Jack Casady bass prob...

htbgen · #1 07-02-2009, 06:02 AM

I've had the JC for about 4 years. Bought it new, love it to bits but I'm pulling my hair out with the electrics. The pots have been a problem from the outset - they crackled & buzzed like crazy if I even looked at them, much less adjusted them. Couldn't get any of the 2.5K pots anywhere - after about a year of searching, the Gibson Europe people (I'm in the UK) came up with 2 pots...soldered them in and...same as the old pots. 2.5K is such a rare pot value that I gave up on the traditional sources & got some from an industrial component supplier...hey, no more crackle & buzz. It's required some mods to get them to fit, and the taper is less than ideal but they work.
Which brings me to the real purpose of this post - when the volume is backed off even a hair from full volume, the tone opens up fully, regardless of the tone pot position. The bottom line is that as soon as the volume is backed off from full, the tone pot is effectively taken out of the circuit. Yeah, I could leave the pots alone and adjust off the amp, but this is a real pita...just not flexible enough on stage. I'll say at this point that this problem has been there since the bass was new, and so is not a result of the new pots. Also, the varitone circuit has always worked fine.
I've thought about ditching the pickup & electrics and replacing with a more conventional system, but I love the unique sounds the JC is capable of, and so am loathe to do this.
If anyone has any ideas on this I'd be eternally grateful - I really want to make this bass work as it should.

daftsubverter · #2 07-20-2009, 07:55 AM

I've had the exact same problem with my Jack Casady Bass. I've searched all over trying to find a solution, but to no avail. It's heartbreaking that the electronics problem prevents this wonderful instrument from reaching its full potential.

SGD Lutherie · #3 07-20-2009, 09:01 AM

2.5K pots are easy to find in audio taper if you go to an electronics parts supplier.

It sounds like the tone control is wired in the wrong location.

Here's the way the bass should be wired:

http://www.gibson.com/Files/schematics/LPSig.Bass.PDF

That's for the original Gibson Les Paul Signature bass, which is what the Jack Casady Bass is a copy of.

The tone pot should be wired right after the pickup.

Is this how they wired the Jack Casady Bass?

The "varitone" is actually an impedance switch which works with taps on the output transformer. A real varitone is something different.

Personally I never turn down the volume control on my basses unless I want to mute the signal.

htbgen · #4 07-20-2009, 04:29 PM

Thanks for the Gibson schematic...here's the JC diagram by way of comparison - I'm not that wised-up on electronics to be able to evaluate, but I'll scratch my head over them for a while.

heroesofalma · #5 07-20-2009, 04:59 PM

Hullo

I had the same problem. Pots slowly ceased to function. Returned the bass to dealer (in Melbourne at the time) and they replaced the pots with two from another Casady bass in shop. Same problem...

In the end I gave up on the mysterious 2.5k Audio Taper pots that Epiphone surely generated thru an OEM order with terrible QC.

I had a tech put in CTS 5k Audio Taper pots currently available for use in vintage Fender amps. It's a happier bass and I can now turn down the volume when using the crazy highest setting on the varitone.

The pots however are smooth shaft and the original Gibson knobs won't fit on. I just popped on some Fender Jazz Bass Vol knobs.

I'm not knowledgeable in this respect, but I can't help feeling the magic spot I used to find with the tone browned off 3/4 the way has shifted and the treble content of this bass has changed?

Good luck Casady owners. It's a great bass at a fantastic price point, but spec wise, I would have taken CTS pots over the bone nut that came installed anyday.

Rob