Speaker repair

[J Burns]

I have a foggy memory of rewinding a tweeter decades ago. I determined the gauge, then checked the resistance of a good tweeter to find out how many feet it had.

As has been said, I'd check each speaker element. A battery would work, but I'd check resistance with a multimeter. If it looked good, I'd clip the leads on and see what happened when I pushed the cone.

Ten years ago, I thought something was wrong with my CD player or my amp. Then I discovered that the foam surrounds on 6 woofers and 4 midranges were rotting. I found a place that sold repair kits.

In the last few years, I've been thinking of complaining to the FCC that lots of FM stations are broadcasting distortion. Then I discovered that my electrolytic crossover capacitors were bad. Some estimate that electrolytics last 5 years on the shelf. Mine were 30 years old. A month ago I replaced 18.

The ones I took out were 10% precision electrolytics. I used regular nonpolar electrolytics because they were cheap and easy to find. The ideal is metal film because they're precise and last indefinitely. Even my crummy replacement capacitors made voices clearer and music better.

[Smarty]

Yes, and I added that attic storage can further contribute new and unexpected issues. Expecting a speaker which was 'blown out' with a fried voice coil on the woofer may surprisingly reveal, after storage, an inoperative tweeter, damaged by attic heat.

My point in posting this caveat was to caution the original poster that the condition of the speaker when it was put into attic storage may not reflect the current status due to the attic environment itself.

[mroberds]

Depends. Were these $500+/each audiopile speakers when new? If so, it might be worth it. Did they come as a set with a $150 stereo system? Maybe not worth it. In between... you have to decide.

You can get replacement drivers in various sizes and power handling levels. You can probably get something "close"; whether that's good enough for you is up to your ears.

The voice coil is more likely to be open. Sometimes you get lucky and it's something easy, like the wire to the connectors/terminals on the back panel has broken, or a push-on connector has fallen off.

For higher-end ($$$) speakers, if you can't get exact replacements, you can probably get parts that have been tested to work well in that particular model. For cheap speakers, you try it and see.

They can.

Yes. You can see if the inductors (coils) are open circuit, and you can check the capacitors for open or short circuits. You most likely will need to unsolder at least one end of each component to make the test.

It might be faster to note how the wires go, disconnect the crossovers, and apply audio to each speaker driver directly. If you get sound, then put the crossover back in line and run audio through it. If the sound goes away or becomes hideously bad, then the crossover network is broken.

A real newsreader will allow you to set the Followup-To: header as you desire. (Outhouse Depressed is not a real newsreader.)

Matt Roberds

[N_Cook]

If this was a UK loft then you've increased the probability of adding bits of iron-corrossion product , now trapped by the magnet , in the VC gap , to give that classic scratchy sound, as well as the original failure

[thekmanrocks]

William Sommerwerck wrote: "You presumably have conventional dynamic speake rs. It's unlikely any of them could stand up to current models in terms of sound quality. (There are exce ptions.)"

A disturbing trend(consumer at least) is toward smaller and smaller mains a ccompanied by or requiring a separate subwoofer. Or taller but narrower fl oor standing mains. I have a pair of dB Plus with 10" woofers and 1" dome tweeters from 1990 that still sound good - at least to me and most company I invite over - and I don't want to go the separate sub route when replacem ent time comes. Simple physics tells me that a floor standing model with only 6" woofers isn't going to touch those old Canucks for bottom end!

As for the o.p.: If the only damage is rotted surrounds, there are online r esources for modern rubber replacements to recone those attic residents.

[NotMe]

If you're blowing out speakers with that regularity I expect a sever miss math in equipment. The second would be a recommendation to have your hearing check as you may have damaged/serious loss of hearing.

All my kids were big into music. I made sure they wore ear protection at concerts and especially when they were performing. Unlike me (too many years near jet engines) they can still hear a pin drop.

[Robert Green]

Those are good points. It's not too bad up there, but there is a good possibility that there's heat or aging damage and replacing a bad tweeter or midrange would just be followed up by the failure of a woofer after the repaired speaker has been run for a while.

Thanks for your input!

[Robert Green]

resources for modern rubber >replacements to recone those attic residents.

Haven't even cracked one open yet - just doing my "survey" on my options before I get to that stage and hopefully will know what to look for. Some speakers I rescued from friends, some died at the hands of a Sony receiver that had a motorized volume control that occasionally went crazy and turned itself to maximum volume, others just sound scratchy, etc.

There's no common cause of death for all of them and most of the attic denizens are bookshelf speakers, hence their employment as bookshelf supports. I suspect that once I inspect them, most of them will be fed to the curbside monster but the larger more expensive ones that weren't stored in the attic may be worthy of repair.

Thanks for your input!

[Smarty]

[Robert Green]

Ironically now that I am cleaning up the attic I realize I never routed the AV net there and I have nothing to listen to as I clean up. I'm hoping that enough of the damaged can be saved to add whole house audio to the attic and more of the basement (there's one TV/speaker setup by the sink area but nowhere else)

I previously said "blown" speakers but "non-functioning" or "bad sounding" would have been more accurate and less likely to result in accusations of murdering helpless speakers. (-:

What do you see?

Since I have so many I'll probably have to just pick a model and go from there. The Technics with the 15" woofer seems to woof OK but the tweeter and midrange seem inert. I have not yet jacked them out of their case yet because it's in an awkward place and because I just noticed the problem the other day. I think I need to round up all the ones worth saving to try to figure out what's what.

