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.
basically you are saying that measurements I took with my meter set to ohms are probably not accurate? @immatthewj Yes. You need a really special Ohmmeter to read the actual resistance of most speaker cables! You were far more likely reading the contact resistance of your probes and probe wires than you were the speaker cables. To read a speaker cable you need an Ohmmeter that can read differences in resistance of only 0.0001 Ohms. That's an expensive and specialized Ohmmeter that can do that! |
You really need a micro-ohmeter to measure such small resistances. best bet is to calculate it. if it is too high, then you need larger wire. the manual only mentioned "resistence" which is a funcion of wire gauge and length only, so the inductive portion of impedance apparently isn’t a problem for these speakers, still it should be minimized. Avoid loops, for example. https://www.engineeringtoolbox.com/copper-wire-d_1429.html Also avoid alloy wires for speakers. Surprisingly, alloys are always higher resistance--add silver to copper and you get an alloy that is a worse conductor than either silver or copper alone. As for your question, the impedence of the speaker is the load where power is turned into sound, the resistance (lets equiate it to impedence) of the cable is the circuit that transmits the signal to the speaker. You don’t want any of the power being disipated there. Jerry |
@atmasphere and @carlsbad2 and @everybody else who tried to dumb this down an explain it for me--thank you. @atmasphere and @carlsbad2 I now know that on a couple of levels I wouldn’t get an accurate reading--for one the meter I was using, and also: the fact that I was taking my reading from the amplifier post (with cables hooked up) to speaker wire post of speaker (with cables hooked up, and then again from amp post to the other end with cables NOT hooked up on speaker end). Either way, that probably screwed up the measurement I was TRYING to take, right? So last question: the actual resistance was probably way lower that the 0.07 and 0.05 that I THOUGHT that I was reading? And as an aside, my speaker cables (Kimber, and I THINK I remember that they they are 8TC and 4TC) probably are longer than what would be considered ideal.
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