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Sterling Passive conversion

#2
I don’t believe the pickup is active in any way, it’s just wired up to an active preamp. The pickup probably has four wires, two going to each coil in the pickup. You have a few options.

1. Volume, balance, tone, which would use the balance control to select the coils in the pickup, and you would probably get hum if you solo either coil.

2. Volume, volume, tone, which is much like Jazz wiring, and would likely come with hum if you don’t have both volumes wide open, just like a Jazz.

3. Volume, tone, which would be like Pbass wiring with the two coils in the pickup permanently wired in series or parallel, or you could put a series / parallel switch in the 3rd hole.

4. Volume, tone pot, rotary cap selector with the volume or tone pot also being a push-pull switch to select series or parallel wiring of the two coils in the pickup.

The simplest is #3, which would require a couple 250k pots and probably a DPST rotary switch to change the pickup wiring between series & parallel wiring, bridge coil, & neck coil, but you would still get hum with either coil solo’d.
 
#3
DoctorZeus said:
...
I want to make it passive. Does anyone have a parts list
...
Click to expand...

upload_2024-2-26_6-54-18.jpeg

upload_2024-2-26_6-55-22.png
 
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#4
Tim Skaggs said:
I don’t believe the pickup is active in any way, it’s just wired up to an active preamp. The pickup probably has four wires, two going to each coil in the pickup. You have a few options.....
Click to expand...

Tim,
Thank you for the reply. My plan would be to pick either series or parallel and just hard wire it up that way. I would not put a switch in the circuit. Have you ever seen a diagram as to how to wire the pickup directly to the pots while eliminating the onboard preamp?
 
#5
No, but a diagram of how a P-Bass is wired would get you there. With a dual coil / 4-wire pickup, “series” would use the two wires currently in use and the other two would stay connected together. For “parallel”, you would separate the two wires connected together, solder one to hot & one to ground (you would need the bass connected to an amp to see whic wire goes where). It wires up the same, but parallel has two wires to hot & two wires to ground.

A dual coil / 4 wire pickup is like having two single coil pickups, and Jazz bass wiring will work. A Jazz has a volume for each pickup and the pickups are in parallel via their volume pots being tied together with a wire going to the output jack. If you wire the pickup in series, it wires up like most PBass pickups, which are usually in series. I just changed the neck pickup (like a PBass pup) in my Ibanez Mikro to parallel wiring this morning.
 
#7
Tim Skaggs said:
No, but a diagram of how a P-Bass is wired would get you there. With a dual coil / 4-wire pickup, “series” would use the two wires currently in use and the other two would stay connected together. For “parallel”, you would separate the two wires connected together, solder one to hot & one to ground (you would need the bass connected to an amp to see whic wire goes where). It wires up the same, but parallel has two wires to hot & two wires to ground.

A dual coil / 4 wire pickup is like having two single coil pickups, and Jazz bass wiring will work. A Jazz has a volume for each pickup and the pickups are in parallel via their volume pots being tied together with a wire going to the output jack. If you wire the pickup in series, it wires up like most PBass pickups, which are usually in series. I just changed the neck pickup (like a PBass pup) in my Ibanez Mikro to parallel wiring this morning.
Click to expand...
Looks like mine is only a two wire pickup. Changing the pots might be in order too. Not sure how to spec that out.
 
#8
DoctorZeus said:
Here is the current wiring diagram....
Click to expand...
You would be taking out everything but the jack and the pickup. The pots are the wrong value to use passively.

DoctorZeus said:
Looks like mine is only a two wire pickup. Changing the pots might be in order too. Not sure how to spec that out.
Click to expand...

I’ll bet your pickup has a red & green wire connected together, putting the two coils in the pickup in series. The picture below shows my bass pickup wire, the end of the insulation that holds all four wires is circled in blue. Wires are black, white, red, & green on mine.
Get two short shaft 250k ohm pots with knobs to fit, a .047uF cap and a P bass wiring diagram. Use the black and white wires. You will have an extra hole. You could put a kill switch in there.
IMG_6154.jpeg
 
#10
DoctorZeus said:
[QUOTE="Tim Skaggs, QUOTE]
So like the attached picture?View attachment 5365596
Click to expand...
Yes, this will work. If you do have a 4 wire pickup, you could experiment wiring the pickup in parallel. It would look the same but you would have black + red going to ground and white + green going to hot. (Could be black +green & white + red).

A PBass pickup will have a jumper between the coils that put it in series. I drew in a red & green wire to represent how your pickup is probably configured now.
IMG_6157.jpeg
 
#11
Tim Skaggs said:
Yes, this will work. If you do have a 4 wire pickup, you could experiment wiring the pickup in parallel. It would look the same but you would have black + red going to ground and white + green going to hot. (Could be black +green & white + red).

A PBass pickup will have a jumper between the coils that put it in series. I drew in a red & green wire to represent how your pickup is probably configured now.
View attachment 5366856
Click to expand...
I have a Sterling Musicman bass so not sure how that pickup is wired yet.
 
#12
Doesn’t matter how it’s wired now if that’s all coming out, but I’m sure it’s wired like the diagram you posted. I’m just saying you have the ability to switch between series and parallel or you have the option to try both before everything is soldered up permanently.
 
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#14
Sub pickup is wired in series internally and potted in epoxy so you can not change that. The P-bass diagram will work, but I doubt you will like the tone from sub pickup in a passive schematic. You can get Danlis pickup from Aliexpress. It is cheap and more like a ray 34 pickup and with 4 wires. The pickup is I think under $40 including free shipping. But once you start that way, who knows when you stop. I can see a month from now you will be putting dark glass preamp and a SD pickup or something like that. Might as well skip the cheap step and just get what you will not doubt.
 
#15
kgbeast said:
Sub pickup is wired in series internally and potted in epoxy so you can not change that. The P-bass diagram will work, but I doubt you will like the tone from sub pickup in a passive schematic. You can get Danlis pickup from Aliexpress. It is cheap and more like a ray 34 pickup and with 4 wires. The pickup is I think under $40 including free shipping. But once you start that way, who knows when you stop. I can see a month from now you will be putting dark glass preamp and a SD pickup or something like that. Might as well skip the cheap step and just get what you will not doubt.
Click to expand...
Interesting. My goal is to make it sound more P bass"ish". I got the bass cheap so it is my experimental rig. I was going to try passive wiring with a pedal/preamp box as a first step. I know it won't sound exactly like a P but closer is the goal for now.
 
#16
IMO the MM PU will sound more like a P bass in passive mode. I replaced my vol with a push/pull pot so I could switch active/passive. That way I kept the existing sounds and added a softer warmer passive sound. I EQed the amp for this sound, and EQed the active sound onboard to fit.

If the 2 coils can be accessed and wired individually, then I would add a 2nd push/pull pot and take advantage of the series/parallel option too.

The PU would wire directly to this switch before the active/passive switch, and the series/parallel option could then be used both actively and passively. More sounds at your fingertips.
 

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