New idea for HB?

[Mike Sulzer]

"Ferromagnetically coupled underneath" implies that they are attached by high permeability material. They are not, but rather are connected by an alnico magnet that has a permeability much less than the steel used for the slugs and screws. And it is a good thing that they are not; if you do connect them with such material, lines from interfering fields are guided through this material in the direction between the two coils and couple up into the screws and slugs with opposite polarity between the screws and slugs. Since the coils have opposite polarity, the signals add, not subtract and you have a hum sensor, not a hum bucker.

Now I know the "original" patent talks about magnetic coupling. Let's remember that the purpose of a patent is to protect the market for a product and also confuse the hell out of the competition if possible. Or maybe Seth Lover just did not understand.

There is nothing wrong with making a hum bucker out of coils with Alnico cores. It will not sound the same, and as you wrote: eddy currents.

The sensing area of a hum bucker is not the area between the coils and slugs, but rather consists of two nearly separate areas over each. The part of the string not strongly magnetized in the direction so as to make a strong B field pointing through the coils contributes little.

Where does this idea for a side to side sensing area come from? It is just one of many myths.

I'm gonna speak out of turn here.

We tend to focus too much on the coils and coil properties, sometimes, and forget that, regardless of the coil properties, whatever you do to an HB still leaves the sensing area between the tops of the two sets of slugs. The two coils, whether one or both are engaged or bypassed, or whether one is of a different form factor than the other (e.g., Duncan P-Rails) are ferromagnetically coupled underneath.

If one wants something in an HB form-factor that can be converted to single coil, AND have something more approximating single-coil tone (and not just / turns, inductance, yadda yadda), one probably needs to physically separate the two physical coils in a way that stops the magnetic coupling and changes the sensing area so that it isx essentially top-to-bottom, not side-to-side.

Talking through my hat here, I imagine it would/could be something like this: One or both coils have true alnico polepieces, such that decoupling them underneath would still leave one coil with a top/bottom sensing area. In HB mode, they would be ferromagnetically coupled underneath by some sort of plate or bar that conducts the field in a way that results in a coiltop-to-coiltop sensing area. In single-coil mode, one of the options becomes a small mechanical device that pushes the coupling plate away from the bottom of the coils. The other option, of course, is that the coupling plate stay in place and one is left with the usual HB sensing area, but with one coil.

Now, I just know that Mike Sulzer or someone is going to tell me this can't possibly work, because of eddy currents or some other aspect of electromagnetic voodoo that I don't understand (I'm a psychologist, not an engineer, Jim!). But certainly the sensing area, if not a replica of what happens with a true SC, would be more in that direction than the usual cancel-one-coil nonsense.

For me, the chief hurdle would be the mechanical challenge of fitting in the plate-separating mechanism so that it would be easily accessible and usable from the top of the pickup (maybe requiring a small "dogear" route on one side of the pickup to allow for a lever that didn't interfere with playing), and not require so deep a hole for the pickup that it could only be used on instrument bodies at least 2" thick or more.

Whatcha think?

[Jim Darr]

I'm gonna speak out of turn here.

We tend to focus too much on the coils and coil properties, sometimes, and forget that, regardless of the coil properties, whatever you do to an HB still leaves the sensing area between the tops of the two sets of slugs. The two coils, whether one or both are engaged or bypassed, or whether one is of a different form factor than the other (e.g., Duncan P-Rails) are ferromagnetically coupled underneath.

Whatcha think?

Mark,

I think you are on to something. I never really considered the flux field pattern while trying to experiment with the topic concept. It now seems obvious that focusing on the bobbin/coil geometry and tapping was only part of the equation. Although I experimented with rod magnets v bar magnets I never considered the basic differences in the flux field patterns of HB v Single coil. I know flux patterns uniquely shape the sound of the pickup for any given coil, but never tied it back to this experiment. Guess I won't make a good research scientist missing something which should be so obvious. I think this explanation is why I was never happy with the results of my experiments.

Back to the drawing board and lab.

Thanks for this insight.

Jim

[Mark Hammer]

I'm gonna speak out of turn here.

We tend to focus too much on the coils and coil properties, sometimes, and forget that, regardless of the coil properties, whatever you do to an HB still leaves the sensing area between the tops of the two sets of slugs. The two coils, whether one or both are engaged or bypassed, or whether one is of a different form factor than the other (e.g., Duncan P-Rails) are ferromagnetically coupled underneath.

If one wants something in an HB form-factor that can be converted to single coil, AND have something more approximating single-coil tone (and not just / turns, inductance, yadda yadda), one probably needs to physically separate the two physical coils in a way that stops the magnetic coupling and changes the sensing area so that it isx essentially top-to-bottom, not side-to-side.

