Pickup Sensing Area

[scolba]

Hey Folks,

Spending some design time on my build and am at a point where I need some advice. There have been a couple of threads on this that I found but didn't get any real definitive answers out of them, so am hoping to find that here.

The question is: How much inside of the sensing area or aperture of a pickup should the strings be? Is there a rule of thumb for that? Additionally, is there a variation on that when considering humbuckers vs single coils?

For my situation specifically, I am looking at a Bart Classic Bass in M4. Plotting the nut string position and bridge spacing, as well as the sensing area inside the pickup, it gives me a bit over 4mm on the neck side of the pickup and 3.5mm on the bridge side.

So, I am currently wondering if that's enough. But also, I would like to learn more about the "why" for future builds. On one hand that seems pretty tight, given how much the strings can move in and out of their center line. But on the other hand, magnetic fields don't exactly stop right where the material stops either, so not sure what to think.

Appreciate any guidance!

edit: Sorry Mods, I probably should have put this in the pups and electronics section.

 

[Freekmagnet]

The strings need to be directly over the poles. The sensing area of the pickup does not extend further than the ends of poles (there is a sharp drop in output). In fact, you should have a little more pole on the bass and treble sides of the poles in order to accommodate string bend and the actual vibration path of the string.

The width of the poles vary depending on the pickup.

 

[scolba]

Thanks Jermey, appreciate it. So when Bart publishes their "sensing area" dimensions, is it safe to assume that those are the widest dimensions of the poles themselves?

In fact, you should have a little more pole on the bass and treble sides of the poles in order to accommodate string bend.

So that kind of comes back to my original question. How much should those poles extend beyond the strings?

 

[Freekmagnet]

Thanks Jermey, appreciate it. So when Bart publishes their "sensing area" dimensions, is it safe to assume that those are the widest dimensions of the poles themselves?

I’d trust what Bartolini says, although I couldn’t tell you if they are widest dimensions of the poles themselves. The only way you can be absolutely sure of anything is to test it out yourself.

If you’re doing a standard string spacing, I wouldn’t imagine you’d run into any sensing area problems.

So that kind of comes back to my original question. How much should those poles extend beyond the strings?

Depends on the style of pole. If it’s a bar pole, anywhere from .06” - .12” extra should be adequate. If the poles are cylindrical, each string should be centered over each pole. However, if it’s a Fender style pickup, the strings are centered between a set of two cylindrical poles.

 

[scolba]

Gotcha, makes sense. Thank you for the info!

 

[ardgedee]

edit: Sorry Mods, I probably should have put this in the pups and electronics section.

You can click the "Report" button at the left below your post and write a note to the mods. I've done that for you already for this thread.