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Hoffman Amps Forum image Author Topic: Diagnose speaker failure?  (Read 3815 times)

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Offline Diverted

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Diagnose speaker failure?
« on: June 09, 2018, 12:30:53 pm »
Hi all,

The finer points of speakers are not my area. So if anyone can help me I'd appreciate it!
I have a bad 1959 Jensen P10R, an Alnico speaker. Pulled it and an identical P10R out of a trashed Fisher console.
One speaker works fine. The bad one shows good voice coil resistance (about 5 ohms) but I get no sound out of it. Just a very, very faint static-y fuzz sound, even with volume way up.
The cone moves up and down freely, so it doesn't look like anything is bound up. But what would cause a complete lack of volume with a good voice coil?
It's definitely the speaker, and not the circuit. I tried it on a few different amps with same issue.

If this does sound familiar to someone, what's the prognosis?

Thanks!

Offline Johntb

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Re: Diagnose speaker failure?
« Reply #1 on: June 10, 2018, 06:31:19 pm »
Do they both measure about 5 ohms each?
Is it supposed to be 8 ohms possibly 10 ohms and you're only getting half or part of the resistance?
I don't know a whole lot about speakers either but  between the cone and where you connect your wires is that braided wire connection good? I have had one with only a couple strands connected and kept the speaker from working.

That's about all I can head sorry I couldn't be more helpful. Good luck.
Proud to be self taught but, my teacher is an idiot.

Offline jjasilli

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Re: Diagnose speaker failure?
« Reply #2 on: June 11, 2018, 09:45:22 am »
Checking the web, the consensus seems to be that the issue is voice coil rub.  This is usually obvious with a scratchy sound, but not always.  Here's one guy's radical solution:  http://www.antiqueradios.com/forums/viewtopic.php?t=126796


I googled:  speaker fuzzy voice coil good


Maybe checkout some of the other hits there.



 


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