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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Repairing an expensive speaker
I am repairing two 15" Tannoys of the Gold series. A $5k unit if we
could get them. Un oscillation in a cassette deck I was using, produced a very lowed sound that damaged the speakers. One of them has 6 turns of the voice coil, lose and can be glued back. On the old days I used to repair speakers using the same type of glue that was used on the assembling of models. A type of glue that use acetone as a solvent. Today we have better types of glue like epoxy and I believe the harder the glue the better the performance, the disadvantage is that using epoxy will make a future repair very difficult. Any suggestions ? The coil on the second speaker is open and in very bad shape. I am looking for a replacement. Tannoy does not carry parts for this type of speaker but there is a place in England that will sell me a cone assembly for about $300 usd. |
#2
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Repairing an expensive speaker
I would contact Annoy and ask exactly which adhesive it uses. Don't
substitute on the assumption that your choice would be superior to Annoy's. |
#3
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Repairing an expensive speaker
In article , "William Sommerwerck" wrote:
I would contact Annoy and ask exactly which adhesive it uses. Don't substitute on the assumption that your choice would be superior to Annoy's. To add to my other post, if he wants orginal, then stay orginal. Also both units should be the identical. greg |
#4
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Repairing an expensive speaker
Meat Plow wrote:
Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. You remove the flex outer rim from the cone. Then you cut out the bulge covering the voice coil and put shims (supplied with the kit) in to center the cone. Then you glue new flex material around the cone, and wait overnight. Then you remove the shims and seal up the bulge with glue. Apart from the overnight wait for glue to dry, it only took me about half an hour the first time. With practice I might be able to get it down to 10 minutes. |
#5
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Repairing an expensive speaker
On 08/07/2010 20:15, root wrote:
Meat wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. You remove the flex outer rim from the cone. Then you cut out the bulge covering the voice coil and put shims (supplied with the kit) in to center the cone. Then you glue new flex material around the cone, and wait overnight. Then you remove the shims and seal up the bulge with glue. Apart from the overnight wait for glue to dry, it only took me about half an hour the first time. With practice I might be able to get it down to 10 minutes. And that takes care of the knackered voice coil does it? Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 1397 of my spam emails to date. Get the free SPAMfighter he http://www.spamfighter.com/len The Professional version does not have this message |
#6
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Repairing an expensive speaker
"Meat Plow" wrote in message ... On Thu, 08 Jul 2010 20:48:38 +0100, Ron wrote: On 08/07/2010 20:15, root wrote: Meat wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. You remove the flex outer rim from the cone. Then you cut out the bulge covering the voice coil and put shims (supplied with the kit) in to center the cone. Then you glue new flex material around the cone, and wait overnight. Then you remove the shims and seal up the bulge with glue. Apart from the overnight wait for glue to dry, it only took me about half an hour the first time. With practice I might be able to get it down to 10 minutes. And that takes care of the knackered voice coil does it? Ron(UK) The 10 minute recone part really bothers me. Sure with production line jigs, shims, guides and people who do maybe a 100 per day that is a tangible goal. But for an average Joe buying reconing parts and being successful is not the average outcome. Sure there are exceptions so if you want to try it on your own good luck. Interestingly, I was discussing exactly this issue with the owner of the music shop that I do a lot of work for, just this week. He rents a lot of biiiiigggg PA equipment out - kilowatt amps and 4 x 15 bass cabs and such. These get damaged by inept users all the time, apparently. I suggested that it must cost him a fortune in replacement speakers, but he said "Oh no - I just re-cone them". I asked him how long he had been doing this and he said years, but I had never seen this going on in his shop. Anyway, I asked him how long it took, and how hard a job it was, and did he have lots of specialist shims and feeler gauges and jigs and what have you. Nope, he said. He reckons it takes him but a few minutes (literally) to do the job. He says that the most time consuming part is making sure that all the crud from the burnt up voice coil, is removed from the airgap. He uses a combination of compressed air, and sticky tape to do this. As to centering the new cone's voice coil, he says that most replacement kits come with a set of four plastic spacer shims, but that many modern designs are fundamentally self - centering anyway. He reckoned that it was basically a piece of **** job that just needed a little care, and that much ******** was talked on the subject. I might ask him to let me know next time he's got one to do, as I would like to watch him at work ... Arfa |
#7
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Repairing an expensive speaker
On Thu, 08 Jul 2010 19:01:39 -0400, Meat Plow wrote:
