Leaving coil ends unconnected or not?

[slide]

Hi,

I've tried searching the answer for my question (as I'm basically sure it must be around somewhere), but sofar no luck...so maybe you can help me out quickly:

I'm trying to think up a guitar wiring scheme for a PRS using their 5 way rotary as well as a push/pull pot.
This should give me all original the sounds of the 5 way (of which I don't want to miss any), plus the combinations "Neck HB + Bridge HB", "Neck Split", "Bridge Split".

Basically I see two variants to achieve this. In one (which I'd prefer because of the layout of the possibilites) this will lead to switching positions, where both ends of an "unused" humbucker coil are connected together, but otherwise are left open (i.e. neither connected to + or -).
I've never seen this before in guitar schematics, usually one end is still either connected to hot or ground...so, is there a reason *not* to wire it that way?

Thanks and Regards,
Andy

[JohnH]

The general view is that if a coil is disconnected at both ends, or connected to ground only, then its all fine and has no influence. If it has just one end connected to hot, it wont add any significant sound, but may contribute to a small amount of noise, acting as an antennae. It would depend on whether the cavity is screened, or if it is a covered HB with a grounded case. Its not always a problem, and is often not a problem, but is best avoid if possible.

An illustrative test you can make to help understand, is to plug a guitar cord into an amp and turn up the gain, which should be fairly quiet if it is a good cord. Now connect a piece of bare wire to the grounded barrel, and it will make no difference, but add one to the hot tip and it will probably pick up a buzz.

[ashcatlt]

JohnH's pretty much got you there, but never really came out and said that you're okay with what you've got. Disconnecting both ends will definitely kill the pickup. Shorting a pickup also kill it. Doing both should be even better!

There is that thing where the shorted coil might steal a bit of vibrational energy from the string, but I think we've pretty much decided it can't be enough to worry about.

[wolf]

slide
I believe that JohnH summed things up rather well. When a pickup has 2 wires (or 4 for a humbucker) plus a separate ground connection, having a wire "hanging from the hot" connection is only a minor consideration.

If you don't believe the Guitar Nutz™, how about Seymour Duncan? If you go to this thread
guitarnuts2.proboards.com/index.cgi?board=modules&action=display&thread=5244
and scroll down to posting #2, you'll see that their Triple Shot Pickup Mounting Ring has a setting that inadvertently leaves a wire "hanging from the hot" connection.

It seems to rest well with the Seymour Duncan Company. Of course if it does make a difference, why hasn't someone discovered this flaw especially since those pickup rings sell for $30?

[newey]

Slide-

Oh, and:

Hello and Welcome to G-nutz2!

[slide]

Hi,

thanks all for the reply.

Oct 11, 2010 18:16:24 GMT -5 JohnH said:

The general view is that if a coil is disconnected at both ends, or connected to ground only, then its all fine and has no influence. If it has just one end connected to hot, it wont add any significant sound, but may contribute to a small amount of noise, acting as an antennae.

This basically solved everything in two sentences...wow, and thanks!

Just to clarify (and for me to learn): What is the general view on "both ends connected to hot"?
Should probably increase the tendency to pick up noise, that would be my guess at a least...

[slide]

Hi,

Oct 11, 2010 22:56:41 GMT -5 wolf said:

slide
When a pickup has 2 wires (or 4 for a humbucker) plus a separate ground connection, having a wire "hanging from the hot" connection is only a minor consideration.

If you don't believe the Guitar Nutz™, how about Seymour Duncan?

I don't have trouble believing this, as this is what already happens in the original 5-way PRS schematic as well...
However "both ends open" doesn't happen...that's what got me thinking if that might be for a reason other than "it happened to be easiest that way with our switching logic".

[JohnH]

Oct 12, 2010 4:40:44 GMT -5 slide said:

Hi,

thanks all for the reply.

Oct 11, 2010 18:16:24 GMT -5 JohnH said:

The general view is that if a coil is disconnected at both ends, or connected to ground only, then its all fine and has no influence. If it has just one end connected to hot, it wont add any significant sound, but may contribute to a small amount of noise, acting as an antennae.

This basically solved everything in two sentences...wow, and thanks!

Just to clarify (and for me to learn): What is the general view on "both ends connected to hot"?
Should probably increase the tendency to pick up noise, that would be my guess at a least...

I dont think that science has yet proven what happens with both ends to hot. My guess is the same as one end to hot, which may be a bit of noise, or not.

[slide]

Oct 12, 2010 6:27:49 GMT -5 JohnH said:

I dont think that science has yet proven what happens with both ends to hot. My guess is the same as one end to hot, which may be a bit of noise, or not.

Taking a closer look at the PRS schematic...it happens for one of the neck coils in position 2...both ends connected to hot.
Since I've never had any noise problems with this wiring, and so far never have heard of noise problems with the PRS wiring, it seems to work out ok, somehow.

So, is there a wiring combination that generally *shouldn't* be used to kill-off a coil? (apart from one end hot, one end ground... ). It seems like everything else is basically ok?

If that has been discussed already, you can also simply point me there...I'm not too lazy to read, I've just not yet found a "guide to coil-killing", somewhere....

[ashcatlt]

Sometimes we end up in situations where we can't avoid leaving the one end connected to hot. It's my understanding that we generally prefer to also connect the other end to hot if at all possible specifically to avoid the noise issue. A shorted coil shouldn't. - in theory at least - be able to generate any noise. This won't work in cases where the bottom of the coil is permanently connected to ground, since you'll then be connecting hot to ground and shorting out the entire guitar.

When two or more coils are connected in series, you can't lift either ( or both) ends of any of the coils without replacing it with a jumper, else it breaks the signal path for all the other coils.

[ashcatlt]

This thread reminded me of urthman who claimed that he had solved the problem of noise in his strat by disconnecting both ends of all unused pickups. The link is to a very long meandering thread with quite a bit of good info in it. That thread led to a second thread which was stickier somewhere or other.

[newey]

Ash-

Your memory is comprehensive and accurate. I hadn't recalled "The Urthman Prophesies".

In that thread, ChrisK tangentially touched on just what we're discussing here, but then moved on without elaboration:

When the pickup is in circuit (both wires are connected and just not shorted together), it primarily functions as a generator (the AC analogy to a DC magneto), with current flow induced by the variations in the magnetic field due to the varying magnetic path coupling thru the locally sensed string masses. (When the leads are shorted together, it still functions as a shorted generator, but this effect is not germane to this tone, er tome.)

This does suggest, however, that there is some "effect".