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Heritage_Head

kappa 15c question

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So I’m going to try these in my la scalas. Two main questions....

 

1.are these the ones I should order https://www.eminence.com/pdf/Kappa_15C.pdf ?

 

2. I’ve read on some replacement woofs for the la scala that a spacer of some kind?....Can’t remember if these were part of that conversation. If so please explain what I’m looking at doing.

 

I know there’s threads on these but got lazy looking ☺️

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42 minutes ago, Heritage_Head said:

So I’m going to try these in my la scalas. Two main questions....

 

1.are these the ones I should order https://www.eminence.com/pdf/Kappa_15C.pdf ?

 

2. I’ve read on some replacement woofs for the la scala that a spacer of some kind?....Can’t remember if these were part of that conversation. If so please explain what I’m looking at doing.

 

I know there’s threads on these but got lazy looking ☺️

Yes, those are the correct woofers often recommended here. Jim and Claude have been very convincing in promoting the virtues of this driver.

I have used it and have to agree. They don't dig any deeper, but are very effortless and the upper bass is excellent. They hand off well to to k400 mid in the LS a Khorn.

Some contend that the woofer could slap the motorboard when rear mounted and playing through the baffle of the folded horns. I have never experienced it even though I have driven mine fairly hard. The suggestion is to cut a thin (1/4") gasket for the perimeter of the woofer where it attaches, to have it stand off a little further. It should be a solid piece with no air leaks. It is probably a good idea to do it just in case. I'm sure more will chime in. 

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4 minutes ago, MookieStl said:

Yes, those are the correct woofers often recommended here. Jim and Claude have been very convincing in promoting the virtues of this driver.

I have used it and have to agree. They don't dig any deeper, but are very effortless and the upper bass is excellent. They hand off well to to k400 mid in the LS a Khorn.

Some contend that the woofer could slap the motorboard when rear mounted and playing through the baffle of the folded horns. I have never experienced it even though I have driven mine fairly hard. The suggestion is to cut a thin (1/4") gasket for the perimeter of the woofer where it attaches, to have it stand off a little further. It should be a solid piece with no air leaks. It is probably a good idea to do it just in case. I'm sure more will chime in. 

Thanks for the info....

 

Yea Claude talked me into it. I’m sure he will chime in as well. Is parts express the only known place to buy new? Anyone know....

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Yes, that's the one.  Highly recommended.  I have yet to have to install any extra gasket, but every situation is different.  I think you will enjoy the new woofer. Give it just a little time to break in, and it will surprise you with it's excellent speed and tone.

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17 minutes ago, jimjimbo said:

Yes, that's the one.  Highly recommended.  I have yet to have to install any extra gasket, but every situation is different.  I think you will enjoy the new woofer. Give it just a little time to break in, and it will surprise you with it's excellent speed and tone.

Claude seemed confident the 15kappa c was la scalas best upgrade behind fresh caps of course. ( comparing to other low budget upgrades). 

 

You agree?

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:facepalm:

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3 hours ago, Heritage_Head said:

So I’m going to try these in my la scalas. Two main questions....

 

1.are these the ones I should order https://www.eminence.com/pdf/Kappa_15C.pdf ?

 

2. I’ve read on some replacement woofs for the la scala that a spacer of some kind?....Can’t remember if these were part of that conversation. If so please explain what I’m looking at doing.

 

I know there’s threads on these but got lazy looking ☺️

Yes, I"m one of the early originators of this recommendation. E pluribus Unum...................NO spacer required because the Xmax is small in a horn.

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I actually don't think the spacers are needed either as it has never been an issue with mine. I even made a few sets of rings for another member for his and didn't cut any for myself. 

I have been corrected before for stating that they aren't needed, so I just thought I'd mention it.

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Simple enough to measure if it clears or not. Surround to gasket surface.

 

 

 

 

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The issue with the Kappa 15C is the “pool noodle foam” gasket. It really does need to be more rigid.

 

The tighter you bolt it down, the more the gasket compresses. I imagine it would loosen up and create other issues if not tightened enough. Bit of a balancing act.

 

In my case I was able to crank it down hard enough to make one of my LS bins buzz at spirited levels. 

 

The designers of the Peavey FH1 bass bin saw fit to router out the motorboard where the woofer is mounted to eliminate this issue entirely. See picture below...

 

Make no mistake about it though, the difference between the venerable K-33 and the Kappa 15C is day and night. I prefer it over the K-43 in both the LS and FH1 bass bins too. 

 

2DFEC7D7-3725-4866-9BC8-C34AFB8BD2C2.jpeg

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If cone travel was so minimal in the design Klipsch would not bother using a thicker gasket, its there for a reason.

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Why is the 4ohm recommended over the 8ohm?

 

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From what I have come to understand from these forums, 4 ohm woofers can produce 3db more bass from a given wattage over an 8 ohm woofer in the same application. Ohm’s law and all that...

 

The crossover for a 4 ohm woofer is also designed for that impedance.

 

Changing impedance of drivers in a given crossover dramatically changes the crossover frequency. This affects other factors engineered into the design. I’m thinking polar responses for starters, 2nd and 3rd order harmonics,... but haven’t fully come to understand those, yet...

 

 

 

 

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The 4 ohm woofer in a La Scala/Khorn, due to the narrow slot and horn, raises the effective impedance of the woofer as seen by the crossover/amp.

 

I don't the how much this happens with something like the MWM horn as it doesn't have the 3x13 slot.

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16 minutes ago, geoff. said:

From what I have come to understand from these forums, 4 ohm woofers can produce 3db more bass from a given wattage over an 8 ohm woofer in the same application. Ohm’s law and all that...

 

In my custom pro-"CornScala's" I tried both the 4 ohm k-48 from a Chorus and the 8 ohm k-45 from a pro sub and honestly could not detect any audible difference between the two and both seemed to have the same level of output and I listened / tested by ear for quite awhile with test tones and lots of music I've familiar with ultimately I stuck with the 8 ohm k-45 because I had a brand new pair as compared to 20+ year old used k-48's. Just sharing my personal experience as I thought there would be a big difference in output going by the numbers but it just wasn't there. 

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14 minutes ago, Marvel said:

The 4 ohm woofer in a La Scala/Khorn, due to the narrow slot and horn, raises the effective impedance of the woofer as seen by the crossover/amp.

 

I don't the how much this happens with something like the MWM horn as it doesn't have the 3x13 slot.

 

 

This brings up a whole other tangential question, don’t mean to hijack but I can’t be the only one asking:

 

Is a bigger slot better than a smaller slot?

 

...get your mind out of the gutter... 

 

For instance, is high end/low end response better/worse with one versus the other?

 

One of the first things that struck me when I opened up the FH1 bins was the larger slot compared to the LS bins.

 

 

 

 

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It is not that simple.

 

What you are referring to is the "throat size". It will affect the efficiency and the bandwidth. This in turn can impact distortion and also tilt the spectral output in one direction or the other. I would suggest using one of the modeling programs (there are a number of them over at DIYaudio) and play/adjust some of the parameters to get a sense of it. 

 

Good Luck,

-Tom

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