leok Posted February 12, 2012 Share Posted February 12, 2012 I've changed the mid and tweeter diaphragms in my Chorus-IIs a couple of times. I purchased them used and they were damaged and then later I upgraded to very nice parts from Bob Crites. Over time I noticed a resonance somewhere in the low KHz range. Eventually it occurred to me the horn screws clamping the diaphragms might be loose. It turns out although they weren't exactly loose they weren't real tight for such beefy screws so I cranked them down. Resonance gone and way better sound and imaging. Today I checked tweeter nuts .. not real tight either so I tightened them. Then I checked the horns on my RF7s. Those assemblies have lock washers which were no longer completely crushed (I assume they should be). I tightened them to flatten the lock washers and then some. That "I assume they should be" is what I am looking for. Does anyone know how tight these screws/nuts should be? Are there torque specifications? All I know now is they should be tight enough to keep the diaphram holder from moving and not so tight they strip or crush something. But then, I don't really know what that is. Thanks, Leo Quote Link to comment Share on other sites More sharing options...
moray james Posted February 12, 2012 Share Posted February 12, 2012 a little wrap of teflon tape (skived pipe fitters tape) and a dab of cheap nail polish on the nut at the base and that should keep them from moving around once snug. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted February 12, 2012 Share Posted February 12, 2012 GLUPTAL is a type of nail polish looking stuff,, to use on screws to keep them from backing out.. Quote Link to comment Share on other sites More sharing options...
moray james Posted February 12, 2012 Share Posted February 12, 2012 that would be great too. So would thread lock. Just about anything will work as it does not take much to essentially jam the nut so it won't turn. Stuff that is easy to remove if you have to work on it later is always nice. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
leok Posted February 12, 2012 Author Share Posted February 12, 2012 I don't think the screws/nuts are backing out. I think the diaphram holder and spacing material are compressing (creeping) causing the relax in compression force, or in my Chorus-II case, possibly I didn't apply sufficient force at installation. But, whatever is the problem, I would like to know how tight to make them in the first place, before applying something to prevent loosening. Thanks, Leo Quote Link to comment Share on other sites More sharing options...
moray james Posted February 12, 2012 Share Posted February 12, 2012 I should think finger tight then one to one and a half turns max with a wrench, you don't want to crush things. Perhaps others will comment. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
DavidF Posted February 13, 2012 Share Posted February 13, 2012 When I have changed compression diaphragms and standard dynamic dome diaphragms I apply a test tone around 1k HZ as I tighten down the holding screws. As with all bolt/screws it's only necessary to tension the bolt to hold the piece. I tighten the bolts on a cross pattern and take each both to "just tight" as I work around the pattern. After all are tightened I use a full sweep of the tone generator and listen for any raspy sounds or obvious distortion.If you over tighten one side of a driver assembly you will notice the coil in contact with the gap. Loosen the bolt or tighten down on the opposite side and the coil will true itself again. Quote Link to comment Share on other sites More sharing options...
leok Posted February 13, 2012 Author Share Posted February 13, 2012 Thanks DavidF .. that seems to address the issue .. as tight as it has to be and balanced. I may use a torque driver with this method to try to avoid getting the coil out of true. I'm just beginning to realize how many ways there are to make perfectly good equipment sound less than optimal. Leo Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 14, 2012 Share Posted February 14, 2012 Tighten till the screw strips out and back it up a quarter turn. You realize I'm kidding right? Quote Link to comment Share on other sites More sharing options...
Marvel Posted February 14, 2012 Share Posted February 14, 2012 You realize I'm kidding right? I'm sure he does...Leo, where have you been? I haven't seen you around for quite a while, and hope you have ben well. Bruce Quote Link to comment Share on other sites More sharing options...
leok Posted February 15, 2012 Author Share Posted February 15, 2012 Hi Bruce, I pretty much got things sounding good enough to enjoy music and that's what I've been doing with the Chorus and RF7 systems. I guess with that enjoyment I continued to expect more as I explored different types of music. Choral music (comparing versions of Morton Lauridsen works by Polyphony and Los Angeles Master Chorale to be exact) exposed the diaphram resonance and distortion issue. That fixed, I'm bach to enjoying the music more than ever. As far as the two Lauridsen recordings, it turns out they're both exceptional recordings of exceptional material .. many of the same works .. one with a small chorus (often 1 voice per part) and one with a very large but very coherent chorus. They're tough on a system, but very beautiful when things work. Much thanks to this Forum, without which I would never have achieved this level of audio performance. Good to hear from you. Leo Quote Link to comment Share on other sites More sharing options...
leok Posted February 15, 2012 Author Share Posted February 15, 2012 CECAA850, Yes. But that's exactly what I can see myself doing. Leo Quote Link to comment Share on other sites More sharing options...
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