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Heresy II Motorboards or "Neurosis Sets In!"


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2 hours ago, RandyH001 said:

Great idea,   but --no can do -

 

Surely you must get a breeze from riding on the back of that truck, holding onto those handles on either side.

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20 hours ago, Deang said:


I don’t think so ... 

I could be wrong its been awhile since i talked to Andy. But im sure the boards and parts were on pallets next to him.  He only built the cabinet the other parts were put in down the line. Maybe he will chime in a tell us the low down...lol

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On ‎6‎/‎6‎/‎2021 at 9:07 PM, Pondoro said:

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

   I plan on bracing a pair of Heresy speakers, but I plan on cutting new half inch plywood backs to brace and leave the originals as they were made so that I don't change/destroy what Klipsch designed. Plywood is still relatively cheap, you can also use a piece of 3/4 and let it stick out the back to stiffen the back too, then use a 1/4 inch round over bit so soften the edges and then use the original backs for transfer the holes for the screws (use longer screws or counter bore for the original ones).  just a thought...

 

Gary

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12 minutes ago, garyeanderson said:

   I plan on bracing a pair of Heresy speakers, but I plan on cutting new half inch plywood backs to brace and leave the originals as they were made so that I don't change/destroy what Klipsch designed. Plywood is still relatively cheap, you can also use a piece of 3/4 and let it stick out the back to stiffen the back too, then use a 1/4 inch round over bit so soften the edges and then use the original backs for transfer the holes for the screws (use longer screws or counter bore for the original ones).  just a thought...

 

Gary

Not a bad plan. I saved a couple of bucks over your plan but your idea keeps the option of going back much more easily. 

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22 hours ago, Pondoro said:

Not a bad plan. I saved a couple of bucks over your plan but your idea keeps the option of going back much more easily. 

As you say, a few dollars.

I  think a 1/4 sheet of 18 mm Baltic birch "30 x 30" will do so $54

https://www.boulterplywood.com/MultiLayerPlywood_4.htm

prices have gone up, (like double in the last couple years) but so have Heresies and all other heritage speakers. I like building so its not a big thing to do.

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