch wiring they look identical. Could the switch be miswired?

JazzBass_2VppSP_1T_reverse by billgwx posted Jul 31, 2017 at 8:27 AM

Fender Standard Jazz Bass LH Wiring by billgwx posted Jul 31, 2017 at 8:28 AM

 

Any J wiring diagram I've come across specifies 250K pots. Not that it means I have to stick with them, but earlier this year I used 500K's in a Telecaster to go along with some high inductance pickups I installed in that guitar and man that thing is too bright...

 

Well I'll be damned. Went to the CTS web site hunting for specs, and found that the "lefty" pots I installed are linear taper, not reverse audio. False advertising by a lot of guitar/bass parts suppliers there!

Oh well, I'll live with it for now since most times I play the pickups mostly either full on or full off, sometimes with the bridge pickup full on and a touch of neck pickup, which may actually be easier to dial in with this taper. Maybe I'll put the old pots back in some time in the future since their volume taper was just fine, or grab some new 250K true reverse log pots via Mouser. Thanks all!

 

I like the switch over the push-pull DPDT so no loss there.

 

Yep it was between 10 and 9...a little too much.

 

Thanks again for all your great pointers! They'll have to wait though as life and recording beckon. Most importantly the bass is functional--the tone taper is better than with the push-pull DPDT series/parallel switch I had prior, and the volume tapers are usable as I mentioned above if not ideal. Replacing all the electronics also solved a noise issue, as I hear much less hum when the pickup volumes are uneven. Also, this could be my ears playing tricks on me, but the bass does sound a little different--I suspect that has a lot more to do with going from super light gauge (30-70) hex core GHS Boomers to medium gauge (45-105) round core Boomers to mix it up a bit.