How do you recognise pickup phase

[MarkusBass]

I mainly fix guitar and bass amps. But sometimes I get a guitar with a request to fix it. Few days ago I've got Ibanez guitar where the owner tried to solder new pickups. Each of three pickups were from different manufacturer (one was no-name). Of course the pickups were soldered completely wrong. After correcting initial problems (completely incorrect wiring) I had to find out how the pickups should be connected - especially regarding phase of the signal. Color diagrams didn't help. Additionally there was a mistake on Ibanez wiring diagram. I managed to connect the pickups but I wonder if there is an easy way to recognise phase on an unknown pickup. This would help me a lot. Any ideas?

Mark

[Steve Conner]

Tap a pole piece with a screwdriver and look at the polarity of the resulting spike on a scope? Kind of like the battery test for speakers, but in reverse.

I've always done it by ear.

[MarkusBass]

Thanks - I will try this method next time. To make it more difficult, the pickups that I was working with were humbackers. So you have two coils in the pickup and possibly they are also soldered incorrectly. But this should be possible to be checked by ear.

Mark

[soundguruman]

Another obvious thing is that if one coil of the humbucker is reversed-it hums more.
Turn one coil around and see if it hums LESS. Basic but it works.

[MarkusBass]

Yes, this is obvious - and this was what I checked. I had 2 humbackers (DiMarzio and Saymour Duncan) and one single pickup (no name). The switch was typical 5 position (double) Ibanez switch. I had problems with the single pickup because it is connected either as just one pickup, or in parallel with one of the humbackers but connected as single. It turned out that in this configuration I had to reverse the single pickup to minimize the hum.
Next time I will try the method posted by Steve.

Mark

[rhgwynn]

All you need is a polarity tester (or a compass) and to be able to see the coil to know which way it's wound....right?

-Rob

[David Schwab]

Another obvious thing is that if one coil of the humbucker is reversed-it hums more.
Turn one coil around and see if it hums LESS. Basic but it works.

On top of that it will sound thin with very little low end, and a honky midrange. It's very noticeable.


If you have an analog multimeter you can also see which way the needle swings when you tap on the coil.

[MarkusBass]

How can you recognise which wire is which with a compass? I think I have one at home.

Mark

[David Schwab]

How can you recognise which wire is which with a compass? I think I have one at home.

Mark

The compass would be for the magnet polarity. Remember that the North end of the compass needle faces South. The Earth's magnetic North is really at the South pole.

[MarkusBass]

Just to recap what exactly is the problem.
There are actually three problems:
1. You have unknown humbacker with two coils and you need to connect them properly.
2. You have two humbackers from two different manufacturers and you need to connect them properly.
3. You have two humbackers and one single pickup (from unknown manufacturer) and you need to connect them properly.
They are not exactly the same problem.

And the problem I had was the problem #3 listed above. I think in the future I will use the method mentioned by Steve (unless it is also possible with a compass - I'm waiting for an answer from Rob).

Mark

[MarkusBass]

The compass would be for the magnet polarity. Remember that the North end of the compass needle faces South. The Earth's magnetic North is really at the South pole.

I know what are magnetic poles. But how do you relate them to the wires from the pickup?

Mark

[rhgwynn]

This might help you some - www.deaf-eddie.net/drawings/phase.pdf

-Rob

[kayakerca]

I know what are magnetic poles. But how do you relate them to the wires from the pickup?

Mark

On the single coil, you can look at the wire coming off the coil. One will come off the outside of the coil and the other will come off the inside of the coil (outside of the very outer edge of the Alnico magnet). Even if they are taped, you will be able to tell fairly easily which is which. From there you can tell if it is wound CW (normal electrical polarity) or CCW (reverse electrical polarity). Combine that with the magnetic polarity and you then know if it is, as an example, reverse wound (CCW) reverse polarity (north up). And the black wire should be ground, but you can change the electrical polarity of the single coil buy just switching the leads if you need the electrical polarity the other way.

[rhgwynn]

From Lollar:

Guitar pickups generate an alternating current meaning the signal goes from positive to negative in a wave form. The current will be either positive or negative at the beginning of the signal depending on if the magnet in the pickup is north or south up and if the coil is wound clockwise or counter clockwise. It's not really the winding direction, it's the direction of the wire between the hot lead and the ground lead. If you look down at the top of a Strat pickup with the lead wires facing you you'll see the black wire will be either on the right or the left. If the white wire is on the right the coil direction goes counter clockwise from white to black. If the white wire is on the left the coil direction goes clockwise from white to black. In a simplistic view a pickup with the magnetic polarity south towards the strings with a counterclockwise coil will make a negative signal initially. A pickup with a south up orientation combined with a clockwise wound coil will give a positive signal. A pickup north up counterclockwise coil will give a positive signal, a pickup north up clockwise will give a negative signal. If you combine two pickups and run them at the same time and one has a negative signal and the other has positive they will be out of phase and the signal will cancel itself out.

In order to sound best both pickups need to have the same phasing. On vintage Strat pickups it's sometimes not as simple as just reversing the leads. You can't necessarily just run black to hot and white to ground to reverse the phase because the coil often shorts out against the magnets. Fenders originally had the inside of the coil attach to the ground wire so if it does short out against the pole pieces it doesn't matter. But, if you were to reverse the leads and make the hot lead the inside wire on a vintage fender and it did short out against the pole piece, by touching the pole piece and the strings at the same time you will loose signal—it will short circuit.

On my Strats the magnets are well insulated so you can reverse the lead wire—black for hot, white for ground—if you need to change the phasing on it to match another manufacturer's pickup.

On teles, the metal plate on the bottom of the bridge pickup is connected to the black lead wire and grounds your strings, also the cover on the neck pickup is connected to its black wire which grounds the cover and helps provide some shielding. If you hook up the black wire to hot your pickup cover will make a racket if you touch it or even worse you'll loose signal if you touch the cover and the strings at the same time Same goes with the bridge—;reverse the lead wire and you'll get a loud buzzing when you touch the strings. This is the same problem with Gibson humbuckers that have vintage lead wire—;the covers are attached to the braided shield which is also attached to the coil. The solution on buckers is to use 4 conductor wire with a separate shield so you can reverse your lead wires separate from the shield wire.

On teles you have to add a separate wire that only connects to the cover or the metal base plate—;a three wire system that isolates the lead wires on the coil from the pickup cover. You also need these separate ground wires on at least one of the pickups if you are going to wire the pickups in series with a 4 way Tele switch. Normally the third wire is added to the neck pickup.

-Rob

[David King]

The traditional approach to determining coil phase is to use an analogue Voltmeter and pull a steel object off the top of the pickup to see which way the needle moves.

I'd like to propose that we can come up with something better than this. How about a tester that has 4 contacts (two for each coil) and an AC electromagnet signal wand that you pass over the pickup to mimic the vibrating string. Each coil would have a phase LED that would light up either red or green. Two green LEDs and Bob's your uncle.
I'd think an Arduino board and a few lines of code could do this and perhaps include some magnetic polarity and field strength info as well. I'd gladly pay $100 for such a device.