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Test a blown speaker?

#21
Chasarms said:
I have never experienced a bass cabinet driver test above the rated impedance. I have tested many, and a 4-ohm driver will almost always be around 2.6. I don't know that I have ever tested on that was higher than 3.

Obviously, competition subwoofers are designed differently than the driver in a bass enclosure, so the results may vary. I have no experience with them except that I love the way a well-installed sub sounds in a car. :)

Although, you are correct that 2 is probably too low and unlikely in a healthy 4-ohm driver, but I would still state that 2.5-3 ohms should be expected with a DMM test of a bass enclosure speaker.
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With an ohm meter, if a speaker tests above rated impedence, there is clearly a problem. It may work now, but know that it will not work forever. Look at it as a bad weather forecast. There is a difference between impedence and resistance, which is what an ohm meter will read.

The battery test is a quick way to tell if polarity is correct and that you do not have an open voice coil. Pushing the cone in and listening for rubbing or scratching can certainly reveal problems. Testing with a Z meter is a very reliable measure of impedence and will tell more of the story than any other measurement tool.

All that said, testing for the 60-65% of rated impedence with an ohm meter as stated above, and pushing the cone in and listening for anomalies is the best layman's test for a dying speaker.

Hope this helps ...
 
#22
OKay so I pulled both cabs apart today, and they both repsonded fine to the "push gently on the cone" and the "battery" test. One of them though (the one I got on ebay a few years back), had been worked on, and the lead and ground wires to the speaker had both been cut and spliced-in the crappiest way possible: The two stripped ends were VERY loosely twisted together wrapped in electrical tape. Probably the worst job I have ever seen. A few quick solders and I should be in business.
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It sounds like you may not have a blown driver. Check to see if the dust cover has come loose. This is a pretty common thing that I've seen more than a couple of times. If fact I just encountered this with my buddy's Bergantino cab.
 
#23
Hmmm, the dust cover on the speaker? Where is that? I doubt that is the issue, as there is a serious volume/sound problem.

I soldered the wires back together, and the problem persists. I am thinking that I either have a blown speaker that I can't identify via the mentioned methods (either because I am doing it wrong, or because it could be blown without being so obvious), or there is some kind of problem with the crossover or something else. Looks like I'm going to have to take it in. Anyone know a good speaker repair place in Nashville?
 
#24
mcapote said:
well having installed well over 500 drivers in my life for various installations both car audio and studio, I have yet to see a 2.5 ohm 4ohm speaker whether you are talking sub, fullrange, mid, or tweeter, so I cant say I agree.
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Sorry mate as a former Celestion technician every speaker we built
measured less in DC ohms than the theoretical nominal Impedance
shown on the driver spec.
Impedance and DC resistance are totally different animals.
The actual impedance in ohms varies quite widely dependent on the frequency applied to the voice coil.:ninja:
 
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#26
So I took it to Corner music-diagnosis is the speaker is blown. Interesting that none of those other tests worked (beyond the ohm meter business, I don't have those tools). Maybe my speaker wasn't blown enough to show the peripheral damage? Not sure, but I will recognise the sound.
 

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