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How do the screws in humbuckers affect tone?

Golem
July 6th, 2011, 12:37 PM
This question has a few different facets.
The first I am curious is about how setting the height on the screws can affect tone.
Second, I am curious as to why there seem to be two different types of screws used on different styles of humbuckers (allen and the ones adjusted with a flat head screw driver) and how this affects tone.
Third and finally, I heard that the length of these screws has an effect on tone as well. I was wondering if this is true and, is so, how it would affect tone.

P.S. A google search of this provides only gross speculation from users on different forums. I am hoping to find information from people who have fiddled with humbuckers a lot of even designed their own.

moonshiner
July 6th, 2011, 01:32 PM
This question has a few different facets.
The first I am curious is about how setting the height on the screws can affect tone.
Second, I am curious as to why there seem to be two different types of screws used on different styles of humbuckers (allen and the ones adjusted with a flat head screw driver) and how this affects tone.
Third and finally, I heard that the length of these screws has an effect on tone as well. I was wondering if this is true and, is so, how it would affect tone.

P.S. A google search of this provides only gross speculation from users on different forums. I am hoping to find information from people who have fiddled with humbuckers a lot of even designed their own.

#1 Tone is a subjective impression of the amount of vibrations that are being discerned by the pickup poles. Moving the pole pieces closer will catch a wider range of vibrations increasing the output/clarity from that string and some from the surrounding strings. They are generally meant to balance or accentuate certain strings/frequencies.

#2 They don't. They are asthetics. The screws are not magnitized but extensions of the magnets which is generally a bar. Unless, you are talking about original WRHBs which have adjustable magnetic (CuNiFe) screws. Uncertain if any other humbucker type dual coils have magnetic screws other than Telenator's WRHB copies.

#3 Doubtful, see #2.

YMMV...

jefrs
July 6th, 2011, 01:51 PM
Magnetism is a weak force, it falls off rapidly with distance.
The signal is generated by the string vibration interfering with the magnetic field, which induces a current in the coil. Only vertical vibration does this significantly, not side-to-side.
To get the output signal balanced in intensity across the strings, one adjusts the pole heights.
In a humbucker, if the poles are all raised high then it is mainly generating signal on that one coil and only using the other for hum-cancelling. Imo better to lower the screws and raise the pickup as a whole, then adjust the screws to balance it out. It's a juggling act.

jefrs
July 6th, 2011, 01:57 PM
The length of the screws is important only in so far as they carry the magnetic field from the magnet. In a full-size humbucker this magnet lives between below and the coils with a steel keeper on either side into which the screws are driven, there should be metal-to-metal contact. The hum-cancelling coil may or may not be fitted with pole screws under the cover or driven in from the back, or just left empty.

LiveOak
July 6th, 2011, 02:01 PM
I just adjust the screws on my LP in an alternating pattern like Dan Earlwine suggested in his guitar repair book, thus:

/ \ / \ / \

The dashes represet the screw notch position obviously.

Golem
July 6th, 2011, 02:41 PM
I appreciate the feedback. So far I have gotten good results balancing my humbuckers sound simply by adjusting the height on different sides but was aware that this could also be done with the screws. I expected that because the different types of pole pieces operate at different heights that there might be at least a minute difference in the sound or tone produced.

pdxjoel
July 6th, 2011, 03:18 PM
You can also adjust a HB's sound by balancing body and pole piece height. As mentioned above, having the poles closer to the strings increases sensitivity. Raising the pup also increases output. By lowering the pup body and raising the pole pieces, you can modify the sound to have more sensitivity to pick attack, etc while balancing output. It tends to sound more single-coilish because one coil is predominating. While you're at it, you can also adjust heights for string-to-string balance.

threadmaker
July 6th, 2011, 06:04 PM
to evolve from this what if you were to have slugs only and no screws?

jefrs
July 6th, 2011, 07:02 PM
to evolve from this what if you were to have slugs only and no screws?

I have successfully pushed strat pickup poles up or down to balance them - "vintage" stagger is for a wound 3rd. Has to be done with a little care using brute force.

jefrs
July 6th, 2011, 07:05 PM
I just adjust the screws on my LP in an alternating pattern like Dan Earlwine suggested in his guitar repair book, thus:

/ \ / \ / \

The dashes represet the screw notch position obviously.

Why? - apart from making a pretty pattern the screw slots have no significant effect on the magnetic field, they're just there to enable you to raise or lower the pole screw. What about Philips head ones?

Wayne Alexander
July 6th, 2011, 09:31 PM
If you want a treblier clearer sound, adjust the body of the pickup lower and the polepiece screws higher. If you want more midrangy darker sound, screw the polepiece screws more into the body of the pickup and raise the pickup body closer to the strings. To make any string louder or quieter, raise or lower the corresponding screw.

The material the screws are made out of, the shape of the screw head, the length of the screws - each of those will make some difference in the sound you get.

Golem
July 7th, 2011, 12:25 AM
This thread has been informative. I think I am going to try what Wayne Alexander mentions and see how this works for me.

jefrs
July 13th, 2011, 08:17 PM
If you want a treblier clearer sound, adjust the body of the pickup lower and the polepiece screws higher. If you want more midrangy darker sound, screw the polepiece screws more into the body of the pickup and raise the pickup body closer to the strings. To make any string louder or quieter, raise or lower the corresponding screw.

The material the screws are made out of, the shape of the screw head, the length of the screws - each of those will make some difference in the sound you get.

I have noticed a difference with screw head shape, whether flat or rounded. More noticeable it its diameter, if you bend a string off the focus of the pole, the output drops, especially so with a narrow head.. I have one pickup where I inserted steel washers under the head of the screws to improve this.

Also whether the hum-cancelling coil has adjustable poles inserted from below, or if it is blind, with no pole screws.

Rob DiStefano
July 14th, 2011, 08:40 AM
none of this screw stuff matters. what does matter about pups is the overall design, components, build and execution.

dusty tolex
July 16th, 2011, 12:05 PM
I note that some pups such as Burstbuckers, have non-adjustable screws.

dt