Bassic Pickup Winding Conversions

[ken]

Hello all,

I've been playing a lot of bass lately, so much that I just bought a 5 string P bass.

My old 4 string P bass has a pickup I really like the sound of, and I'd like to make a 5 string
version of the pickup for my new bass.

Given the different bobbin dimensions of the 5 string pickup compared to the normal one, how do I change the 5 string's pickup design so I can keep the 4 string's sound?

Thank you,
Ken

[Mike Sulzer]

I doubt that you can make it the same in all respects, but since the bigger coil will have somewhat greater inductance, I would expect that somewhat fewer turns would help. But I think this is a case where you have to try and listen.

Hello all,

I've been playing a lot of bass lately, so much that I just bought a 5 string P bass.

My old 4 string P bass has a pickup I really like the sound of, and I'd like to make a 5 string
version of the pickup for my new bass.

Given the different bobbin dimensions of the 5 string pickup compared to the normal one, how do I change the 5 string's pickup design so I can keep the 4 string's sound?

Thank you,
Ken

[copperheadroads]

Same height & except longer ? the coil estimator should help you with the math .

[big_teee]

Some p-bass 5 string bobbin dimensions would be great to have, for records, and future reference.
If anyone has these dimensions, please post them here.
T

[David King]

Find the shells or reuse the ones on your new bass but I'd first figure out what the current 5 string pickup is. It might be plated steel pole pieces with ceramic magnets stuck to the back. Just taking those out and stuffing Alnico poles into the plastic bobbins could get you close enough.

[LtKojak]

Some p-bass 5 string bobbin dimensions would be great to have, for records, and future reference.
If anyone has these dimensions, please post them here.
T

MAGNETICS PICKUPS-Magnetics P532A

Not actual measures, but if the smallest is like the standard P-bass, the one for three strings is easy to calculate, even from the photo.

HTH,

[big_teee]

Outside to outside magnet bobbin length measurements is what I was looking for on the 3 string bobbin.
If anyone has one they could mic, that would dismiss the guess work.
Bobbin Core Dimensions, length, width, height, flange?
Thanks,
T

[ken]

The 5 string P bass pickup bobbin I'm looking at is basically a stretched version of the 4 string with two extra magnet holes. The ones here are cheep plastic way too tall with red coilwire steel poles and ceramic mags... the usual. I want to make mine the way Leo intended. I am assuming that the space between flats, polepiece distance, etc. would be the same as a normal P bass bobbin.

This is the bass pickup style I'm referring to... Fender American Professional Precision Bass V Maple Fingerboard | Musician's Friend

I was really curious about the coil, as if you wind the 3 string bobbin to match the smaller 2 string bobbins resistance, the turn count, inductance and other factors go out the window. If you match turn count, the math goes the other way with too much resistance and inductance. Remember the P bass pickup is a humbucker...

Weird.

Ken

[rjb]

From the peanut gallery

I was really curious about the coil, as if you wind the 3 string bobbin to match the smaller 2 string bobbins resistance, the turn count, inductance and other factors go out the window. If you match turn count, the math goes the other way with too much resistance and inductance. Remember the P bass pickup is a humbucker...

Here's an arbitrary suggestion:

Wind the 3-string bobbin so its turns x coil area product is the same as the 2-string bobbin.
Then measure the coil inductances just for comparison, and test in the bass to see if you have good volume balance between the two coils.
Remember that the pickup's total inductance is just the sum of the individual coils (more or less - I'm guessing that mutual inductance is negligible).
Remember that you can finesse resonant frequency and Q with external capacitors and/or resistors.

You've got to start somewhere....

[Mike Sulzer]

The 5 string P bass pickup bobbin I'm looking at is basically a stretched version of the 4 string with two extra magnet holes. The ones here are cheep plastic way too tall with red coilwire steel poles and ceramic mags... the usual. I want to make mine the way Leo intended. I am assuming that the space between flats, polepiece distance, etc. would be the same as a normal P bass bobbin.

This is the bass pickup style I'm referring to... Fender American Professional Precision Bass V Maple Fingerboard | Musician's Friend

I was really curious about the coil, as if you wind the 3 string bobbin to match the smaller 2 string bobbins resistance, the turn count, inductance and other factors go out the window. If you match turn count, the math goes the other way with too much resistance and inductance. Remember the P bass pickup is a humbucker...

Weird.

Ken

As long as the two coils are connected in series, it is the total series inductance that counts for setting the frequency response, that is the resonance with the cable capacitance. That is, you have one circuit because two circuit elements of the same type in series become one. This is not quite true because the two individual coil capacitances are not the same, and that gives a bit of "individuality" to the two halves of the circuit, but they are less important because the cable capacitance is larger. So, do not worry about different inductances.

Presumably you want the sensitivity of the two coils to be the same. If the magnets are the same, putting the same number of turns on each will get you close. Making the resistances the same would give you significantly different numbers of turns, and that would not have the same sensitivity.

[Mike Sulzer]

Here's an arbitrary suggestion:

Wind the 3-string bobbin so its turns x coil area product is the same as the 2-string bobbin.

I do not agree with this because the component of time varying flux pointing through the coil is mostly confined to the area near the corresponding pole piece. Thus the area of the whole coil is not a good predictor of sensitivity.

**When computing inductance, or the response to an external hum field (which does cover the whole area), it would be the proper thing to use.

[rjb]

I do not agree with this because... Thus the area of the whole coil is not a good predictor of sensitivity.

**When computing inductance, or the response to an external hum field (which does cover the whole area), it would be the proper thing to use.

As long as the two coils are connected in series, it is the total series inductance that counts for setting the frequency response... So, do not worry about different inductances.

Presumably you want the sensitivity of the two coils to be the same. If the magnets are the same, putting the same number of turns on each will get you close....

Ha! I knew someone who knows his stuff would chime in!

I do suppose that matching coil sensitivities should have priority over "perfect" humbucking....

But on the other hand, maybe you'd want the coil under the fatter strings to have slightly lower sensitivity- for the same reason that Charlie Christian pickups had a notch under the 2nd string....

But on the other other hand, I guess you could compensate with staggered pole heights....

So many choices. So many tradeoffs. But I bet the "perfect" number of winds is somewhere before Mike's and my suggestions.

-rb

[Chris Turner]

Could this be achieved by making two of the 3-string bobbins, but on one, say where the A string is (which would have two sets of poles underneath), don't magnetize the poles? Seems this would solve the coil size problem and possibly the inductance problem, too.

I could be way off, but intuitively it seems right.

Then again, this makes for a weird looking set of P bass pickups.

[Mike Sulzer]

Could this be achieved by making two of the 3-string bobbins, but on one, say where the A string is (which would have two sets of poles underneath), don't magnetize the poles? Seems this would solve the coil size problem and possibly the inductance problem, too.

I could be way off, but intuitively it seems right.

Then again, this makes for a weird looking set of P bass pickups.

I think that is a good idea, but I would want to test before committing.

[David Schwab]

Most of the time you will find that pickup makers stick to the same number of winds. So the 5 string models will have a bit more wire on them. This is even true with something like EMG pickups.

I just do the same number of winds for 4, 5, and 6 string pickups. They don't sound different enough to worry about it.

For split coil pickups with an uneven number of strings, you run into the issue with each half of the pickup sounds different, such as on a 5 string P bass, or split J pickup. Then you need to juggle winds to balance tone vs. hum cancelation.

I came up with a solution for that, but I'm keeping it to myself.