On Thu, 08 Jul 2010 20:48:38 +0100, Ron wrote: On 08/07/2010 20:15, root wrote: Meat wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. You remove the flex outer rim from the cone. Then you cut out the bulge covering the voice coil and put shims (supplied with the kit) in to center the cone. Then you glue new flex material around the cone, and wait overnight. Then you remove the shims and seal up the bulge with glue. Apart from the overnight wait for glue to dry, it only took me about half an hour the first time. With practice I might be able to get it down to 10 minutes. And that takes care of the knackered voice coil does it? Ron(UK) The 10 minute recone part really bothers me. Sure with production line jigs, shims, guides and people who do maybe a 100 per day that is a tangible goal. But for an average Joe buying reconing parts and being successful is not the average outcome. Sure there are exceptions so if you want to try it on your own good luck. A little OT... Took me some hours to resolder bad joint between cone wire and the flex wire, by the time I found and arranged some foam rubber to lift the cone outwards enough to gain access, clean off some of the black insulator stuff very carefully to find the wires underneath and the bad solder joint. The speakers date back about 30 years. Then many attempts to get a good solder joint, the low-mid 7" speaker has very fine wire to the cone. But the repair done with much patience, and has lasted a few years now It's worth the effort to try repair expensive speaker drivers, at worst, you're still stuck with a bad speaker needing replacement. Nothing but time to lose? Grant. |
#8
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Repairing an expensive speaker
Ron wrote:
And that takes care of the knackered voice coil does it? Ron(UK) Not at all, the voice coil, spider, and the cone itself are not affected. Sorry if I missed something in the original post. |
#9
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Repairing an expensive speaker
On Thu, 08 Jul 2010 18:56:33 -0400, Meat Plow
wrote: On Thu, 8 Jul 2010 19:15:18 +0000 (UTC), root wrote: Meat Plow wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. Trust me, it isn't an easy fix. Just what ****ing experience do you think I might not have had with reconing. Don't make assumptions. This has been a very interesting and informative discussion but until now nobody has answer my original question that was the type of glue to use to glue the coil to the 2" tube. Since we want the sound to come out of the cone, the connection between the cone and the coil should be as rigid as possible and that suggests the use of epoxy but what about heat dissipation and how to remove a coil glued with epoxy to the tube, if some thing goes wrong? |
#10
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Repairing an expensive speaker
On 7/9/2010 8:56 AM, John wrote:
On Thu, 08 Jul 2010 18:56:33 -0400, Meat This has been a very interesting and informative discussion but until now nobody has answer my original question that was the type of glue to use to glue the coil to the 2" tube. Since we want the sound to come out of the cone, the connection between the cone and the coil should be as rigid as possible and that suggests the use of epoxy but what about heat dissipation and how to remove a coil glued with epoxy to the tube, if some thing goes wrong? Airflex 400 bob --- news://freenews.netfront.net/ - complaints: --- |
#11
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Repairing an expensive speaker
In article , John wrote:
On Thu, 08 Jul 2010 18:56:33 -0400, Meat Plow wrote: On Thu, 8 Jul 2010 19:15:18 +0000 (UTC), root wrote: Meat Plow wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. Trust me, it isn't an easy fix. Just what ****ing experience do you think I might not have had with reconing. Don't make assumptions. This has been a very interesting and informative discussion but until now nobody has answer my original question that was the type of glue to use to glue the coil to the 2" tube. Since we want the sound to come out of the cone, the connection between the cone and the coil should be as rigid as possible and that suggests the use of epoxy but what about heat dissipation and how to remove a coil glued with epoxy to the tube, if some thing goes wrong? If your afraid if something goes wrong, you take the advice and get somebody to do it. Airflex 400 is flexible, for surrounds and other repair. The type of treatment is going to depend on what you have. Whats the VC made out of, what kind of wire does it have. How is it wound. What kind of glue did they use. By the way, I NEVER work on just one speaker. Units must be matched for sound. Try superglue. Try COIL DOPE. polystyrene plastic dissolved in a solvent, toluene You really want to use that thermal epoxy don't you. greg |
#12
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Repairing an expensive speaker
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#13
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Repairing an expensive speaker
This has been a very interesting and informative discussion
but until now nobody has answer my original question that was the type of glue to use to glue the coil to the 2" tube. But the question /has/ been answered -- contact the manufacturer and ask it what the appropriate adhesive is. You want us to give you the answer you'd like to have -- and I, for one, am not going to do it. The manufacturer should know best. |
#14
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Repairing an expensive speaker
When voice coils are wound the former which you refer to as a 2" tube,
