Pickups with Air Coils

[big_teee]

Has anyone tried making Humbuckers with one air coil.
If the slugs are left out of one side will this make a Humbucker sound more like a P90?
Also if one coil is reverse polarity to the other will there be any humcanceling without a slug in that coil?
Ideas and Discussion welcome.
Terry

[LtKojak]

Has anyone tried making Humbuckers with one air coil.
If the slugs are left out of one side will this make a Humbucker sound more like a P90?
Also if one coil is reverse polarity to the other will there be any humcanceling without a slug in that coil?
Ideas and Discussion welcome.
Terry

You can try it for yourself: just take out all polepiece screws of a humbucker and listen to the sound.

Easy Peasy!

[Mark Hammer]

Has anyone tried making Humbuckers with one air coil.
If the slugs are left out of one side will this make a Humbucker sound more like a P90?
Also if one coil is reverse polarity to the other will there be any humcanceling without a slug in that coil?
Ideas and Discussion welcome.
Terry

Yes.
Maybe.
Yes.

So-called "dummy coils" are "air coils". In the absence of slugs or polepieces, and especially since they are sometimes not situated under the strings (although they could be), ALL they sense is hum and EMI/RFI. Consequently, since they don't pickup up and string signal, when wired out of phase with a true sensing coil, only the extra stuff they pick up (hum, etc.) gets cancelled. As always, when two such "sensing antenna" are combined in anti-phase, the degree of cancellation corresponds to the matching of signal levels between the coils. So, if the air coil pics up either noticeably more, or noticeably less, hum than the other coil, hum-cancellation will be less than perfect.

As for sounding like a P90, there is far more to the sound of a P90 than simply being one coil. Theoretically, one could have a flatter wider coil with the same magnet structure, in tandem with an air/dummy coil and get a hum-free P90 sound. But I imagine there'd be much trial and error experimentation to get you there. It would not come diorectly from simply aiming for a flat wide coil, and comparable magnet structure + a dummy coil.

It hasn't been that long since their release, and they're kind of pricey to tinker with, but I'm curious as to whether anyone has removed the slug in the slender coil of a Duncan P-Rails to achieve hum-cancellation using the P90-sized coil only?

[Mike Sulzer]

Has anyone tried making Humbuckers with one air coil.
If the slugs are left out of one side will this make a Humbucker sound more like a P90?
Also if one coil is reverse polarity to the other will there be any humcanceling without a slug in that coil?
Ideas and Discussion welcome.
Terry

If you remove the screws (it's easier) you will:

1. Increase the hum. (If you are in an environment with little electrical noise but a lot of magnetic noise, you can hear the hum increase as you remove each screw. There is still some hum rejection left when you get all six out.)

2. Somewhat increase the resonant frequency since you have lowered the inductance of the screw coil.

3. Sample only the string region near the coil with the remaining slugs. The area of the strings over the (removed) screw coil is no longer much magnetized and so you get little signal even though the coil still has significant sensitivity even with the screws removed.

You are sort of moving in the direction of a P-90, but I do not think you are going to get there.

[big_teee]

If you remove the screws (it's easier) you will:

1. Increase the hum. (If you are in an environment with little electrical noise but a lot of magnetic noise, you can hear the hum increase as you remove each screw. There is still some hum rejection left when you get all six out.)

2. Somewhat increase the resonant frequency since you have lowered the inductance of the screw coil.

3. Sample only the string region near the coil with the remaining slugs. The area of the strings over the (removed) screw coil is no longer much magnetized and so you get little signal even though the coil still has significant sensitivity even with the screws removed.

You are sort of moving in the direction of a P-90, but I do not think you are going to get there.

By taking the screws out, the Keeper bar remains, does it still have a little magnetic effect?
After all it is right against the magnet?
Terry

[Mike Sulzer]

By taking the screws out, the Keeper bar remains, does it still have a little magnetic effect?
After all it is right against the magnet?
Terry

Sure, but it is far from the strings, and without the screws, the magnetic filed lines tend to come out it in a direction parallel to the strings and loop around. The B field perpendicular to the strings at the strings is small.

[big_teee]

Sure, but it is far from the strings, and without the screws, the magnetic filed lines tend to come out it in a direction parallel to the strings and loop around. The B field perpendicular to the strings at the strings is small.

I will be trying this some, I will let you what I think!
Terry

[big_teee]

I did pull the screws out of a Bridge pickup in a Strat.
It did Pick up some 60hz, but was quieter than the 2 Single coils in the guitar.
It surprised me, it still sounded good, Don't know about a P90 Sound.
I will do more experimentation tomorrow!
T

[David Schwab]

Also if one coil is reverse polarity to the other will there be any humcanceling without a slug in that coil?

One coil IS reverse polarity in a humbucker.

I have made humbuckers with one air coil. It sounded like a single coil, but as a little weak sounding.

[big_teee]

One coil IS reverse polarity in a humbucker.

I have made humbuckers with one air coil. It sounded like a single coil, but as a little weak sounding.

I have given that a lot of thought.
One coil is RP, until you pull the screws then I think it would just Be a continuation of the same coil?
Not sure about that, Help us out Mike Sulzer!
My Amp here in my house is next to the desk with the Phone, LapTop, Router, 4 Flourescent bulbs and a ceiling fan.
It has some Noise on Humbucker Mode.
It Really raises Hell with the Screws out.
I have been wanting to try that for some time.
It seemed pretty Anemic!
Don't think that will fit my Need!
T

[Mike Sulzer]

I have given that a lot of thought.
One coil is RP, until you pull the screws then I think it would just Be a continuation of the same coil?
Not sure about that, Help us out Mike Sulzer!
My Amp here in my house is next to the desk with the Phone, LapTop, Router, 4 Flourescent bulbs and a ceiling fan.
It has some Noise on Humbucker Mode.
It Really raises Hell with the Screws out.
I have been wanting to try that for some time.
It seemed pretty Anemic!
Don't think that will fit my Need!
T

Taking the screws out does not change the polarity, but it does make that coil less sensitive, and so the hum does not cancel nearly as well.

David Schwab remembers my "discussion" with the electronics guy at MIMF. He insisted that an air core coil cancels just as well as one with screws. He had done everything 20 years before and knew everything. He eventually got me thrown out.

Your signal goes down quite a bit with the screws out (almost 3 db), and so anemic is a good description.

I will be starting a discussion in the next couple days about how a humbucker samples the string, using comparisons of the sound of one and both coils. Doing it right takes careful matching and active electronics so you can keep the levels and the frequency responses from the resonances both the same.

[Mike Sulzer]

Mike, I didn't get your thrown out of anywhere...

"He" refers to the electronics guy, not you. Read it again. When someone in authority insists on pushing obviously wrong ideas, you have to push for the truth. If you get thrown out, well, that is too bad, but you get to use that case as an example of how not to run a discusision. Discussions are not of much use if they must be based on wrong fundamental ideas.

It is perfectly normal for people to think that wrong ideas are truth. There are many reasons for it. But there are no reasons for not allowing ideas to be challenged, even when the process is messy. You might want to go back and review what happened here. Your desire to throw me out is normal, too. But it is wrong and it is not something that you should be allowed to do.

[David Schwab]

"He" refers to the electronics guy, not you. Read it again.

I stand corrected. Sorry for the misunderstanding.

[Jazz P Bass]

Had to read that twice, myself

[Mike Sulzer]

I stand corrected. Sorry for the misunderstanding.

No problem. I look forward to future discussions.