So what does one do with all those scraps ......

[Steve Manning]

Well I've had a pile of lbl scraps (~4 ft cube) taking up too much space in the garage. Some of you may remember these came from the Minerva project as drop out's when we had the parts cnc'd. I decided to follow Ron's advise and wing on something and decided to make some wall diffusors.


This is the pile waiting for some attention ....



Spent some time at the table saw with the crosscut sled and did some trimming.



Started laying out the pieces on some 1/2" mdf.



Like everything it's a bit time consuming.





It looks like I should get 2 panels that are ~36" X 18" when done and should use ~70 of the scrap pieces.

[---k---]

Looking good. I like the waves pattern.
After moving to a house with an unfinished bacement and noting there is absolutely no echo with the open joist ceiling, as opposed to normal empty rooms, I could be misusing empirical evidence, but I'm convinced that diffusion works very well.
Are you going to stain it or anything.

[Steve Manning]

Looking good. I like the waves pattern.
After moving to a house with an unfinished bacement and noting there is absolutely no echo with the open joist ceiling, as opposed to normal empty rooms, I could be misusing empirical evidence, but I'm convinced that diffusion works very well.
Are you going to stain it or anything.

Thanks ..... The shape just happened to be there so I went with it. I'm going to frame the whole thing with a contrasting wood, I've got some cherry on hand that I might go with. Then hit it with a clear coat of something.

I've seen coffered ceilings be used for dispersion where folks don't want panels hanging on the ceiling. I imagine your joist are doing something similar.

[cochinada]

It looks as if you're going to build your own anechoic chamber in the house. Cool! :T

[wkhanna]

those are V nice!
are there any concerns that the lack of variation in the profiles will limit its effective frequency range?

[Steve Manning]

those are V nice!
are there any concerns that the lack of variation in the profiles will limit its effective frequency range?

Thanks Bill ...... I have absolutely no idea what frequency range these will work over. There was no math, physics or anything other than ...... that looks cool. :B Now I did offset the rows of "waves" with spacing in between each of those. I figured that might count for something. If I were to make more I would certainly put some actual acoustics theory into it.

Not exactly sure how one would test these anyway.

[JonMarsh]

I think this is called using what comes to hand.... looks like a judicious choice and nice design! :T

Now, with Fuzzmeasure, and it's new architectural acoustics capabilities in version 4, we could quantify just what it does...,

Very nice design approach using what had on hand with minimal additional effort!

[cochinada]

Steve, I had an idea but I don't know if you have enough material.

It occurred to me that you could assemble a larger square by juxtaposing four sub-parts as the one you have, each rotated by 90 degrees. So, each big square would be formed by four smaller squares.
I can think of the following "advantages":
- better aesthetics (subjective of course).
- theoretical or intuitively better frequency diffraction due to the different patterns.
- more sophisticated look.

Alternatively my suggestion is to mount the individual panels (how many are you going to make?) on the wall/ceiling in horizontal and then vertical orientation and so on and so forth.

[Steve Manning]

Steve, I had an idea but I don't know if you have enough material.

It occurred to me that you could assemble a larger square by juxtaposing four sub-parts as the one you have, each rotated by 90 degrees. So, each big square would be formed by four smaller squares.
I can think of the following "advantages":
- better aesthetics (subjective of course).
- theoretical or intuitively better frequency diffraction due to the different patterns.
- more sophisticated look.

Alternatively my suggestion is to mount the individual panels (how many are you going to make?) on the wall/ceiling in horizontal and then vertical orientation and so on and so forth.

For ease of handling one could certainly cut these in half, as well as everything else you mention, I briefly thought about that, but did not feel like adding the additional work/time. I have one done, in rough mode and it's 36" X 16". That's not very big, but it is a bit stout ..... you need to add ~ 4" in thickness and that puts it in perspective. My plan is to make a second one and of course I have the option of going either horizontal or vertical. I'm going to use french cleats and drywall anchors so there should be no issues with weight.

If I make more I can look into other options then.

[Steve Manning]

I think this is called using what comes to hand.... looks like a judicious choice and nice design! :T

Now, with Fuzzmeasure, and it's new architectural acoustics capabilities in version 4, we could quantify just what it does...,

Very nice design approach using what had on hand with minimal additional effort!

I could send you one for testing ...... if nothing else you could use it for a small raft with all that rain you've been having.

[JonMarsh]

Double duty- acoustic improvement and rescue gear!

we had a big blast yesterday, slow drizzle earlier today, and now it's building up again, supposed to be quite steady over the next 12 hours or so. Bev's nieces have arrived on time- no travel issues, fortunately. But Sundy's storm is supposed to be a Lola palooka...

[Navy Guy]

Have you thought about using a strip of acoustic absorption material between the slats. This might work well to help absorb and scatter.

[Steve Manning]

Have you thought about using a strip of acoustic absorption material between the slats. This might work well to help absorb and scatter.

I have thought of doing that with some other stuff in the works, but not for this.

[wkhanna]

these panels provide diffraction which is different than absorption.
they reduce echoes and reflections by scattering sound waves in many directions.
this is good for first reflection points, like side walls & ceilings, & are good for eliminating timing issues in the mid & upper frequencies.
absorptive materials like the corning 703 are used primarily for bass issues, typically in room corners.

