Hum from covered humbucker on Strat build

markuus99

New member
Messages
13
So I have been putting together my first build this year- an HSS Strat. I decided I'd prefer the look of the bridge humbucker with a metal pickup cover, so I covered the pickup myself. It looks great and mostly sounds great, but I'm having hum/noise issues with the (covered) bridge pickup.

I went with the noiseless Quiet Coil prewired Strat pickguard from Mojotone. None of the pickups are true single coils.
https://www.mojotone.com/Pickups_x/easy/Mojotone-58-Quiet-Coil-HSS-Strat-Prewired-Pickguard

I transplanted the pre-wired harness into a Warmoth pickguard so I could get a proper sized cutout for the covered bridge humbucker. I also wanted to minimize fit issues with the Warmoth body cavity by using a Warmoth pickguard.

In position 1, you get the bridge humbucker alone. In position 2, the bridge pickup is split, so it's one coil of the bridge pickup along with the middle pickup. I get hum in both positions. The hum isn't overwhelming and is only audible with gain, but I'm only have the issue with the one covered pickup. The hum is worse in position 1 (just the humbucker) than position 2 (one bridge coil plus the middle pickup).

The baseplate of the humbucker pickup was already grounded. I just scuffed up the inside of the pickup cover and soldered the cover to the baseplate in two places to ensure it was grounded.

I shielded the body cavity with conductive paint and (very imperfectly) applied copper shielding tape to the bottom of the pickguard. I believe the shielding tape is slightly in contact with the pickup cover. There's also little gap in the shielding tape right next to the bridge pickup.

The hum gets better or worse if I move the position of the guitar. The hum doesn't change if I touch the pickup cover or baseplate or both.

I was wondering if something being in contact with the conductive paint inside the guitar could be causing something, but the hum remains if I pull the pickguard out of the guitar. Again, the middle and neck pickups are fine with the pickguard on or off.


Any suggestions?
 

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mayfly

Senior member
Messages
8,309
So - just thinking out loud here: you get hum with the humbucker (with two coils and split), but no hum with the single coils. 

That tells me that there is something wrong with that pickup. 
 

markuus99

New member
Messages
13
Mayfly said:
So - just thinking out loud here: you get hum with the humbucker (with two coils and split), but no hum with the single coils. 

That tells me that there is something wrong with that pickup.

The "single coils" are noiseless, so they aren't actually single coils- they have two very narrow coils under the plastic covers to buck the 60 cycle hum. So technically all three pickups are humbuckers from that perspective.

The noise changes if I move the guitar around, and I get more noise from the "single coils" if I lift the pickguard out of the body while it's plugged in with gain on, so I feel like that points to electrical hum/buzz/noise from interference or something like that, as opposed to the classic 60hz hum. I'm an old house with old wiring, so that likely doesn't help.

It's just the covered pickup is worse, and noticeably noisy even in the shielded body. I'm wondering if there is an issue with the shielding, the way the cover/pickup is grounded, or if I possibly did something to the pickup when heating it up to put the cover on.

 

PhilHill

Senior member
Messages
1,654
Just a thought, what material is the pickup cover made of ?  Seth Lover, when describing his development of the humbucker, said that the material a dual coil's cover is made of can have a good or bad effect on the signal produced.
 

markuus99

New member
Messages
13
PhilHill said:
Just a thought, what material is the pickup cover made of ?  Seth Lover, when describing his development of the humbucker, said that the material a dual coil's cover is made of can have a good or bad effect on the signal produced.

It is this one from Mojotone. It is nickel silver clad in chrome.
https://www.mojotone.com/guitar-parts/53mm-Humbucker/Humbucker-Pickup-Cover-Chrome-53mm

I might reach out to Mojotone and see if they have any suggestions as well.
 

PhilHill

Senior member
Messages
1,654
markuus99 said:
PhilHill said:
Just a thought, what material is the pickup cover made of ?  Seth Lover, when describing his development of the humbucker, said that the material a dual coil's cover is made of can have a good or bad effect on the signal produced.

It is this one from Mojotone. It is nickel silver clad in chrome.
https://www.mojotone.com/guitar-parts/53mm-Humbucker/Humbucker-Pickup-Cover-Chrome-53mm

I might reach out to Mojotone and see if they have any suggestions as well.

