Dummy Coils and Coil Taps?

[Heft]

Hey,
If I have a coil tap and a dummy coil will I run into issues when I enable the coil tap? My understanding is the dummy coil has to be approximately the same number wraps to cancel out hum. When I tap the coil won't the dummy have (approximately) twice the wraps?
What would end up happening?
Is this an issue in practice?
Thanks

 

[stratamania]

Are you asking about coil splitting a Humbucker or something else?

A coil tap is not actually a coil split though people misuse the terms.

A dummy coil is not the second coil of a humbucker that you might want to split.

So I really do not know what you are asking, can you clarify?

 

[Heft]

The dummy coil in this case would be a single coil with its poles knocked out and magnets removed. I want to put this RW/RP in a circuit to cancel hum.
My understanding of a coil tap is that it takes the signal from the first half of the wraps from a single coil.
I wan't to know if the dummy coil is equal in length to the real pickup, what happens when the real one is tapped. The dummy would be (in ratio) twice the wraps.
Is there a problem having more wraps in the dummy coil that in the main coil?

 

[stratamania]

Okay I got it now you are trying to do something more like an Illitch  or Suhr silent coil system.

I don't think it would be an actual problem but it would have an imbalance to a degree but how much practical difference this might make is debatable, perhaps it may be noisier.

Experimentation would probably reveal in practical terms what it would mean.  Perhaps you could set something up where when you tap the single coil it also taps the dummy coil.

 

[DuckBaloo]

It's really hard to calculate. A dummy coil will always affect tone. The trick is, how much change in tone are you willing to accept versus how much hum is acceptable.

Some various theories on minimizing the effect of dummy coils...

• Keep them away from the strings and other pickups, this is why many factory installations are in the control cavity, a dedicated route, or at the back of the guitar (like the Suhr/ILITCH system)
• Wider is better
• Lower resistance is better
• Use only when needed....wire it so it's switched out when using a HB or two RW/RP singles

Your mileage will vary, it's best to approach it as a trial or error thing. Myself? I thought they were a really neat idea, but eventually I gave up. I do think the ILITCH backplate (formerly the Suhr SSC) may be the better of the ones I tried and reversible.