Speaker repair

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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.
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amdx wrote:

Hi, El Cheapo amps blow speakers more. MY HT is 7.1 all Paradigm speakers driven by Anthem MRX700. 2 ch. stereo is an old British Quad I mod'd with pair of Mirage M7s.
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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.
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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.

http://www.repairfaq.org/sam/audiofaq.htm#audloud

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
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On 22/05/2014 00:24, Robert Green wrote:

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

Hmmm, Not only high power blows speakers. El Cheapo amps can blow speakers much easier than good amps. Why? Cheap amps have too much garbage in the output signal. My kids are in music since toddlers. Piano, sax, flute, drum, guitars. I don't have to tell, they wear ear plugs when they jam. Me? I am lower brass lifer since high school days. Still active with local concert band.
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On 05/29/2014 08:59 AM, Tony Hwang wrote:

It's the clipping in the Power Amp that puts DC pulses of opposite polarity into the voice coil. Pulses always destroy better than steady current.
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On 05/30/2014 07:16 AM, dave wrote:

RMS = Peak (in a square wave situation afaik)
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On Wed, 21 May 2014 19:24:27 -0400, "Robert Green"
over

I kept all my college texts. I even occasionally lend them out. I keep much of my pleasure reading as well.

pine

blow

night

speakers?

If you can get or make parts.

an

multimeter?
Yes but it is rare. Yes, they can. They are just capacitors and inductors, separate them and test the components themselves, capacitors dying is by far the most frequent failure mode. Replacement parts may be hard to get.

ch

searching

not

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On Wed, 21 May 2014 10:49:50 -0400, "Robert Green"

Depends on the speaker and what's blown. If it's just the "surrounds" that have gone on a decent quality speaker it is well worth fixing them. A lot of the speakers from the sixties and seventies are every bit as good as the crap you buy today - even the "high end" chinese junk.

Yes, they can go bad. Test right at the speaker terminals - inside the box.. If the speaker itself is good, cheap chinese crossovers are almost litterally "a dime a dozen" on Flea Bay. Relatively good ones are not terribly expensive either.

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On 5/21/14, 10:49 AM, Robert Green wrote:

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.
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<stuff snipped>

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!
--
Bobby G.




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On 5/22/2014 9:05 PM, Robert Green wrote:

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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!
--
Bobby G.



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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.

down

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.
--
Bobby G.



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On 5/23/14, 3:34 PM, Robert Green wrote:

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.
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<stuff snipped>

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!
--
Bobby G.




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On 5/23/14, 4:16 PM, Robert Green wrote:

The surround is supposed to keep the cone (and voice coil) centered. I think scratching was how I realized something was wrong with my surrounds. When I glued in a new surround, I'd let the glue set, then move the cone to be sure it didn't scratch. Of ten speakers, I think I had to reset one surround. I'm glad I caught it while the glue was soft.
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