Strange buzz in a humbucker

[Artur pickupmaker]

How do you know? The only valid test involves measuring DC resistance with an ohmmeter (not an Extech LCR meter).

I've tested with the multimeter touching this parts and the rest of the ground parts (low parts of the circuit), also the noise reduces when I touch the cover with the fingers.
This parts are wired to the same shielding parts as the bridge humbucker, but only the neck one is noisy, that makes me think the problem may be in the coil wires.

"Wire size cannot matter."

-I know, I mean its a different and older wire than my #43 I used in the bridge, it could have insulation fails. I'm considering any possible cause for this hum.

"A broken coil wire can cause buzzy noise by reducing sensitivity forcing you to turn the gain up to get the music loud enough. What is the DC resistance of the coil?"

3 Kohm + 5 Kohm. There is no gain or volume problem and the pickup tone is fine, the problem is the buzz.

[David King]

Artur,
Are the turns counts the same? Your DCR off-sets seem way too large for just a jump from 43 to 42. You can't go much past 10% turns offset before you start losing your CMRR advantage.

Isolate each coil and see if the buzz is any worse in single coil. Are you absolutely sure that magnet poles are reversed?

[Artur pickupmaker]

What is CMRR advantage?

Yes, the polarity of the coils are opposed.

The single bobbin have a stronger buzz, but is much stronger than what should be, the two bobbins have a unexpected buzz too. No comparison with the bridge pickup which have higher DC resistance but lower hum, in the humbucker option it is very low.

I can't understand where this hum cames from, everything seems to be right.

[automan]

If everything is wired correctly, both coils do it when selected independently,all grounds are in place and it does it with the cover off, I would replace the 4 conductor lead wire. It's the only thing left that is common once each other thing has been selected individually.

[J S Moore]

If everything is wired correctly, both coils do it when selected independently,all grounds are in place and it does it with the cover off, I would replace the 4 conductor lead wire. It's the only thing left that is common once each other thing has been selected individually.

If a ground loop isn't possible I would go with the 4-conductor being the culprit.

As an aside I had a low buzzing in my guitar after I had replaced the wiring harness. It was separate from the hum that goes away when you touch the guitar strings and didn't change in volume or character. I was in the cavity about two weeks ago and noticed that along with a wire grounding all 4 pots I had soldered the tail piece ground wire to both the volume and tone pots. I un-soldered the one connection and the buzzing disappeared. I'm honestly curious as to why that would be so. If a ground loop isn't possible then maybe I just happened to have had a cold solder on the connection that I undid.

[Mike Sulzer]

I am still puzzled by something: why you grounded the cores of one bobbin, but not the other (if I understood correctly).

What is CMRR advantage?

Yes, the polarity of the coils are opposed.

The single bobbin have a stronger buzz, but is much stronger than what should be, the two bobbins have a unexpected buzz too. No comparison with the bridge pickup which have higher DC resistance but lower hum, in the humbucker option it is very low.

I can't understand where this hum cames from, everything seems to be right.

[FunkyKikuchiyo]

JS - I think you're right. I've had the exact same thing. Poor continuity to ground (as opposed to simply being miswired) sometimes will fool you. Cold solder joints can be frustrating as you can't make them act up by any jiggling or shaking or the other normal tests as we all know... Whether that is what Artur is dealing with or not I can't say, but I'm glad you brought it up! You probably had some component that wasn't really grounding although there were wires hooked up, and it was just intermittent enough to show up correct when you measured it with a meter. Can't be too anal about grounds or solder joints...

[David Schwab]

What is CMRR advantage?

Yes, the polarity of the coils are opposed.

The single bobbin have a stronger buzz, but is much stronger than what should be, the two bobbins have a unexpected buzz too. No comparison with the bridge pickup which have higher DC resistance but lower hum, in the humbucker option it is very low.

I can't understand where this hum cames from, everything seems to be right.

Each coil has opposite magnetic polarity?

[Joe Gwinn]

I've tested with the multimeter touching this parts and the rest of the ground parts (low parts of the circuit), also the noise reduces when I touch the cover with the fingers.
This parts are wired to the same shielding parts as the bridge humbucker, but only the neck one is noisy, that makes me think the problem may be in the coil wires.

Something isn't grounded properly.

"Wire size cannot matter."

-I know, I mean its a different and older wire than my #43 I used in the bridge, it could have insulation fails. I'm considering any possible cause for this hum.

A broken wire more often produces weak music than increased hum or buzz.

"A broken coil wire can cause buzzy noise by reducing sensitivity forcing you to turn the gain up to get the music loud enough. What is the DC resistance of the coil?"

3 Kohm + 5 Kohm. There is no gain or volume problem and the pickup tone is fine, the problem is the buzz.

These values of DC resistance imply that the coil wire is not broken in either winding. If there were a break, the DC resistance would be infinity (probably rendered as Overload).


The evidence is that some components are not properly grounded. (Touching has no effect on humbucking.) What are the DC resistances from each the various touchable metal components to the shell of the 1/4" output jack?

[David King]

Artur,
CMRR = Common Mode Rejection Ratio = humbucker.
You still haven't told us what your number of turns offset is.
If you have 4500 turns of 42 on one coil and 6500 turns of 42 on the other -you don't really have a humbucker anymore. Am I wrong?

[David Schwab]

If you have 4500 turns of 42 on one coil and 6500 turns of 42 on the other -you don't really have a humbucker anymore. Am I wrong?

It's still pretty quiet if you don't go too far out. My old Hi-A pickup is 3.2K on one coil and 4.5K on the other. That's probably around 1,000 turns. 2,000 turns might start to get noisy.

A better way to make a humbucker that sounds good when split is make the single coil side tapped, so you switch to the lower tap when in humbucker mode, and the higher tap when split.

[Artur pickupmaker]

The slugs of just one bobbin are grounded because these slugs are touching the baseplate, the slugs of the other coil are smaller and doesn't touch the baseplate. I think this is not the problem because I've seen that in many pickups the slugs are not grounded and they are not specially noisy, but I know ground all the slugs is better.

The magnetic pollarity of the coils are opposed.

Yes, I did 2 taps for the single coil, in the "single" position the switch this two taps works in series, in the "humbucker" position the lower coil is turned off but keep grounded at one side and the side coil is turned on. I made one tap over the other to get the Strat single coil bobbin height, this give me some work. I did the same thing in the bridge humbucker and it worked fine.

2 Kohm is not a great difference that results in so much hum, if it were wu should neve make single coils. I did this way because it sounds good to me, different to the same number of turns in each coil, and I don' care of a little hum or single coil hum since I always make eletric shielding in my guitars that reduces this noise a lot.

I've mesured the resistence between the baseplate/copper foil and the jack output, it measured 2,0 ohm. Seems to be fine, about the same between the bridge humbucker cover and the jack output. So is the cold solder possibility discarted?

Now I ask:
The wire I used were made in 1989. It's possible the insulation, not the wire itself, have brokes or fails causing eletrical shorts in the coil, and it causes this buzz? It's the only difference for the bridge humbucker plus the copper foil around one bobbin. For the bridge I used a newer wire.
I used the same 4 conductor wire for both pickups.

[David King]

If the wire insulation were seriously bad you would see it in your DCR readings.

Time for a re-wind and see if it was the wire. I still think it's your offset but what do I know?