Question about STC-3M3 preamp and multiple volume knobs

unshokie

New member
I have the STC-3M3 preamp installed in a P-Bass currently and really like what it does for the sound. I am thinking of building a P-Bass with a jazz bass style humbucker in the bridge position and using this preamp in it. My question is why are there varying pot values in the wiring diagrams and what pots should I be using in a P/J setup with this preamp (passive pickups). The diagrams show a 10k pot, unless you use 2 vol pots, in which case it calls for 250k. Why the jump?
1vol.JPG2vol.JPG
 
Re: Question about STC-3M3 preamp and multiple volume knobs

250k pots match with passive Fender-derived bass guitar circuitry. Pots in the 25k - 100k range match with active pickups.

To use the STC-3M3 or M4 with a PJ pickup array will require the addition of either a balance panpot od suitable desistance, a second volume pot or a pickup selector switch à la Stingray HH and Sabre Bass.
 
Re: Question about STC-3M3 preamp and multiple volume knobs

I'd prefer to use two volume pots for this setup instead of a balance/pan pot and avoid a selector switch. I still don't get the 10k pot with a passive MM pickup, which is how the diagram is laid out.

Oh, and thanks for the help!
 
Re: Question about STC-3M3 preamp and multiple volume knobs

The volume pot is 10k because it interacts electronically with the preamp, and not the pickup (like a traditional passive volume control). If you want to use 2 volumes, you'll want to use 250k and connect the pickups to them the same way as a pair of Jazz Bass pickups hooks up to the volumes. Then, you just eliminate the 10k volume by connecting the input wire to the output wire (essentially hardwiring around it).
 
Re: Question about STC-3M3 preamp and multiple volume knobs

connecting the input wire to the output wire (essentially hardwiring around it).

Pickup output directly to volume pot input is precisely what I did when installing an active pickup and STC-2 in a Fleabass.



There are arguments for sequencing the circuitry PU > Balance > EQ > Volume > jack socket but these are not relevant to this thread.
 
Re: Question about STC-3M3 preamp and multiple volume knobs

Thanks Scott! That was the answer I was looking for on the 10k pot and I appreciate the help from both of y'all with this setup!
 
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