mustang guy Posted October 26, 2011 Share Posted October 26, 2011 I have recently discovered a problem with one of the LaScalas in my 6.2 setup. I was running the Spears & Munsil HD Benchmark on my Oppo BDP-93m and there is a scene in TrueHD that has a note piano note that reoccurs often, and that note was causing a great deal of noise manifested as resonance. That resonance was causing the cap on the back of the squaker to vibrate and make a hell of a noise. I used some black silicone gasket maker around the fringe of that squaker cap, and it helped. That actually made me realize the matching AL-3 LaScala was also making the distorted noise, just to a lesser degree. I next put on a Beatles LP, and went around in all channel stereo, and found the mid-high tones are much better on the other 4 LaScalas which have newly re-capped AA networks, two of them with new tweets as well. My questions are this, do you think it is the squaker, or the AL-3 network that is to blame? Also, is there a test I can perform to check? When I first set this system up, the AL-3 speakers sounded a good bit cleared than the other 4 with the AA's with the fresh sonicaps. 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 26, 2011 Author Share Posted October 26, 2011 Update: I put an ohmeter on the worst squaker, and it checks out at 10.4 omh resistance. I found that on Crites K-55V replacement page. 1 Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 26, 2011 Share Posted October 26, 2011 A lot of folks like the sound of the AA networks. Since you have 4 already, best bet would be to switch out the 5th one and make it also an AA network. 1 Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted October 26, 2011 Share Posted October 26, 2011 It is not the AL-3 network. I had this same thing happen to a pair of AL equipped cabs. It's the K-55M driver. It is certainly the black cap on the back of the driver that makes the most racket at war volume. It's not unheard of. Any disbonded area is going to leak and / or vibrate. While you have the driver removed, change the o-ring between the horn and the driver too. See:http://forums.klipsch.com/forums/p/129225/1318307.aspx also: http://community.klipsch.com/forums/p/83610/837975.aspx and: http://forums.klipsch.com/forums/p/72281/710282.aspx#710282 and: http://forums.klipsch.com/forums/p/129225/1318307.aspx 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 26, 2011 Author Share Posted October 26, 2011 I replaced the rubber washer on every squaker when I did all the AA rebuilds. It is only a few months old. The back where the black plastic cap is has been sealed airtight. As for the AA or the AL-3 network preference, I did prefer the AL-3. It was crisper, and it was easier to hear lyrics with them. They have somehow degraded or something has changed. What should the resistence of the tweeters be? Maybe that is the problem. Also, does anybody have an AL-3 wiring diagram. Are there any reverse polarities? Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 26, 2011 Author Share Posted October 26, 2011 It was a slightly out of round voice coil. I took the speakers apart, and ran my finger and thumb around the coil, and felt a slight irregularity. I manipulated the variance out of the coil as well as I could reassembled, and the noise went away. The other speaker is making the noise to a lesser degree, but at least now I know what is wrong. I don't know what caused the warpage. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted October 26, 2011 Share Posted October 26, 2011 Pictures?? [] Quote Link to comment Share on other sites More sharing options...
djk Posted October 26, 2011 Share Posted October 26, 2011 " It was crisper, and it was easier to hear lyrics with them" Try bridging a single 1µF cap across both of the 2µF caps in the AA network, this will give it the same response as the elliptical filters (AL, AK types). Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 26, 2011 Author Share Posted October 26, 2011 No pics. I kinda fixed it as I found the imperfection. I didn't even think it would be fixed when I stuck it back together. It was such a slight imperfection, I couldn't see it with the naked eye. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 26, 2011 Author Share Posted October 26, 2011 " It was crisper, and it was easier to hear lyrics with them" Try bridging a single 1µF cap across both of the 2µF caps in the AA network, this will give it the same response as the elliptical filters (AL, AK types). Could you give a little diagram of that? Is that a bypass cap? Quote Link to comment Share on other sites More sharing options...
djk Posted October 27, 2011 Share Posted October 27, 2011 The cap goes from terminal #5 of the T2A to the + on the tweeter. "Is that a bypass cap?" No, it changes the transfer function to elliptical, similar in function to the AL, AK types. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 28, 2011 Author Share Posted October 28, 2011 I see what you mean now. Thank you! Quote Link to comment Share on other sites More sharing options...
