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speaker impeadance
Sun, 02/28/2010 - 6:24pm
Disclaimer: this question, while related in concept to bass amps & cabs; is stemming from a problem in my home audio system.
Moderators: if this is innapropriate forum, feel free to move as appropriate with my apologies in advance.
Any of you ugs out there with significant tech expereince care to weigh in...
Is there a way to measure speaker impeadance?
I know that true impeadance is dependant on the frequency of the applied signal, and that the impeadance rating of a speaker or cabinet is what is considred nominal impeadance. I have a fairly nice home audio reciver (Marantz SR-18) that recently expereinced a blown power stage. I generally don't drive it that hard, so I was expecting to find a shorted out speaker wire or speaker coil. The tech at the repair center tells me it was one of the surround channel power stages that took the hit.
Looking at the mfg. spec's on my speakers, they are all rated at 8 ohms nominal impeadance, with the interesting exception of the surround speakers, which are rated at 6 ohms impeadance.
I measured DC resistance of the speakers, and they show 5.3 ohms on the front mains, 3.4 ohms on the center channel; and the culprit center channel speakers are showing 3.0 ohms dc resistance.
I expect to get my Marantz back from repair soon, and I'm reluctant to hook speakers back up that could again damage the unit. On teh other hand I really don't want to spend money I don't have to either....
My bass cab also reads 5.3 ohms, but its label is sort of worn and you can't read the manufacturer's stated nominal impeadance on the label.
thanks for your comments.
Jeff
Sun, 02/28/2010 - 8:02pm
#2
impedance is impedance is
impedance is impedance is impedance and it applies to bass rigs as well as stereos, without which life would suck.....
i didn't think odd impedances were too uncommon on home stereos, but i cold be wrong.
Sun, 02/28/2010 - 8:13pm
#3
Except this is nominal
Except this is nominal impedance.
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WARLORD OF THE BASK ARMY http://www.myspace.com/caricaturesband [band split, still proud of what we accomplished]
Now rocking http://www.myspace.com/terrasolis
Sun, 02/28/2010 - 8:34pm
#4
i meant the concept in
i meant the concept in general and its appropriateness, not any actual technical definition in this case..... 
but i agree with your statement to contact the mfr or look up the specs of the speaker.
Mon, 03/01/2010 - 1:18am
#5
Don't diss the Fox...
... when he's talkin' electronics!!!
Personally it's alien to me, but I do know if you don't match the speakers to your amp properly it can have a hernia. (electronically speaking)
5.33 ohm is what you get with 6 8 ohm speakers in series/parallel, when you are talking nominal impedance, and it is usually marked up as 6ohm.
Measuring dc resistance is usually the way to check, ideally, open it up and check the woofer direct, if there is a tweeter in there too, as the crossover can cause some oddness. Usually the dc resistance is a little less than the nominal impedance, have you looked at the speakers in you bass cab to see what they are, then figured how they are wired?
To properly measure speaker impedance, you get a graph, the rough average between 500 and 1000hz is the nominal impedance.
Ideally, check with the manufacturer of the speakers.
WARLORD OF THE BASK ARMY http://www.myspace.com/caricaturesband [band split, still proud of what we accomplished]
Now rocking http://www.myspace.com/terrasolis