dummy coil tele testing

[Rob DiStefano]

cav lion bridge pup for an esquire - 10612 turns of 42awg formvar, alnico v .690" poles, 8.34k resistance. i routed humbucker hole as close as possible to the bridge, and used a pre-wound asian emg hz tele bridge pup (probably wound with 42awg poly that meters at 7.1k) and double stick taped it in the cavity. i removed the slugs (it had used an underslung ceramic mag to fuel the steel poles), and wired it in series with the lion, with the finish/finish leads wired to an spst switch that would short out the dummy and just allow the lion to function. yes, the dummy air coil does kill some of the humbuzz ... sound bytes to follow ...

[Rob DiStefano]

dumy air coil test sound bytes

the cav lion esquire plugged directly into a li'l dawg champster special (jj 6v6, 12" weber 12a125), guitar's 250k vol pot dimed, tone pot completely out of the circuit except for byte 3 where the .0047uf 'cocked wah' cap is switched in, and byte 4 where the tone pot is kicked in about 1/3 (.022uf cap) ... the amp's volume is nearly dimed (no amp tone control), live recorded to a zoom h2 in stereo cd quality mode with no editing, wav file exported to mp3 via audacity ... playing done with fingers/nails, no pick ... cav lion first, then with the dummy air coil added (series connection) ... watch yer speaker volume, some bytes are loud, overdriven and aggressive! ... note the different humbuzz levels before and during playing, and any changes in tone you perceive. ah yes, amp was right next to the guitar, under a dual florescent shop light!

one two three four five six

next up is to wind a coil with taps for 8000, 9000 and 10000 turns, and see how that affects both the hum cancelling and tone.

[David Schwab]

Stick the steel poles back in the dummy coil. That will increase the hum sensitivity.

You don't need to have it close to the pickup. It could have been placed anywhere, including in the control cavity. You could also put it under the Tele pickup, but the bridge plate will shield it too much. In my experience stacked Tele bridge humbuckers don't work as well because of this effect.

Two questions, why would you route a humbucker cavity? And why not just use a humbucker bobbin so you don't have all that flange you don't need taking up space.

[Rob DiStefano]

it's all good

Stick the steel poles back in the dummy coil. That will increase the hum sensitivity.

tried that, steel un-magnetized poles, didn't make any noticeable difference - that needs more trialing on my part ...

You don't need to have it close to the pickup. It could have been placed anywhere, including in the control cavity.

i think series links are always best kept close - i did some tests with a tele bridge and strat neck pup run thru a 4-way, it was a smoother/better series connection when the strat pup was right next to bridge pup ... besides, it's all under the pickguard so who's to know?

You could also put it under the Tele pickup, but the bridge plate will shield it too much.

no way - that'd require deepening an already deep rout

In my experience stacked Tele bridge humbuckers don't work as well because of this effect.

been there, done that - too much loss of single coil tone. all of this dummy stuff will be a compromise of sorts

Two questions, why would you route a humbucker cavity?

why not? if i'm gonna make a hole, a bigger one gives me more options - including a possible oversized coil with less windings ... i've got lots of rout templates and was even thinking of doing a swimming pool trem rout hah!

And why not just use a humbucker bobbin so you don't have all that flange you don't need taking up space.

... exactly - as i said, room for a bigger coil, a pair of cheapo asian bumhucker coils glued to a ply plate with the coil running the outside of both. as it was, i had this cheapo pup hanging around so it got drafted as the first dummy test. overall, i like the results, but lots of 'sperimentin' left to do and and so little time ...

[David Schwab]

tried that, steel un-magnetized poles, didn't make any noticeable difference - that needs more trialing on my part ...

It's pretty well established and how most of the new stacked pickups work.

i think series links are always best kept close - i did some tests with a tele bridge and strat neck pup run thru a 4-way, it was a smoother/better series connection when the strat pup was right next to bridge pup ... besides, it's all under the pickguard so who's to know?

The dummy's not picking up any sound so why would it sound smoother?

no way - that'd require deepening an already deep rout

Not for a humbucker bobbin.

been there, done that - too much loss of single coil tone. all of this dummy stuff will be a compromise of sorts

It's pretty much the same thing you are doing, unless it wasn't done correctly.

why not? if i'm gonna make a hole, a bigger one gives me more options - including a possible oversized coil with less windings ... i've got lots of rout templates and was even thinking of doing a swimming pool trem rout hah!

I meant for a same size coil. A larger coil wound with heavier wire is a better idea.

... exactly - as i said, room for a bigger coil, a pair of cheapo asian bumhucker coils glued to a ply plate with the coil running the outside of both. as it was, i had this cheapo pup hanging around so it got drafted as the first dummy test. overall, i like the results, but lots of 'sperimentin' left to do and and so little time ...

Why a pair of humbuckers? If you have them wired as a humbucker they wont work as a dummy coil. The dummy coil needs to pick up hum.

[Rob DiStefano]

thanx for yer comments, david.

i don't want that stacked 'bucker tone, just looking to kill off some of the humbuzz without compromising too much of the single coil tone that i like ... and in as simplistic a fashion as possible.

it's not about transducing sonics (picking up sound), it's about the relationship of having an rw coil in series with the real pickup and how that kills off frequencies, some bad, some good.

you had talked about stacking the existing pickup - *that* would require routing the tele bridge pup cavity deeper. not going there at all.

yeah, i think a vastly larger rectangular bobbin with heavier wire is where i need to go next.

not a pair of humbuckers, just two humbucker bobbins with wire around the outside perimeter - makes it a much larger coil, with heavier wire and less turns.

