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Alexander

Roxul Rockboard 60 - will it work/hold up?

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10 hours ago, Lbk said:

Interesting idea with the vinyl, I have a window where it could be useful. So thick vinyl tighly staped and what looks like vinyl side towards window?

 

Yes, they call it MLV here (Mass Loaded Vinyl), and it is specifically used for soundproofing applications. You can read more about it here: https://blog.soundaway.com/2018/02/everything-you-need-to-know-about-mass.html

 

I stapled the MLV to the back of the frame as a backing, so yes, on the window side, with the acoustic dampening material (Rockwool) in between, and then the front covered with acoustically transparent material. 

 

I hope this helps.

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4 hours ago, inMotionGraphics said:

 

Yes, they call it MLV here (Mass Loaded Vinyl), and it is specifically used for soundproofing applications. You can read more about it here: https://blog.soundaway.com/2018/02/everything-you-need-to-know-about-mass.html

 

I stapled the MLV to the back of the frame as a backing, so yes, on the window side, with the acoustic dampening material (Rockwool) in between, and then the front covered with acoustically transparent material. 

 

I hope this helps.

Yes helps alot, thanks!

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Won't the black rubber smell when it gets hot?

 

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1 hour ago, Negatron said:

Won't the black rubber smell when it gets hot?

 

I haven't noticed any smells and the big one is covering a window that gets direct sunlight for the entire afternoon, so no, it shouldn't smell when it gets hot.

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That is good...I would have been worried when it gets hot . If it does smell later, I would try a layer of white muslin cloth or drapery material over the black.

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I used 3' thick Roxul Safe n Sound inside. I used ¾" plywood frames, glued and (air) nailed with 2"x 2" x 3/4" pine gussets in each corner. I covered them with G of Maine fabric and a "felt" material on the back to ensure no rockwool fibers are flying around. Also used screw in "hooks" in the ceiling and eye bolts in ceiling panels Simple Z brackets are going to be utilized to hang wall panels. Now, who has the down low on finding the first reflection points on K horns. Everybody i have asked tries to explain it to me as if I didnt say I had Klipschorn and had "square" speakers. Mirror trick doesnt seem to work. Pics coming. 

Acoustic Panels.jpg

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Well, below you'll see the reverberation time plot ("RT60") from a REW measurement of a Klipschorn in an acoustically untreated room:

 

1669305825_KHorn-RoomReverberationTimeUntreated.thumb.jpg.a66998faf66271d38ffd7dab4ef63fea.jpg

 

The curves show a rise in reverberation times up to about 1 kHz, upon which the RT values begin to fall again.  Of particular interest is the cyan-colored trace, which dramatically drops at 2 kHz.  This is the "early decay time" curve.  Why are these curves important?  Some observations:

  1. The problem frequencies for the room are between about 200 Hz and 10 kHz.  The maximum values here should be below 500 milliseconds (the vertical axis), and they're all above 600 ms. This means that the room needs broad-band absorption from 200 Hz to 10 kHz. The owner of this room can cover about 25% of the front wall and nearby side walls with absorption panels to get the overall RT values down to below 500 ms (above 70 Hz, where most bass traps fall off in their effectiveness due to the finite length of the bass traps as absorbing Helmholtz resonators). 
     
  2. The Early Decay Time ("EDT" cyan-colored trace) shows an abrupt roll-off above 2 kHz.  This is the frequency below which the midrange K-400 or K-401 horn will put excess midrange energy on the ceiling and floor, all the way down to about 250 Hz, below the center 400 Hz crossover point between the midrange horn and bass bin. 

    This is the problem with all Klipsch Heritage loudspeakers having "pattern flip" (otherwise called "collapsing polar") midrange horns, like the K-400 through K-700 horns used in the Khorn, La Scala, Belle, Cornwall (I through III, but not the newest CW IV, which avoids this problem) and Heresy.  This is due to the short vertical dimension of the K-400 midrange horn mouth not constraining the midrange acoustic energy, and thus losing directivity control.  This is why so many people don't like the sound of Klipsch Heritage, I believe. 

    You need a lot of absorption on the floor between your listening position and the corner-located Khorns to begin to treat that issue.  Also, if your WAF is amenable, I'd also recommend adding ceiling absorbers or diffusers ("Skyline", etc.) to further control ceiling bounce. 

