Blown speaker?
September 10, 2015 6:57 PM   Subscribe

I just recently picked up a pair of 1980s-era Celestion 3 bookshelf speakers and they sound great. Well, the right one sounded great until something happened today. I may have been listening to The Cars' "Candy-O" a little too loudly when the speaker started going, "thup-thup-thup" and then lost the woofer.

Maybe the woofer? I took the cover off the front of the speaker and poked the woofer and the speaker sounded full again. Then it didn't, then I gave it a light poke with my finger again and it was great for a few seconds when the woofer went out again. Is there anything I can do to fix this? I hope so 'cause them things sound great combined with a subwoofer.
posted by NoMich to Sports, Hobbies, & Recreation (15 answers total) 1 user marked this as a favorite
Loose connection, maybe? Check that the wires connected to the cone itself are secure, and work your way back to the external terminals.
posted by Johnny Wallflower at 7:00 PM on September 10, 2015

What are you driving the speakers with, power-wise? Your description kind of sounds like an over-driven voice coil. According to Stereophile The Celestion 3 has fairly low power requirements.
posted by Thorzdad at 7:28 PM on September 10, 2015

How is the foam surround that goes around the speaker cone? On older speakers the foam dries out and crumbles away. It's possible to replace the foam for a lot less money than replacing the entire speaker driver.
posted by zsazsa at 7:30 PM on September 10, 2015 [2 favorites]

Response by poster: What are you driving the speakers with, power-wise?

A 1970s-era Marantz 2216 receiver. It's a 16wpc unit (though, I realize that it's probably more than that).
posted by NoMich at 7:33 PM on September 10, 2015

If the sound keeps coming back fully then dropping back out, it does sound like a loose or corroded connection.

It's possible the foam is deteriorated enough that in the right position the sound is fine, but then drops out. You should be able to see if the foam is cracked or deteriorating.

If it is a deteriorated foam surround (not uncommon in speakers of that vintage), Amazon sells repair kits.

I recently repaired the foam on a pair of 1980s era Allison 6 cube speakers that way it they sound great. It took a few hours but was easy to do.
posted by The Deej at 8:36 PM on September 10, 2015

The woofer cutting out entirely makes me think bad crossover. But pushing it making it come back in?

Can you post a photo of the front of the speakers with the grille off so we can see the surrounds? I really really doubt you blew the coil(trust me, i've tried, on plenty of speakers) but it totally cutting out makes me think it might not necessarily think it's just, or necessarily, the surrounds. And plenty of speakers from that era have surrounds that don't deteriorate, even though some do.
posted by emptythought at 2:29 AM on September 11, 2015

Are you sure its not your receiver/amp causing the problem? Try reversing the left and right speaker wires to be sure.
posted by DarkForest at 5:25 AM on September 11, 2015

Response by poster: I should clarify in that the sound doesn't completely disappear from the speaker. I think the tweeter might still be working. But it seems like the speaker drops to about 25% of its original amount of sound.

I'll post pictures later on today when I get home from work. Maybe even a video if I can figure out how to share the video file.
posted by NoMich at 6:22 AM on September 11, 2015

I had an issue with decayed foam surrounds a few years back, and bought new surrounds and installed them and they started working again. But I never had an issue with the woofer going completely out--it only sounded distorted. (If I put my finger on the foam, it would damp the extra vibrations and sound normal while my finger was on it, then go back to sounding crappy once I removed it). That said, they were also 1980s-era speakers.

I think Johnny Wallflower may be on the right track here--the connection on the back of the speaker is possibly a little loose or corroded, and when you pushed on it it reconnected for a few seconds before going out again.
posted by thecaddy at 6:40 AM on September 11, 2015

I'm guessing everybody is thinking the cone is travelling to far and getting outside the coil? I can buy that. Yeah, let's look at the surround.

Another check is to try it at lower levels, and tap it and see if it's good and stays good, then ramp the volume up and see if it does that again.

It being an '80s speaker means that, well, the foam surround is almost certainly trash anyway. The foams they had back then were just crap in terms of longevity. Everybody used them because they were great in terms of speaker surrounds.