Talking through my hat here, I imagine it would/could be something like this: One or both coils have true alnico polepieces, such that decoupling them underneath would still leave one coil with a top/bottom sensing area. In HB mode, they would be ferromagnetically coupled underneath by some sort of plate or bar that conducts the field in a way that results in a coiltop-to-coiltop sensing area. In single-coil mode, one of the options becomes a small mechanical device that pushes the coupling plate away from the bottom of the coils. The other option, of course, is that the coupling plate stay in place and one is left with the usual HB sensing area, but with one coil.

Now, I just know that Mike Sulzer or someone is going to tell me this can't possibly work, because of eddy currents or some other aspect of electromagnetic voodoo that I don't understand (I'm a psychologist, not an engineer, Jim!). But certainly the sensing area, if not a replica of what happens with a true SC, would be more in that direction than the usual cancel-one-coil nonsense.

For me, the chief hurdle would be the mechanical challenge of fitting in the plate-separating mechanism so that it would be easily accessible and usable from the top of the pickup (maybe requiring a small "dogear" route on one side of the pickup to allow for a lever that didn't interfere with playing), and not require so deep a hole for the pickup that it could only be used on instrument bodies at least 2" thick or more.

Whatcha think?

[Lyrebird Steve]

I have also tried this but couldn't get a sound I really liked in either mode.

I built an almost full height "strat" bobbin as a slug and wound with 42 HFV to 7200 tapping at 5000. I wound the screw coil with PE to 5000.

The height of the "strat" bobbin required me to mount the bar magnet underneath the base plate. In the end I mounted it in my brothers traveller guitar which wasn't the greatest test bed.

[Steve A.]

I have also seen pickups using a HB dual blade and a proper single in a humbucker format, in that instance you have effectively two pickups in one unit.... another option

Good point... I think that SD or DiM makes a humbucker-sized pickup that is both a HB and a P90 (my favorite single coil pickup- sorry, Leo!)

Steve Ahola

P.S. About 35 years ago I thought my SD Broadcaster pu was too thick so I tried unwinding a few hundred wraps (I was not a pickup winder but an unwinder!) I had done this before but I managed to doze off, dropping the pickup and tearing the leads, never to make it whole again, so I unwrapped the coil wire and used it to add wraps by hand to existing pickups, often as selectable taps. I "created" a tele bridge with taps at 7.5k, 8.5k and 9.5k that was my favorite for years. (I did not think it was possible for a mere human to create a pickup from scratch.)

So I do like the idea of tapped pickups...

[Lollar Jason]

I made a few where there was a third coil under the slug side- the slugs were rod magnets, the bottom plate was steel so it transferred magnetism to the screw side coil and you could add the third coil in series to the upper slug side coil- it was essentially the size of a strat coil and you could cut the screw side coil, worked ok. didnt nail it but close

[Jim Darr]

Done it! Not a mayor success in my case

Same here. Tried various versions. No keepers yet.

[mr fab]

hi steve
I approached this same issue differently

I made what is effectively a hot WR humbucker (ie with magnet poles) in both bobbins .. in other words, two single coils RWRP connected together in series

the pickup sounds great in both humbucker and single coil mode, and also has quite a realistic humbucking single coil sound when wired in parallel however its quite bright, (a la original musicman sabre pickups). but nonetheless allows 4 sounds from one pickup. you just have to find the right balance between a good HB sound and single sound (you have a choice of either coil on this pickup for added flexibility).

of course tapping one coil would also be a possible solution, however my results were very good and most useable

I have also seen pickups using a HB dual blade and a proper single in a humbucker format, in that instance you have effectively two pickups in one unit.... another option

hope this helps

[Peter Naglitsch]

Done it! Not a mayor success in my case

[David King]

Larry Polack at Aero Pickups had been doing this for decades on his bass HBs and I'm sure he wasn't the first. The question in my mind is does the unused portion of the winding degrade the currently tapped section? Could they be physically separated to minimize any eddy losses to the "zombie coil" from the tapped coil. (Notice I coined an expression there?)

[jack briggs]

New idea for HB?

My friend Felix was asking about a humbucker with a strong single coil mode. So how about this: one coil wound to, say, 5k and the other wound to 10k with a 5k tap used for dual coil mode? Of course it would require more than a SPST coil cut switch...

Anybody make such as animal?



Steve Ahola

done it with a bridge single coil; 8200 turn tap to work well with middle pickup, 9200 turns full single coil.
no reason not to try with HB, except that you'd have to use 43 or 44 gauge.


cheers,

[Steve A.]

New idea for HB?

My friend Felix was asking about a humbucker with a strong single coil mode. So how about this: one coil wound to, say, 5k and the other wound to 10k with a 5k tap used for dual coil mode? Of course it would require more than a SPST coil cut switch...

Anybody make such as animal?

Steve Ahola