Sancho Panza Posted April 18, 2014 Share Posted April 18, 2014 (edited) Both Tweeter & Mid. Edited April 18, 2014 by Sancho Panza Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 18, 2014 Share Posted April 18, 2014 I suspect mine have been replaced & Youth's haven't. Quote Link to comment Share on other sites More sharing options...
Rhetor Posted April 18, 2014 Share Posted April 18, 2014 How do you inspect to see if diaphragms have been replaced? Diaphragm? On a crossover? We have just been talking about caps on the crossovers. Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 18, 2014 Share Posted April 18, 2014 Diaphragms Quote Link to comment Share on other sites More sharing options...
beeker Posted April 18, 2014 Share Posted April 18, 2014 Both Tweeter & Mid. it depends which model like k77 or a k76 or k79 for tweeters the k55 in your mids in your ls's are likely stock Quote Link to comment Share on other sites More sharing options...
Rhetor Posted April 19, 2014 Share Posted April 19, 2014 (edited) Diaphragms Sorry, Sancho . . . Somehow I missed your post #102 and got confused. Edited April 19, 2014 by Rhetor Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 19, 2014 Share Posted April 19, 2014 I suspect mine have been replaced & Youth's haven't. Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 19, 2014 Share Posted April 19, 2014 Yes & so, most likely are Youth's. So, an inspection is called for. Both Tweeter & Mid.it depends which model like k77 or a k76 or k79 for tweeters the k55 in your mids in your ls's are likely stock Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 19, 2014 Share Posted April 19, 2014 Maybe if you inspect them they then HAVE to be replaced??? Quote Link to comment Share on other sites More sharing options...
Deang Posted April 19, 2014 Share Posted April 19, 2014 Any of you ever look up the word "phenolic"? Quote Link to comment Share on other sites More sharing options...
Rhetor Posted April 19, 2014 Share Posted April 19, 2014 (edited) I suspect mine have been replaced & Youth's haven't.Again, sorry I missed that post.I had a blown K77 in one of my first La Scalas. Found out you can buy a diaphragm, but it is not going to be a factory equivalent . . . they just are not manufactured to satisfaction. So, I sourced an original working vintage K77 round magnet to match. Of course I first bought a pair of CT125s, but went back to old school. On a K77 or a K-55 on an older speaker, hard to tell without opening. And when you open a K77 at least, probably going to destroy the phenolic diaphragm every time. K-55 factory level replacements, as I understand it, are readily available and I would not be concerned if it was replaced. Probably knew of the best ways to tell if it has been replaced is if it has a super crappy solder job on the wire leads. But better minds than mine need to jump in in this one. Edited April 19, 2014 by Rhetor Quote Link to comment Share on other sites More sharing options...
Rhetor Posted April 19, 2014 Share Posted April 19, 2014 Any of you ever look up the word "phenolic"? I just wrote that "better minds" would need to jump in . . . ;-) Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 19, 2014 Share Posted April 19, 2014 (edited) Any of you ever look up the word "phenolic"?Were you a lawyer in your past life? LoLAnyhow, I've worked with enough mechanics to know most diaphragms are 1 time use. Edited April 19, 2014 by Sancho Panza Quote Link to comment Share on other sites More sharing options...
Deang Posted April 19, 2014 Share Posted April 19, 2014 There is a very good chance that the diaphragms in those drivers are of better quality than the replacements that are available. If the drivers are working, there's no reason to mess with them. If I were to dump money into the tweeter end of things, it would be Al and Dave's B&C DE120 drop in replacement. I posted impulse response and waterfall plots of all the drivers for comparison a few months ago in the Technical Section -- no contest, not even close -- a complete no brainer for the money. Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 19, 2014 Share Posted April 19, 2014 (edited) Thanks; I usually think if it's working, don't fix it. The idea being to put all my money in acquiring more speakers, then improve. Unless, like Youth, I had oil can type caps, which are likely out of spec; or, at least potentially Hazardous for Toxic Fluid leaks (PCBs). The PCB I like is a Beach! Edited April 19, 2014 by Sancho Panza Quote Link to comment Share on other sites More sharing options...
Deang Posted April 19, 2014 Share Posted April 19, 2014 I haven't rebuilt near as many as Bob and Michael, but I've only ever run into few sets that had the PCB type oil, most of the cans usually say "no PCBs". Still, I would do a close visual inspection to see if they're leaking. This involves removing the screws that are holding the capacitors down and taking a look underneath. Regardless, I agree that the capacitors need to be replaced. Quote Link to comment Share on other sites More sharing options...
Rich_Guy Posted April 19, 2014 Share Posted April 19, 2014 The Pro Line Speakers are BLACK!! Come to the DARK side Youth, Come to the DARK side Youth!!! Twisted by the Dark Side, young Youthman has become. 2 Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted April 19, 2014 Share Posted April 19, 2014 That's good to know. I have much to learn & stand corrected. Is there a cut-off time as to when they ceased using PCB type oil? Quote Link to comment Share on other sites More sharing options...
Deang Posted April 19, 2014 Share Posted April 19, 2014 I THINK the original paper in oils from the earliest of days up through the 60s are probably the PCB oil types. They then went to Mylar in oil, which is what we are normally used to seeing, and what Youthman has on his. DJK says the original cans are hermetically sealed with glass, which is pretty cool. 1 Quote Link to comment Share on other sites More sharing options...
Rhetor Posted April 19, 2014 Share Posted April 19, 2014 I THINK the original paper in oils from the earliest of days up through the 60s are probably the PCB oil types. They then went to Mylar in oil, which is what we are normally used to seeing, and what Youthman has on his. DJK says the original cans are hermetically sealed with glass, which is pretty cool. Thanks, Dean, for the clarification. I think old caps are pretty cool too and why I kept them after replacing them. They sit on a shallow pan above my shop workbench and are a great conversation piece. Since they were not leaking, just did not want to throw them away, and will dispose of them safely when the time comes. One question. I have heard when they are 20+ years old (mine were all between 32-38 years old) that they simply lose capacitance over a 20+ year period. True or myth? Quote Link to comment Share on other sites More sharing options...
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