    The sidewall "first reflection point" absorption approach doesn't really work very well with Klipsch Heritage, I've found.  So almost all the issues with Khorn+room acoustic treatments is focused on the midrange horn and its spraying of acoustic energy on the ceiling and the floor--but not really the side walls.  You can put absorption or diffusion panels near the Khorns on its side walls, but don't expect a lot of difference in sound in-room.
     
  3. The Khorn loudspeaker box itself re-radiates that spilled midrange acoustic energy between 250-2000 Hz.  This means that you need to put a significant thickness of absorbing material across the top of the top hat to absorb these re-reflections from the midrange.   Additionally, you can put some absorption material down the front of the Khorn below the level of the top hat--on the bass bin--to control midrange re-radiation here, too.  A lot of people won't do this because they want to look at that bare wood from on the bass bins.  The fact remains, however, that placing absorption across the front up high on the bass bin will significantly help the midrange EDT curve problem. 

Chris

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You could also upgrade the Khorn top hat to a K-402 horn and a good 2" compression driver (bi-amping) to eliminate that midrange pattern flip issue of the K-400 series midrange horns.  I believe that user @Delicious2 (Mark) has done this (before eventually upgrading to a full Jubilee configuration).  I helped dial-in both the K-402/Khorn bass bin and his Jubilees using a Xilica DSP crossover.

 

Here's the equivalent "RT60" measurement plots from REW for the left Jubilee in my listening room:

 

18537587_K-402JubileeReverberationTimes(LeftJub).thumb.jpg.339059b6fbe240fbe8b5d26f137f88e5.jpg

 

 

Chris

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Thank you for the info. Where would one procure the K 402 horn, and what is the preferred driver? 

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Two very different questions, of course.  You can contact Cory at @Paducah Home Theater for a quote on the K-402 assemblies.  You're looking for the "KPT-402-HF" assemblies. I took a picture of mine back in December 2007, and here it's sporting a K-69-A driver (i.e., a P.Audio BM-D750 series I with modified phase plug):

 

CRW_2205.gif

 

Here on top of a Jubilee bass bin (KPT-KHJ-LF):

 

404959460_KudretsJubilee.thumb.jpg.9e92f236db62357d8655380e25339160.jpg

 

The drivers that usually come with the K-402s are K-691s, which are apparently B&C DE75s with modified phase plugs.  I personally would (eventually) recommend swapping out the K-691s with BMS 4592NDs (dual diaphragm drivers, thus making your loudspeaker into a three-way), or the more expensive Radian 950BePB (beryllium diaphragm)--if you're looking for the best reproduction quality.  The K-691 is a solid driver, but will have some chatter (non-pistonic modes) above 13 kHz, which can be heard if playing music with a lot of ride cymbal, such as bebop jazz, etc.

 

Chris

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Alexander, et al,

 

 

Here's a great video showing not only how to construct fabric covered panels but also how to easily mount them to your ceiling (or walls) using a version of the French cleat. I wouldn't mess around with one inch Roxul (or any absorbing material)---get the two inch. You can also space the finished panels away from the walls or ceiling and gain more absorption.

 

Treat Roxul just as you would Owens Corning compressed fiberglass panels---wear a respirator, long sleeve (disposable) shirt, disposable gloves, goggles or safety glasses, etc. Work outdoors unless you want a room full of particulates from the cutting and handling. Be sure to round the corners of your frames--it'll look nicer and won't tear the fabric when you pull it tight.

 

https://www.youtube.com/watch?v=XIP2Mix_bwM

 

 

Lee

 

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Thanks, an excellent video

 

 

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I had a wood french cleat installed on our walls that goes all around the room. Now I can hang my acoustic panels and anything else I want to hang from the cleats. The area on our loft that has a wood french cleat is currently being used as a hanging planter with the cleat too. Our front heights and rear heights are also held by the wood french cleats.

 

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That's a great way to hang ceiling panels.

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On 6/4/2020 at 4:15 PM, Ol_mcdonald said:

I used 3' thick Roxul Safe n Sound inside. I used ¾" plywood frames, glued and (air) nailed with 2"x 2" x 3/4" pine gussets in each corner. I covered them with G of Maine fabric and a "felt" material on the back to ensure no rockwool fibers are flying around.

 

Your acoustic panels look good.

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