Music Man bass pickup with screw poles

[Alberto]

A customer asked me to build a custom Music Man Bass pickup with screw poles instead of rod magnets or slugs, is there anyone willing to help me with insights and possible ways to go?

This is what I figured out till now:

- 42AWG wire. Each coil approx. 4k

- I have some flatwork to cut the bobbins to the specified measures (Coil Height: .246", Coil Width: .678", Coil length 2.922"). I’ve found the specs here (Coil Height: .246", Coil Width: .678", Coil length 2.922")

- I’ll build a wood spacer 6mm (0.246’’) tall for the screws and to hold the bobbins flatwork together.

- I’ve found some zink plated, low carbon, slotted head cheese screws. The head has a 8,28mm (0.325’’) diameter.

- I only have standard humbucker bar magnets. Would these fit?

- What a about a metal spacer for the screws? To I need to build and drill one?

Any help would be really appreciated!!!

Thanks,
Alberto

[big_teee]

Good luck on your project.
If you are going to that much trouble, I would make multi-coils.
Like the Wal bass pickups.
https://www.google.com/search?q=wal+...w=1366&bih=592
Try searching for Wal Pickups here.
There has been some projects like that in the past.
T

[mr fab]

possibly an easier way would be to buy a cheap chinese copy and take it apart. you will have the cover, bobbins and other parts already without going to so much effort

as for polepieces, I would use hex grub screws which should be easy enough to find, or if you want slotted then I would use pieces of treaded steel rod which you can cut slots into

just my 2c worth...

[mr fab]

almost forgot... I have an old music man Sabre guitar here and the pickup bobbins are wired in parallel .... I suspect the bass pickups were similar

[Alberto]

Thank you Terry! What would be the advantages of a multi-coils design over two standard bobbins? A multi-coil it's a lot of winding!

[Alberto]

almost forgot... I have an old music man Sabre guitar here and the pickup bobbins are wired in parallel .... I suspect the bass pickups were similar

Parallel? Good to know, thanks, I would have gone with a serial wiring.

I'm also considering cunife threaded magnets, but I've never used them on a bass guitar. Maybe a couple of ceramic magnets are the easiest and most effective way to go.

[mr fab]

Parallel? Good to know, thanks, I would have gone with a serial wiring.

I'm also considering cunife threaded magnets, but I've never used them on a bass guitar. Maybe a couple of ceramic magnets are the easiest and most effective way to go.

yes or maybe some small neo disks

I don't know if you can get cunife that easily these days... good luck

[big_teee]

Yes, MCs are a lot of work, but IME the sound is worth it.
However I build mine with 3/8 rod magnets, I like the tone of Alnico.
Things to keep in mine with MM pickups?
If going in a regular MM bass, they are routed differently, so make sure your design will fit.
If you want the MM sound, ceramic, and Neo will probably sound different that regular MM Alnico coils.
As far as Parallel vs. Series?
If you are using a preamp, I would go parallel, if no preamp I would go Series.
You can try wiring them both ways.
T

[David King]

Find out what this customer thinks they will achieve by having steel threaded poles vs the alnico slugs of the original design.
If they just want adjustable poles then consider staggered alnico poles or threaded magnets (glue some springs aka thread repair kits to the outside of 5/16" poles and grind a slot in the top of each magnet with a Dremel tool so it can be turned with a screwdriver.
If the customer thinks that steel is going to add some magical element to their sound then I'd base the design as closely as possible on a Ken Smith (Kent Armstrong) pickup which already sounds great rather than trying to reinvent the wheel. Ceramic magnets, M6x1.0 setscrews that may be annealed or lower carbon to start with. Possibly around 5k turns of 42 on each coil.

[Alberto]

Thanks to all for your advices!
I'll investigate with the customer to better understand his needs and then go for either a ceramic design, similar to the Kent Amstrong MM pickup, or one with threaded magnets (Sensmag could have them?). I'm also going to suggest him a push-pull pot for serial-parallel wiring.

Alberto

[jbltwin1]

A lot of info here: Home - Musicmanbass.org, Music Man, Musicman, Music Man Bass, Musicman Bass, Music Man Guitar on MM bass stuff if you're interested.

[Alberto]

A lot of info here: Home - Musicmanbass.org, Music Man, Musicman, Music Man Bass, Musicman Bass, Music Man Guitar on MM bass stuff if you're interested.

Thank you! I came across that site yesterday, lots of infos in there!

[Peter Naglitsch]

It might be covered in the page to were the link point, but from my experience the musicman pickups get most of their sound from the fat, wide magnets and the ability to switch between series/parallel. The question about why the customer want adjustable poles is valid. What is he looking for? It will not sound like a MM pickup anymore if you don't go with the excellent suggestion from David King to make ordinary alnico magnets adjustable

[Alberto]

I didn't understand David King's suggestion at first But now I get what he means! I've found a source for some M8x1.25 Helicoil thread repair inserts, I think they will do. I'm a bit worried about the dremel part, I've never used one, I think I should look for someone more skilled than me...

[David King]

The thread inserts exist to replace stripped female threads in things like engine blocks. They are very much nonstandard threads (on the outside) that require a special tap. Normally the inserts are sold with their tap, Sensmag threaded alnico magnets might actually be a cheaper way to go. Of course you are threading into a rather soft material, forbon and if you drill the right sized hole in forbon the helicoils or sensemags will easily form their own threads. Helicoils are steel hence magnetic so they will change the sound possibly.
the M8x1.25 thread has a minor diameter of between 6.6mm and 6.9mm so your magnets couldn't exceed that...
Here's a table https://mdmetric.com/tech/LimitingDimensions.htm Unfortunately there aren't metric helicoils that have an internal thread dia that matches up will with any standard magnet sizes.
You could check SAE NSF thread charts to see if there's a good fit.