How much hum can a humbuck buck?

[David King]

Toss this pickup into the ebay bin and start over already. If it hums it hums. How Duncan managed to screw it up is anyone's guess.

How you're going to dampen the cover of the Gibson pickup is a mystery short of drilling a hole through the top and filling it with something. I suppose you could file through a corner and then solder over that once it's filled.

[loudthud]

I guess coils must also be magnetically balanced, not sure how having solid slugs on one and adjustable ones on the other may affect that; I love experimenting and would put an unmounted humbucker close to, say, a transformer or a fluo reactance to induce extra magnetic hum and then adjust polepieces, I'm quite certain that will allow very fine tuning.
Any takers?

This seems reasonable to me. I think a Firebird pickup is just a mini humbucker with two non-adjustable bobins in a cover with no holes. Is that right? What about the idea of making a full size humbucker with a pair of non-adjustable bobins or even two adjustable bobins? Anybody ever tried that?

[copperheadroads]

This seems reasonable to me. I think a Firebird pickup is just a mini humbucker with two non-adjustable bobins in a cover with no holes. Is that right? What about the idea of making a full size humbucker with a pair of non-adjustable bobins or even two adjustable bobins? Anybody ever tried that?

No The original firebird pickups had Bar magnets for poles & were wound different than Mini-humbuckers ..Mini's sounded more like a PAF . Firebirds sound more like a fat single coil
From what I've seen in the latest Firebird/tribute pickups the use a close cover & use 2 blade poles with a humbucker sized bar magnet underneath & wound to vintage spec .so it's kind of a hybrid

[guitician]

Yeah, that Duncan sounds like it is wound asymmetrical. I took some windings off of a Gibson Classic that was hum free before, and now it has some hum. But it sounds more like an old pickup.

[big_teee]

Two slug bobbins wound symmetrical, in a no holes nickel cover, well grounded?
Should be about the quietest noise and hum wise.
If possible make sure the internal parts, like the slugs are grounded.
It shouldn't make as much difference inside the metal cover, but ideally all parts should be grounded IME.
Then pot it all in wax.
I've built that pickup before and it works great!
T

[kmensik]

There was a post here 10 or 15 years ago that observed that in at least one case there was better humcancelling when a ceramic magnet was used, perhaps because the ceramic magnet conducted no current.
Steve A.

Yes sir, it is exactly like this. Alnico bar magnets make all the noise in humbuckers. I blame the eddy current. Baseplates made of steel are even worse, so the combination of conductive and magnetic makes the problem, because brass baseplates are quiet. It is tricky to recognize nickel silver from nickel plated steel by eye, easy with a magnet.
I remember a Bulgarian testing noise on a SH-4 vs. a ceramic Yamaha pickup, then swapping the magnets and testing again. The noise was always on the alnico side.

[Mike Sulzer]

Yes sir, it is exactly like this. Alnico bar magnets make all the noise in humbuckers. I blame the eddy current. Baseplates made of steel are even worse, so the combination of conductive and magnetic makes the problem, because brass baseplates are quiet. It is tricky to recognize nickel silver from nickel plated steel by eye, easy with a magnet.
I remember a Bulgarian testing noise on a SH-4 vs. a ceramic Yamaha pickup, then swapping the magnets and testing again. The noise was always on the alnico side.

I think it is the permeability of the magnet that is most of the problem, not the conductivity. Alnico has much lower permeability than steel, but higher than the usual ceramic magnet. I once made a humbucker using slugs on both coils with them connected together on the back with laminations of transformer steel. The permanent field was supplied by neo buttons on the back under each pole piece. It had the worst hum possible. If you follow out the magnetic circuit, the magnetic field induced in anything connecting the pole pieces of the two coils adds through the coils, not subtracts. Has to, right? That is why the string works! But I had not thought this through, thinking that coupling the coils together magnetically would give higher output. Sure, but you cannot do it at that cost.

[kmensik]

I have a similar experience. Had a humbucker with a ceramic magnet, which was a bit too narrow between the polepieces, so they added a shim of transformer steel, even soldered a ground wire to the silicon steel. Buzzed like hell. Ungrounding hlelped a little, removing the shim hleped a lot. Made it an airbucker out of necessity, heureka.
BTW the pickup was a Czechoslovak Jolana factory product. The magnet was not made for pickups, but a stack of commonly available magnets produced for snap on torches.