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Droogne

La Scala bassbin Hornresp parameters

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Anyone who can help me with the Hornresp parameters to model the La Scala bassbin? 

 

Any help is appreciated!

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3 minutes ago, Droogne said:

Anyone who can help me with the Hornresp parameters to model the La Scala bassbin? 

 

Any help is appreciated!

 

 

You may find the answer in this thread 

https://community.klipsch.com/index.php?/topic/148054-quarter-pie-bass-horn-measured-fr-how2build-and-hornresp/&tab=comments#comment-1688771

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9 minutes ago, Droogne said:

Anyone who can help me with the Hornresp parameters to model the La Scala bassbin? 

 

Any help is appreciated!

Ha LaScala is not a bass bin it starts to roll off at about 140 Hz. and should be crossed over to a bass horn at 80 or 90 Hz. for best results at the bottom end and 350 - 400Hz. at most on the top end. It was not designed as a bass horn below 80 Hz. it acts just like a leaky box. This should not in any way be taken as an indictment of the LaScala it is simply telling the op what a LaScala was designed to do. At 60Hz. the LaScala has the same response as a Heresy but it will play a lot louder.

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I would not dismiss the La Scala so quickly. It does many things well (given the foot print and size...).

 

Please remember that HornResp is a model and not reality. It is very useful  for the builder to plot the inside path length and the outside path length. This disparity points to where the low pass roll off  will be (it is not the driver ....). I did this, painstakingly, for the Jubilee. It is very informative!!!

 

HornResp is a powerful tool, but there are some things that need to be highlighted: dispersion, path length differences, loading from the room (floor, walls etc). Keep these in mind when you do your modeling. 

 

Good luck,

-Tom

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Yes man... nice to hear from you...they be hoping you for

the situation... cool...

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15 hours ago, moray james said:

Ha LaScala is not a bass bin it starts to roll off at about 140 Hz. and should be crossed over to a bass horn at 80 or 90 Hz. for best results at the bottom end and 350 - 400Hz. at most on the top end. It was not designed as a bass horn below 80 Hz. it acts just like a leaky box. This should not in any way be taken as an indictment of the LaScala it is simply telling the op what a LaScala was designed to do. At 60Hz. the LaScala has the same response as a Heresy but it will play a lot louder.

I used the word bassbin, but yes maybe mid-bassbin is more applicable. I do realize it's roll of. I have had 8 of them, and measured them multiple times. Now I want to repurpose a few of them, and want to see what kind of woofers I'd need. Also having the hornresp parameters is a good way to evaluate the amount of hornloading (both cornerloaded as in free space) I will get.

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14 hours ago, PrestonTom said:

I would not dismiss the La Scala so quickly. It does many things well (given the foot print and size...).

 

Please remember that HornResp is a model and not reality. It is very useful  for the builder to plot the inside path length and the outside path length. This disparity points to where the low pass roll off  will be (it is not the driver ....). I did this, painstakingly, for the Jubilee. It is very informative!!!

 

HornResp is a powerful tool, but there are some things that need to be highlighted: dispersion, path length differences, loading from the room (floor, walls etc). Keep these in mind when you do your modeling. 

 

Good luck,

-Tom

I will not neglect them. It's more for driver simulation than for anything else so I'm good I think. 

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15 hours ago, moray james said:

Ha LaScala is not a bass bin it starts to roll off at about 140 Hz. and should be crossed over to a bass horn at 80 or 90 Hz. for best results at the bottom end and 350 - 400Hz. at most on the top end. It was not designed as a bass horn below 80 Hz. it acts just like a leaky box. This should not in any way be taken as an indictment of the LaScala it is simply telling the op what a LaScala was designed to do. At 60Hz. the LaScala has the same response as a Heresy but it will play a lot louder.

 

Below 100hz, it works/acts more like a DR. With the two cabs I have, I can hear, and for me it's satisfying, the B on a five string bass. It just happens to be the synergy with all the rest of the parts in my system.

 

Can't wait to hear when I get MWMs next week. Had to wait a few months to pick up, but the time is soon.

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15 hours ago, Edgar said:

Thanks man!

 

Here is the output of my LaScala loaded up with an Eminence Kappa 15A driver, simulated to hit it's Xmax (4mm) at 60hz, which is at ~20% RMS (17.5V, instead of the Em Kappa 15A 60V). 60hz is a cutoff I regulary use in home. In home I would apply a lot of EQ to flatten it to this 60hz, so output will be limited even more in the higher ranges. I used 2pi for better comparison with the following simulations. 

image.png.436312133313d1472659d26c9b1189b6.png

 

Here is the same driver mounted in a sealed cabin with same volume as the LaScala sealed compartment, also Xmax limited at 60hz (19V input):

image.png.3455aec490f7931e7a67eacc770435b0.png

 

There looks to be around 3-4dB hornloading in the 60-100hz range, and 6dB in the 100-500hz range.

 

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Driver simulation will be for a 80-150hz range. Yes this a very narrow range, but it's still in the LaScalas hornloaded range and I already have them. I might use completely different cabins, but the simulations will tell me if I actually have to.

 

Em Kappa 15A: Xmax limited output at 80hz (0dB), 2pi. 

 

image.png.1707a44a8864b536d77accb1a2635dd8.png

Reason for modelling can be best shown with a displacement graph showing the Em Kappa 15A at 80hz:

image.png.383ecd09f546f9f0fd1147e70fa29620.png

It's clear displacement skyrockets around 120hz.. I actually need a -3dB or -6dB point around 80hz, which is easy with the natural roll of this setup, but I need more displacement to allow the driver to be used fully down to 80hz. 

 

At this Xmax limited 80hz point I would end up with a 125dB (-3dB) or 128dB (-6dB) lever from 110hz and 130 respectively.

 

 

And yes, 80-150hz is a narrow range, but it does mean 2 things:

 

1. using more of the hornloading the LaScala provides

2. Being able to stack the LaScalas when lowering the 150hz to 143hz. 1/4th WL of 143hz is 60cm, which is the exact distance between the acoustic center of a pair of stacked LaScalas. Acoustic coupling will increase the output with an extra 3dB on top of the +3dB from doubling the amount of bins. So +6dB total extra output.

 

=> a stacked LaScala pair loaded with a Eminence Kappa 15A would result in a 128dB level at 80hz, and 131dB at 110hz (which will be the level where I will flatten the response to actually be within 3dB of 80hz).

 

For my project I needed 135dB at 80hz, so it's pretty far away from this. It looks like the displacement will be the deciding factor in the output at 80hz. Using a -6dB crossover point might also help. If the Em Kappa 15A would be able to be used at its full RMS power the output would be 128dB at 80hz! So 134dB for a pair, which is almost exactly where I need to end up.

 


 

 

 

image.png

image.png

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EDIT:

 

I forgot to include the larger horn mouth when coupling the LaScalas. Modelling this by going from 2pi to 1pi allows for more hornloading into the lower ranges which significantly flattens the response at 80hz. Using the drivers in parallel and the appropriate RMS to reach the Xmax limited output at 80hz I get this response:

image.png.13aaefe5cf3fa2713c05567d2690bc92.png

This looks already way better! Almost the 135dB I require. Might model some more woofers to achieve even better responses (with lower displacement at 80hz for better sound quality).

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