Unbalanced humbucker coils...the sneaky way

[Whiskeyrebel]

I saw a guitar on Ebay with DiMarzio pickups that have the usual 12 allen-head polepieces, only this particular one had three screws removed from each coil. So one coil had screws for the three bass side strings and empty spots under the plain strings, while the other coil was done the opposite. That got me thinking.

In a humbucker that has a slug coil and a screw coil, would be the effect of replacing the screws with non-magnetic or less magnetic screws? Like brass or stainless. The only reasons I'm thinking not to just leave them vacant is to keep dirt out and, well, just for appearance.

Would it reduce output? What effect would it have on frequency response?

[Whiskeyrebel]

Is G.I.G the wrong page for the question? Would Technical Info be more appropriate?

[gtrnstuff]

Maybe. But you got me remembering a quick and dirty way of making a humbucker split coil that I read on a Seymour Duncan forum. Just remove the pole screws from the bobbin. The non-removable poles keep that coil active.

[ManliusGuitar]

There would be no loss in 'output' per se, the overall output of a pickup has more to do with impedance than magnetic field. I do wonder of the validity of this setup, as the 'dead' slugs and screws may tend to deaden and dampen the overall response of the pickup. I think there are better ways to balance b/w treble and bass response.

Mick

[Whiskeyrebel]

Well, the DCR would not change but the reactive impedance would have to change because it would have one iron core coil and one air core, instead of two iron core coils. Well, a conductive but nonmagnetic screw could develop eddy currents in it if the coil carried a significant current, but it wouldn't carry any flux.

[Joe Naylor]

Done this many times. The output does drop considerably, around 30%. But I've had very good tonal results. It basically sounds like a single coil without the hum.

Technically, non-magnetic poles will have some effect, but my guess is it won't be huge. Might reduce some treble due to capacitance-to-ground introduced between the coil and grounded pole. Easy enough to test.

Or you can buy those no-holes black plastic covers, and drill them for the polepieces. It looks pretty slick, and you don't have to worry about the empty holes.

[Whiskeyrebel]

Thanks, Joe! I'll have to give it a try.

[ManliusGuitar]

The impedance of the coil will not drop when replacing the ferrous material with non ferrous material. Your magnetic field will change, sure, but you have the same mass. The non-magnetic poles still have an effect. I think to better drop the output of the pickup, if that is the desired effect, would be to remove the poles altogether. That will have a larger impact on the output. But i'm not even sure if that is a desired effect you are looking for.

If you want to replace the poles with non-ferrous material, look at mcmaster-carr for the 5-40 stainless screws and you can get stainless slugs from fastenal, I believe. Or you could cut and sand 3/16" stainless rod - which you can find from mcmaster - if you have the capability to cut the steel and want to go that far in the experiment.

That will keep the similar appearance, but with this mod. Again, for balancing treble and bass, i think you will find better options. But this is a neat experiment...

[Joe Naylor]

Keep in mind, stainless can be magnetic, depending on what grade it is.

I'd suggest this mod only if you're looking for a brighter, cleaner, more percussive sound... like a single coil.

[Deaj]

Lindy Fralin makes a PAF type pickup with unbalanced coils called the 'Unbucker'. I have one in the bridge position of myUSACG Super Strat along with a pair of Fralin Real 54's in the middle and neck position. It sounds fantastic as a humbucker and split for single coil use. This is my only experience with unbalanced humbuckers.

[ManliusGuitar]

Keep in mind, stainless can be magnetic, depending on what grade it is.

I'd suggest this mod only if you're looking for a brighter, cleaner, more percussive sound... like a single coil.


But most readily available Stainless is non-ferrous and will be fine for this experiment.

I get the analogy to a single coil in some regards, but you may also find that it is a similar response as to dropping the pickups much further away from the strings. In essence, the output of the pickup is the same, but the overall sound is dampened b/c there is less magnetic pull from the smaller number of poles. This could weaken the overall tonal response and produce a flat and dull sounding pickup.

Maybe if you do this keep the pickups right up to the strings - I think that would really help give you some more usable tones - and get you right in that single coil ballpark....

[Mike9]

You could get something like a Humbucker from Hell and just swap a coil on each pickup. I've done it with Gibson pickups with good results, but as Mick said it might not yield the results you are after.

