# Opinions on this design



## Talley (Dec 8, 2010)

Gonna make some diffusion panels. Here is what I came up with to trying to keep it to as simplistic as I can.

The idea is to use some 1x4 material to build a frame (box) the back of this box would have 3/16" paneling to make sorta a mini bookshelf look. The box would measure 48" x 10.5" to the inside. Then inside would sit this material.

The material would consist of:

Frame
2 -1x4x8 (left overs for other frames)
1 - 4x8x3/16 paneling $13.00

Inside pieces
1 - 1x2x8 $2.50 ea
3 - 2x4x8 $3.50 ea

Rip all this material in half would yield enough for two panels. Then you would rip all three of the 2x4s to 3" wide and use one flat for the center and then one each tall spaced for the two taller blocks.

This is an inverse QRD 7 type panel. Obviuosly diffusion would only be from 1300hz-4500hz but I would build 7 of these into a larger QRD panel with larger spacing for a bit better into the upper midrange.

I would place these where ever.

The nice thing is using the frame and the design your frame is 12" outside width so that means on one sheet of 4x8 paneling you can get 8 of these made. It really minimizes the waste to virtually nothing

So for 8 pieces total your total build cost is in the neighborhood of $100-$150 depending on the choice of finish. This gets you 4' tall x 8' wide worth of diffusion. (albeit upper range)

Any thoughts and/or comments?


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## Lumen (May 17, 2014)

Hi, Talley. Looks like you've done some good homework. I'm just surprised to find out you're planning diffusers before hearing what the room sounds like. I was once told my main 16Wx24Lx8H listening room was too small for diffusion by a certified audio engineer, but he didn't give a reason I could understand at the time and now I don't remember it. Do you have an idea in what size rooms diffusion should be considered? Just curious. Thanks!


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## Talley (Dec 8, 2010)

BlueRockinLou said:


> Hi, Talley. Looks like you've done some good homework. I'm just surprised to find out you're planning diffusers before hearing what the room sounds like. I was once told my main 16Wx24Lx8H listening room was too small for diffusion by a certified audio engineer, but he didn't give a reason I could understand at the time and now I don't remember it. Do you have an idea in what size rooms diffusion should be considered? Just curious. Thanks!


I base it on many articles I've read, I've owned the master handbook of acoustics since I was 15 (now 33). I've always been intrigued by the idea of acoustical treatment yet never was financially ready to make the investment toward audio equipment. I've been an avid home theater junkie since I was 15 as well yet just now am investing in a system.

I also lean on my uncle a lot as you all my know but aside from that when the situation arrives the purpose of of treatment is to decay the reflections enough and control them to get the room to interact as little as possible with the audio and/or control that interaction to get the results you want.

Most will say this. Diffusion wins. The problem with absorption is your room after furnishings is usually enough absorption to do the trick. Only key placements should be necessary. Too much and the room becomes dead. The problem with diffusion is artifacts/wierd issues when sitting too close. 

Am I 100% right... no. Every room is different and every body has a different feeling of what things should sound like. 

I want to make some of these diffusion panels and then also make some poly diffusers and then I can swap around and try different things to see what I feel sounds the best.


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## Talley (Dec 8, 2010)

oh and right now I know what my room sounds like.... bare and full of reverb.


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## Lumen (May 17, 2014)

Talley said:


> oh and right now I know what my room sounds like.... bare and full of reverb.


Good point. I meant what does it sound like without treatment while a system is,playing in it, but you answered for me.

Sent from my iPad using HTShack


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## Talley (Dec 8, 2010)

After more research this is the plan moving forward:

2 - 1x2x8s furring strips - $0.76ea
6 - 2x2x8s furring strips - $1.37ea
2.25 - 1x6x8 White Pine Softwood Board - $8.88ea
.25 - 4x8x3/16 paneling - $13.37ea

The math brings it to $36 for a 1x8' QRD 7 inverse strip or about $18 for each 1x4 strip Add in some consumable costs (nails, liquid nail glue, paint or stain) and you figure a $40 cost for an 8' piece or $20 for the 4'. I'll be picking up the materials this evening to begin working on these. I may build one tonight.

The materials choosen is nothing fancy, it's furring strips which means it's plain jain nothing fancy. I'm not going for fancy. if I built these from solid Oak then the cost would go up dramatically. I'm going for function. I will either paint or stain these or even leave them plain wood as I really don't care what they look like... I want them to work.

Looking at my image in my first post the walls of the frame have to be 5.23' in height so I'll just use a standard 1x6 to frame it out which gives me 5.5 and I'll call it good. I believe this will be important even though the other material only brings it to a maximum 3" in height simply because it's an inverse design and will need the height of the frame to give the proper design.

In keeping to my plan in the image below to start with. 