Ok. That eliminates that possibility, nickel-silver is the acceptable material..... :headbang:
 

TBurst Std

Senior member
Messages
2,664
You didn’t reference your process for putting the cover on

Can you verify you adhered to the basic rules?
https://www.google.com/search?source=hp&ei=99DTX7rtL_Dy5gLajpjwCA&q=affixing+a+cover+to+a+humbucker+pickup&oq=affixing+a+cover+to+a+humbucker&gs_lcp=ChFtb2JpbGUtZ3dzLXdpei1ocBABGAAyBQghEKABOgcIKRAKEKABOgIIKToICAAQ6gIQjwE6CAgAELEDEIMBOgsIABCxAxDHARCjAjoICAAQxwEQowI6CwguELEDEMkDEJMCOgUILhCxAzoFCAAQsQM6CAgAEMcBEK8BOgsIABCxAxCDARDJAzoICAAQsQMQyQM6AggAOgoIABDJAxBGEPkBOgcIABCxAxAKOgQIABAKOgUIABDJAzoGCAAQFhAeOgkIABDJAxAWEB46BQghEKsCOggIIRAWEB0QHjoHCCEQChCgAVCsFljdgAFgzo0BaAJwAHgAgAHyAYgBxh6SAQcxMy4xNi4ymAEAoAEBsAEP&sclient=mobile-gws-wiz-hp#kpvalbx=_CtHTX8jQE7Gw5wLol5nQAw4
 

markuus99

New member
Messages
13
TBurst Std said:
You didn’t reference your process for putting the cover on

Can you verify you adhered to the basic rules?
https://www.google.com/search?source=hp&ei=99DTX7rtL_Dy5gLajpjwCA&q=affixing+a+cover+to+a+humbucker+pickup&oq=affixing+a+cover+to+a+humbucker&gs_lcp=ChFtb2JpbGUtZ3dzLXdpei1ocBABGAAyBQghEKABOgcIKRAKEKABOgIIKToICAAQ6gIQjwE6CAgAELEDEIMBOgsIABCxAxDHARCjAjoICAAQxwEQowI6CwguELEDEMkDEJMCOgUILhCxAzoFCAAQsQM6CAgAEMcBEK8BOgsIABCxAxCDARDJAzoICAAQsQMQyQM6AggAOgoIABDJAxBGEPkBOgcIABCxAxAKOgQIABAKOgUIABDJAzoGCAAQFhAeOgkIABDJAxAWEB46BQghEKsCOggIIRAWEB0QHjoHCCEQChCgAVCsFljdgAFgzo0BaAJwAHgAgAHyAYgBxh6SAQcxMy4xNi4ymAEAoAEBsAEP&sclient=mobile-gws-wiz-hp#kpvalbx=_CtHTX8jQE7Gw5wLol5nQAw4

I referenced that same video and this video as well when I put the cover on:
https://www.youtube.com/watch?v=jJqIK93MC9Q

It was a while ago that I did the process, but I believe I basically:
Covered the non-screw lugs with tape
Put some parafin wax inside cover
Scored the surface of the inside of the cover to expose some of the core metal for soldering
Backed out the screw lugs a little bit to align with the holes in the cover
Put the cover on
Soldered the baseplate to the cover in two places where I had scored the inside of the cover
Heated the cover with a hairdryer to melt the wax on the inside
 

markuus99

New member
Messages
13
Posting back here in case anyone can benefit from my mistake in future...

Mayfly and rick2 were right here. The issue was not a grounding or wiring issue. It appears I must have inadvertently shorted one of the coils somehow when I put the cover on the humbucker. That meant only 1 coil was working on the humbucker, and therefore I got hum! Either I got solder somewhere I shouldn't have when I put on the cover or else (maybe more likely), the metal cover made contact with something in the pickup that caused one coil to connect straight to ground.

In bridge position, I was getting just 1 coil from the humbucker, so of course I got quite a bit of hum.

In position 2, I was getting 1 coil from the bridge pickup plus both coils from the noiseless 'single coil' style middle pickup. That's three coils, which won't properly cancel hum. This was actually correct and to be expected, since it was wired to auto-split the humbucker in position 2.


I really had a hard time trying to get the cover off the humbucker, and I also decided I didn't like the auto-split in position 2 because it by definition doesn't cancel hum. I bought noiseless pickups because I live in a very old building and am bound to get a lot of 60 cycle hum. So I ended up swapping out the humbucker for Seymour Duncan Pearly Gates and wiring it up without the auto-split.

Now I am noiseless in all positions. I was worried the humbucker might overwhelm the middle pickup in position 2, but I actually find it's a nice blend between the single coil and humbucker style sounds, and I'm happy with this wiring.
 
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