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jwc

If Crossover at 400Hz, what LF cabinet is preferred: Jubilee or Khorn?

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The same plot for the KPT-Jubilee-535 (the 3-way Jubilee with the K-510 HF module on top):

 

1670534866_KPT-535-JubileeHorPolars.thumb.JPG.b1e49971c3bb74da323ee6ab9303df2d.JPG

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Well it is almost impossible to get more than a few degrees off axis in my room.

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Ten degrees?  Plus the effects of inconsistent early reflections vs. frequency in that band due to those narrow polars.

 

I find that the midbass and lower midrange presence/clarity is much higher using a loudspeaker with consistent and controlled polars throughout the 100-500 Hz region.   You should go listen to the Danley Synergies to hear what I'm talking about.  It isn't subtle.

 

Chris

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Well if I am reading you right then there are no Klipsch bifurcated horn woofer speaker systems that would meet those expectations.  But you have Jubs.  I can only imagine your pain from the beaming.

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No, there is one that doesn't have the issue: the La Scala bass bin--which is horn-loaded bass bin that doesn't have a truncated mouth.  A dual-mouth bass bin closure into one aperture is something that I believe draws many people to that particular bass bin design.

 

Chris

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On 5/30/2018 at 9:23 AM, jwc said:

It appears to me that the majority of the Jubilee owners here are XO their Jubes at 400Hz.  Why would you pick one LF over the other if you were to put the current K402 horn/B&C691 driver on top?  Regardless whether active or passive.  Assume Khorn had a Back built onto it like some have done on their own or like the modern production Khorn has.

 

 

I've been under the impression that the upper extension of the jubilee bass bin is what enables the 2-way design to work well.  Below is a graph of a K-horn (black) vs. Jubilee (red) with no crossover applied, that's just the natural response.  By the time you get to 700 hz that's a 15 db difference.  Getting the response to extend above 500 hz was one of the biggest driving forces in designing the jubilee cabinet in the first place, but yeah they used to have a higher crossover point.  

 

No automatic alt text available.

 

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The issue remains that the plot you posted is showing on-axis response only.  If you get 15+ degrees off-axis, the high frequency response above 210 Hz changes significantly (i.e., less SPL).  This encourages crossing at the lowest frequency that the K-402/2" compression driver can cover since its polar coverage is ~90 degrees by ~60 degrees at those frequencies (250-500 Hz). 

 

This is like having three bass bins in each room corner--one with very good polars and frequency response but with very narrow coverage horizontally, and two on either side of the center bin having poor frequency response above 210 Hz:

 

KPT-KHJ-LF (Jub Bass Bin) Directivity plot.jpg

 

KPT-KHJ-LF (Jub Bass Bin) Directivity plot - Vertical.jpg

 

The Khorn bass bin is reportedly worse in terms of its HF polar coverage lobing (from the JAES article by PWK and Roy) due to the increased spacing of the two horn mouths and their increased splay angle relative to the Jub bass bin.

 

Chris

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4 hours ago, MetropolisLakeOutfitters said:

I've been under the impression that the upper extension of the jubilee bass bin is what enables the 2-way design to work well.  Below is a graph of a K-horn (black) vs. Jubilee (red) with no crossover applied, that's just the natural response.  By the time you get to 700 hz that's a 15 db difference.  Getting the response to extend above 500 hz was one of the biggest driving forces in designing the jubilee cabinet in the first place, but yeah they used to have a higher crossover point.  

I would agree.  That was the impression I got when hearing of the Jubilee and why it was created.  PWK wanted a 2 way setup and wanted a Higher XO point of the LF.    

 

However, After starting this thread, I forgot about those distortion measurements.

 

I would be curious to see what "acoustical XO point" would be chosen if the K402 was placed on top of the Khorn.  Sounds to me...that the Khorn can work as two way.

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1 hour ago, Chris A said:

The Khorn bass bin is reportedly worse in terms of its HF polar coverage lobing (from the JAES article by PWK and Roy) due to the increased spacing of the two horn mouths and their increased splay angle relative to the Jub bass bin.