I'll do two 8' long pieces to go on each side of the projector along the crown molding. This is my first priority since I get a ton of flutter/echo from the crown areas. The really nice thing is by keeping it to 8' pieces the only cut I'll have to make is the two 12" pieces and the panel just do one rip. 3 cuts total! I could build this thing in 10 minutes!


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## Lumen (May 17, 2014)

Your plan seems well-balanced! And your marked-up pic is the coolest. I especially like the color scheme for the added graphics.


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## Savjac (Apr 17, 2008)

I am sure there is no easy answer here, but I have to ask anyway.
How do you decide what panels need to go where. For example how does one determine when diffusion as opposed to absorption is needed ? 

I too like the colors and recommend you use those colors for the fabric on the various items


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## Talley (Dec 8, 2010)

BlueRockinLou said:


> Your plan seems well-balanced! And your marked-up pic is the coolest. I especially like the color scheme for the added graphics.





Savjac said:


> I am sure there is no easy answer here, but I have to ask anyway.
> How do you decide what panels need to go where. For example how does one determine when diffusion as opposed to absorption is needed ?
> 
> I too like the colors and recommend you use those colors for the fabric on the various items


Ha... Thanks guys. I completely rock in microsoft paint.  In fact I rock so much my 8yr old could do better. It does get the point across.

The ceiling will be done like the image below. 

I do alot of research but honestly I try to stick with what works. Ever play pong? Or thrown bouncing balls around the house as a kid? 

The easiest thing to do is watch kids playing in the pool. Watch the waves.... see how the waves interact because isn't that suppose to be the pressure waves of sound albiet in a 2 dimension fashion (surface of water) so sound is 3 dimensional.

I sit and stare in my room and I envision sound waves and how they would interact bouncing around. Seriously it's too complex and you tend to start to go insane thinking about it but an interesting article and many acoustical experts have said similar things. I start to see patterns of consistency with acoustical design. I'm not saying my design will be perfect but I think it will be effective.

My idea is better than my uncles baskets on the wall IMHO. In the end you just want proper decay time, tuned MLP to listen to the primary signal first with controlled decay to give a sense of space. Aborsption = dead so you definately do not want to load your room with walls full of absorption as then you lose the sense of space. Remember your room is a speaker. If you played an instantaneous gun shot through your speakers your speakers will play silent after that gunshot but your room (giant speaker) will keep playing. How you treat it will affect how that gun shot will sound. 

Most everyone will say diffusion is the best method of treatment but in most cases you need "some" absorption to quickly bring decay times to preferred levels. My design is a tad heavy on absroption on the back wall/ back ceiling but thats because I will stick to mainly diffusion along the front wall, side wall and front ceiling part. It will help bring out ambiance on the front stage.... how it interacts with SS&I I have no idea but the best part of acoustic design is there is NO one right rule... many different ways to achieve the same result.

Answer me this though... those giant music halls... why are 90% of the treatment curved and angled surfaces? To control the direction of reflection in a fashion to create a sense of space that is free of echo. Our ears love spacey sounds.

I'm rambling now... and I could be wrong about everything.... to sum it up. build and try it out and build other and try it out then YOU pick what works. Don't just throw up panels and call it good. Listen.

...from an obsessive tweaker.


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## Talley (Dec 8, 2010)

Well I built two of them that are 12" x 86" each.

Total cost = $85. Nothing fancy but effective. Each 12"x48" panel would cost around $22 making these very effective and will work in the 1000-4500hz range.

Will start mounting the stuff I've made this weekend. The BEST part was total time for two of these to build was 1.5hrs and that was bringing all the tools out... building... and cleanup and this includes moving the wifes expedition in and out of the garage


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## Talley (Dec 8, 2010)

I will use two pieces of 1x2 and make a french cleat to hang them on the wall. These are going directly under the crown on each side of the projector to capture first wave concentrated reflections at the wall/ceiling joint.


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## Talley (Dec 8, 2010)

Well I stacked them two high on the back of the couch just for giggles and sat my black computer chair in front of the couch so I'm 32" off the back of the wall and I could hear a very good improvement in the depth of the soundstage with just this added.

I'm really getting excited, I think I may end up building eveything for my room this month alone.


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## BangkokMatt (Jun 21, 2015)

Such a shame that you have to be the short way on the room. That screen is MASSIVE. I don't suppose it would fit if you rotated 90 degrees to go the long way, much better from an acoustic standpoint. And i don't suppose you can get the couch away from the wall any significant amount?


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## vidiot33 (Dec 12, 2013)

Savjac said:


> I am sure there is no easy answer here, but I have to ask anyway. How do you decide what panels need to go where. For example how does one determine when diffusion as opposed to absorption is needed ? I too like the colors and recommend you use those colors for the fabric on the various items


I've heard that diffusion can useful in a surround situation at the rear. For smaller rooms, there already should be plenty of ways for the sound waves to bounce around, without worrying about diffusion. Also, generally, bass needs absorption, it's the higher frequencies that are diffused.

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