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1980 Klipschorn, beginner help.


BFaught

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I recently acquired a pair of 1980 KCBR Khorns. After some reading I am planning on leaving them totally original and having the crossovers rebuilt to factory. They make a very faint hiss when powered and no source playing, my Latino ST-120 is dead silent on its own so am I correct to assume the crossover caps are going bad? 

 

I am planning on using pipe foam to seal the corners against the wall to improve the bass. Only problem is both of these have a clover shaped cut out on the rear panel I have not seen on any other pics and I can only imagine that the hole is allowing the bass pressure to pass through and is killing the sound. I have seen other Khorns with what looks like black plastic over the backs. Does anyone have any experience with said clover shaped hole or is this likely something the first owner cut in himself? I can take a few pics if that would help.

 

Thanks in advance for the help.

 

-Ben

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9 minutes ago, BFaught said:

They make a very faint hiss when powered and no source playing, my Latino ST-120 is dead silent on its own so am I correct to assume the crossover caps are going bad? 

 

Welcome Ben-

 

What do you mean “dead silent on its own” when describing your amp?  Do you mean it is turned on but not connected to speakers? In my experience, K-77/T-35 tweeters have some degree of low level his under the conditions you describe, especially with tube amps.  My class D amps are the first amps that produce no discernible hiss from K-77s under the conditions you describe.  Every tube amp I’ve tried had a faint hiss.  I would not be concerned.

 

Irrespective of the hiss issue, the calendar is signaling that “the crossover caps are going bad.”  I suggest contacting Bob Crites, @BEC.  Google “Crites speakers.”  Bob can offer crossover solutions to fit your budget and/or DIY skill or enthusiasm.

 

 

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That makes sense about the heritage tweeters, I was using slightly newer studio monitors and no noise at all with my ear against the speaker. This is my first pair of heritages so it's all pretty new.

 

The strange thing is the clover hole is cut in both of them but you can see from the marks around it something was rubbing there. DizRotus is probably correct about the obstruction. Any insite as to what I should use to patch/cover them?

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20 minutes ago, BFaught said:

DizRotus is probably correct about the obstruction. Any insight as to what I should use to patch/cover them?

Welcome to the Klipsch forum!  With the Khorns, you are starting at the top!

 

There are people here with more woodworking experience than me, so listen to them when they weigh in.  My suggestion would be to cut a perfect square out of that cloverleaf, then make a perfect square out of plywood to fit inside your cutout, and glue it in.

 

Use a polyurethane glue like Gorilla Glue which expands to seal the seams.  You can get it at Lowes or Home Depot.

 

original_gorilla_glue_white_bg_v2.jpg


 

Quote

 

The product that started it all. Original Gorilla Glue built a name for itself with its incredible, industrial holding power and versatility. The water activated polyurethane formula expands into materials to form an incredibly strong bond to virtually anything making Gorilla Glue your solution for almost any project or repair.

https://www.gorillatough.com/product/original-gorilla-glue/

 

 

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I agree with a Dave, @wvu80, but not as to a “perfect square.”  Sealing the  corners of a perfect square would be more difficult than a circle.   In a perfect world,  cutting  perfect circles in the tailboards and filling them with other perfect circles would be ideal.  

 

In the real world, I’d cut circles larger than the holes from 1/4” or 1/2” plywood, or even, brace yourself, MDF. :o  Overlapping the holes from the insides or outsides would, IMO, have a negligible impact on the bass horns’ performance.  Please let us know what you do.

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What about two thin pieces of overlay 1/4-1/8" thickness, cut to rectangles to fit over the entire inside of the back panel toward the sub compartment on both top and bottom. I would like to avoid cutting more away from the original frame if possible. 

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You have a pair of the rare KHorns that were modified to exact specifications that the owner wanted for his bass output. It was a lot of trial / error / re-sizing / pattern changes (see pencil marks).

I have the plug that fits in and could be persuaded to sell.
 

Cloverleaf.jpg

 

Or you could just stuff it with foam for a test.

Welcome!

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4 minutes ago, USNRET said:

You have a pair of the rare KHorns that were modified to exact specifications that the owner wanted for his bass output. It was a lot of trial / error / re-sizing / pattern changes (see pencil marks).

I have the plug that fits in and could be persuaded to sell.
 

Cloverleaf.jpg

 

Or you could just stuff it with foam for a test.

Welcome!

Mike is on an early roll this morning.....

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5 minutes ago, BFaught said:

What about two thin pieces of overlay 1/4-1/8" thickness, cut to rectangles to fit over the entire inside of the back panel

I would be concerned with resonance, having the thin wood vibrate.

 

@jason str ^^^ is a woodwork guy.  Listen to him, not me.  B)

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7 minutes ago, USNRET said:

You have a pair of the rare KHorns that were modified to exact specifications that the owner wanted for his bass output. It was a lot of trial / error / re-sizing / pattern changes (see pencil marks).

I have the plug that fits in and could be persuaded to sell.
 

Cloverleaf.jpg

 

Or you could just stuff it with foam for a test.

Welcome!

That clover plug looks to be slightly more detailed than the cut out on the back of my speaker. Maybe that's from a more modern edition when the clover plug cutting technology had improved some. Still what's your asking price for such a rare item?

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10 minutes ago, jason str said:

Just replace the panel. Remove, trace, cut and install.

 

Patching is ugly and undesirable for resale value.

Got it, I will just replace them. Thanks for the solid answer. I am going to rebuild the crossovers myself after just assembling the Latino amp kit I am pretty sure of my soldering skills. Would you guys recommend buying the kit from crites or can I comfortably source the caps myself if I can find the schematic?

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