[cochinada]

And what about rear walls? I heard people defending absorption but some say diffraction works best.

[Steve Manning]

And what about rear walls? I heard people defending absorption but some say diffraction works best.

I'm actually considering the rear wall, which is a partial wall .......





Thinking about putting it above the DVD rack to help offset the opening on the other side.

[wkhanna]

of course, i was speaking in 'general' terms.
& as Mark Twain said, "All generalizations are false, including this one".

actual results will always be room-dependent.

[Steve Manning]

these panels provide diffraction which is different than absorption.
they reduce echoes and reflections by scattering sound waves in many directions.
this is good for first reflection points, like side walls & ceilings, & are good for eliminating timing issues in the mid & upper frequencies.
absorptive materials like the corning 703 are used primarily for bass issues, typically in room corners.

I have a plan for doing treatment in the room ...... much as you laid out Bill. Unfortunately it's on hold until I get back to work and make some money to pay for it. The diffusors I'm making at the moment are more of a playing around exercise since I had all that material laying under foot ..... kind of killing two birds, as it where. Who knows it could actually help the sound.

[wkhanna]

it is my 'uneducated' guess the diffraction panels will prove effective on the that partial back wall. :W

[Steve Manning]

Diffusors got put on the back burner for a little bit. My cross cut sled required a rebuild after a tussle with gravity and loosing. While I was at it, I decided to add an outfeed table to go with it. Though I got the first diffusor mostly finished, before starting that. Of course sanding and trim work need to be done as well as a little finish.

[wkhanna]

sweet!

[---k---]

Those look ready for a little stain and hanging to me. :T

[Carl V]

looking good...weight?

[JonMarsh]

Yeah, I'd suggest Steve should send them out for extended acoustical testing, but...

A) no system setup now
B) I think the shipping would be a bit pricey... :W

Looking good, though! :T


The other thought, of course, is what would it cost to make this on purpose this way? from scratch?

[Steve Manning]

Thanks guys ...... Initially when I was moving them around at ~30% finished I figured these where not going to be that heavy. Now that it's done, I've changed my mind, 8O my guess is ~50 lbs, or so. I'm now toying with Joaquim's suggestion of making the remaining one in two pieces.

[---k---]

50 lbs is heavy. But one large drywall anchor can often take that or more. A screw into wood is rated for double or more. Your French cleat won't stress at all. So I wouldn't worry about the weight until it's too much to lift.

[Steve Manning]

I've become a fan of these guys, https://www.lowes.com/pd/TOGGLER-Sna...nchors/3183257. Even if I can't find a handy stud to screw into a few of these and I'll be good to go.

[---k---]

Yep those are my go to. I got a stock pile of those

[Steve Manning]

Update ....

Still making some progress on the scrap project. After getting the initial diffussor done, I opted to make two smaller ones with the material I had left. The plan was to mount these behind the speakers, with the larger one on the back wall.

This one is done with sanding and just needs trim to be installed.



Went with a French Cleat for mounting.



Pulled out some cherry that I have on hand. This will have to go through the milling process before finial work.



First diffusor in place ....



Everything moved back where it was .....

[Steve Manning]

Pretty Much Done ......

Well got things framed out in cherry and some finish thrown on the two front diffusors ..... the rear will be following shortly.

[Carl V]

Nice looking, as always. Your work is well thought out & well executed.
So, how does it sound? Sorta curious, I wonder how much
the Front Diffuses will impact the sound. Placed in between where
your Picture/art work is I can see...or reflection points.

[Steve Manning]

Nice looking, as always. Your work is well thought out & well executed.
So, how does it sound? Sorta curious, I wonder how much
the Front Diffuses will impact the sound. Placed in between where
your Picture/art work is I can see...or reflection points.

Thanks Carl ..... Have not done a lot of listening yet, though I want to say there is a little more detail, real or wishful thinking is yet to be determined. I plan on some with and without testing. Your certainly right though, they are not in an ideal location. First reflection points are a bit problematic since one side has a window and the other my computer desk. If I ever end up getting a dedicated music server the computer (current music source) and desk will go to another room and more than likely I'll go with some absorption on the left wall since I have some heavy drapes to deal with the window. At the moment I did not want to move the artwork (gift from the in-laws) until I tried them out first. I'll update when I have some more details to offer up.

[wkhanna]

turned out great!

[JonMarsh]

Looks very good, Steve- the $64 question, is how much do they weight and what kind of wall anchors did you have use? :W

[Steve Manning]

Thanks gents ..... Jon, my guess is the small ones are ~40lbs and the larger one is ~65lbs. Following the philosophy of someone I know, "You know how some of us feel… if some’s good, more is better, and too much is just enough!" I went with 3 anchors each on the small guys and 5 on the large one. Each are rated at 75lbs in 1/2" drywall ... so only a little overkill.

[JonMarsh]

Sounds about right to me, but then here on the left coast, we have to be concerned about acceleration forces due to unexpected earth movement, so over building has to be a way of life... :W