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Heresy II Motorboards or "Neurosis Sets In!"

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On 6/3/2021 at 2:07 AM, KT88 said:

perhaps similar to the parts of a chassis in racing cars, which only gain stability as a whole when they are mounted on the engine block and at the same time the position of the engine is strengthened. I think that the strength of the chassis is distributed

 if you sit on it  , you will break it ,  it is simply a design feature  , the new k76 lens in the H2 was bigger , and with  front mounted drivers   ,  they even had to  add a  cutaway for the mids horn lens  for all drivers to fit -----  the Heresy -3-4 are relatively the same - with a  taller cab on the H4  -

 

-   the  H5  will have a much bigger tweeter lens , alike the AK6-AL5  and the current H4 cabinet is tall enough to fit  the largest Klipsch tweeter lens currently manufactured  -

 

image.jpeg.a2a934b5b76189bd34a7d677099c5ec7.jpegKlipsch Heresy IV – Paducah Home Theater201904_klipsch1_med_hr.jpeg

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19 minutes ago, RandyH001 said:

the  H5  will have a much bigger tweeter lense

 

The H5?  Where do you get this information?  Or is this just conjecture as usual?

 

It's lens, not lense.

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I have a pair of H1's and I design stressed members for a living. I also build cajons, box drums about the size of a Heresy but much thinner. I have built about thirty wooden box drums and measured the frequencies of the sides and then sometimes braced the sides and measured the frequency again. I'm an expert in vibrating wooden rectangles.

 

That motor board is going to be flexible. Imagine it as a sheet of leather and you beat it like a drum, it will dish in and then belly out. It is thick, but they have removed a lot of material to make the holes. Now imagine that stiff metal woofer rim tied to a heavy magnet. The cone is what moves, the magnet will try to sit there. To visualize that put your 250 pound brother in law in a kid's wagon and let him shake a can of spray paint. Wait, the speaker is pushing on air. So let him sit in a wagon and wave a large fan. The wagon doesn't move much because brother in law is a lot heavier than the aerodynamic forces of the fan, and weighs a lot more than the thin vibrating fan. So now that thin motor board is tied to a circular shape that hates to move. The woofer just thrashes back and forth moving air. The air hits stuff in the room and might shake a wall so much that a picture rattles. Probably not, but maybe. That motor board doesn't really know what to do. It wants top flop in and out like a drum head, and it has been carved up and weakened. But that big magnet doesn't want to move much. The two horns are heavy and stiff and putting out much higher frequency vibrations. Those high frequencies are harder to vibrate along with. In the end a guy with a good computer could model the system and tell you that there are 12 or 16 vibrational modes in the low frequency spectrum. You'd like them all to be much higher frequency than 20,000 Hz but they will not be that high, I can tell you that by looking. But the mere existence of those modes does not mean they will become active. To understand which ones are active you build and test. PK built and tested in the 1950's, when the computers required to predict all of those vibrational modes did not exist. He built some and tested some and may have thickened or thinned some parts. In the end you hear the woofer and whatever sympathetic vibrations exist and the speaker made him happy. It did not make him as happy as Cornwalls or K Horns but he did not seem embarrassed to sell the Heresy speakers. So it sounds the way it sounded when PK quit improving it. As the photo of the stiffened motor board shows stiffening that motor board is not easy - there is nothing to tie it to. The backs are thin. I actually stiffened the back of my Heresy's and a tap test showed I had stiffened them a lot. The sound of the speaker did not change a bit as far as I could tell. I would not personally mess with stiffening the Heresy, my back stiffening experiment involved $2 worth of scrap wood and told me it was worth nothing too the sound. I have attached a picture of the panel modes of a plain rectangle. The front would be a lot more complex.

Rectangular Panel Mode Shapes per Drussell.jpg

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More on bracing the back. Once again I remind you that there is no reason to do it in my opinion. But we are tinkerers. If you look at the 12 lowest modes of a panel in my previous post we do not know the exact frequency of any of them, but we know lower modes are easier to excite. To get exact frequencies we would need to know stiffness data for the  plywood and I'll bet it is difficult to get. We would need to make assumptions about the stiffness of the screwed edges. People who design speakers for a living know this stuff, if they have analyzed and tested a lot of speakers. The other way to approach vibration is to "kill them all" (all the modes). Here is a picture of the braces I added to the back of my Heresy speakers. Each brace is 3/4" thick and 1" in depth. They are not perfectly symmetric on purpose. If you compare them to the modes pictured above they interfere with all of them. They interfere the least with 2,3 and 3,1. They interfere a lot with the entire top row and the first mode in row 2 (2,1). So they do attack the lowest modes. I braced the back of one speaker and then reassembled the speaker and tapped it. I tapped the unmodified back. The resonance of the braced back was a definitely higher, but not twice as high. This test only tells what happens when I tap the board, not what a speaker does. I played music, I could not tell one speaker from the other. I modified the second speaker. The wood came from my scrap bin, but I could have used it in a different project so it was not "free." I used glue and drywall screws. Total cost was maybe $2. I do not even know if total cost was $2 per speaker or total, it doesn't matter. Like I said, I could not hear any difference. If you tap the sides of your Heresy you will note that they are a lot stiffer than the back. I would not bother to stiffen the sides. There is no easy way to stiffen the motor board without using a lot of wood (as seen in the picture provided by someone else, who actually did it). I saw pictures of some larger speakers that Klipsch made using the same drivers. If I was desperate to improve my Heresy's I would build larger enclosures, copying whatever Klipsch did. I say this as a woodworker, there are other "Super Heresy" ideas that involve the electronics. But if all I had was a table saw and some plywood I would upsize he cabinets and make the motor board thicker, or make the back really thick (like 1.5") and run braces from the now really stiff back to the motor board. With the current price of plywood it may be better to just buy used Cornwalls.

