Problem with stacked humbuckers and 42AWG

[Stakkz]

Hi,

I hope i can get some help understanding an issue i´ve had with 42AWG Formvar and Poly wire when winding stacked humbuckers.
For some reason the total inductance does not increase when connected in series but when i use 43AWG Poly there´s no issues everything works fine all other factors being equal.
Has anyone else experienced this?
When i measure the coils individually all the numbers (DCR and Inductance) read as they should.
I´m gratefull for any insigh, thoughts, ideas etc.

[Helmholtz]

When i measure the coils individually all the numbers (DCR and Inductance) read as they should.

Do the individual coil DCRs add up in seies wiring?

[Stakkz]

Do the individual coil DCRs add up in seies wiring?

Yes the dcr adds up but not the inductance.

[Helmholtz]

Very confusing.

It can't be the wire type/gauge.

How do you wire the coils? Which end is grounded?

Can you post pictures?

How do you measure inductance?

[Stakkz]

Very confusing.

It can't be the wire type/gauge.

How do you wire the coils? Which end is grounded?

Can you post pictures?

How do you measure inductance?

I follow the Seymour Duncan colour code;
Bottom coil is green start, red finish.
Upper coil is black start, white finish.
Red and white is joint for series.
I’ve tried winding the coils the same direction (with opposite polarity) and also winding one clockwise and the other counter clockwise.
So green is the ground, I’ve tried with black as ground to.
Strangely enough i haven’t had this issue with 43AWG and it seems unlikely that it should be the wire gauge.
For DCR and inductance ive used a LCR-meter.
Sorry for not attaching a photo the file was to big.

[Helmholtz]

It looks as if one of the coils was accidentally shorted while measuring total inductance.

[Stakkz]

It looks as if one of the coils was accidentally shorted while measuring total inductance.

If one coil is shorted it wouldn’t be able to double the dcr. I’ve measured it several times and same thing happens.

[Helmholtz]

If one coil is shorted it wouldn’t be able to double the dcr. I’ve measured it several times and same thing happens.

True.

The only other explanation I can think of would be that one of the coils has some shorted turns. That would not necessarily show in much lower DCR but would considerably lower inductance.
OTOH, you said you measured individual coil inductances?

[Stakkz]

True.

The only other explanation I can think of would be that one of the coils has some shorted turns. That would not necessarily show in much lower DCR but would considerably lower inductance.
OTOH, you said you measured individual coil inductances?

Yes I’ve measured both coils individually and there where nothing wrong

[Mike Sulzer]

Just a check: The inductance should go up, but it should not double. There is always some mutual inductance, and if the coils are properly connected in series for humbucking, the mutual inductance is negative. If you wire the coils in series the other (wrong) way, the inductance should more than double. The amount of MI depends on the cores, etc. What are you using for cores? What are your actual measurements for both ways of wiring for both wire sizes?

[JRT]

It seems to me that something could be wrong with the wire coating. I would try a new wire spool.

[Helmholtz]

The inductance should go up, but it should not double. There is always some mutual inductance, and if the coils are properly connected in series for humbucking, the mutual inductance is negative. If you wire the coils in series the other (wrong) way, the inductance should more than double.

I just noticed this.

Actually the total inductance of a correctly wired PAF type humbucker is increased by around 20% due to magnetic coupling.

[Mike Sulzer]

I just noticed this.

Actually the total inductance of a correctly wired PAF type humbucker is increased by around 20% due to magnetic coupling.

For a stacked humbucker the mutual inductance is negative because the flux from the bottom of the top coil enters the top of the bottom coil, but they are wired out of phase.

[Helmholtz]

For a stacked humbucker the mutual inductance is negative because the flux from the bottom of the top coil enters the top of the bottom coil, but they are wired out of phase.

Oh yes, I missed that the topic was stacked humbuckers (where coupling should be minimized anyway).
Thanks for clarification.