Checking cable impedance

You can only measure dc resistance with a multimeter. It will be near infinity from conductor to shield, and near zero from one end to the other. This is of no significance.

How would one then go about trying to determine this? Would you need special equipment? Want to use an unused XLR inter as a digital cable and want to see how close to the spec'd impedance it is...

Hi Owl.

Characteristic impedance, which is what you're looking for, is different than simply measuring impedance which, more correctly, is resistance. A lot of folks use the term impedance and resistance interchangeably and as a result the terms are somewhat misunderstood.

A DMM will not give you characteristic impedance. A good piece of equipment capable of an impedance measurement starts at somewhere around $5000.00!

Probably best in your case is to install the cable and use your ears. Doubtful though that the cable is 110 Ohm AES/EBU Standard. Still, you may like what you hear. You've got nothing to loose so...Give it shot!

Regards,
Robert

Owl when we have a DC signal trough the cable, resistance is the big parameter. But audio is an AC signal, so we must take in account the capacitance and indutance of the cable.
The capacitance can be measured with a capacimeter. The inductance needs more work, but it can be done if you have some electrical background.
But this wont tell the impedance of the cable, because the impedance of a cable is frequency dependent because of the capacitive and inductive reactance. The impedance must be displayed graphically or it's value must be given at a certain frequency.