General advice:
At Jantzen Audio, we control measure all coils when we manufacture them, to make sure they keep within nominal tolerances on inductance.
The DCR of a coil will be not only be a function of the inductance, but parameters like coil shape/dimensions and if a ferromagnetic core is used, will impact the DCR value.
This means that as example two air core coils made from the same wire gauge and having the same inductance, may have significantly different DCR values.
If you wish to control measure coils on your own, please note that you cannot correctly measure coils with a hobby type “multimeter”, if the coil in question has a lower DCR than around 0.1 ohms.
However, for all coil measurements, regardless of DCR, we recommend using a professional grade LCR meter with a milliohm function.
To measure coil data correctly, the equipment needs a certain level of resistance, to perform the measurements/calculations correctly.
For air cored inductors it does not matter what voltage and frequency parameters you use to measure a coil.
For ferro-magnetic cored coils we recommend using the audio industry standard of measuring at 1 volt / 1 kHz.
Measuring C-Coils (Toroidal gap-core inductors):
To correctly measure the inductance and DCR of C-Coils, you either need a professional grade LCR bridge or to use a special measurement setup in addition to using a professional grade LCR meter with a milliohm function.
If you wish to control measure C-Coils yourself, please contact us and we will send you a PDF guide describing the setup and the process.