 

 

See my "thought experiment" post from 12/8/2007: https://community.klipsch.com/index.php?/topic/89015-jubilee-alternate-folding/&tab=comments#comment-965018

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Yes, your idea is another way to close the spacing between the two horn mouths...

 

Alternate Jubilee 3.png

 

or like was posted above to extend the horn mouth until the two-mouth closure is achieved (a solution that could be added to their Jub bass bins--adding a "nose")

Levanhorn.jpg

 

to look more like this...with the two horn mouths fully rejoined:

DSCN2714.JPG

 

If starting a horn-loaded bass bin design from scratch again today, I'm really not sure why one would use bifurcated bass bin horns now we're aware of the effects of off-axis polars on the sound of the mid-bass and midrange from these bass bin types.

 

Chris

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They are what there are.

 

To build a Corner horn at 24" depth to hit sub 40Hz notes is very difficult.  I've done it but never shown it here.   

 

So they are both bifurcated and that can be one of the many compromises.

 

This thread has reminded me of some things I forgot......since I'm not scratching down design ideas all the time.  My mind has been in other places for the last several years.

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12 minutes ago, jwc said:

To build a Corner horn at 24" depth to hit sub 40Hz notes is very difficult.

Yes.  That's a good frequency to cross over to a subwoofer, I've found.  But having some overlap with the sub is required--so it must go lower--like 30 Hz. 

 

The issue really isn't how low the bass bin horn bins go, but how high. 

 

For instance, if you take a K-402 and put small 6" woofers on off-axis ports about 2" (axially) from the throat of the horn, then you can run the K-402 down to 200 Hz...no sweat...and avoid the midbass/midrange polar problem altogether.  Those off-axis ports also load better at lower frequencies than if the small cone driver(s) are located at the throat (see Danley's paper on the subject, pg. 4).  It's a cheap way to split the problem into separate issues without significant compromise. 

 

It may be possible to set up a passive crossover for these extra two off-axis drivers, too, since they will be time-aligned as-is.

 

Chris

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Yes.  I see.

 

I'm not interested in re-exploring new designs with this thread.  I was needing a recap of Jube VS Khorn again.  In the past this generated nasty arguing.

 

I got the answers I needed.

 

Thanks all.

 

jc

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First let’s put some things into perspective and that is if the bifurcated mouth when used in the average listening room was so detrimental how has the KHorn survived for over 72 years..🙂

 

Don’t get me wrong though in that in theory a single mouth with coverage angles kept in mind would be a design goal if a worse compromise didn’t develop while trying to achieve that goal.

 

I believe it also is important to keep in mind that the comb filtering effects due to the bifurcated mouth is one of almost incalculable amounts that occurs when even a single source loudspeaker is placed in a listening room yet our ear/brain system has the ability to ignore as well as fill in the missing information or sound reproduction wouldn’t even be possible in the home.

 

jwc I wouldn’t have a problem using a K402 with the Khorn LF but I would also close in the back of the LF like the 60th version so that I could rotate the system to optimize the loudspeaker/room/listener integration.

 

miketn

 

 

 

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I’d love to see some 510 horns on top of my old khorns soon now that I have jubes in my living room. 

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the fifteen inch woofer in a Khorn starts to get into the soup starting at about 325 Hz and that is the very reason that the Jubilee was designed to have a wider available bandwidth so you could cross to a more domestic size mid horn. There are other horn designs which will get you where you are going like the University and one by Ernst Georg Beck called the California are two good examples.

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Perhaps it's a better idea to use LaScalas below K-402 and stick a Jubilee in a corner to cover below 60hz?

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I haven't had the fortune to hear Jubilees, but the La Scala IIs with 402s on top sound pretty good, plus I just upgraded mine to K691 drivers a couple of weeks ago, which improved the sound quality a bit more.

 

Using a Jubilee as a subwoofer doesn't sound like the best use of one, when there's a big selection of subs already on the market.

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