Deang Posted March 17, 2018 Author Share Posted March 17, 2018 I wish I would have sent the K-55's to Bob to be tested before I replaced the diaphragms. There was an obvious improvement when I first installed the Allen drivers, but after the diaphragm change out on the K-55-V's, not so much. There is a difference. They do curve ever so slightly different, with the Allen driver being just a bit smoother. I mean, it's not much, but it's measurable, so shouldn't be discounted. I did use the system every night for almost a week before putting the Allen drivers back in. Distortion: John Warren measured a K-55-M on a K-401 horn, and sent this to me via email ... "K55M on K401 horn, voltage to horn terminals set for 110dB at fundamental, 1m from mouth of K401. No filter on horn. The FFT triggers off input sinewave. FFT bandwidth to about 48kHz. Second and third order make up the bulk of the distortion. %THD shown is average of 5 samples. %THD+N is a smidge over 0.5%..." Al measured 1.5%, but used a K-55-V, and I don't know which one, or what condition the diaphragm was in. I think I've decided that 30 year old diaphragms should probably be replaced. Quote Link to comment Share on other sites More sharing options...
jjptkd Posted March 18, 2018 Share Posted March 18, 2018 So there was a notable improvement with the new diaphragms, interesting. Are the new replacements OEM factory ones, the same exact ones that were already in there or aftermarket? I'm just curious if the improvements are from replacing a worn out unit or with a superior one? I've wondered myself if age could be an issue with the old soldered lug k-55v's as from what I understand all of the old used ones found online are around 35 years old. I'm still running soldered lug 55's in my Chorus II's and they sound great but they do sound a little different than my A55-g's which seem smoother to me. Either way I like having complete brand new drivers in my speakers, magnets and diaphragms helps me sleep better at night. I know the magnets are pretty resilient but you have to wonder when they start getting close to half a century old. If there weren't any suitable replacements available than fine but thankfully we have the technology! Quote Link to comment Share on other sites More sharing options...
Deang Posted March 21, 2018 Author Share Posted March 21, 2018 Now that the secret is pretty much out, the dual phase plug version is getting kind of scarce. They don't come up near as often on eBay as they used to. Also, when they do come up, sellers know what they have. I feel the same way -- it's nice to have a new driver, where you don't have to worry about it's history. I think anyone using the single phase plug version with the older filters is really cheating themselves. I mean, the driver is 20dB down at the crossover point. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted March 23, 2018 Share Posted March 23, 2018 Dean, was the K-55V diaphragm swap out straight forward (no unsoldering, re soldering) disassemble, remove and replace? My main seven speakers all have the dual phase plug K-55V's in them so I will replace them in pairs. Was the difference audible to you? Where did you source the replacement diaphragms? Quote Link to comment Share on other sites More sharing options...
absolve2525 Posted March 23, 2018 Share Posted March 23, 2018 For some reason, the EV-made dual-phase plug K55M don't seem to bring the high $$ that the Atlas-made dual-phase plug K55V does. Since we know from Bob Crites that that K55M can accept K55V diaphragms with minor modifications, has anyone compared the EV with new diaphragms, or even without? Just curious! Quote Link to comment Share on other sites More sharing options...
Deang Posted March 24, 2018 Author Share Posted March 24, 2018 On 3/23/2018 at 12:23 PM, Frzninvt said: Dean, was the K-55V diaphragm swap out straight forward (no unsoldering, re soldering) disassemble, remove and replace? My main seven speakers all have the dual phase plug K-55V's in them so I will replace them in pairs. Was the difference audible to you? Where did you source the replacement diaphragms? No, you have to desolder, and then solder them in - soldered lugs, right? :-) Yes, I could hear the improvement. When I first bought the Allen drivers, they were clearly better sounding. After the diaphragm changout, they sound more alike than different (still a difference though). I bought the diaphragms from Bob. Bob is getting them straight from Atlas (the boxes were stamped with Atlas logos, etc). Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted March 24, 2018 Share Posted March 24, 2018 Thanks Quote Link to comment Share on other sites More sharing options...
Deang Posted March 24, 2018 Author Share Posted March 24, 2018 On 3/23/2018 at 4:06 PM, absolve2525 said: For some reason, the EV-made dual-phase plug K55M don't seem to bring the high $$ that the Atlas-made dual-phase plug K55V does. Since we know from Bob Crites that that K55M can accept K55V diaphragms with minor modifications, has anyone compared the EV with new diaphragms, or even without? Just curious! That’s because there are no direct diaphragm replacements, and many of the EV drivers are having issues with backs coming loose due to issues related to the adhesive. Quote Link to comment Share on other sites More sharing options...
absolve2525 Posted March 24, 2018 Share Posted March 24, 2018 The backs can't simply be re-glued? The Atlas diaphragm apparently fits the EV by removing the gasket. I understand the EV driver doesn't have original manufacturer parts for them anymore. I'm curious if anyone has tried them with new Atlas diaphragms, and compared to the other dual phase plug units. Thanks Quote Link to comment Share on other sites More sharing options...
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