Increasing treble/bite and reducing midrange in humbucker

[Tone Meister]

I have a bridge pickup with the following specs and want to increase the treble bite and slightly scoop the midrange in the area of 500-800 Hz while keeping total output the same or slightly lower.

• Alnico 5 polished
• 11.2k total DCR
• Mismatched coils (7.1k and 4.1k)
• Slug coil (7.1k coil) oriented inside
• Fillister screws 3/4" long (4.1k coil) oriented bridge side

• Pickup is installed in maple body, rock maple neck, rosewood fretboard, vintage tremolo unit, and I believe the maple body has something to do with the lack of bite and excess midrange.
• I have this same pickup in two other guitars and it does not lack treble bite, and the midrange is not excessive

I really want to keep this pickup because it mates very well with the the two single coils (HSS) and the split (7.1k) tone is perfect with the middle pickup. The midrange is a bit overbearing when the humbucker is used by itself though.

Q: What is the best way to mod this pickup to get the frequency response I want?
Q: Shorter fillisters?
Q: Hex screws the same length or shorter?
Q: Magnet swap?
Q: Flip the pickup around?
Q: A combination of one or more of the above?

[John_H]

... I have this same pickup in two other guitars and it does not lack treble bite, and the midrange is not excessive...

Do all three guitars have the same pots, capacitors, switching etc.?
The easiest fix would be to add a treble bleed circuit.

[Chuck H]

Well I'm not a pickup winder, but in my experience mid heavy pickups are that way due to either high capacitance or too much loading. With high capacitance the coils self capacitance (and the guitar cable capacitance) combine with the coils inductance to form a pronounced resonant peak. The higher the capacitance the lower the peaked frequency will be. The only way to reduce the pickups own capacitance would be to rewind it (pretty much as a different pickup ). Too much loading would be something like a very long guitar cable, a control arrangement that has two tone controls engaged on some switch settings, two volume controls in parallel with some switch settings or some combination of these things. You might be able to get more treble bite by using a shorter cable. Like a ten foot if you usually roll with a twenty foot. Or you might be able to arrange your switching to disengage the tone control when that pickup is selected. If you are using 250k pots, maybe try 500k. The shorter cable would raise the resonant peaks frequency and the other things would actually increase the resonant peak by a couple of dB making the pickup "brighter". Even when the volume is at full.

[Tone Meister]

I am asking specifically about ideas to tweak the existing pickup. No doubt the issue is the maple wood in this guitar body and I want to adjust it out.

All my guitars have treble bleeds - and the TBs have no affect on the circuit when the volume is wide open.
I use 10' cables to my pedalboards always, 22 pF/ft
I have 500k pots

[big_teee]

Turning the pickup around is worth a shot.
Put the larger coil toward the bridge. Larger coil toward the bridge should make it a little brighter than other way around?
Another thing you can try is to wire the humbucker out of phase.
If you like that sound, put in a push pull so you can flip the phase back and forth on the humbucker.
Also what about the gauss of the magnet. Does it seem the same as the others?
Not all A5s sound the same, you can try swapping magnets.
I would try A2, A5, and A8s. If you use A2, I like them fully charged.
A8s can be discharged a bit, or full charge, which ever you prefer.
GL,
T

[John_H]

...and I want to adjust it out...

That's a good way to describe it. Anything you do will be subtraction. You can't 'make the pickup have more treble response other than very subtle changes by varying the screws, slugs etc.
I wonder what the resonant peak is in humbucker mode with such a huge amount of offset in the coils?

[Chuck H]

Agree! I generally like the more open sound of mismatched coils. I haven't had the unfortunate experience of ever perceiving one as mid heavy. But it was mentioned that the guitar is greatly responsible for this. I like T's idea of having the larger of the two coils at rear. Worth a shot. Also, if there's any way to tilt the pickup or adjust screws so the magnetism over the smaller coil is giving a higher proportion of signal compared to how it's adjusted now.?.

[John_H]

I doubt that changing the orientation will have much effect as the pickup coils are acting in concert.

[Chuck H]

I doubt that changing the orientation will have much effect as the pickup coils are acting in concert.

But not with the exact same signal. Why couldn't the stronger of the two coils being positioned closer to the bridge be brighter? I know it means that the weaker coil would have it's relative string length position altered analogous as well, but it still seems plausible to me. I might be missing some physics attribute of the principals at work here.

[John_H]

But not with the exact same signal. Why couldn't the stronger of the two coils being positioned closer to the bridge be brighter? I know it means that the weaker coil would have it's relative string length position altered analogous as well, but it still seems plausible to me. I might be missing some physics attribute of the principals at work here.

I'm no physicist, but it seems to me that the two connected coils form a common inductor. Another thing to consider, reversing the pickup would put the pole screws further away from the bridge, and could have the opposite effect.

[Helmholtz]

The only way to reduce the pickups own capacitance would be to rewind it (pretty much as a different pickup ).

The influence of PU self-capacitance on sound is generally weak. Most PUs have a capacitance between 50pF and 200pF. This adds to the guitar cable capacitance of several hundred pF.
Rewinding the coils using the same gauge and lenght of wire can hardly change PU capacitance by more than 50pF if any.

[Helmholtz]

I wonder what the resonant peak is in humbucker mode with such a huge amount of offset in the coils?

Offset doesn't matter for resonance, as the inductances of both coils just add (+ an increase by 10...20% caused by magnetic coupling) for total inductance.

[Jim Darr]

Two thoughts come to mind without rewinding the coils, assuming the wiring (signal path, pot value(s), pot tapers, caps, etc) is not the issue:

1) Try fully charging the A5

2) If you know what the alloy content is for the slugs & screws, try changing that ( ie 1018 to 1022)

Be careful when changing screws and slugs so you don't damage the actual coil or the bobbin. Some molded bobbins actually expose part of the slug/rod to the magnet wire by design...so unless you are wiling to potentially rewind the bobbin keep the current slugs in place.

[Chuck H]

I really want to keep this pickup because it mates very well with the the two single coils (HSS) and the split (7.1k) tone is perfect with the middle pickup. The midrange is a bit overbearing when the humbucker is used by itself though.

I guess everyone has tried to go easy about this so far. And of course you're aware too, but...

Anything you do to significantly change how the pickup sounds by itself will have an equal affect on it's sound when paired with other pickups. So you can't keep the combined pickup sounds you have now and only change the individual pickup sound by making changes to the pickup or how it's mounted. You may be able to make changes to the circuit that are exclusive to that pickup being selected alone though. That would allow you to keep all the existing combined pickup sounds you have now.

Can you provide a wiring schematic for the guitar? And are you currently using only one half of a dual 5-way blade switch?

[Tone Meister]

Wow, lots of great techinical contributions to this topic.

UPDATE: Changed the 3/4" fillisters over to 1/2" hex (socket cap machine screw made from black oxide coated plain 1022 steel). Was told the shorter screws would alter the magnetic field and thus add some degree of treble response. The concave hex screws were reported to reduce some midrange as well. Lowered the pickup some and raised the hex screws up about 1/8" above the bobbin

RESULTS: Most definitely headed in the right direction. Treble response was increased noticeably and I do perceive an ever so slight decrease in midrange, although that perception could well be in error because of increased treble information.

NEXT MOVE: I will use the guitar tonight and see how it responds in the rig. I do plan to try an unoriented rough case A5 next before shutting the hood on it. Stay tuned