Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Klipsch Bass Horn Acoustic Analysis
Klipsch Bass Horn Acoustic Analysis
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 23rd January 2019, 02:51 AM   #1
jimmosher is offline jimmosher  United States
diyAudio Member
 
Join Date: Oct 2018
Default Klipsch Bass Horn Acoustic Analysis

Hi,

I did a search through the bass woofer design area of the site, and did not find a dedicated analysis of the K-horn. With that in mind, I tried to consider factors which could affect the acoustic performance of this corner horn.

My hope is that others who have more experience will contribute to this thread.

A Klipsch corner bass horn is analyzed for acoustic performance potential by:
  • Constructing the physical cabinet using software
  • Unfolding the acoustic sound path
  • Determining the rear cabinet trapped air volume
  • Determine the effect on acoustic performance

This shows a portion of the internal construction of the Klipschorn horn loudspeaker.
01.jpg

One quarter of the cabinet is shown in this view. This is an approximation of the average acoustic air propagation path.
02.jpg

The 3D model of the cabinet is broken into a 2D image so that the acoustic air propagation path can be determined mathematically.
03.jpg

The 2D path is then dimensioned for both area and acoustic length. Key measurement areas are identified with markers.
04.jpg

This shows the detail around the horn throat. Area dimensions are shown in green and path lengths in red.
05.jpg

Wherever possible, acoustic path lengths consider the “nominal” distance, not max or min. This is a top view of cabinet, where it folds toward the corner wall.
06.jpg

All the areas and acoustic lengths are tabulated here. The areas listed amount to ¼ of the total horn area (for sqin.) The area listed in sqcm is the total area.
07.jpg

Now the corner horn acoustic path can be unfolded with dimensions as shown below.
08.jpg

The drawing is then re-rendered without all the dimensions, which tend to obscure the drawing. One can clearly see the abrupt change in area near the horn throat. David McBean informed me that this is referred to a "rubber throat" by Klipsch.
09.jpg

The rear chamber trapped air volume is modeled based on numerous 2D dimensions around the speaker mounting plate.
10.jpg

Continued....

Last edited by jimmosher; 23rd January 2019 at 03:10 AM.
  Reply With Quote
Old 23rd January 2019, 03:04 AM   #2
jimmosher is offline jimmosher  United States
diyAudio Member
 
Join Date: Oct 2018
Default Klipsch Bass Horn Acoustic Analysis - cont.

Another view of the rear cavity volume.
11.jpg

Finally, a third view of the rear cavity volume. The trapped air volume is 4968 cubic inches. This volume does not consider the effect of the speaker frame and magnet assembly.
12.jpg

Modeling the K-horn with a K-33 driver as shown below. I am assuming low values for Fr and Tal as shown below. Note that David McBean helped verify the K-33 parameters. Thanks David.
13.jpg

Examining the horn schematic clearly shows the “step” in the horn throat. Apparently this was done by design, by Klipsch.
14.jpg

The low end frequency response starts at about 45 Hz and then starts to drop noticably above 300 Hz.
15.jpg

Jim.

Last edited by jimmosher; 23rd January 2019 at 03:32 AM.
  Reply With Quote
Old 23rd January 2019, 03:46 AM   #3
jimmosher is offline jimmosher  United States
diyAudio Member
 
Join Date: Oct 2018
Updated HR output screen shots, since I can no longer edit the previous post.

The rear chamber volume should have been 81.4 Liters, not 50 L as shown previously.

13.jpg14.jpg15.jpg

Jim.
  Reply With Quote
Old 23rd January 2019, 07:34 AM   #4
David McBean is offline David McBean  Australia
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by jimmosher View Post
One can clearly see the abrupt change in area near the horn throat. David McBean informed me that this is referred to a "rubber throat" by Klipsch.
Just to clarify - Paul Klipsch referred to the initial parabolic segment shown in red in the attachment, as a "rubber throat".

To quote PWK:

"The initial taper is such that the horn area doubles in a length of about 8 inches, corresponding to a cut-off of 100 cycles. The remainder of the horn flares at such a rate that the area doubles every 16 inches so that the nominal cutoff is 47 cycles. This results in a "rubber throat" the area of which is about 100 square inches up to 100 cycles and decreases with frequency until at 400 cycles the effective throat area is 50 square inches."
Attached Images
File Type: png Attach_1.png (52.2 KB, 268 views)
__________________
www.hornresp.net
  Reply With Quote
Old 23rd January 2019, 08:38 AM   #5
David McBean is offline David McBean  Australia
diyAudio Member
 
Join Date: Jun 2007
Default Found It!

For what it is worth, my early attempt at simulating a Klipschorn nearly 50 years ago, based on information contained in Paul Klipsch's original 1941 "Low Frequency Horn of Small Dimensions" J.A.S.A. paper.

