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Blew my La Scala II tweeters - how big of a deal?


JFHSQT

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9 minutes ago, Thaddeus Smith said:

Blown tweeters in primary speakers. Blown woofer in backup pair.. Maybe cool your jets on the volume knob a bit?

 

Two very different situations that shan't be repeated again. The tweets were because I was booting up my Mac Mini after moving my Luxman L-509X and not realizing the volume knob had brushed against my chest and been turned up to 12... immediately after turning on sent a burst of digital noise at over 100 dB... the tweeters never had a chance. The JBLs were the stupid result of trying to volume match a 90 dB sensitivity speaker with a 104 dB sensitive La Scala II in the other channel. 

90% of the time I'm listening at night at around 85 dB tops... But I have learned some hard lessons over the past few weeks :)

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On ‎12‎/‎7‎/‎2018 at 7:44 PM, BEC said:

Lots of CT120s have been installed in the Lascala II.  Problem is that at some point Klipsch stopped squaring the corners of the cutout for the tweeter.  The K-77D does not need them squared but the CT120 does.  A few guys have fixed that in a couple of minutes with a file, but not a job for everyone.  I do not know exactly when that change to the rounded corners happened but at least the first several years of production, there was not that problem.

 

On another subject, lots of tweeters get blown in the Lascala II.  I sell lots of diaphragms and K-77D tweeters to fix those.  Problem is that, in my opinion the polyswitch is just not quick enough to operate and prevent damage when something really quick happens.  The polyswitch has to heat up so is good for protection from high continuous power, but sudden high power or a quick transient just takes the 2 watt rated tweeter right out.  Even in the olden days when the polyswitch was used in the old AL networks, when that network was used in the Pro version Lascalas, they put in zener diodes.  Those will handle the quick transients. 


Bob Crites

Thnx for the info . I was concerned when I heard the CT120's needed a cabinet mod, but looking at how small a round that is there that really would be a few mins with a file to fix. My main concern was the mod would mean I couldn't go back to the original tweeters but this isn't the case.

Today my 85 yr old mother asked me what she could get me for x-mass....now I'm thinking a pair of CT120's 😁

Perhaps you can sent me a pm with a price  :)

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On ‎12‎/‎7‎/‎2018 at 10:56 PM, JFHSQT said:

 

Two very different situations that shan't be repeated again. The tweets were because I was booting up my Mac Mini after moving my Luxman L-509X and not realizing the volume knob had brushed against my chest and been turned up to 12... immediately after turning on sent a burst of digital noise at over 100 dB... the tweeters never had a chance. The JBLs were the stupid result of trying to volume match a 90 dB sensitivity speaker with a 104 dB sensitive La Scala II in the other channel. 

90% of the time I'm listening at night at around 85 dB tops... But I have learned some hard lessons over the past few weeks :)

You still made me feel better, I only blew one LSII tweeter 😃

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  • 1 month later...
On 11/26/2018 at 8:39 AM, RadBlue said:

Hi, I'm in the same boat as you, I blew my right tweeter last week. ATM I'm waiting for my replacement to arrive.

I can walk ya threw the disassembly of the top-hat.

First remove the grill , I used a butter knife slipped between the grill and faceplate frame and gently pried it out. Theres 4 lil magnets holding it.

Once the grill is off you can see 4 screwheads (what the lil magnets hold onto) remove these and the faceplate comes off. Now you can see all the motor-board screws, leave them for now.

Next flip the box face down so you can see the back screws, remove all the screws along the edges. Gently lay the box flat like it would be on the bass-bin.

The crossover is mounted on the backplate so gently pry it off and lie it down(crossover up) and then pull the bass wires up threw the  bottom hole.

Disconnect the mid wires at the driver and then the tweeter wires at the  crossover circuit board. You can now move the backplate off to the side.

next flip the box face up to get at the motor-board crews and remove them. Then flip box face down and lift the box off the motor-board.

You now have easy access  to the tweeter screws.

  These directions helped a lot. Thanks!!

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7 minutes ago, Schu said:

I've had several sets of La Scala II's... with and without tweeter protection... I've never blown a driver.

You also said you listen at 75 DB and have neighbors in close proximity if memory serves correctly.   These guys stated that they got hammered and had a cranked session.   I never blew any drivers in any klipsch heritage, vintage or current regardless of those type of sessions.   Has to be underpowering, boosted eq or..... Perhaps using too small a speaker for too large a space.   

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22 hours ago, Westcoastdrums said:

You also said you listen at 75 DB and have neighbors in close proximity if memory serves correctly.   These guys stated that they got hammered and had a cranked session.   I never blew any drivers in any klipsch heritage, vintage or current regardless of those type of sessions.   Has to be underpowering, boosted eq or..... Perhaps using too small a speaker for too large a space.   

 

I don't know if you're referring to my original post... definitely not a case of being hammered and having a cranked session - stated a couple of times it was a burst of digital noise from having the wrong input running through my integrated. However in that time I have definitely had cranked sessions, and the louder they get the better they sound. 

 

I was out of town for the last week and came home Friday morning, wife took the kids to school then went to the gym. While she was gone, I put on Judas Priest's Sad Wings of Destiny, through the Luxman 509X integrated and tube preamp and into the La Scala IIs, it had to be at least 105 dB. I get a text from my wife, she's in the driveway. It says "I don't even want to come in." Apparently the windows on her Lexus were rattling... and she got out in the driveway and across the street, a neighbor was staring at the house. "Sorry, my husband is listening to music," she said to the guy. 

 

Tweeters held up nicely.

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6 minutes ago, JFHSQT said:

 

I don't know if you're referring to my original post... definitely not a case of being hammered and having a cranked session 

Perhaps it wasn't you that said that. Another fella here.   I forget the story, maybe friends were over?   Doesn't matter. Seems than more than a few pairs of these tweeters have gone out.    Maybe it's just because they are a newer tweeter on an expensive speaker and therefore there have been a few threads on the matter.  

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On 12/10/2018 at 3:58 PM, RadBlue said:

Thnx for the info . I was concerned when I heard the CT120's needed a cabinet mod, but looking at how small a round that is there that really would be a few mins with a file to fix. My main concern was the mod would mean I couldn't go back to the original tweeters but this isn't the case.

Today my 85 yr old mother asked me what she could get me for x-mass....now I'm thinking a pair of CT120's 😁

Perhaps you can sent me a pm with a price  :)

 

I ran into the same issue when I got CT125s for my original La Scalas.  The new tweeters were larger in diameter than the K-77s, so the lids of the speakers were just a little too low.  Since the 1974 LSes have removable lids, it was easy to remove the lids, flip them over, and chisel a 1/4" deep relief that was only about 3" across and 1-1/2" from front to back.  The lids are 3/4" thick, so there's still 1/2" of wood left.  No worries, and the closely matched CT125s were a big improvement over the 32-year-old K-77 tweeters that varied from each other in output by 2-3 dB.  The sound was also noticeably clearer.  I was completely pleased with the CT125s, and I still am.

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