[Mike Sulzer]

Canceling two signals means getting them nearly the same, but out of phase. I do not think that you have achieved that. Cores in, cores, out makes a difference of several times in the sensitivity to magnetic fields. If you do not notice the difference, something is not working right.

When you put a dummy in series, one that is pickup sized as opposed to a "whole guitar sized" coil, you are going to approximately double the inductance and kill the highs. "Buzzing" is higher harmonics of 60 Hz hum. If you are reducing the buzzing, maybe it is because you are killing the highs rather than canceling anything.

[Mark Hammer]

The dummy and magnetically active pickup need to sense the same amount of hum to cancel out optimally If one senses more than the other, or less than the other, you get reduced hum-cancellation. The amount of hum sensed is a function of the number of turns, the shape of the coil, the location of the coil, and the iron in the coil. I've had some limited success with a non-loaded dummy coil in the control cavity of a Telecaster, although the distance from active to dummy meant that some guitar orientations (relative to the source of hum) would result in noticeably more audible hum leaking through. That's the thing about conventional humbuckers that people have taken for granted and overlook: the coils are matched and snuggled up beside each other such that they have equal distance from, and sensitivity to, the EMI source. When you add a dummy coil somewhere that is NOT always equidistant from the EMI source, compared to the live pickup/s, orientation/position can alter the amount of hum equally sensed, and the net cancellation effect.

The Suhr system is clever because the dummy coil surrounds all 3 Strat pickups, such that it is rarely facing somewhere that the selected pickup isn't. Of course, it has the good fortune to be installed in an extremely popular design that has the convenience of an easily accessible/detachable back plate covering just the right area. Not the sort of thing you can deploy as easily on a Tele, a P90-equipped Gibson slab-body, or a Harmony Rocket.

[greenfingers]

The Suhr system is clever because the dummy coil surrounds all 3 Strat pickups, such that it is rarely facing somewhere that the selected pickup isn't. Of course, it has the good fortune to be installed in an extremely popular design that has the convenience of an easily accessible/detachable back plate covering just the right area. Not the sort of thing you can deploy as easily on a Tele, a P90-equipped Gibson slab-body, or a Harmony Rocket.

You actually can get it for Gibsons with P-90 now.


Ilitch Electronics [www.ilitchelectronics.com] - pickups

[Rob DiStefano]

appreciate yer comments, folks.

all of this dummy pickup stuff, like all-things-guitar, is a subjective compromise at best. i mean, if there was a *perfect* answer that solved the problem at hand for everyone (the sc 60 cycle mamba), there wouldn't be threads like this. what i'm looking for is not noiseless sc tone nirvana - that ain't gonna happen - but some kinda compromise of both function and simplicity that works for a specific pickup, guitar, application. the quest continues, as it should ..........

[David Schwab]

i don't want that stacked 'bucker tone, just looking to kill off some of the humbuzz without compromising too much of the single coil tone that i like ... and in as simplistic a fashion as possible.

On the newer designs the bottom coil is a dummy. You are using a dummy. What's the difference? None.

it's not about transducing sonics (picking up sound), it's about the relationship of having an rw coil in series with the real pickup and how that kills off frequencies, some bad, some good.

The dummy coil is not picking up the strings, so there is no frequencies being killed off. It's only picking up hum.

you had talked about stacking the existing pickup - *that* would require routing the tele bridge pup cavity deeper. not going there at all.

Not if the dummy coil is shallow enough. You think routing a humbucker cavity is more work than routing an existing cavity deeper??

not a pair of humbuckers, just two humbucker bobbins with wire around the outside perimeter - makes it a much larger coil, with heavier wire and less turns.

Why even bother with the bobbins then? You can wind a coil around anything.

I'm sorry but a lot of what you are saying seems very arbitrary.

[Dave Kerr]

greenfingers, wouldn't all that shielding paint in the control cavity reduce the effectiveness of the Ilitch/Suhr coil? You'd just be picking up the noise signal from the rear of the guitar?

[Mike Sulzer]

appreciate yer comments, folks.

all of this dummy pickup stuff, like all-things-guitar, is a subjective compromise at best. i mean, if there was a *perfect* answer that solved the problem at hand for everyone (the sc 60 cycle mamba), there wouldn't be threads like this. what i'm looking for is not noiseless sc tone nirvana - that ain't gonna happen - but some kinda compromise of both function and simplicity that works for a specific pickup, guitar, application. the quest continues, as it should ..........

You can keep the tone but kill the hum with a dummy coil and a active preamp. You cannot keep the tone the way you are doing it. This is not a subject compromise.

[Rick Turner]

Mike is absolutely correct...to a point, and that is that if your idea of tone includes the capacitive loading of internal wiring and then a guitar cable, you'd have to monkey with some caps to make an active hum canceling system sound like a single coil pickup with no hum. Guitarists are incredibly used to the tone that comes from a bunch of things being "wrong" with high impedance guitar and bass pickups. You've even got raging arguments here over perceived tone differences from simply changing from one supplier of magnet or a formula of pole piece alloy, to say nothing of active vs. passive differences or of putting a coil in series with another, no matter the impedance of the different coils.

I must say, I like that deal with the P-90 hum canceling system. You could go RWRP with one P-90 and then switch the hum canceling coil in and out depending on whether you were using one pickup or two. P-90s just sound so good...

[Rick Turner]

And David Kerr, don't confuse magnetically induced hum with electrical interference. Shielding, unless it's specifically magnetic shielding (see Lace...), doesn't affect the single coil vs. humbucker or hum canceler issue.