mwiener Posted July 12, 2015 Share Posted July 12, 2015 (edited) I purchased a set of K55Vs with solder lugs off eBay. They came out of a pair khorns in Canada that were being parted out. I tested them in my LaScalas, but they sounded a little flat. I then tested them with my test rig, they show a full 5db down at 2k hz as compared to my push pin K55Vs. When I tested the resistance it was 10.2 on one, but 11.2 on the other. I expect that means I need to replace the diaphragm on the one reading 11. Can anyone confirm? Thanks, Mike. Edited July 12, 2015 by mwiener Quote Link to comment Share on other sites More sharing options...
garyrc Posted July 12, 2015 Share Posted July 12, 2015 I purchased a set of K55Vs with solder lugs off eBay. They came out of a pair khorns in Canada that were being parted out. I tested them in my LaScalas, but they sounded a little flat. I then tested them with my test rig, they show a full 5db down at 2k hz as compared to my push pin K55Vs. When I tested the resistance it was 10.2 on one, but 11.2 on the other. I expect that means I need to replace the diaphragm on the one reading 11. Can anyone confirm? Thanks, Mike. There is a frequency response graph somewhere on The Dope from Hope comparing the response of the solder lug v.s. the push pin version. As I remeber, the solder lug had smoother response, reducing a dip at about 4K. The DfH would be about 1980, which is when the K55 was changed. It was a phase plug thing, I tink. There was also an interview in Speaker Builder, in which PWK briefly discusses this. For new Khorns (post 2002?) the crossover point and slope was changed, so the phase plug alteration was no longer necessary. Quote Link to comment Share on other sites More sharing options...
mwiener Posted July 12, 2015 Author Share Posted July 12, 2015 I was doing some research, and supposedly a brand new diaphragm will measure 11 ohms. I think I get my test rig out again and test each speaker independently and see if the 5db loss is right, left, or both. When I get some time I will put my push pin K55Vs back in and verify that everything is fine with the old drivers. I am wondering if it is a brand new diaphragm, maybe it was not installed correctly? Any other ideas what might be going on? Mike. Quote Link to comment Share on other sites More sharing options...
djk Posted July 13, 2015 Share Posted July 13, 2015 "Can anyone confirm?" Is it only one, or the pair? Do they have K55V logos on the back? Is there a threaded hole in the middle of the back? http://www.av-iq.co.uk/avcat/images/documents/dataSheet/AS100N_Datasheet.pdf Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted July 13, 2015 Share Posted July 13, 2015 In addition....did you replace the gaskets with new ones? Quote Link to comment Share on other sites More sharing options...
cradeldorf Posted July 13, 2015 Share Posted July 13, 2015 (edited) most phragms vary like that, anything below 8 ohms is an 8 ohm phragm, anything over 8 ohms is a 16 ohm phragm. You have 16 ohm drivers. Edited July 13, 2015 by cradeldorf Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 13, 2015 Share Posted July 13, 2015 m, I was going to say that something odd is going on if they both measure 5 dB down. But now in you later post it seems that you're making further investigation to test left and right. So maybe your first test did not determine that they're both 5 dB down. Let us know. WMcD Quote Link to comment Share on other sites More sharing options...
mwiener Posted July 14, 2015 Author Share Posted July 14, 2015 Here is what I have found thus far. The K55V that measures 10.2 ohms appears to have a lower output. I would say the overall lower output for the one unit is about 5-7db down in some spots but specifically between 2050 and 3450hz. I admit that I did not change the gaskets. The K55Vs are sequentially serial numbered. They appear to be K55Vs, they have the same metal button and logo on the back as my push pin units. One thing I did notice, my push pin K55Vs have a newer serial number than the solder lug K55Vs. That could be explained if they changed the serial numbers when they switched over to the solder lug type. Does anyone know if that happened? My push pin units are in the 160xxx range and the solder lug units are in the 147xxx range. If not, the only conclusion I can come up with is these units were doctored to look like the solder lug units. Mike., Quote Link to comment Share on other sites More sharing options...
garyrc Posted July 14, 2015 Share Posted July 14, 2015 Here is what I have found thus far. The K55V that measures 10.2 ohms appears to have a lower output. I would say the overall lower output for the one unit is about 5-7db down in some spots but specifically between 2050 and 3450hz. I admit that I did not change the gaskets. The K55Vs are sequentially serial numbered. They appear to be K55Vs, they have the same metal button and logo on the back as my push pin units. One thing I did notice, my push pin K55Vs have a newer serial number than the solder lug K55Vs. That could be explained if they changed the serial numbers when they switched over to the solder lug type. Does anyone know if that happened? My push pin units are in the 160xxx range and the solder lug units are in the 147xxx range. If not, the only conclusion I can come up with is these units were doctored to look like the solder lug units. Mike., All I know is when the solder lug units came out in about 1980, Klipsch said you could identify the K55 with the new phase plug because they had the soldered lugs, while the ones without it were push pin units. Much later, Klipsch went to the K55X, using a different upper crossover (4.5KHz, instead of the old 6KHz). Quote Link to comment Share on other sites More sharing options...
mwiener Posted July 15, 2015 Author Share Posted July 15, 2015 I swapped the K55V drivers between speakers and retested. The drop follows the driver, but it was less pronounced than I tested before. It looked like it was only about 4db down, but the same spots. The cross over and cables stayed the same, the only thing that changed between the speakers was the driver. In my mind it is clearly the driver, but I have no idea what could cause that. I am still wondering if these are solder lug drivers to begin with. I have an option to return them, and I might just do that. Quote Link to comment Share on other sites More sharing options...
OO1 Posted July 19, 2015 Share Posted July 19, 2015 I swapped the K55V drivers between speakers and retested. The drop follows the driver, but it was less pronounced than I tested before. It looked like it was only about 4db down, but the same spots. The cross over and cables stayed the same, the only thing that changed between the speakers was the driver. In my mind it is clearly the driver, but I have no idea what could cause that. I am still wondering if these are solder lug drivers to begin with. I have an option to return them, and I might just do that. you can unscrew the k55v and split the driver whithout damaging the diaphragm - this can give you a look at the diaphragm - you can see if it is damaged or scratched and even dirty - by comparing both , you can also swap the drivers halves and test them that way - -if you can return them - do it before it is too late - Quote Link to comment Share on other sites More sharing options...
Deang Posted July 19, 2015 Share Posted July 19, 2015 The diaphragms need to be replaced. In all likelihood, the drivers just saw hard use over their lifetime. Consider that those things are 25 years old. Even if they had worked without issue, diaphragm replacement should be in the budget. I have five pair of these things, and even though they sound fine. I know I need to do it. They're worth it. I would only send them back if they showed evidence of rough handling (paint chipped off like possibly being dropped, etc.). Quote Link to comment Share on other sites More sharing options...
mwiener Posted July 25, 2015 Author Share Posted July 25, 2015 Well, I am going to go ahead and keep them. Once I made that decision I opened the driver up, de soldered the diaphragm and did determine it is the correct 2 piece phase plug. Now that I know I have the right driver I am going to package them up and send to Bob Crites for new diaphragms. Still don't understand the serial numbers on the drivers. Why a newer solder lug driver has an lower serial number 146xxx than a older push pin driver with a160xxx number I don't understand. I guess that is just one nugget of knowledge I can contribute back to the forum. Serial numbers on the K55Vs don't mean a whole lot. Mike. Quote Link to comment Share on other sites More sharing options...
Deang Posted July 25, 2015 Share Posted July 25, 2015 I would imagine those drives had their own series of numbers, separate from the spring loaded versions. Quote Link to comment Share on other sites More sharing options...
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