Coil Tapping vs Coil Splitting

[Laimon]

Hi everybody, I recently purchased a guitar with two humbuckers, with a push-pull pot for coil splitting. To my surprise splitting the coils introduces A LOT of hum (and I mean a lot, very very noticeable even on cleans). I have had a lot of guitars with high gain pickups and coil splitting, and never had this much hum, really.
While asking around for possible solutions, somebody suggested that the reason for the hum is the coil splitting as opposed to coil tapping, because by grounding one coil you defeat the hum-cancelation properties of running both, whereas in coil tapping you take the intermediate signal without grounding anything, and the hum cancellation still happens.

So first, very important question: is this true?

Should that be the case, here's what happens now: the push-pull pot has six lugs, that is 2 north lugs, 2 center, and 2 south lugs. When the pot is pushed (that is, normal position) center and south are connected, while when it's pulled north and center are connected.
At the moment, north is connected to ground, south is connected to nothing, and center is connected to both the end of the first coil and the beginning of the second coil, for each humbucker. This means that normally the full humbuckers are active, but when pulled the first coil is grounded and we get coil splitting.
Now, it should suffice to remove the end of the first coil from the center and put it on the south, to get coil tapping: when the pot is pushed, the two coil are still serially connected, and when it's pulled only the beginning of the second coil is grounded, but the first one keeps working (we don't use it's output, but it keeps on eliminating the hum).

Do you think this makes sense? And if you think it's wrong, why so?

Thanks a lot!

 

[jeremy]

Re: Coil Tapping vs Coil Splitting

in order to tap a coil, it needs to have a second set of hot leads. most humbuckers do not have this capability

 

[Laimon]

Re: Coil Tapping vs Coil Splitting

in order to tap a coil, it needs to have a second set of hot leads. most humbuckers do not have this capability

These have the typical 4 leads: south start, south finish, north start and north finish. You mean still more leads?

 

[jeremy]

Re: Coil Tapping vs Coil Splitting

yes. inorder to tap the pup you'd need a tap between the start and finish wire. VERY rare on a humbucker. you see it on hotter single coils more frequently but its still not all that common.

if you want to keep humcancelling but have a brighter lower output sound, look at parallel wiring

 

[Zhangliqun]

Re: Coil Tapping vs Coil Splitting

The basic concept of a tap vs. a split is that they are essentially the same thing. The difference with the humbucker split is that the tap happens to be at the joint between the two coils rather than coming out of the interior of one coil.

 

[PFDarkside]

Re: Coil Tapping vs Coil Splitting

Zhang, have you built a 7 lead (6 + ground) Humbucker for both tap and split?

 

[AlexR]

Re: Coil Tapping vs Coil Splitting

What the person may well have been suggesting is parallel wiring, not tapped.

The hum you have now seems to indicate part of the ground circuit is cut out when the switch is triggered.

 

[Laimon]

Re: Coil Tapping vs Coil Splitting

What the person may well have been suggesting is parallel wiring, not tapped.

The hum you have now seems to indicate part of the ground circuit is cut out when the switch is triggered.

Hi, thanks everybody for your replies. I did not refer to parallel wiring (at least, not of coils of the same humbucker, though that might be a last resort option).
Everything seems soldered properly, extremely well, but indeed the hum is so loud that it would really suggest a weak ground connection when the pot is pulled.

 

[koshikas]

Re: Coil Tapping vs Coil Splitting

Hi, thanks everybody for your replies. I did not refer to parallel wiring (at least, not of coils of the same humbucker, though that might be a last resort option).
Everything seems soldered properly, extremely well, but indeed the hum is so loud that it would really suggest a weak ground connection when the pot is pulled.

forget the weak grounding, if u have soldered well enough, the hum is because of the coil split not cancelling the stray RF noise anymore. if u are not getting as much hum on your other split buckers, then maybe the guitar cavity needs shielding. the parallel wiring mentioned can very easily get u split coil sound while remaining hum cancelling.

Sent from my XT1033 using Tapatalk

 

[Laimon]

Re: Coil Tapping vs Coil Splitting

forget the weak grounding, if u have soldered well enough, the hum is because of the coil split not cancelling the stray RF noise anymore. if u are not getting as much hum on your other split buckers, then maybe the guitar cavity needs shielding. the parallel wiring mentioned can very easily get u split coil sound while remaining hum cancelling.

Sent from my XT1033 using Tapatalk

I guess I will have a luthier check the grounding connections on the push-pull pot, as that seems to be the problem. Should it not, then I'll probably keep parallel wiring in mind as alternative...

 

[ItsaBass]

Re: Coil Tapping vs Coil Splitting

Coil tapping is rarely a feature of guitars/pickups. I would imagine that everything you've owned has been coil splitting, not coil tapping. I think you might have a missing wire or bad connection. Can you post a pic of your control cavity that shows the wiring clearly?

 

[Laimon]

Re: Coil Tapping vs Coil Splitting

Coil tapping is rarely a feature of guitars/pickups. I would imagine that everything you've owned has been coil splitting, not coil tapping. I think you might have a missing wire or bad connection. Can you post a pic of your control cavity that shows the wiring clearly?

I don't have anything better now, and I am away for christmas so these two are the best pics I can provide. Hope they help!

 

[GuitarDoc]

Re: Coil Tapping vs Coil Splitting

It appears that you are indeed wired for coil splitting, but as others have suggested, you might be better off going to parallel instead of split. I personally like the tone of parallel better than split and it is quiet too!

 

[koshikas]

Re: Coil Tapping vs Coil Splitting

^^^^ you can't go wrong with this

Sent from my XT1033 using Tapatalk

 

[Laimon]

Re: Coil Tapping vs Coil Splitting

It appears that you are indeed wired for coil splitting, but as others have suggested, you might be better off going to parallel instead of split. I personally like the tone of parallel better than split and it is quiet too!

Well, truth be told, I am interested mostly in the inner coils of each hb in parallel, that's my "go-to" sound for cleans. As long as that configuration sounds quiet, I will be fine
On the DiMarzio forums I was given the following advise to achieve that:

"If you want the middle position to be humcancelling this could be achieved two ways:

Option 1: wire the neck pickup so that the screw coil stays active in split mode. For this you would need to wire black to hot, red+green to the coil split switch and white and bare to ground.

Option 2: flip the magnet in one of the pickups (a la PRS) and wire this one green to hot, black+white to the coil split switch and red and bare to ground.

It is not too difficult to reverse a magnet - there is an excellent youtube tutorial video on that if you are interested. Option 1 should be very simple for any guitar tech to perform."

So I most likely will have a tech check for the ground connections first, and then - if it's needed, flip the cables as described in the first solution.
I also wouldn't mind changing the first and third positions (neck split coil and bridge split coil) with parallel neck coils and parallel bridge coils, respectively, but I honestly couldn't come up with a diagrama for a 3 way switch + push-pull pot that would achieve this...