is placed an a mandrel with an expanding collet. In better speakers, it is "wet wound" in glue under precise tension onto the former to create a mechanically homogeneous coil, using a precision "coil winder" which advances the width of the wire for each turn of the mandrel. Without the mandrel and the collet, you cannot apply the correct tension to the wire, assuming you knew what it was. Old cones are not good cones and become tired, particularly after an event like you describe. New cones have a break-in period of several months until the spider and surround stabilize at their nominal compliance. Tannoy speakers are high efficiency with relatively small magnets which point to a tight gap. This is very unforgiving with respect to egging the coil and former, extra glue from the repair, misalignment, debris, nonlinearity of the reworked spider, surround and cone. You do not mention centering the coil in the excursion, which is critical for low distortion and is 90 degrees away from the shims. Since this alignment opposes the spring action of the suspension, the cone and spider must have no glue grooves to the former. In short, buy the cone kits or better still, ship the drivers to allow someone who does vintage Tannoy work to install them and preserve those $5,000.00 speakers through restoration. A top notch shop may also have a magnet charger to restore the specified flux density to the gap. Tell you friend that there are few "Vintage" cassette decks and for what this repair is going to cost he should look for something newer. About glue....a bit of acetone can be used (in areas other than the coil where it may create a shorted turn) to rewet and bond glue that has cracked. GC Radio and TV Service Cement was the old fashioned method used by TV repair shops. Real speaker reconers use the OEM glues. Adding epoxy to a solvent based glue joint is a cobblers repair. Using epoxy in place of a solvent cement is better, but still different. While tougher, epoxy often lacks the Q of a solvent cement joint that has aged, particularly when mixed and applied by hand which yields entrapped air and sloppy nonuniform ratios. These observations do not apply to modern 1KW drivers used in PA systems and beaten to death every weekend. Your friend's solution is perfectly valid in this application and a little DEVCON goes a long way toward a reasonable operating cost. Tom Maguire TMI Engineering |
#15
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Repairing an expensive speaker
On 09/07/2010 16:33, TMI wrote:
When voice coils are wound the former which you refer to as a 2" tube, is placed an a mandrel with an expanding collet. In better speakers, it is "wet wound" in glue under precise tension onto the former to create a mechanically homogeneous coil, using a precision "coil winder" which advances the width of the wire for each turn of the mandrel. Without the mandrel and the collet, you cannot apply the correct tension to the wire, assuming you knew what it was. Old cones are not good cones and become tired, particularly after an event like you describe. New cones have a break-in period of several months until the spider and surround stabilize at their nominal compliance. Tannoy speakers are high efficiency with relatively small magnets which point to a tight gap. This is very unforgiving with respect to egging the coil and former, extra glue from the repair, misalignment, debris, nonlinearity of the reworked spider, surround and cone. You do not mention centering the coil in the excursion, which is critical for low distortion and is 90 degrees away from the shims. Since this alignment opposes the spring action of the suspension, the cone and spider must have no glue grooves to the former. In short, buy the cone kits or better still, ship the drivers to allow someone who does vintage Tannoy work to install them and preserve those $5,000.00 speakers through restoration. A top notch shop may also have a magnet charger to restore the specified flux density to the gap. Tell you friend that there are few "Vintage" cassette decks and for what this repair is going to cost he should look for something newer. About glue....a bit of acetone can be used (in areas other than the coil where it may create a shorted turn) to rewet and bond glue that has cracked. GC Radio and TV Service Cement was the old fashioned method used by TV repair shops. Real speaker reconers use the OEM glues. Adding epoxy to a solvent based glue joint is a cobblers repair. Using epoxy in place of a solvent cement is better, but still different. While tougher, epoxy often lacks the Q of a solvent cement joint that has aged, particularly when mixed and applied by hand which yields entrapped air and sloppy nonuniform ratios. These observations do not apply to modern 1KW drivers used in PA systems and beaten to death every weekend. Your friend's solution is perfectly valid in this application and a little DEVCON goes a long way toward a reasonable operating cost. Tom Maguire TMI Engineering Interestingly, a similar discussion has been going on over in alt.audio.pro.live-sound, tho mainly concerned with repairing cracked magnets. I was surprised (after seeing a program on tv - to find out that ferrites are magnetised _after_ assembly with the motor and basket assembly Veejo here http://www.youtube.com/watch?v=VN0tmyyC0ak Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 1438 of my spam emails to date. Get the free SPAMfighter he http://www.spamfighter.com/len The Professional version does not have this message |
#16
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Repairing an expensive speaker
This is a horse of a different color.
