Speaker wire impedance? Speaker impedance?


I finally got into the owner’s manual for the speakers I bought last May (Revel M126Be) and under "SPEAKER CABLE" Revel is saying that, "High loop resistances that exceed 0.07 Ohms (for each wire run) will cause the loudspeaker’s filter network to be mis-terminated, resulting in considerable degradation of sound quality."

I ohmed out my (longer than I think is optimal) single run (the Revels are not bi-wireable) of (what I think I remember being) Kimber 8TC and I read 0.07. My B&Ws were shotgun bi-wired, so today I also doubled up my single runs with the other bi-wire cable (so two wires are terminating on one speaker post for + and - for both speakers) and rechecked the impedance and read 0.05 ohms which I assume is a variance going in the proper direction.

But I have a probably stupid and probably very basic question (as I make NO claims of having a tight grasp on this stuff). If a lower impedance run of speaker cable makes for an easier load for an amp to drive, why is it that a speaker with higher impedance is a easier load to drive? Can this be dumbed down for me?

I apologize because I am sure this has been asked before, but I cannot find the right combination of words for a search engine that is yielding an answer.

 

immatthewj

I suspect you measured wrong. Kimber 8TC is gauge 9 that is 0.0008 ohm/ft. In order to get 0.05 ohm you would have to have 31 ft cables. For 0.07ohm it would be 44 ft. Revel is likely concerned that additional resistance in series with speaker’s crossover can affect (misalign) it. I’m sure Revel speakers work with tube amps that might have output DCR way higher than 0.07 ohm, so I wouldn’t worry about it.

@kijanki , they are actually longer than usual runs because of the way I had my system set up in the last room.  (The equipment was, and is, off to the side of the speakers as opposed to being in between the speakers.  I'll measure the length, hopefully, tomorrow.

Keep in mind the test leads on the DMM are not resistance-free and the DMM itself has a tolerance at different ohm readings, but usually don’t state or promise any tolerances when measuring below 500 ohms. Measurements in the milliohm ranges should be done by more precise instruments or at least a 4-wire Kelvin test (plenty of info on Google how to do that).