K-77M buzzing...fixed!

[Quiet_Hollow]

The gaskets inside my K77 tweeters loosened up last week while watching Terminator 2 at reference level. The system got real bright sounding afterwards.

Similar to what I experienced when the K55 squawkers took a nose dive , but response had tilted up instead of down this time. I was actually turning the system down a good bit to compensate. [:S]

Triangles and whistles for example had become overly pronounced.

Couldn't quite sort it out until today when listening to Bjork & Vince Mendoza's collaboration "Overture" from the Selmasongs soundtrack at full-tilt.

The buzzing coming from the back of the cabinets was loud enough to be heard clear across the living room. Yeow![8o|]

Checked the 55's and the 401 horns. Nothing. Then I reached way in and pressed my fingers up against the back of the 77's. Bingo! [:^)]

The four screws that hold the magnet / horn assembly together required tightening. A firm pass with the screw driver and the fasteners snapped free from their threadlock, and took another healthy 1/4 of a turn or so before cinching down tight again.

Checked with the same song and listening level.

Fixed! ..and the speakers sound wonderful again! [8][Y]

My speakers are only 23 years old and I've had to service the compression drivers, tighten up the tweeters, and re-tape the gasket on the bottom panels...all with noticeable sonic improvement. It's got me thinking just how many older Heritage cabinets are out there that don't sound like they should simply from the abscence of this specific maintenance? [*-)]

*edit* Fixed broken link

Edited November 8, 2013 by Quiet_Hollow

[mustang guy]

I had a K-55 that was making a buzzing sound and it took me forever to figure out what it was. As it turns out, it was the snare drum that was sitting about 10 ft away. At certain frequencies it would resonate. Oddly, you couldn't tell it was coming from the drum. []

[Quiet_Hollow]

At certain frequencies it would resonate. Oddly, you couldn't tell it was coming from the drum.

I've got that same problem with the Tuba HT and the walls of the room. []

[CECAA850]

Seems like a dot of blue Locktite would be in order when working on speaker and crossover hardware from what I've read. I'm surprised no one's recomended it before, at least not that I've seen. The blue will hold but come apart if you need to in the future. Be sure you don't use red.

[juniper8]

When I worked on my raw birch cornwalls, the wood was so old and dry some of the screws in places came out with a very gentle twist. I took all the speakers out, the crossovers, and back panels, and did the toothpick and glue trick but added slivers of hardwood, worked wonders.

[Quiet_Hollow]

Interesting thing was that magnet screws had not come loose. They were still tightly held by the factory thread-locking compound.

It's just that the paper gaskets sandwiched inside had finally shrunken enough to let the diaphragm shift around inside and leak. Everything inside needed(s) to be squeezed tightly together in order to function correctly.

It might sound counter intuitive, but I actually had to break the screws free (from the thread-lock), in order to tighten them down further. Rotating them beyond where they were previously held tight.[:S]

I'm also going to add, the sonic improvement is not subtle. For simply twisting a few screws a 1/4 turn, it sounds like I have an entirely new set of tweeters. [:|]

[Quiet_Hollow]

Seems like a dot of blue Locktite would be in
order when working on speaker and crossover hardware from what I've
read.

[Y] I'm definitely going to do this, but I've got some 222 (purple) on hand instead. I gather that will be enough to re-lock them.

To my ears it was pretty noticeable that something was wrong, I just couldn't tell if it was the speakers, or the amp, until the thing started buzzing from the back side like a bumble-bee on the really loud stuff.

[CECAA850]

Makes perfect sense. Like a cork valve cover gasket.

[BEC]

Interesting thing was that magnet screws had not come loose. They were still tightly held by the factory thread-locking compound.

It's just that the paper gaskets sandwiched inside had finally shrunken enough to let the diaphragm shift around inside and leak. Everything inside needed(s) to be squeezed tightly together in order to function correctly.

It might sound counter intuitive, but I actually had to break the screws free (from the thread-lock), in order to tighten them down further. Rotating them beyond where they were previously held tight.

I'm also going to add, the sonic improvement is not subtle. For simply twisting a few screws a 1/4 turn, it sounds like I have an entirely new set of tweeters.

That is a relatively new replacement diaphragm in your picture and not what would have been in a 1990 Lascala originally. The diaphragm you are showing is the replacement diaphragm for the K-77F used by Klipsch now. The OEM made by EV would have looked like the picture attached. Notice the copper-beryllium flat leads used on the OEM diaphragm.

Bob Crites

[Quiet_Hollow]

That alloy on the OEM piece would definitely make a nice heat sink for the voice coil.[Y]

The photos I grabbed were from another vendor, and only to detail the location of the gaskets.

I didn't open mine. Caught it before anything got out of hand.

[OO1]

thank you Mr Crites for showing the pictures of the 2 - -

-I had 3 of these OEM diaphragms made by EV - with the copper-beryllium flat leads - I recently installed them - no comparison at all with the k77F or aftermarket diaphragms - they have this consistent tone reproduction of sound in the high frequencies - even at low power - this type of copper -alloy is also very highly conductive -

-the aftermarket and K77F tweeters on the other hand are less clear in sound reproduction - one needs to raise the power to hear the detail of the melodies - hence , as they are always pushed to their limits - they will fail prematurely -