[hunter]

But most readily available Stainless is non-ferrous and will be fine for this experiment.

FYI, stainless steels are always ferrous. That is because their main constituent is iron and that makes em ferrous by definition. Non-ferrous materials would be nickel, titanium or copper based for example.

Typical 300 series stainless steels are "non-ferritic", not "non-ferrous". Ferritic stainless steels (which are also ferrous) are magnetic. 300 series stainless steels are austenitic and non-magnetic unless cold worked at which point they can become magnetic. Some 300 series bolting material is cold rolled stock and as a result may be magnetic. Always best to check.

All to do with crystal structure. Gets deeper from there.

hunter

[Joe Naylor]

But most readily available Stainless is non-ferrous and will be fine for this experiment.

I get the analogy to a single coil in some regards, but you may also find that it is a similar response as to dropping the pickups much further away from the strings. In essence, the output of the pickup is the same, but the overall sound is dampened b/c there is less magnetic pull from the smaller number of poles. This could weaken the overall tonal response and produce a flat and dull sounding pickup.

Maybe if you do this keep the pickups right up to the strings - I think that would really help give you some more usable tones - and get you right in that single coil ballpark....

My point about the stainless is that you'll get very different tonal results between magnetic and non-magnetic screws.

The result is not like dropping the pickups at all. It is as I described. This is because removing a row of poles narrows the magnetic field considerably, sensing a smaller section of the string, much like a single coil. Again, I've done this mod many times, I have a box full of pickups like this, and I'm reporting results from actual use.

[Whiskeyrebel]

The pickup is a 490R in and SG Standard. I really dig the tone when I tailor the settings for the 498T so I don't really wanna readjust everything around the neck pickup.

The 490R/498T middle setting is quite nice though.

I'd like to brighten it and tame its signal level a bit because the amp settings that work best with the 498T tend to sound a bit bassy and overloaded with the 490R. So it sounds like pulling or swapping the screws would be a move in th eright direction.

If he change is too drastic I'll probably reinstall the stock screws and try adjusting the pickup's body further from the strings and raising the screws.

The impedance of the coil will not drop when replacing the ferrous material with non ferrous material. Your magnetic field will change, sure, but you have the same mass. The non-magnetic poles still have an effect. ......

The resistance will not change. The inductance will definitely be lower.

If I wanted to keep the coil's inductance close to the same, and reduce the field over the screw bobbin to a lesser degree, this is what I'd do:

I'd replace the polepiece screws with screws of the same kind of steel, but cut them too short to reach the steel spacer beneath the bobbin. That would add an extra air gap in the magnetic field's path but still allow the screws to couple the field among the coil's windings. It would probably need a slightly larger screw to bite the holes in the bobbin since the threads in the spacer would not be holding them.

[Whiskeyrebel]

Incidentally, what size and thread pitch screw will I need?

[Mr Deluxe]

Might I suggest checking your pots... If they aren't 500k and your looking for brightness swap them out, you may be happy with such an easy change.

It's easy to roll the knobs back to take away what you don't want, but hard to go the other way sometimes..

[Whiskeyrebel]

They are only marked 'Gibson' and no resistance value is marked on them. I'd have to clip or desolder the pickup lead to check that and just haven't done it yet. The guitar was made in 1998.

[Joe Naylor]

I'd like to brighten it and tame its signal level a bit

Sounds like the mod for you.

I have one pickup where I covered the empty holes with the heads from aluminum siding nails. I filed off the white paint, clipped the nail about 1/4" below the head, then hot glued 'em into place. Looks pretty good, and I couldn't hear any difference in tone.

Here's a cool mod for drop D players:
My personal guitar has two PAF style humbuckers with chrome covers. On both pickups I yanked out the slug under the low E string only, then slightly raised the remaining screw. I play in drop D exclusively, with a heavy gauge low string for better intonation (10 set with 52 low string), and this mod really tightened up the previously too bassy/unclear tone.

[Whiskeyrebel]

Thread resurrection alert.
I 86ed the polepiece screws on the 490R neck pickup before restringing today. The change is dramatic. It really sounds much more like a single coil neck pickup. I may even have to raise it to balance signal strength with the bridge, and it used to overpower the bridge. I have another guitar with single-double coil switching on its neck pickup, and the no-screw pickup with both coils in series sounds more like a real single coil than the pickup with only one coil switched in!