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Buzzing, Ringing Mid-Driver on LaScalla


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Awhile back I posted a question about some problems I was having with my LaScallas, but the answer apparently applied to an older driver. Now that I've looked at the problem in more detail I'll ask a similar question to my original with hopes that I've given a better description this time.

One of my skwaker drivers started to make a buzzy sound awhile back. You can actually hear it out of the back, more than the front, but sometimes I can hear it all the way back at my listening position (I listen at a reasonable volume for jazz and classical) over the music. Typically, pure piano recordings are the worst offenders, producing the loudest and longest buzzes. I've moved the offending driver from cabinet to cabinet, and it follows the driver, thus eliminating the cabinet or the x-over. Other instruments don't seem to induce this problem (other than the occasional vocal). I've put rope calk on the back, pulled off the aluminum Klipsch disk with no avail. I called Klipsh and they said they hadn't heard of this problem.

One of the earlier replies described a process to disassemble the driver and pull felt hairs out of the throat. I followed the instructions, but the description was so different than what I had that I can only assume he had an earlier model (mine are from 86).

Can anyone tell me:

1) why does Klipsh use felt in the mid driver?

2) Can anyone confirm having this problem with an 1986 vintage LaScalla, and what his or her solution was?

3) Are there any other drivers out there better suited to the LaScalla that I can buy that don't have this problem?

4) When I take my driver apart, the diaphragm stays attached to the front half (that threads into the horn). It is stuck on fairly well. Is this a glue, or some kind of a cold "weld" from years of compression. In otherwords, how do I gently remove it for inspection purposes? I've seen no wear on the side I can see, so I don't think that it's "blown" or missalligned.

5) When I look at the inside of the back half, there is a little black plastic plug with a few small holes in it. What does this do? I see no felt hairs or anything of the sort on the back half

Recently, the other driver started making the same noise under the same circumstances, which has upped the pressure. I don't want to pay the $170.00 each for a new driver if mine really isn't "broken". I've looked at other drivers, but most have a titanium driver, as opposed to the klipsh phenolic. I assume that they would sound too bright. Is there a difference between a compression driver for PA and one for Hi-Fi?

I build most of my own hi-fi gear, so I'll try anything. I drive them with low-power tube amps (not to the point of clipping the output stage) so I'm confident they haven't been blown. I also have the wicker grill cloth across the front of the Mid- and Hi-, so I don't think any debris can get in that way.


James J.

Silver Spring, MD

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Is the driver a K-55-M?

If so, Place your hand on the black plastic part on the back of the driver. If this stops the sound, then you may be able to fix the driver.

Look for the glue joint around the outside edge of that black piece. If you find that it has come loose, take a razor knife and cut the glue all the way around the black piece. Once free, lift it up just enough to put some epoxy back under the edge. Then put the piece back in its place and weight it down until the glue dries.

This should stop the sound.

If not, you may need to replace the diaphragm or whole driver.

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  • 3 weeks later...

Hey everybody (esp. HEYU),

I followed HEYU's instructions and put a new epoxy seal between the black plastic cover on the back and the metal magnet structure. Sure enough, it stopped the problem dead. I'm still surprised that Klipsh maintains no knowledge of this problem, unless HEYU and I are the only two people who have ever experienced the problem. Considering the size of the glue lots they must buy, I'd imagine there would be consitency between drivers made from the same glue lot, and therefore more failures, especialy considering the relatively quiet levels I listen to (waaaaay under 60 Watts).

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