You can't repair a cracked magnet and get the same flux in the gap because the crack adds extra gaps. Getting the magnet to crack in the first place usually means something horrible happened to the driver. Buy a new one. If you ever tried to assemble something with a charged magnet, particularlly something with a gap you did not want to close, it would make a lot more sense. The assembly acts to protect the charge from being deminished by nearby magnets. It also allows you to achieve the specified flux in the gap of the assembled speaker, where the rubber truly meets the road. Tom Maguire TMI Engineering Interestingly, a similar discussion has been going on over in alt.audio.pro.live-sound, tho mainly concerned with repairing cracked magnets. I was surprised (after seeing a program on tv - to find out that ferrites are magnetised _after_ assembly with the motor and basket assembly Veejo here http://www.youtube.com/watch?v=VN0tmyyC0ak Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 1438 of my spam emails to date. Get the free SPAMfighter hehttp://www.spamfighter.com/len The Professional version does not have this message- Hide quoted text - - Show quoted text - |
#17
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Repairing an expensive speaker
"Meat Plow" wrote in message ... On Fri, 9 Jul 2010 01:45:22 +0100, "Arfa Daily" wrote: "Meat Plow" wrote in message ... On Thu, 08 Jul 2010 20:48:38 +0100, Ron wrote: On 08/07/2010 20:15, root wrote: Meat wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. You remove the flex outer rim from the cone. Then you cut out the bulge covering the voice coil and put shims (supplied with the kit) in to center the cone. Then you glue new flex material around the cone, and wait overnight. Then you remove the shims and seal up the bulge with glue. Apart from the overnight wait for glue to dry, it only took me about half an hour the first time. With practice I might be able to get it down to 10 minutes. And that takes care of the knackered voice coil does it? Ron(UK) The 10 minute recone part really bothers me. Sure with production line jigs, shims, guides and people who do maybe a 100 per day that is a tangible goal. But for an average Joe buying reconing parts and being successful is not the average outcome. Sure there are exceptions so if you want to try it on your own good luck. Interestingly, I was discussing exactly this issue with the owner of the music shop that I do a lot of work for, just this week. He rents a lot of biiiiigggg PA equipment out - kilowatt amps and 4 x 15 bass cabs and such. These get damaged by inept users all the time, apparently. I suggested that it must cost him a fortune in replacement speakers, but he said "Oh no - I just re-cone them". I asked him how long he had been doing this and he said years, but I had never seen this going on in his shop. Anyway, I asked him how long it took, and how hard a job it was, and did he have lots of specialist shims and feeler gauges and jigs and what have you. Nope, he said. He reckons it takes him but a few minutes (literally) to do the job. He says that the most time consuming part is making sure that all the crud from the burnt up voice coil, is removed from the airgap. He uses a combination of compressed air, and sticky tape to do this. As to centering the new cone's voice coil, he says that most replacement kits come with a set of four plastic spacer shims, but that many modern designs are fundamentally self - centering anyway. He reckoned that it was basically a piece of **** job that just needed a little care, and that much ******** was talked on the subject. I might ask him to let me know next time he's got one to do, as I would like to watch him at work ... Arfa I've been around when my buddy Bart reconed some pro-audio speakers. It all comes down to people doing it the way they have learned. It's not as easy as you think but it isn't hard either. He chose to buy specific tools and glues and treatments not relying on kits for shims and glues. He knew what he was doing and reconed all my speakers. Never had a re-run because of a botched repair. Hey if you can learn the essentials and want to give reconing a try go for it. Maybe it's for you maybe it's not. I don't reckon I've got the patience, Meat. I had always thought that it was quite a tricky and skilled job, so I was just interested to have a watch next time Dunc does one, as he reckoned it was so straightforward ! Arfa |
#18
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Repairing an expensive speaker
On 09/07/2010 19:36, TMI wrote:
This is a horse of a different color. You can't repair a cracked magnet and get the same flux in the gap because the crack adds extra gaps. Getting the magnet to crack in the first place usually means something horrible happened to the driver. Buy a new one. Cracked ferrites _are_ repaired but only as a last resort in cases where there's no alternative. We've been through this recently on another n/g. It's not recommended, but it can be done. According to a large professional loudspeaker repair company I contacted on the subject, de-magnetising and remagnetising also is to be avoided as it loses flux. Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 1445 of my spam emails to date. Get the free SPAMfighter he http://www.spamfighter.com/len The Professional version does not have this message |
