Volume pot value question.

fretmeister

I just noticed that the EBMM Joe Dart original sign model - the passive Ray / Sterling hybrid - has a 100Kohm volume pot and nothing else.

IIRC most bass pots are 250Kohm, so what would be the effect of a 100Kohm pot?
Is this specific to using a MM type pickup passive or just part of the custom options he wanted?

ICBM

It actually makes a lot of sense - the EB Stingray pickup is parallel-wired, meaning it has a lower impedance than a normal single coil or humbucker, so a lower pot value would suit it. Also, in a Jazz Bass, the same is true when both pickups are on - and that has two 250K volume controls in parallel, giving an effective load of 125K, so 100K is probably about right for a passive Stingray pickup.

fretmeister

ah - I had not even thought about the lack of a tone control making a difference.
That makes a lot of sense.

Well - that's a lot less wiring for me to get wrong then!  

ICBM

fretmeister said:

ah - I had not even thought about the lack of a tone control making a difference.

Yes, that will probably make the remaining difference between 125K and 100K, since the tone pot makes a small difference even when it's up full.

Funkfingers

Regular Stingray, Sabre and Sterling (the model, not the brand) basses have onboard active EQ. IIRC, there is a buffer somewhere in the circuit. The fully passive Joe Dart model does not require any buffering.

fretmeister

ICBM said:

fretmeister said:

ah - I had not even thought about the lack of a tone control making a difference.

Yes, that will probably make the remaining difference between 125K and 100K, since the tone pot makes a small difference even when it's up full.

I'm assembling / butchering bass to make a passive ray type and while I love the simplicity of just a volume, sometimes I can't get to my amp controls when on stage.

So I'll probably stick with a Vol and tone at 250K each. The body already has the holes in it anyway!

ICBM

fretmeister said:

…sometimes I can't get to my amp controls when on stage.

So I'll probably stick with a Vol and tone at 250K each.

That’s what I would do too. In fact, if you want even more control from the bass, you can use the ‘amp type’ or ‘variable treble pass’ wiring for the tone control, which allows you to brighten the sound as well as dull it.

Connect the volume pot as normal, with the pickup to the clockwise end terminal and the jack to the middle.

Connect the middle terminal of the tone pot to the pickup on the volume pot. Connect the normal tone cap (.047 or .1uF) between the anticlockwise terminal and ground, as normal.

The extra bit - connect the treble-pass cap (470pF or 1000pF) between the normally unused clockwise terminal of the tone pot and the middle terminal of the volume pot. Now, when the tone is up full and you back the volume off, the sound gets brighter. It’s not as effective as the treble boost on an active bass, but I think it would work well with the Stingray pickup.