Braced Back Klipsch Heresy.png

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6 hours ago, jimjimbo said:

 

The H5?  Where do you get this information?  Or is this just conjecture as usual?

 

It's lens, not lense.

 ...and it's a horn, not a lens.

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7 hours ago, RandyH001 said:

the  H5  will have a much bigger tweeter lense , alike the AK6-AL5  and the current H4 cabinet is tall enough to fit  the largest Klipsch tweeter lense currently manufactured  -

 

The Heresy has a horn, not a lens. These terms are not interchangeable.

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42 minutes ago, Blvdre said:

 ...and it's a horn, not a lens.

Actually, it’s a horn lens.

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52 minutes ago, Blvdre said:
7 hours ago, jimjimbo said:

 

The H5?  Where do you get this information?  Or is this just conjecture as usual?

 

It's lens, not lense.

 ...and it's a horn, not a lens.

You might delete that before your Huckleberries tell you what a lens is. 

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29 minutes ago, Woofers and Tweeters said:

You might delete that before your Huckleberries tell you what a lens is. 

I can’t wait 

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3 hours ago, Blvdre said:

 

The Heresy has a horn, not a lens. These terms are not interchangeable.

 

3 hours ago, jimjimbo said:

Actually, it’s a horn lens.

 

 

3 hours ago, Blvdre said:

 ...and it's a horn, not a lens.

Wink GIF - Stevecarrell GetSmart GIFs

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When I was growing up,

 

This was a horn:

t2380bi_vert_medium.jpg

 

And these were lenses:

JBL ACOUSTIC LENS MODEL 2310 DOREESJbl 2308 / L91 Style Kenrick Sound Brand Lenses | Perfect Reproduction

 

... and we had to walk 5 miles through the snow to school.

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I think once you fasten the woofer and mid range HORN on there it will be stiff enough. 

With out the Heresy Klipsch would not be here it basically saved the company. I think Andy said he built 300 a day.  If anyone has the correct production numbers please let us know. I know they didn't build Heresy's everyday  So lets say 100 days x 300 a day thats 30,000. 

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11 hours ago, Pondoro said:

The other way to approach vibration is to "kill them all" (all the modes). Here is a picture of the braces I added to the back of my Heresy speakers. Each brace is 3/4" thick and 1" in depth. They are not perfectly symmetric on purpose. If you compare them to the modes pictured above they interfere with all of them. They interfere the least with 2,3 and 3,1. 

Braced Back Klipsch Heresy.png

 

You always have a compromise. If you make the cabinet walls thicker or use a lot of braces, the time in which sound is stored could increase. This can manifest itself as time-smear and unmusical coloration. In the pdf link is an article from the year 1977 of the BBC research department. In figure 13 and 14 you can see that e.g. the double wall thickness sounds worse.

http://www.diy-audio.narod.ru/litr/1977-03.pdf

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1 hour ago, KT88 said:

You always have a compromise. If you make the cabinet walls thicker or use a lot of braces, the time in which sound is stored could increase. This can manifest itself as time-smear and unmusical coloration. In the pdf link is an article from the year 1977 of the BBC research department. In figure 13 and 14 you can see that e.g. the double wall thickness sounds worse.

http://www.diy-audio.narod.ru/litr/1977-03.pdf

I will read this with great interest. Thanks!

I've heard people fight before, one person says, "I prefer the sound of wood cabinets" and a smart#$@$@ replies, "If you hear the cabinet then your sound is colored!" But you always hear the "system." I learned quickly with my drums that thicker walls do not always sound better. 

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Several British speakers, Harbeth I believe is one, build cabinets defined as “loosy” or with built in flex in the structure. Minimal bracing and thin walls, compared to the tuning of a guitar or violin. 

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3 hours ago, ricktate said:

 I think Andy said he built 300 a day.

300 a day divided by 8 hours , that 38 speakers  per hour  , Andy was a MACHINE - 

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Heresy, too small of a cabinet to want or require any bracing.

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37 minutes ago, RandyH001 said:

300 a day divided by 8 hours , that 38 speakers  per hour  , Andy was a MACHINE - 


I don’t think so ... 

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6 hours ago, garyrc said:

When I was growing up,  , we had to walk 5 miles through the snow to school.

same here ,  under 5 miles , you walked , over 5 miles, you got a bus ride -

 

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13 hours ago, jimjimbo said:

Actually, it’s a horn lens.

 

Take it back. And it's spelled Ye olde horne lense.

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