#19
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Repairing an expensive speaker
On Fri, 9 Jul 2010 08:22:27 -0700, "William Sommerwerck"
wrote: This has been a very interesting and informative discussion but until now nobody has answer my original question that was the type of glue to use to glue the coil to the 2" tube. But the question /has/ been answered -- contact the manufacturer and ask it what the appropriate adhesive is. You want us to give you the answer you'd like to have -- and I, for one, am not going to do it. The manufacturer should know best. That was the first thing I did and the answer from Tannoy was: "We don't have the kit but you may get it from company x. Then send the complete assembly to the closest Tannoy service center (200 miles from my residence) and we will do the reconing. We don't recommend changing the coil." The installation of the kit is easy. It is self center and it doesn't have play adjustments. In order to do a god job, I should order 2 cone kits from England but the total cost including transportation, duty an taxes will be more than $1k. The speaker with less damage has about 6 turns dislocated as a group from the rest of the coil that looks solid. I am going to read again your recommendations about the glue, paint the 2" tube with that glue and slide the 6 turns group into their previous position. If this works I may try to rewind the other coil "fat chance" Then I may order one or two kits from England and do the reconing myself. Thanks for all your help. John |
#20
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Repairing an expensive speaker
Ron wrote:
On 09/07/2010 16:33, TMI wrote: When voice coils are wound the former which you refer to as a 2" tube, is placed an a mandrel with an expanding collet. In better speakers, it is "wet wound" in glue under precise tension onto the former to create a mechanically homogeneous coil, using a precision "coil winder" which advances the width of the wire for each turn of the mandrel. Without the mandrel and the collet, you cannot apply the correct tension to the wire, assuming you knew what it was. Old cones are not good cones and become tired, particularly after an event like you describe. New cones have a break-in period of several months until the spider and surround stabilize at their nominal compliance. Tannoy speakers are high efficiency with relatively small magnets which point to a tight gap. This is very unforgiving with respect to egging the coil and former, extra glue from the repair, misalignment, debris, nonlinearity of the reworked spider, surround and cone. You do not mention centering the coil in the excursion, which is critical for low distortion and is 90 degrees away from the shims. Since this alignment opposes the spring action of the suspension, the cone and spider must have no glue grooves to the former. In short, buy the cone kits or better still, ship the drivers to allow someone who does vintage Tannoy work to install them and preserve those $5,000.00 speakers through restoration. A top notch shop may also have a magnet charger to restore the specified flux density to the gap. Tell you friend that there are few "Vintage" cassette decks and for what this repair is going to cost he should look for something newer. About glue....a bit of acetone can be used (in areas other than the coil where it may create a shorted turn) to rewet and bond glue that has cracked. GC Radio and TV Service Cement was the old fashioned method used by TV repair shops. Real speaker reconers use the OEM glues. Adding epoxy to a solvent based glue joint is a cobblers repair. Using epoxy in place of a solvent cement is better, but still different. While tougher, epoxy often lacks the Q of a solvent cement joint that has aged, particularly when mixed and applied by hand which yields entrapped air and sloppy nonuniform ratios. These observations do not apply to modern 1KW drivers used in PA systems and beaten to death every weekend. Your friend's solution is perfectly valid in this application and a little DEVCON goes a long way toward a reasonable operating cost. Tom Maguire TMI Engineering Interestingly, a similar discussion has been going on over in alt.audio.pro.live-sound, tho mainly concerned with repairing cracked magnets. I was surprised (after seeing a program on tv - to find out that ferrites are magnetised _after_ assembly with the motor and basket assembly Veejo here http://www.youtube.com/watch?v=VN0tmyyC0ak hahaha. Skip to 2:10 they magnetize the ferrite with the operator panel from a reel to reel tape drive or some washing machine sized hard drive, and by pushing the Fault button. |
#21
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Repairing an expensive speaker
Cydrome Leader wrote:
http://www.youtube.com/watch?v=VN0tmyyC0ak hahaha. Skip to 2:10 they magnetize the ferrite with the operator panel from a reel to reel tape drive or some washing machine sized hard drive, and by pushing the Fault button. Yeah, I thought the button legends were a bit odd. Equally funny is watching the whole thing jump in the fixture. Jeff -- “Egotism is the anesthetic that dulls the pain of stupidity.” Frank Leahy, Head coach, Notre Dame 1941-1954 http://www.stay-connect.com |
#22
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Repairing an expensive speaker
