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Damaged Speaker - Impedance Reading Varies

Posted: Thu Apr 07, 2011 11:59 am
by Kevin
Hey fellas,

I picked up an old bass cab with a damaged speaker and I'm trying to figure out what's wrong with it.

When I measure the speaker's impedance, the reading climbs to about 6 ohms (probably where it should read for an 8 ohm speaker), and then it jumps around between 10, 14, 20, whatever and sometimes come back down to 6.

It will sound alright for a bit, and then will cut out and crackle.

The speaker in question is a 16" (yes, actually 16") Altec Lansing, I believe. It has an aluminum dust cap and actually sounds pretty good when it works properly for a few seconds.

I'm probably just going to sell it as is, but I'd like to know what is wrong with it beforehand.

Thanks for any info.

Re: Damaged Speaker - Impedance Reading Varies

Posted: Sun Apr 10, 2011 7:50 pm
by ohmygodtheykilledkenny
Sounds to me like a loose or somewhat intermittent connection somewhere. Perhaps the vibrations from it running loosen this connection. I'm just thinking that because in theory on open circuit will have infinite impedance, so while it's not reading mega high, the resistance is still climbing. Maybe one of the leads that that goes from the terminals to the motor is partially disconnected, or frayed?

These are just shots in the dark, I'm hoping that either Jim or the gent from celestion who is sometimes around can field this one with some more knowledge.

Re: Damaged Speaker - Impedance Reading Varies

Posted: Sun Apr 10, 2011 7:54 pm
by Scumback Speakers
A wire is loose, either in the voice coil, or the leads from the speaker tabs. If it's a wire lead from the tabs, it's an easy fix to resolder. If it's in the voice coil itself, it's recone time.

Re: Damaged Speaker - Impedance Reading Varies

Posted: Mon Apr 11, 2011 9:16 am
by Kevin
Thanks, guys. I'll look into that.

Re: Damaged Speaker - Impedance Reading Varies

Posted: Mon Apr 11, 2011 10:28 am
by Wattever
If it IS the leads at the terminals, be careful when you re-solder them. They don't just LOOK like Solder-Wick, they work like it!

Probably how the Solder-Wick dude had his eureka moment. :wink: