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A Rather Odd String Spacing Question

Hi there, fellow TB'ers!

I recently finished a project in my high school metal shop class. This means that until all of the mentally 4 year old freshmen finish (which should be quite a while) I have free time and access to machines (lathe, vertical mill, drill press, files, welders, hacksaws).

I was hoping to build a custom pickup that I have yet to design because I have way too much homework and don't know certain dimensions. The latter brings to my rather unusual question: If you were going to build a pickup for a five (5) string bass, what string spacing would you use?

Just so you guys know, it's probably going to be a double humbucker, off set somewhat like a Warwick Corvette (I think). I'll use aluminum or steel for the outside (whatever my shop teacher can get cheapest) and either carefully milled or purchased magnets. To prevent buzzing, I will find some sort of thin rubber coating for the space between the magnets and the case.

Any answers or comments based on anything I said are appreciated! TIA!
 
String spacing is about as subjective as it gets. Depends entirely on the player, and his/her hands.

To prevent buzzing, I will find some sort of thin rubber coating for the space between the magnets and the case.

You need to properly pot a pickup with either wax or epoxy, to prevent microphonics. The reason that pickup builders place mechanical barriers between coils and the pole pieces they are wound on is to prevent damage to the coils and wire insulation, if the pole pieces need to be removed or adjusted later on.
 
I'm playing a Squier Affinity Jazz, 19 mm spacing. I really like it, and I never have any problems with the spacing.

However chances are I wouldn't use the pickup on my own build, unless I found a great deal on some nice wood. I will probably sell it here or (God forbid) on eBay. I will however try to build a bass when I get older and have a good job if I can't now, so I was hoping for some fun and experience.
 
Although i've never played 5 string, i do prefer a tighter string spacing on my 4's.
What if you made your pickup with blade magnets? That would make it useable with any spacing, providing that the lowest and highest strings don't vibrate off the magnetic field. Just Imo
 
Not to put a wrench in your plans (I like DIY projects) & I ain't no pickup guru, but metal (especially ferrous metal) might not be the best material for a pick-up casing...

Does your metal shop have a "winding machine"?

Anywho... I like 19mm at the bridge, but the location of your pick-up & nut spacing will determine the location of your poles...

Good Luck with the project & post progress pics...
 
Not to put a wrench in your plans (I like DIY projects) & I ain't no pickup guru, but metal (especially ferrous metal) might not be the best material for a pick-up casing...

It depends on tonal preference. Metallic casing influences the flow of Eddy currents, changing the voicing of the pickup a little bit. That's why some people like naked humbuckers, and some people like covered humbuckers, on guitars. Also, some metals can influence the shape of the magnetic field. A big part of the Telecaster vibe, for example, was the effect the bridge had on the bridge pickup. I'm citing guitar examples, because it's not as common to see these things factored into bass design choices. You really only see metal covers on Gibson-esque pickups.

I've never heard of a MM style pickup with a metal cover, however. I definitely wouldn't recommend choosing steel or aluminum based on which is least expensive. Steel is ferrous, while aluminum is not, and thus, there will be significant changes in tonality to factor into the design.
 
Okay... So a lot of people seem averse to the idea of a metal humbucker case. To at least try to prove myself right: http://www.talkbass.com/forum/f57/super-ambitious-first-build-no-woodworking-experience-855144/index19.html Suraj, who was apparently born with a gift for woodworking, used a metal case for his pickup. The pickup I plan to make will be similar, but not the same and with only two lines of magnets.
 
Okay... So a lot of people seem averse to the idea of a metal humbucker case. To at least try to prove myself right: http://www.talkbass.com/forum/f57/s...no-woodworking-experience-855144/index19.html Suraj, who was apparently born with a gift for woodworking, used a metal case for his pickup. The pickup I plan to make will be similar, but not the same and with only two lines of magnets.

Just because someone else did something, does not necessarily mean it is the best option for you. And just because someone else did something, does not necessarily mean that it turned out well for what it was intended for.

Focus on what you want, and how your design choices are going to help you achieve it, or work against it.
 
I've only ever heard of a couple of people machining plastic overs. They are usually molded.

As soon as I read my post I knew it sounded weird :p Molded is what I meant. What about non-magnetic stainless steel? I may be able to get access to that thru my teacher, or just buy some on my own.

BTW, I'll have a VERY rough first draft photoshop image coming out soon. Keep in mind that I am not a "pickup guru," so if there are any serious concerns or impracticalities, please feel free to tell me. I do take these things well. :D Thanks for all the help so far guys.
 
CAFED7F4-A2BF-4633-A66C-32037926C21A-1197-0000011EE5533313_zps91aafb11.jpg


So here she is. I realize that it is quite long, the point is to maximize range. The black dots are the magnets, the gray box is the case, the gray lines represent strings. Like I said, very rough, so please don't criticize me for that.
 
CAFED7F4-A2BF-4633-A66C-32037926C21A-1197-0000011EE5533313_zps91aafb11.jpg


So here she is. I realize that it is quite long, the point is to maximize range. The black dots are the magnets, the gray box is the case, the gray lines represent strings. Like I said, very rough, so please don't criticize me for that.

It would be MUCH easier to do a blade pickup instead of having 10 magnets, especially because your case design makes it impossible to wind the pickup. If you still want individual poles, thicken up that casing!

It's also not a good idea to make covers out of metal because it screws up your magnetic field. Plastic is cheaper and easier.
 
Were the coils originally planned as individual for each string?

A single bar would be much simpler. You could even use two bars to form a humbucker and still angle them.
Just offset them to keep the poles lined up with the strings.

Stewart-MacDonald (stewmac.com) has pickup parts plus fiber flatwork material for making custom bobbins.
The information on their website might give you some ideas.

I would design the bobbins first, and then design a cover to go over them, if you are going to make your own
cover.

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