I'll bet they don't have the machine required to degauss and
remagnatize your speaker. Or you are talking to a salesman trying to manimize profit. There is no loss of flux with the correct size equipment. In fact, there will be more flux in a newly charged magnet compared to one that has been in service for a while. In the macro economics of it all, a reconer has to charge you so much to repair that magnet that it exceeds the value of a good basket core (speaker without the cone/voice coil). It will never be exactly like the uncracked one on the other side. No used speaker is worth more than a core + the recone job and that is very close to the cost of a new speaker. Now there are some unique drivers out there that are not available anymore but in most cases it makes real sense to measure the TS parameters of the remaining driver and make a good substitution using those numbers if a true replacement cannot be found. Someone who is REALLY into restorations might have a similar piece of ferrite or other magnetic material to replace the cracked magnet. There is NOTHING wrong with repairing a magnet that way, then charging the assembly. I have been doing this for 4 decades and that is my professional opinion. Tom Maguire TMI Engineering On Jul 9, 4:08*pm, Ron wrote: On 09/07/2010 19:36, TMI wrote: This is a horse of a different color. You can't repair a cracked magnet and get the same flux in the gap because the crack adds extra gaps. Getting the magnet to crack in the first place usually means something horrible happened to the driver. Buy a new one. Cracked ferrites _are_ repaired but only as a last resort in cases where there's no alternative. We've been through this recently on another n/g. It's not recommended, but it can be done. According to a large professional loudspeaker repair company I contacted on the subject, de-magnetising and remagnetising also is to be avoided as it loses flux. Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 1445 of my spam emails to date. Get the free SPAMfighter hehttp://www.spamfighter.com/len The Professional version does not have this message |
#23
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Repairing an expensive speaker
Arfa Daily wrote in message
... "Meat Plow" wrote in message ... On Fri, 9 Jul 2010 01:45:22 +0100, "Arfa Daily" wrote: "Meat Plow" wrote in message ... On Thu, 08 Jul 2010 20:48:38 +0100, Ron wrote: On 08/07/2010 20:15, root wrote: Meat wrote: Seek out a professional reconing shop. You need some specialized tools of the trade and some talent to recone. My good friend did it for a living until he passed away recently. He would advise the same even if you didn't chose his service. You can buy kits for reconing speakers. It isn't a hard job. You remove the flex outer rim from the cone. Then you cut out the bulge covering the voice coil and put shims (supplied with the kit) in to center the cone. Then you glue new flex material around the cone, and wait overnight. Then you remove the shims and seal up the bulge with glue. Apart from the overnight wait for glue to dry, it only took me about half an hour the first time. With practice I might be able to get it down to 10 minutes. And that takes care of the knackered voice coil does it? Ron(UK) The 10 minute recone part really bothers me. Sure with production line jigs, shims, guides and people who do maybe a 100 per day that is a tangible goal. But for an average Joe buying reconing parts and being successful is not the average outcome. Sure there are exceptions so if you want to try it on your own good luck. Interestingly, I was discussing exactly this issue with the owner of the music shop that I do a lot of work for, just this week. He rents a lot of biiiiigggg PA equipment out - kilowatt amps and 4 x 15 bass cabs and such. These get damaged by inept users all the time, apparently. I suggested that it must cost him a fortune in replacement speakers, but he said "Oh no - I just re-cone them". I asked him how long he had been doing this and he said years, but I had never seen this going on in his shop. Anyway, I asked him how long it took, and how hard a job it was, and did he have lots of specialist shims and feeler gauges and jigs and what have you. Nope, he said. He reckons it takes him but a few minutes (literally) to do the job. He says that the most time consuming part is making sure that all the crud from the burnt up voice coil, is removed from the airgap. He uses a combination of compressed air, and sticky tape to do this. As to centering the new cone's voice coil, he says that most replacement kits come with a set of four plastic spacer shims, but that many modern designs are fundamentally self - centering anyway. He reckoned that it was basically a piece of **** job that just needed a little care, and that much ******** was talked on the subject. I might ask him to let me know next time he's got one to do, as I would like to watch him at work ... Arfa I've been around when my buddy Bart reconed some pro-audio speakers. It all comes down to people doing it the way they have learned. It's not as easy as you think but it isn't hard either. He chose to buy specific tools and glues and treatments not relying on kits for shims and glues. He knew what he was doing and reconed all my speakers. Never had a re-run because of a botched repair. Hey if you can learn the essentials and want to give reconing