Tony Reed Posted April 3, 2006 Share Posted April 3, 2006 I have a pair of really old K77's that play really weak. The sound is clear, just not as loud as it should be (compared to other K77's). Is there any truth that old drivers need to be re-magnetized? If so, where can I have this done? I really want to keep these tweeters. Thanks, Tony Quote Link to comment Share on other sites More sharing options...
mark1101 Posted April 3, 2006 Share Posted April 3, 2006 Are your networks up to spec? You're sure it's the tweeters? Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted April 3, 2006 Author Share Posted April 3, 2006 I've tried these tweeters with the following networks, AL, AL-3, A & AA. I always get the same results. Tony Quote Link to comment Share on other sites More sharing options...
Deang Posted April 3, 2006 Share Posted April 3, 2006 Bill at Great Plains Audio can remagnetize Alnico magnets. www.greatplainsaudio.com Quote Link to comment Share on other sites More sharing options...
mark1101 Posted April 3, 2006 Share Posted April 3, 2006 Can I ask what makes them de-magnetize? Time? Quote Link to comment Share on other sites More sharing options...
BEC Posted April 3, 2006 Share Posted April 3, 2006 Time, to some extent. Exposure to another magnet. A powerful neodymium magnet may kill an alnico very quickly. A mechanical shock is the most likely thing. Like shipping them back from a place that re-mags them. Bob Crites Quote Link to comment Share on other sites More sharing options...
Deang Posted April 3, 2006 Share Posted April 3, 2006 [][] Quote Link to comment Share on other sites More sharing options...
SilverSport Posted April 3, 2006 Share Posted April 3, 2006 Time, to some extent. Exposure to another magnet. A powerful neodymium magnet may kill an alnico very quickly. A mechanical shock is the most likely thing. Like shipping them back from a place that re-mags them. Bob Crites WOW!!! [][]...Bill Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted April 3, 2006 Share Posted April 3, 2006 I have a pair of really old K77's that play really weak. The sound is clear, just not as loud as it should be (compared to other K77's). Is there any truth that old drivers need to be re-magnetized? If so, where can I have this done? I really want to keep these tweeters. Thanks, Tony Tony sometimes this can be caused by a corroded connection at the rivet and solder terminal of some K77s, do you no what the resistance of these read? If not try reading their resistance at the solder terminals and if it's high (should read approx. 6.2 ohms) then try reading the resistance in the middle of the rivet (where the voice coil wire is soldered) that holds the solder terminal and if it's around the 6.2 ohms then you can probably repair them by wrapping a fine piece of wire around the solder terminal and soldering it to the terminal and to the center of the rivet where the voice coil wire is soldered. One other thing that I've seen cause Alnico to loose its strength is exposure to Heat which happened from the speakers being used outdoors in the sunlight. mike[] Quote Link to comment Share on other sites More sharing options...
Tony Reed Posted April 4, 2006 Author Share Posted April 4, 2006 I have a pair of really old K77's that play really weak. The sound is clear, just not as loud as it should be (compared to other K77's). Is there any truth that old drivers need to be re-magnetized? If so, where can I have this done? I really want to keep these tweeters. Thanks, Tony Tony sometimes this can be caused by a corroded connection at the rivet and solder terminal of some K77s, do you no what the resistance of these read? If not try reading their resistance at the solder terminals and if it's high (should read approx. 6.2 ohms) then try reading the resistance in the middle of the rivet (where the voice coil wire is soldered) that holds the solder terminal and if it's around the 6.2 ohms then you can probably repair them by wrapping a fine piece of wire around the solder terminal and soldering it to the terminal and to the center of the rivet where the voice coil wire is soldered. One other thing that I've seen cause Alnico to loose its strength is exposure to Heat which happened from the speakers being used outdoors in the sunlight. mike[] I'll be pulling these out of the cabinets soon for a closer inspection and to test across for resistance. Thanks, Tony Quote Link to comment Share on other sites More sharing options...
BEC Posted April 4, 2006 Share Posted April 4, 2006 Tony, If those are very old K-77s they may be 16 ohm. In that case look for about 11 ohms when measuring the coil if the diaphragms are original and about 9 ohms if they have been replaced. Bob Quote Link to comment Share on other sites More sharing options...
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