All of the above but the scope's a pretty cheesy penscope not good for much. I want to be able to check the crossover networks and haven't come across much help in that area on the web. I have a DVM that has a capacitance checker built-in, but I recall from previous threads about the flood of bad caps a few years back, that the DVM can't really check out all the possible flaws in a bad cap.

I know the basics. I just need to find out more about crossover network troubleshooting and how to determine what kind of replacements I should use for speakers/tweeters/woofers that don't have and characteristics marked on them. I'm busy reading up on the design of cross-over network so I can better understand their function in the world of the Dead Speakers.

Thanks for your input, Dave.

[Robert Green]

It's a fairly high humidity Washington DC attic.

I didn't know that ferrous debris in the VC gap was an issue. I thought the scratchy sound came from the voice coil detaching from the paper/plastic cone.

Thanks for your input!

[WW]

I've got a lot of big, small and medium speakers that have blown out over the years. Typically I take them to the attic where they usually make pretty good bookshelf supports.

In the spirit of domestic harmony, I am cleaning out said attic (anyone

*really* refer to their old college texts or books they have read in the past anymore?). So with all the books being "de-accessioned" (librarian-speak for "thrown out") I am left with a lot of bowed knotty pine planks and burned out speakers.

If they can be salvaged, I can use them, but if they're likely to just blow out again, I will send them to the curb monster that comes by late at night before trash day.

So my question is this. Is it worth repairing 10 or 20 year old speakers? Can replacements be readily had?

Is there a good site for diagnosing speaker problems? I almost always assume it's a fine wire winding in the voice coil that shorted when a speaker no longer even responds to a battery "click" test but I that's an assumption.

Is it possible to match the characteristics of the old speakers closely enough without manufacturer info like a parts list?

Do crossover networks ever go bad? Can they be tested with a multimeter?

And yes, I googled it,

but I didn't like very many of the sites it revealed. I'll keep searching but Google ain't what she used to be.

Hmm, should have added "blown" to the search term - much better. Still not great, though.

Thanks in advance for your input.

[gregz]

Rubber usually does not rot, and it's not regular rubber. There are three basic surround types.

Too many drivers, but solid cabs.

Probably did not get blown out, but may have fallen out. For what it's worth, I know a lot about these.

It's funny the OP seems to be ignoring posting pictures or makes. Maybe we got some Sound Design goodies. fishers ?

I've built many speakers, and have fixed many. It's not usually quick and easy fix.

I can't cross post.

Greg

[Ian Field]

I don't know the correct names for speaker bits - but if the cone has been over extended to the flexible webbing that supports the cone around the speech coil has torn, there could be all kinds of crap settled in the gap between the magnet poles.

A tiny minority refurbish their own speakers, a not much bigger minority take them to specialist rebuilders - either way is unlikely to be cheaper than buying new ones.

[Ian Field]

Its when you can't hear a speaker cone hit the opposite wall you need to worry!

[J Burns]

I've had capacitance checkers in the past, but they went bad. A crossover capacitor may be beyond the range of a checker, anyway.

Big ones can be checked by the time constant using a couple of DMMs and a calculator. (I used three DMMs, two to determine the voltage and resistance of the third, on it's highest resistance range.) I found out that bad nonpolar electrolytics give whacky results.

As I recall, the other thing to check is the capacitor's resistance. I'd skip that.

It's usually electrolytic capacitors, not coils or resistors, that go bad. I have a Radio Shack DMM from 1979. I pull it off the shelf when I need to check audio voltages up to 20kHz; most won't do that. A scope can also show you where you're losing the signal, but if one side of the audio circuit is grounded, you have to be careful where you clip the ground lead.

I didn't bother to check with signals. Checking a few capacitors with time constants made a believer of me; so I replaced them all. I needed a chisel to get the circuit boards unglued from the cabinets and to get the capacitors unglued from the boards. Their values were marked.

[Robert Green]

Sometimes attics are like purgatory. You put things up there that you don't have the heart to throw away at the time. The books died a slow death up there, making it easy to decide to recycle them as waste. No library would want them. It was very easy to see which publishers used cheap paper and which didn't. Some pages just crumbled when turned.

The speakers that served as spacing blocks for the shelves will probably soon follow the books. I connected one up that had a scratchy midrange and watched the woofer speaker cone just shred at tje edges after just a few seconds of operation. Ironically, that same fate befell a speaker stored under much better conditions. Time seems to be a serious enemy of the speaker as much as sub-optimal storage conditions.

I have to admit that on occasion, the attic has "healed" things that were previously non-functional. Certainly not as often as it hastened their doom, but often enough to encourage a temporary retirement to the attic before heading out to feed the curb monster.

[Ian Field]

Some allegedly high quality speakers have some sort of flexible foam rubber as the suspension round the outside of the cone - it usually perishes sooner rather than later.

[William Sommerwerck]

Foam has largely been abandoned because it eventually self-destructs. It isn't rubber, it's a synthetic polymer.

I have a pair of original Advents (final green-tweeter iteration), with foam surrounds in perfect condition. Why, I don't know.

[Unquestionably Confused]

Nothing allegedly about it. I have a pair of Infinity speakers (~ 30 yrs old now) and had to replace the surrounds on several of the speakers a year or so back. Foam becomes brittle (age? atmosphere? dog farts? sun/ambient light?) and just starts to disintegrate.

Fortunately, found an outfit on line that sells kits for DIY repair. Figured that I had nothing to lose I popped for the kits and repair was a piece of cake. All's well and I'm good for another 30 years (well, not me, but the speakers)