a try go for it. Maybe it's for you maybe it's not. I don't reckon I've got the patience, Meat. I had always thought that it was quite a tricky and skilled job, so I was just interested to have a watch next time Dunc does one, as he reckoned it was so straightforward ! Arfa Reading through this I see no ref to 3 or 4 slices of credit card to align voice coil with the slot, maybe an omission or another reconing job I'm remembering This is my experience of reconing a Peavey Black Widow speaker Not made for the UK climate, stored in a (normal for UK) damp garage for 3 years, came out making nasty "amp clipping" noise. I don't know how general this is for different manufacturers but for unsticking the contact adhesive of the original cone and spider skirt. I tried hot-air gun , oven cleaner and acetone but the one that worked on the one I did this week was petrol. Some strips of tissue paper soaked in petrol and covered with some circular strips of plastic and leaving for half an hour to soften the glue Now it is totally apart, small bits of aluminium oxide in the voice coil slot were causing the distortion along with loose skirt biased to one still retained side. 15 inch size with aluminium basket. The voice coil is in perfect condition and no imperfections to the cone despite 30 years old. Prior to me getting to look the owner had removed the 3 magnet retaining bolts and removed some perished foam filter from inside under the mesh cover and squirted in WD40. The white oxide formations had burst the glued skirt off , about 80 percent of its rim, and the same for the cone rim (after removing the periphery bolts) and nothing much holding on the remainder, easy to prize off. masked off the central voice coil slot area before abraiding back the lands to take contact adhesive to replace the skirt and cone. Then air blast and run thick plastic around the slot to clear any crud. The magnet does not seem to be corroded, shiney, no obvious rust spots. The 0.08mm thick aluminium dome must have been press-formed or by metal spinning with a cylinder extension to the dome and the cylinder section is glued to the inside of the VC former. So had to cut around the dome to remove and hope the final gluing-back holds up against the air pumping process. I just used 4 ball point pens in the rim mount holes for rough alignment and some clothes pegs to give a bit more clearance gap for laying down the glue. Removed them prior to dropping the cone in case they gave some bias. |
#24
Posted to sci.electronics.repair
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Repairing an expensive speaker
FYI.....
HI Tom, We only recone with authentic Tannoy parts returning the speaker to exact new condition. I haven't priced this kit recently, but about one year ago, charges for us to recone the low frequency were $440.00 each. I can check the price on Monday to make sure there haven't been any major changes, but generally there are only a few dollar differences or none at all. The more important question will be availability and if you are interested, I will pursue that too. I'm glad you saw our Over the Tannoy Post. What did you think of it? the website? Cathy Satin The Speaker Exchange® 1250 E. Hillsborough Avenue • Tampa, FL 33604 Phone:1-800-849-6972 • 1-813-237-4800 Fax: 1-813-238-3558 Mon-Fri 10-5:30 est, 1st Sat of e month 10-3:00 AIM:cathyspex Skype: speakerex http://www.twitter.com/speakerex Speaker Sales, Service, and all your repair needs since 1977 Please send us your impressions, comments or suggestions concerning our new improved site www.speakerex.com SHIPPING instructions and REPAIR FORMS: http://tinyurl.com/2c3e27k On Jul 9, 9:31*pm, TMI wrote: I'll bet they don't have the machine required to degauss and remagnatize your speaker. Or you are talking to a salesman trying to manimize profit. There is no loss of flux with the correct size equipment. In fact, there will be more flux in a newly charged magnet compared to one that has been in service for a while. In the macro economics of it all, a reconer has to charge you so much to repair that magnet that it exceeds the value of a good basket core (speaker without the cone/voice coil). It will never be exactly like the uncracked one on the other side. No used speaker is worth more than a core + the recone job and that is very close to the cost of a new speaker. Now there are some unique drivers out there that are not available anymore but in most cases it makes real sense to measure the TS parameters of the remaining driver and make a good substitution using those numbers if a true replacement cannot be found. Someone who is REALLY into restorations might have a similar piece of ferrite or other magnetic material to replace the cracked magnet. There is NOTHING wrong with repairing a magnet that way, then charging the assembly. I have been doing this for 4 decades and that is my professional opinion. Tom Maguire TMI Engineering On Jul 9, 4:08*pm, Ron wrote: On 09/07/2010 19:36, TMI wrote: This is a horse of a different color. You can't repair a cracked magnet and get the same flux in the gap because the crack adds extra gaps. Getting the magnet to crack in the first place usually means something horrible happened to the driver. Buy a new one. Cracked ferrites _are_ repaired but only as a last resort in cases where there's no alternative. We've been through this recently on another n/g.. It's not recommended, but it can be done. According to a large professional loudspeaker repair company I contacted on the subject, de-magnetising and remagnetising also is to be avoided as it loses flux. Ron(UK) -- I am using the free version of SPAMfighter. We are a community of 7 million users fighting spam. SPAMfighter has removed 1445 of my spam emails to date. Get the free SPAMfighter hehttp://www.spamfighter.com/len The Professional version does not have this message- Hide quoted text - - Show quoted text - |
