Volume pot value with 3 Band Preamp

SunDevil

Turns out I was wrong thinking I was new to playing bass - I actually bought one in about 1998, which has been in my folks loft since I fledged

It's an Acepro Jazz / MM humbucker jobbie in which I'd installed a set of Baseline pups,  a 3 band EQ, blend and volume

I found it at the weekend and amazingly it all still works (original battery too) isn't all that bad as an instrument

The only issue is the sweep on the volume - it does nothing for the first 90% of it's travel and then rolls off abruptly to zero

I re-soldered the ground lug to earth and it definitely rolls off rather than going from full to zero

I'm thinking it's the pot value or solder leak onto the track? ..doubt I even used the volume back in the day ..either way, I'm going to replace it

So do I need a regular 250k pot or something different with the active preamp?

Funkfingers

Are the onboard electronics the stock AcePro parts or a Duncan/Basslines STC-3P? 

With a Duncan/Basslines pre-wired harness, the only difference between the versions for passive and active pickups is the resistance value of the Balance pot. 

On both Duncan/Basslines versions, the volume pot is rated at 10k Ohms with a push-pull to activate a preset Contour function. I rarely find the sweep on these satisfactory. Replacement values could go as high as 100k Ohms without loading the system and dulling the tone very much.

If the onboard electronics are the AcePro parts, please upload some photographs. 

SunDevil said:

The only issue is the sweep on the volume - it does nothing for the first 90% of its travel and, then, rolls off abruptly to zero.

Are either you or the bass guitar left-handed? It is possible that the volume pot has already been replaced once with an unsuitable component whose audio resistance taper is working in the opposite direction to the one you require.

SunDevil

Can't remember the make of the preamp but it's not stock - I'd guess it's a Bartolini based on a very vague memory, but it could also equally be an Axesrus special?

FWIW: Bartolini seems to suggest the stock 250k pot with their preamp

I don't know the existing pot value at present, but it's not short on brightness

The pot soldering has clearly been done by 'an expert' and I'm guessing I re-used the existing pots

It's all right handed and the volume sweep is in the correct direction, it's just the taper that's the issue

Funkfingers

Bartolini usually supply cheap-looking "dime" pots. IMO, their pickups deserve better.

In your situation, I would begin by cleaning the pot resistance tracks with electro-lubricant spray.

SunDevil

They are certainly dime sized pots..

I haven't tried spraying the pot yet, so worth a shot - ta!

If I need to replace, what value do I need though?

Funkfingers

SunDevil said:

If I need to replace, what value do I need though?

You options are 10k, 25k, 50k and 100k. 

ICBM

Is the pot wired 'backwards' - with the input to the rotor and the output from the end of the track? That works tolerably well with passive pickups (in fact Jazz Basses and Rickenbackers are wired like that) but not with active ones or a preamp, I think it will do exactly what you're describing.

I would also add 250K to the list Funkfingers gave, it will be fine with a preamp too. A standard good-quality Log pot of any of those values - although I would avoid 10K unless you know it's compatible - should do the job properly.

SunDevil

It's a bit of a birds nest - 'whoever' wired it up originally didn't bother cutting any of the wires to length (..I ask you!) but best I can see, the preamp goes to lug 1 and the wiper goes to the jack, but I'll check again this eve - thanks!

SunDevil

..nope, you were right as ever @ICBM - wired with the hot to the middle lug!

Seems my soldering skills were as good then as they are now!

PS - tried to 'double wisdom you' only to remove the one I did earlier, so have a 'Wow' for a change :-)