Now, if the coil is failing, you can replaced the entire driver, but you'd want to replace both sides so they match. It's a 5" paper cone speaker, so not hard to find, indeed, I suspect this would be a drop in replacement with the possible exception of screw holes (which I can't find an exact pattern on.) The specs on these particular ones are close enough that you shouldn't need to change the crossovers.
posted by eriko at 6:43 AM on September 11, 2015

Best answer: If it sounds "thin", then yeah, it's your woofer cutting out. You should disconnect your other speaker and just listen to the one that's giving you problems so your ears aren't fooled by the sound out of the other speaker.

Having it kick back in when you push on it suggests a loose connection, which might be fixable, but it also suggests that your voice coil might have warped with age, use & heat, or that your spider may be cracking, which are basically not fixable as a DIY project. Except insofar as you could replace both woofers.

A speaker is essentially a coil of copper wire suspended inside a magnet. One of the basic principles of electromagnetism is that when you run alternating current through said suspended coil, the coil will move. This moves the cone of paper, producing sound.

Here's a cutaway picture/diagram of a speaker. The bit labeled "voice coil" is a coil of copper wire, and you can see that there should be a gap between the coil and the outer magnet, and that the coil is wrapped around a "former", which slides up and down the pole piece in the center. Running A.C. through the coil of wire produces heat, which can over time warp the coil or former so either the coil rubs on the outer wall of the magnet, or the former rubs on the pole piece. Or if the spider develops a small crack, the two edges of the crack can get stuck on each other as the spider moves up and down. In either scenario, this sometimes results in a situation where the speaker gets "stuck", and can be unstuck by giving the speaker a gentle push or light tap. Unfortunately, this is just the first sign that the speaker is on its way to an inevitable death. Speakers can be reconed, but it's not really a DIY project, and probably not really cost-effective for bookshelf home stereo units.

But it could be a loose connection somewhere, which you're "fixing" by tapping the speaker (or is just "fixing" itself in a bit of coincidental timing - this is definitely a thing that happens.) From pics I've found of the Celestion 3, it looks like the actual speaker is attached to a plate. Unscrew the plate and carefully pull the speaker out. Try to handle it only by the plate or the metal edges of the speaker. First make sure that the wires are securely seated in the terminals, then look at the tinsel leads that run from the terminal to the voice coil (you can tug on them gently, they should move a little but obviously not come totally free.) If those are broken you could possibly solder across the break.

You can also push gently on the cone of the speaker while looking at the spider to see if there are any breaks or cracks in the spider.

If that all seems OK, the crossover (a collection of electronic components that sends low frequencies only to the woofer and high frequencies only to the tweeter) seems to be on the back of the jack panel where you plug in your speaker wires. Pic here, I think. Look closely at all of these connections, something may have broken loose but still be making connections intermittently, or a solder connection is cracked. If you (or a friend) know how to solder, you could possibly touch up these connections. Sometimes cracks can develop which are not readily visible to the naked eye, and re-soldering all the connections can fix the problem.
posted by soundguy99 at 7:26 AM on September 11, 2015

Response by poster: OK, finally got time to really dive into this. Unfortunately, I don't think it's something as simple as a loose wire or the foam or any other bits of the speaker that I could see/touch. I lightly tugged on each wire and they all felt quite solid. Also, the foam and the cone dust cap are in practically perfect condition. Nothing is overly dry or crumbling or anything. Even all of the connections look in just about brand new shape.

ETA: I couldn't really inspect the spider closely, so that could be the issue and I don't really know it.

Close up of woofer - What may look like tears in the cone are not. It's all in solid condition.
Connections inside of speaker cabinet - Those connections all felt snug.
Woofer outside of cabinet - These connections felt nice 'n snug as well. Even the tinsel lead (the very thin wires you see) felt snug.
posted by NoMich at 12:30 PM on September 12, 2015

In that woofer outside of cabinet: did you test the wires that disappear into the cone frame?
posted by Johnny Wallflower at 1:04 PM on September 12, 2015

Response by poster: Yes. All connections inside of the cabinet and the driver felt snug. Nothing felt loose.
posted by NoMich at 1:06 PM on September 12, 2015

Response by poster: After further investigation, the culprit was one of the super fine tinsel leads. A friend has re-soldered the connection and says that it should be good for another 30 years.

A big thank you to all of those that contributed.
posted by NoMich at 6:25 PM on October 7, 2015 [1 favorite]

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