In the attached the Hornresp model, the driver parameters have been updated to K-33 specifications, but the horn and chamber dimensions remain unchanged. The first segment was originally specified as Con because I didn't have a parabolic horn model back then. It turns out that there is virtually no difference in the response anyway, even when the theoretically more correct Par expansion is used.
Attached Images
File Type: png Attach_1.png (54.0 KB, 287 views)
File Type: png Attach_2.png (45.8 KB, 279 views)
File Type: png Attach_3.png (63.6 KB, 298 views)
__________________
www.hornresp.net

Last edited by David McBean; 23rd January 2019 at 08:55 AM.
  Reply With Quote
Old 23rd January 2019, 08:50 AM   #6
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Klipsch Bass Horn Acoustic Analysis
Not just a great work, but also another (strong) confirmation of PWK's genius engineering mind .......

thank you , both
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 23rd January 2019, 09:05 PM   #7
jimmosher is offline jimmosher  United States
diyAudio Member
 
Join Date: Oct 2018
Quote:
Originally Posted by David McBean View Post
Just to clarify - Paul Klipsch referred to the initial parabolic segment shown in red in the attachment, as a "rubber throat".
Hi David,

Thanks for the clarification. Looking at the unfolded horn shape of the Klipsch, I never would have guessed that the rubber throat section was further downstream from the throat.

Jim.
  Reply With Quote
Old 23rd January 2019, 09:17 PM   #8
jimmosher is offline jimmosher  United States
diyAudio Member
 
Join Date: Oct 2018
Quote:
Originally Posted by David McBean View Post
For what it is worth, my early attempt at simulating a Klipschorn nearly 50 years ago...
Oh, oh, you don't want to give away your age too quickly. :-)

Quote:
Originally Posted by David McBean View Post
...., based on information contained in Paul Klipsch's original 1941 "Low Frequency Horn of Small Dimensions" J.A.S.A. paper.

In the attached the Hornresp model, the driver parameters have been updated to K-33 specifications, but the horn and chamber dimensions remain unchanged. The first segment was originally specified as Con because I didn't have a parabolic horn model back then. It turns out that there is virtually no difference in the response anyway, even when the theoretically more correct Par expansion is used.
David, I also noticed several other things from your parameter screen shot:
  • Your measured total horn length is 148 cm and mine is 172. I did carry the length along with wall as if there was a "top-hat" on top of the bass cabinet, so that could be the difference.
  • Your final mouth opening is smaller by a proportional amount.
  • The Vrc of your model is some 37% smaller. I would bet that you have considered the effect of the K-33 driver volume reduction. I did not have one to model.
  • Fr and Tal are both zero on your model, and this would match the cut-away pictures I have seen of K-horns from various sources.

This raises a question that I have wondered about for some time now. David, did you create Hornresp to model a K-horn? Was that your first stimulus for creating the program?

Jim.
  Reply With Quote
Old 23rd January 2019, 09:24 PM   #9
jimmosher is offline jimmosher  United States
diyAudio Member
 
Join Date: Oct 2018
Quote:
Originally Posted by Zen Mod View Post
Not just a great work, but also another (strong) confirmation of PWK's genius engineering mind .......

thank you , both
Zen Mod, thank you for the kind words. :-)

And I agree with your assessment of Mr. Klipsch. I have admired the K-horn for many years, probably more due to it's quirkiness and high efficiency than anything else. There something magical about a bass sound that emanates from inside the cabinet and comes out each side, along the walls. A true corner horn!

Jim.
  Reply With Quote
Old 24th January 2019, 12:43 AM   #10
whgeiger is offline whgeiger  United States
diyAudio Member
 
Join Date: May 2004
Location: Pensacola, Florida
Default Previous Analysis

by Harris.
Hope this helps.
WHG
Attached Files
File Type: pdf KH-RMH1r.pdf (136.2 KB, 101 views)
File Type: pdf KH-RMH2.pdf (525.6 KB, 55 views)
File Type: pdf KH-RMH3.pdf (392.6 KB, 47 views)
File Type: pdf KH-RMH4.pdf (520.2 KB, 51 views)
File Type: pdf KH-RMH5.pdf (480.8 KB, 38 views)
File Type: pdf KH-RMH6.pdf (407.1 KB, 42 views)
File Type: pdf KH-RMH7.pdf (807.5 KB, 51 views)
  Reply With Quote

Reply


Klipsch Bass Horn Acoustic AnalysisHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Trying to mellow out Klipsch KG 4.5 tractrix horn rongon Multi-Way 49 17th August 2018 02:28 AM
Klipsch Horn Woofer designs.... moray james Subwoofers 48 20th March 2018 11:57 PM
Horn analysis question... Brian Steele Subwoofers 12 30th June 2017 03:26 AM
Klipsch bass horn(La Scala) rvrazvan Multi-Way 28 3rd January 2012 09:35 PM
Finished horn modelled with MJK's analysis worksheet awhite1159 Full Range 25 3rd September 2007 02:28 PM


New To Site? Need Help?

All times are GMT. The time now is 09:41 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki