Newly wound pickup coil reading differently after "cooling down"

[Helmholtz]

There were a couple of times that I took a reading too soon and clipped the wire before it had settled in. A couple hours later I'm left with a pickup with a lower res. then planned.

It's number of turns that defines output and frequency response for a given PU design - not exact resistance. Otherwise PU sound would change with ambient temperature.

[Brian W.]

As soon as you are done winding the reading will be higher. Let it sit for a hour or two. I have never seen soldering for 1second to bring the reading up.

There were a couple of times that I took a reading too soon and clipped the wire before it had settled in. A couple hours later I'm left with a pickup with a lower res. then planned.

[mozz]

As soon as you are done winding the reading will be higher. Let it sit for a hour or two. I have never seen soldering for 1second to bring the reading up.

[Brian W.]

A few months ago I actually thought my coils were being wound too loose so I put more tension on the wire.......and the wire started breaking. After a couple of days of this I took a close look at the pickups and noticed how much tighter the coils were after they had sat around for awhile. Lesson learned.... it had to be the heat.

[Leo_Gnardo]

What you've observed has to do with the temperature coefficient of conductivity of your wire. Copper is approximately 0.4% per degree (Centigrade or Kelvin). I've noticed differences in coil resistance measurements when measured on my workbench in cold winter ambient temp compared to hot summer temps.

A couple of my customers think pickup coil resistance is an important factor in the sound of their pickups, and this difference in measurements drives 'em crazy. "What's wrong with my pickups ?!?!?" "Aw, they're cold. Or hot. Do they sound good? Get over it."

Wiki here: https://en.wikipedia.org/wiki/Electr...d_conductivity

Go about halfway down the page and you'll find a handy chart of coefficients for lots of popular metals, alloys, and other materials. Copper is second & third on the list, plain & annealed, not much difference.

Also, as we know metal expands when hot, shrinks when cooled. This explains the tightening of your coils as they cool.

[copperheadroads]

If you are soldering the lead wires before taking a dcr reading ,the heat from the solder gun is what usually creates the higher dcr , if you sand the insulation off & take a reading before you solder you should have a lower & more accurate reading .

[Brian W.]

Been noticing it's not a good idea to take an ohm reading from a newly wound coil. It's always noticeably higher than after it's been cooling down for awhile. The coil also seems to tighten up on the bobbin after cooling down, too. I wind by hand [with a sewing machine] so the heat from my hands seems to heat the coil whist winding.