mustang guy Posted December 15, 2011 Author Share Posted December 15, 2011 " It was crisper, and it was easier to hear lyrics with them" Try bridging a single 1µF cap across both of the 2µF caps in the AA network, this will give it the same response as the elliptical filters (AL, AK types). I finally got around to trying this. I used a sonicap. IMO, this did not create the desired effect. It was nothing like the AL-3 crossover. It sounded more like a hissy version of the AA. Certain guitar solos sounded much cleaner, but voices suffered. I played Muddy Waters, Kid Rock and Elton John, all on mono. What it did to the voices was kind of make the inhale breath sound like a hiss instead of an inhale. I noticed this on both Kid Rock and Elton. Elton records are very good tests of voice, as you cannot understand the lyrics if the speakers aren't reproducing well. Conclusion, if I wanted to listen to classical guitar, the bridge might be of interest. I recomend against this mod. Thank you for the tip anyway. [] It was a fun experiment! Quote Link to comment Share on other sites More sharing options...
djk Posted December 16, 2011 Share Posted December 16, 2011 It's good that you were able to try it, and didn't waste too much time or money. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted December 16, 2011 Author Share Posted December 16, 2011 It's good that you were able to try it, and didn't waste too much time or money. Was a cheap experiment. I will hang on to the 1.0 sonicaps (I bought 2). They might come in handy for other experiments later. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted August 24, 2012 Share Posted August 24, 2012 I was playing some synth music on my system that was distilled from pink noise. Then I heard it. Grit in the midrange. When I got up closer to the speakers, I could hear a buzzing sound coming from the rear of the squawkers. A touch of the hand to the black cap piece, and the buzzing would change pitch or stop all together. Since then, for about the last 4 weeks, my midrange performance has been noticeably harsh. A call to Bob for driver / horn gaskets and time to pull the drivers from the La Scala. Here's some pics and notes for anyone else that would like to attempt the repair. I took one driver completely apart to show how the K55-M is assembled. However, it is not necessary to take apart the entire compression driver to repair a leaky air chamber. The air chamber is glued in two areas using two different adhesives. -Around the outter lip using a hard glue that's brittle (even on my 1990 speakers) and subsequently leaks -Around the inner circumference of the pole piece using a incredibly tenacious shellac that looks suspiciously like Indian Head™ A light tapping with a finger around the outer lip revealed my air chamber glue had finally let go in a few places. I could hear a click where the plastic was de-bonded. Directions: Inserting a razor blade and working it around the edge worked very well at cutting through the remaining glue. Masking off the cap (air chamber), I left the blade in there to induce a very small gap that would allow the Loctite 380 to wick into the joint. I would apply the glue for about 1.5 inch, scoot the blade around, twist the blade slightly to let the adhesive bead fold under the lip of the plastic, then apply another 1.5 inch of bead. I continued this process all the way around the outter lip, then placed the driver on an inert surface (Loctite 380 has strong fumes) and placed a weight on top until everything cured. Leak solved! [Y] BTY - One of my driver / horn gaskets was hardened beyond serviceable condition. The other, was not far from the same. [:S] Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted August 24, 2012 Share Posted August 24, 2012 The air chamber removed. Note the shellac around the pole piece insert and the felt wadding that damps out the diaphragm back wave. It took about 10 minutes, a putty knife, and a firm but careful prying to remove this from the driver. That shellac is very tough stuff and definitely not the cause of my buzzing problem. *edit* - uploaded a picture with better exposure Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted August 24, 2012 Share Posted August 24, 2012 Loctite 380. Expensive and very irritating to the skin, lungs, and eyes. Especially when applied to the ABS plastic air chamber. Bob Crites suggested giving it go...and it appears to work exceptionally well for this application. [Y] Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted August 24, 2012 Share Posted August 24, 2012 A close up of the underside of the pole piece. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted August 24, 2012 Share Posted August 24, 2012 Lightly scraping with a razor blade fully removed the hardened glue from the outer lip of the cap. Quote Link to comment Share on other sites More sharing options...
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