inline humbucker with different size bobbins?

[wilser]

Hello,
I'm starting design for a 5 string bass that will use inline humbuckers but it occurred to me that everything I've read (and have experienced) about humbuckers is that they should have the same geometry and (approx.) number of turns. How would this work on a 5 string pickup where one would bobbin would span 3 strings and the other 2?

Thank you!

[Spence]

Actually it's not so rigid. You can get away with quite a large difference between bobbins in terms of turns and geometry but orientation is quite important. But then you'll have them in the same orientation anyway I suppose.

The other option is to make a choke to sit in series with your pickup system.

[wilser]

Sorry, but what exactly do you mean by 'choke'?

[Spence]

a small humbucker without magnets.

[Zhangliqun]

...aka, a dummy coil?

[NightWinder]

Killin Hum

[Spence]

...aka, a dummy coil?

Yes but a dummy humbucker. ie two coils that will take out the 60 cycle hum as the signal from the pickup passes through.

[David Schwab]

How would this work on a 5 string pickup where one would bobbin would span 3 strings and the other 2?

I've seen it done with two different size coils, and also with two same size coils. Mostly it seems to be done with a larger coil for 3 strings and a smaller for 2.

Now the question is, do you wind the same number of turns per coil (since turns=output) or do you wind to the same DC resistance, even though the geometry is different for each coil.

I haven't made any of these, so I don't have an answer. It's been on my To Do list, but I've been so happy with my regular humbucker design that I haven't bothered.

I'd try it both ways and see (unless the first way you try works out). I agree with Spence that it's not that rigid. Personally I would do same turn count on both coils first.

[wilser]

Any more recent wisdom or tests done on this subject out there?

[David Schwab]

Any more recent wisdom or tests done on this subject out there?

Wind each coil with the same amount of turns, regardless of the size of the bobbin.