#25
Posted to sci.electronics.repair
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Repairing an expensive speaker
On Fri, 09 Jul 2010 17:15:17 -0400, John wrote:
Some one made some reference to the use WD40 to melt the glue I had an interesting experience with that powerful staff: The spring load cover of an outdoor power outlet that I have, made a screeching noise when lifted. I sprayed it with WD40 and the cover toke off like an Arab rocket. Einstein once defined a stupid person the one who does the same thing and expects a different result so I did the stupid thing of installing a new cover and spray again with WD40 and obviously the result was the same. Installed another cover and no more spraying. The nasty WD40 melted the plastic holding the spring. Ref: Material to hold the coil in position : I used, 65 years ago, strips of plastic from photographic film negatives. Boston Acoustics sells a speaker with a removable voice coil and attached to the cone by screws. There is a metal ring with threaded holes glued to the cone. Thank you to everybody . Fantastic help John |
#26
Posted to sci.electronics.repair
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Repairing an expensive speaker
On Fri, 09 Jul 2010 17:15:17 -0400, John wrote:
Some one made some reference to the use WD40 to melt the glue I had an interesting experience with that powerful staff: The spring load cover of an outdoor power outlet that I have, made a screeching noise when lifted. I sprayed it with WD40 and the cover toke off like an Arab rocket. Einstein once defined a stupid person the one who does the same thing and expects a different result so I did the stupid thing of installing a new cover and spray again with WD40 and obviously the result was the same. Installed another cover and no more spraying. The nasty WD40 melted the plastic holding the spring. Ref: Material to hold the coil in position : I used, 65 years ago, strips of plastic from photographic film negatives. Boston Acoustics sells a speaker with a removable voice coil and attached to the cone by screws. There is a metal ring with threaded holes glued to the cone. Thank you to everybody . Fantastic help John |
#27
Posted to sci.electronics.repair
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Repairing an expensive speaker
In article , John wrote:
I am repairing two 15" Tannoys of the Gold series. A $5k unit if we could get them. Un oscillation in a cassette deck I was using, produced a very lowed sound that damaged the speakers. One of them has 6 turns of the voice coil, lose and can be glued back. On the old days I used to repair speakers using the same type of glue that was used on the assembling of models. A type of glue that use acetone as a solvent. Today we have better types of glue like epoxy and I believe the harder the glue the better the performance, the disadvantage is that using epoxy will make a future repair very difficult. Any suggestions ? The coil on the second speaker is open and in very bad shape. I am looking for a replacement. Tannoy does not carry parts for this type of speaker but there is a place in England that will sell me a cone assembly for about $300 usd. I noticed Parts Express also does reconing. Pretty cheap. greg |
#28
Posted to sci.electronics.repair
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Repairing an expensive speaker
On Thu, 08 Jul 2010 10:40:20 -0400, John wrote:
:I am repairing two 15" Tannoys of the Gold series. A $5k unit if we :could get them. : :Un oscillation in a cassette deck I was using, produced a very lowed :sound that damaged the speakers. : :One of them has 6 turns of the voice coil, lose and can be glued back. : :On the old days I used to repair speakers using the same type of glue :that was used on the assembling of models. A type of glue that use :acetone as a solvent. :Today we have better types of glue like epoxy and I believe the harder :the glue the better the performance, the disadvantage is that using :epoxy will make a future repair very difficult. : :Any suggestions ? : :The coil on the second speaker is open and in very bad shape. I am :looking for a replacement. : :Tannoy does not carry parts for this type of speaker but there is a lace in England that will sell me a cone assembly for about $300 usd. Are these the speakers? http://www.44bx.com/tannoy/gold.html#anchor2238478 If so then they should be fairly easily repaired. A good repair shop will remove the surround and the spider (probably with acetone) and they can re-attach the winding or rewind if necessary. Where I am in the most remote capital in the world we have a repair shop who could do it http://www.shortfuse.net.au/ He is frequently asked to perform this type of repair on Altec, Goodmans, Wharfedale etc. |
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