Two humbuckers, out of phase with each other

[Bellboy]

I'm doing up an old SG-style guitar with pretty standard wiring. Previously the connections on the 3-way toggle switch were wrong, resulting in only two sounds being available. I've 'fixed' that, but now I find that the two pickups are out of phase with each other, resulting in a very quiet middle switch position.

At least, I think they are out of phase. It doesn't particularly SOUND out of phase, just quiet, and it's only really noticeable on cleanish effects. But I've looked at the waveforms in recording software when just plucking a single note and they do look inverted so I'm pretty sure they're out of phase.

But they are bog-standard pickups with just one hot wire and one earth wire, so I don't see how I can have caused this with a soldering alteration, surely they must always have been like this? I note that the bridge pickup is rotated 180 degrees in the body cavity compared to the neck pickup, but as far as I am aware this shouldn't alter the phase.

Can I simply invert the 'earth' and 'hot' connections coming from one of the pickups to the volume pot? Or will the fact that the metal pickup casing is soldered to the earth wire cause problems if I do that?

[bbsailor]

I'm doing up an old SG-style guitar with pretty standard wiring. Previously the connections on the 3-way toggle switch were wrong, resulting in only two sounds being available. I've 'fixed' that, but now I find that the two pickups are out of phase with each other, resulting in a very quiet middle switch position.

At least, I think they are out of phase. It doesn't particularly SOUND out of phase, just quiet, and it's only really noticeable on cleanish effects. But I've looked at the waveforms in recording software when just plucking a single note and they do look inverted so I'm pretty sure they're out of phase.

But they are bog-standard pickups with just one hot wire and one earth wire, so I don't see how I can have caused this with a soldering alteration, surely they must always have been like this? I note that the bridge pickup is rotated 180 degrees in the body cavity compared to the neck pickup, but as far as I am aware this shouldn't alter the phase.

Can I simply invert the 'earth' and 'hot' connections coming from one of the pickups to the volume pot? Or will the fact that the metal pickup casing is soldered to the earth wire cause problems if I do that?

Bellboy,

Do not invert the wires of a two conductor (shield wire and one center wire) pickup as the pickup case will become hot. The only way to properly invert the phase of a pickup is to use a pickup that has two or more center conductors where the ends of the two series coil wires are brought out to separate center conductors and the shield is only connected to the pickup case. This way you can put a push-pull pot that switches the phase of one pickup relative to the other. This only works when the two pickups are on.

If you try this, here is another secret to get the most value out of this setup.
Wire the volume pots like the Fender Bass where each volume control independently adjusts the individual pickup volumes even when both pickups are on together. Normal pickups have the ground on the end pot lug and the pickup hot on the other end pickup lug with the pot output attached to the center lug. Just reverse the pot center and hot pickup wires so that each pickup volume control output now comes from the outer end lug.

When you use two pickups and flip the phase of one pickup, you can now adjust the volume of either pickup volume control and get a varatone-like tonal change. This effect only works in a very narrow range of the pickup volume control but I have done this for a few professional guitarists who use this and love it.

Joseph Rogowski

[Bellboy]

Normal pickups have the ground on the end pot lug and the pickup hot on the other end pickup lug with the pot output attached to the center lug. Just reverse the pot center and hot pickup wires so that each pickup volume control output now comes from the outer end lug.

It sounds interesting. I currently have the tone capacitors soldered to the outer hot lug, would this need to be moved to the centre lug also?

As for as reversing the phase of one of the pickups... the only options are to fit new pickups with more connector wires accessible, or to actually open up the pickup and reverse the magnet (or alter the connections in there)? This seems odd as they both seem to be the original pickups for the guitar, and from the same manufacturer. Perhaps it was designed to be out of phase originally, but this seems an odd choice for off-the-peg wiring. Unfortunately I bought it second hand when it was already about 15 years old and have no real idea of its history.

[bbsailor]

It sounds interesting. I currently have the tone capacitors soldered to the outer hot lug, would this need to be moved to the centre lug also?

As for as reversing the phase of one of the pickups... the only options are to fit new pickups with more connector wires accessible, or to actually open up the pickup and reverse the magnet (or alter the connections in there)? This seems odd as they both seem to be the original pickups for the guitar, and from the same manufacturer. Perhaps it was designed to be out of phase originally, but this seems an odd choice for off-the-peg wiring. Unfortunately I bought it second hand when it was already about 15 years old and have no real idea of its history.

Bellboy

To modify your existing pickup:
1. Obtain a short length of two conductor shielded cable. Radio Shack may still sell it as a roll of 2 conductor mic wire.

2. Open the pickup and remove the one coil lead that goes to ground and is attached to the coax shield.

3. Remove the hot pickup wire from the coax center conductor.

4. Attach the new 2-conductor coax in the following way.
4.1 2-conductor coax ground to the pickup ground, where the other coax wire was connected.
4.2 Connect the hot lead to one center conductor and put a piece of heat shrink tubing over the connection to keep it from shorting out.
4.3 Connect the new hot lead (previously connected to the pickup ground) to the other center wire of the 2-conductor shielded cable.


Joseph Rogowski

[David Schwab]

Alternately, you can also open the pickup and flip the magnet over so the poles are opposite. That will put the two pickups back in phase.

All you have to do is loosen the bottom screws that hold the bobbins in slightly and slide the magnet out. Flip it over and slide it back in, then tighten the screws.

[Mike Sulzer]

Maybe they are not out of phase. The "treblely" sound should be quite recognizable. Initially you had only two sounds. Why? To get two sounds should require two pickups, and if they were both working, you should have gotten the third sound when the switch connected them both. Is it possible you still have a wiring problem or a bad switch?

Before taking a pickup apart, check to see if the magnetic polarities are the same on both with a small magnet.

Make sure pickups, switch, and pots are working normally before making any modifications.

[Bellboy]

The toggle switch has 3 contacts - the output in the centre, and an outer contact on either side that each pickup connects too. Previously, for some reason, the output was soldered to the same contact as one of the pickup inputs. So this meant that, in the central position, both pickups were 'on', but in either the up or down position, the bridge pickup was selected. The bridge pickup also often worked intermittently, for a reason I never worked out, whereas it always worked on the central position. When it wasn't working, perhaps I was only getting the neck pickup with the switch in the central position, but I couldn't be sure of this now. Either way, it seems to have been a wiring fault at the switch and not in the pickup as I don't get this intermittent problem now.

All I have done is move the output wire to the central contact of the switch. I don't really know how I can have done any damage doing this, and I certainly can't have altered the phase of either pickup because there is only one output and one shield connection from each. I can only presume that the pickups were always out of phase and I just never noticed because I wasn't checking everything as much as I am now I've 'fixed' it.

If you can suggest another reason why either pickup individually works fine, but connecting them in parallel creates a noticeable volume drop, then I would be happy to check out that possibility. The reason I think it is a phase issue, despite it not sounding particularly trebly, is looking at the waveforms in my recording software as I mentioned before. I can post some screen grabs of this later if it would help.

On a related note - What exactly is the earth/ground wire connected to in a pickup with a single output like this? Is it connected to one end of the pickup coil, or just to the metal casing? On one of my pickups the insulated cable goes right into the casing and I can't see what it does, but on the other pickup I can see that the shield actually ends outside the pickup (soldered to the casing with a short wire) and only the inner wire goes inside. Is this a fault that needs addressing also?

[Mike Sulzer]

Your analysis assumes that the switch is working correctly. It would be a good idea to check it.

Yes, a pickup wire must be connected to ground. Check the resistances of both pickups.