Pickup spacing / interference (for luthiers!!)

[eddododo]

If this gets moved to pickups, I understand, but I intend this for an audience focused on design; pickup location in this context will be much less common for an audience focused more on retrofitting upgrades

What kind of considerations must be made for pickups in close proximity to one another? I’ve seen little snippets of pickups being too close or touching ‘interfering’ with eachothers’ magnetic field, but with no context of what that would actually mean for the sound or perhaps electrical characteristics. I’m assuming it’s mostly nonsense, but as great as I am with electronics, the magnetic aspect remains a little magical lol.

I’ve certainly seen basses where two sets of soapbars are right up against eachother (I’ve seen it on some gospel-style basses, and a couple of Janek Gwizdala’s basses), so clearly nothing catches fire, but are there considerations to be made with this approach, in terms of any effect on resonance or things like phase scooping?

At a certain point, are you just creating a big MM pickup that wasn’t wound like one?

 

[Flamingo21]

I’ve seen it on some gospel-style basses

Off topic: what are "gospel style basses"? I thought gospel music uses regular musical instruments?

 

[eddododo]

Off topic: what are "gospel style basses"? I thought gospel music uses regular musical instruments?

A major trope of gospel bassists is an emphasis on the sound of pickup positions from sweetspot to jazz bridge ish. It’s not uncommon to see dual soapbars touching or nearly touching, concentrated in that middy growly area. There’s also plenty of J bass and Jbass like setups, for sure

 

[MPU]

When side to side humbuckers work fine (two coils literally side to side inside a cover) I doubt there is any trouble mounting any pickups side by side.

 

[SpaceJockey]

I've seen a variety of basses with closely spaced pickups, most notably Dingwall. Many of their basses have 3 pickups, all snuggled up next to each other.

This begs the question, how are the magnetic fields shaped? And how do they interact with each other? Is the field from pickups even strong enough for them to affect each other significantly?

 

[ZachM]

I don't have a lot to offer here, except that I'm curious about other peoples experience with closely mounted pickups. My first guess is that the pickups probably don't interfere with each other, but the closer you space them, the more you'll get big dips and peaks in the harmonic spectrum from phase cancellation.

This bass always caught my eye when thinking about this effect. I love neck pickup tone on thunderbirds and don't ever use bridge pickups except in combination with the neck, so this instrument seems like it would be a dream! Sadly it's impossible to find any recordings of it.

Link Removed

 

[eddododo]

When side to side humbuckers work fine (two coils literally side to side inside a cover) I doubt there is any trouble mounting any pickups side by side.

yeah, I don’t think any critical failure is imminent.

When side to side humbuckers work fine (two coils literally side to side inside a cover) I doubt there is any trouble mounting any pickups side by side.

That’s certainly how I’m thinking it works out, but my reservation was the notion that they are wound how they’re wound in a way that complements the inherent characteristics caused by the proximity (along with all the other factors of course)

Seems like the best approach for me would be to simply mount them up on my test body and look for any change with them soloed, and to establish whether they sound good 50/50 (for alternatively, whether or not, I need a 50-50 option)

 

[Bruce Johnson]

I agree with what everyone is saying here. I doubt that there's any noticeable effect from the magnetic fields "colliding" between two pickups placed right against each other. Even with the covers removed and the coils touching. The magnetic field does extend out beyond the coils a little bit, but it's much weaker out there.

If the magnets of the two coils are facing the same direction, the two fields will kind of glue themselves together into one larger field covering both coils. And they will wiggle, synchronized, when the string above them wiggles.
The field strength over each coil won't necessarily be more powerful. It's just a wider field that spans over a larger area. If you switch on one of the coils, the sound should still be the same as if the other one wasn't there.

If the magnets of the two coils are opposite polarity, one North and one South like a humbucker, it's still a similar effect. There will be a narrow dead zone line between the two fields, where the fields are fighting each other. But the big majority of each field will still cover its own coil. And the two fields will still wiggle together, synchronized, following the wiggling of the string above them. Each coil, switched on by itself, will still sound very much like it would if the other coil wasn't there.

