humbuckers in combination

[jlipoth]

I recently put a SH-2 and a JB in my les paul and I've been loving it! I don't know if it's supposed to do this, because I've never payed attention to this in other guitars before, but I noticed that when I have a lot of gain on my amp and I switch pickups, I get a lot more hum on the neck or bridge position, but I get significantly less when I run both. In regards to hum, they're almost acting like single coils. I know the hum is definitely different from the single coil hum though, because I have a coil split wired to compare with. I don't think I have a ground/wiring problem, or do I?

[larry_emder]

Exactly the same happens to mine.....a tiny bit of hum when the humbuckers are selected individually......then when they are connected together the hum dissappears.

I am at a loss!!! So i just accepted that it 'was so' and got on with it

And i'm nearly 100% with my wiring i think.


Someone help us out!

[octavedoctor]

Even humbuckers will have a small amount of inductive hum. When the pickups are a matched pair this will be suppressed when both pickups are in circuit especially if the lead and trailing coils of each humbucker are in opposed polarity. Perhaps more significantly the impedance seen by the input of the amp drops to as much as half compared with each humbucker singly.

There is another thread on thius subject and we are currently debating whether this hum is a feature of alnico magnets; well we know that it is, it's more about why this happens. The leading theory at the moment is that it's due to the different magnetic permeability of the two materials although I feel that it is not just this but the fact that the alnico is a large, inadequately earthed slab of conductive material adjacent to the signal path creating a floating potential which intensifies the inductive noise effect.

[larry_emder]

So....how do you earth the magnet????

[octavedoctor]

The only thing I can think of is to ensure that there is good contact between the baseplate and the magnet. Some makers put a film of contact adhesive between the mag and the baseplate, but the jury is still out on the exact cause of alnico noise; i'm still not sure myself whether this floating potential theory is the actual cause.

[larry_emder]

Well i'll make sure my magnets are connected to the baseplate and report back....i know theres a fair bit of wax in there atm that might be getting in the way...

[4lejandro]

Hi, I just installed an SH-4 on my Highway 1 Strat, I have a considerable amount of hum on the bridge position, when I switch to position 2 (which I wired to get an inbetween tone using the middle single coil and the screw coil on the JB) it gets SUPER quiet, my Strat DID NOT have hum cancellation on positions 2 and 4 before, also pos. 2 sounds identical to pos. 3 (middle only), Any ideas of what I did wrong??

P.S. I love the sound of the JB!! Except for the noise.

[Jocelyn]

I have excatly this same problem. If I switch to my Brifge Jb i get a hum, it diff from the hum i get rom the neck single coil, but it is a hum. But if I use both pickups the humis almost reduced. Could this be because of lack od\f Cavity Sheilding?

[octavedoctor]

It's very important that you get the cavity shielding right before considering the hum issue as your perception of it is clouded by the presence of inductive buzz.

As I said before, the prevailing theory is that Alnico pickups hum more than ceramics.

[4lejandro]

It seems ilogical to me because positions 2 and 3 (??!!) are hum cancelling and you can really tell the diference, I don't expect them to be super quiet but I would think they should make the same amount of noise as the hum cancelling combination, I think I wired something wrong...