RCA-4 Bass wiring

[OctoberBassRCA-4]

JimC.,
Yes I further researched some Simon posts and I was wrong, 250K bassier, 500K treblier.
My kit came with 500K pots. Whether I use them or find some others, I guess I'll go that route till I choose later to change.
I do want to hear this combination of pickups, but things may change as I go along.
Just trying to understand the wiring process, and by doing that, I get the basic setup starting to formulate in my feeble mind.
Was just recounting the wiring process in my head during a mundane chore. That's a good thing?
I keep researching.

[fender3x]

The rule of thumb is that you use 500K pots with humbuckers and 250K pots with single coils. It's just a rule of thumb, and not a bad one in my limited experience. Single coils can have a fairly harsh top end, and 250K pots take some of the edge off. 500K pots also take off some of the high end, just not as much.

Neither pot does much of anything to lower frequencies. The same pickup may sound a little bassier with the 250K pots but that's just because it's taking a little more off the top so you're hearing a little more bottom, or at least hearing it more clearly.

You can play with these values. The only really good way of doing that, though is through experimentation. I wrote something in the wiring forum about the "resister trick" which is helpful for seeing how different value pots will sound when dimed if you want to try it.

In my experience with single coils (like lipstick tubes for example) you may want a lower value like a 100K because they pump out so much treble that they can be fairly harsh without a fair amount of resistance (lower number, higher resistance).

Humbuckers are the opposite. The same property that takes out the hum can also take a fair amount of the highs. So, it's not uncommon to see higher values, like 1 meg pots, on humbucker volume controls.

Gibson uses some values lower than 500K on their humbucker basses, and I have no clue as to why. They have a reputation for muddiness and lower values only seem like they'd contribute to that rep.

Tone caps are a different story. The volume pot will take some high end off your pickup's tone whether or not you turn the knob (unless it is a no-load pot). But tone caps only come into the circuit when you turn the tone knob. So if you dime the tone knob, the cap does not effect your sound.

Tone caps have a similar "rule of thumb" .047 uF for single coils, and .022 uF for humbuckers. I think the rule may be good for guitars, but in my experience values lower than .047 don't really roll off much treble. On the Bill Lawrence humbuckers on my last build .022 did very little to role off tone, and .033 didn't do enough. .68 meant most of the turn of the tone knob was too dark for my taste, so .047 is what I went with. There are basses with tone caps that are lower than .047, and it may be good with some pickups, but I have found that humbucking pickups on basses mostly like a cap that is a little lower than their guitar counterparts. I have limited experience, however.

So...a lengthy way of saying the diagram is probably a decent starting place, but you can also experiment to see what sounds best to you. You can also always change things later ;-)

[fender3x]

That should but .068 uF rather than .68....

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[OctoberBassRCA-4]

OK, with more research, and everybody's input, it's getting clearer.
In series wiring, one pickup runs thru the other to attain a tone and volume. Pot values and caps values effect that tone.
So... if the PBG supplied Single coil Neck pup-In Series (250K) back thru my GFS Humbucker (500K), "less highs" will be the result.
The reverse, HB thru Single coil, In Series, will the HB affect the overall tone adversely to the Single coil? Can that be done, is it a tone desired and how would one reverse the Series?

[Simon Barden]

If you connect two pickups in series, it doesn't matter which is the 'first' pickup, the sound will be exactly the same. You are basically adding the pickup inductances together but reducing the overall capacitance. The inductance will have the greatest effect on the sound, giving a bigger resonant hump at what is effectively the low-pass filter frequency. But you've also got other things like the pickup spacing to consider, as you'll also get some frequencies cancelling (either partially or fully) and likewise other frequencies summing in a similar manner.

And as you'll have three coils connected, you end up with a non-humbucking situation, so it won't be a hum-free position (unless you also tap the bridge humbucker so that you just get one of its coils connected and that coil is RWRP compared to the neck coil.

But my feeling is that the bridge pickup in series mode will be big and fat enough sounding that adding in the neck pickup in series won't really add much more. The bridge pickup in parallel mode is already big and fat sounding.

[OctoberBassRCA-4]

Good stuff Simon, thank you for clearing up how Series wiring works.
Shielding the bridge pup will be necessary then.

[OctoberBassRCA-4]

How about a Blend Knob Pot?
I know Rick's use them on six strings.
2 volume (HB bridge as a Coil Split), 2 tone, 3-Way Switch and the Blend Knob as the 5th knob.
Blend would dial in a pickup incrementally onto the other pup, and visa versa?
Maybe be more functional than the Rick setup?

Is this something that can be done?

[JimC]

Personally I've never to my knowledge even touched an instrument with a blend control, so I have nothing useful to offer!

[fender3x]

A blend knob would give less options than a master and individual pup vol knobs, and also be somewhat confusing IMHO.

Jazz basses sometimes replace the two individual volume controls with a master vol and a blend. I had mine set up that way at one point.

A master vol with vol for each pup is better and gives you more options as well as being somewhat intuitive...at least for me. Gretch has used this on guitars quite a bit, and on a bass or two as well.

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[Simon Barden]

The Ric guitar blend control apparently only works when you have stereo outputs and then allows you to add some neck pickup to the bridge pickup output. Or maybe the other way round. But how well it would work with bass pickups, I don't know. But you need to be using 'stereo' outputs (bridge and neck on separate jacks).