 

[ardgedee]

I agree with what everyone is saying here. I doubt that there's any noticeable effect from the magnetic fields "colliding" between two pickups placed right against each other. Even with the covers removed and the coils touching. The magnetic field does extend out beyond the coils a little bit, but it's much weaker out there.

If the magnets of the two coils are facing the same direction, the two fields will kind of glue themselves together into one larger field covering both coils. And they will wiggle, synchronized, when the string above them wiggles.
The field strength over each coil won't necessarily be more powerful. It's just a wider field that spans over a larger area. If you switch on one of the coils, the sound should still be the same as if the other one wasn't there.

If the magnets of the two coils are opposite polarity, one North and one South like a humbucker, it's still a similar effect. There will be a narrow dead zone line between the two fields, where the fields are fighting each other. But the big majority of each field will still cover its own coil. And the two fields will still wiggle together, synchronized, following the wiggling of the string above them. Each coil, switched on by itself, will still sound very much like it would if the other coil wasn't there.

Huh. Now you've got me wondering whether it's possible to shape the aperture of a pickup by surrounding it with magnets. Hypothetical example: would a single-coil pickup with North up, bracketed on either side by magnets South up, have a narrower aperture?

 

[MPU]

I guess you need a coil around the magnets to get any sound. If you have magnets around the coil (unless they are strong enough to make difference in the movement of the string) they will have very little effect on the sound. Sidewinder pickups are different animals, there you can change the width of the aperture with different magnet positions.

 

[Bruce Johnson]

Huh. Now you've got me wondering whether it's possible to shape the aperture of a pickup by surrounding it with magnets. Hypothetical example: would a single-coil pickup with North up, bracketed on either side by magnets South up, have a narrower aperture?

Yes, I think that would work. You can mess around with the shape of the magnetic field by placing extra magnets on the outsides of the coil(s). In your example, bracketing South magnets outside of a North single coil, Yes, you'd probably narrow the aperture along the string. And, the sound would probably be a lot softer and muddier, humbucker-like. I'm not sure why you'd want to do that, but you could.

If you bracketed it with North magnets, the field and aperture would be a lot wider, and the sound would be clearer.

 

[ardgedee]

If you bracketed it with North magnets, the field and aperture would be a lot wider, and the sound would be clearer.

Hmm. That implies you could build something with the aperture of two pickups but without the comb filtering that multiple pickups would have.

 

[Bruce Johnson]

Hmm. That implies you could build something with the aperture of two pickups but without the comb filtering that multiple pickups would have.

Yep. You can do a lot of things with shaping the magnetic field. Including lining up multiple magnets along the line of the string:

Here's a multi-coil arrangement with three 1/4" A5 rod magnets per unit, in a row along the string. A narrow aperture across the string, and a wide aperture along the string.

 

[ShadowGroover]

Here's a multi-coil arrangement with three 1/4" A5 rod magnets per unit, in a row along the string. A narrow aperture across the string, and a wide aperture along the string.

How does it sound, on its own, and relative to more traditional pickups? It looks cool, for sure.

 

[Bruce Johnson]

How does it sound, on its own, and relative to more traditional pickups? It looks cool, for sure.

Actually, not a whole lot different. If you took one of these pickups and mounted it crosswise, like a normal pickup, it would sound about the same as the four of them together. Turning the pickup from crosswise to along the string doesn't really change the sound much. And using four separate coils doesn't make it four times as loud. A multi-coil doesn't necessarily have higher output level than a single coil. Also, extending the aperture along the string doesn't, by itself, increase the output level. Unless you are adding more and stronger magnets, and increasing the field strength.

In this particular case, the pickups are Hi-Fi type; powerful magnets and tall narrow coils with the turns wrapped tightly. That geometry makes them clear and very wide range, and fairly flat curve. So that's what they sound like: A Hi-Fi humbucker. It has very little to do with them being a quad multi-coil.

The reason I made that pickup as a quad multi-coil is because of the fingerboard radius. That model bass has a 4" radius fingerboard, and I needed a pickup that could adjust the poles to that small of a radius. So, I made it four separate coils, each with its own height adjustment.

What does it sound like? Picture two Seymour Duncan Quarter Pounder Jazz pickups, wired together as a humbucking pair, and adjusted to be balanced over the 4" radius.