The Skyline Diffusor Experiment.

neekomax · « **on:** 22 Aug 2011, 03:55 am »

So my girl and I had a lot of fun today with our Sunday project... a 2'x1' 'skyline' diffusor panel that we made from cedar and pine. It was kind of a test run to see how it would turn out. I'll use this one somewhere though. On the coffee table?

Lessons learned:

1. Even cedar is probably too heavy for a full size panel. Going to have to figure out some sort of foam product solution. Or balsa wood (Though I think it's $$$)?

2. Glue the smallest blocks first. Getting to them after bigger ones are in is a PITA.

3. Having a girlfriend who is down for this stuff is great. We use her table saw, by the way

.

Here's a view:

JohnR · « **Reply #1 on:** 22 Aug 2011, 12:38 pm »

That's way cool.

neekomax · « **Reply #2 on:** 22 Aug 2011, 05:50 pm »

Thanks man.

The next one is going to be 4'x3', and be made from some kind of foam, although were still trying to figure out what the material should be for ease of working with it and cost effectiveness. The black packing rubber foam that I've gotten in certain boxes seems perfect, but I have no idea where to get a lot of it. Wary of styrofoam because of how crumbly it is, might be a nightmare to cut with a table saw.

Anybody make one of these before and have recommendations for foam material?

S Clark · « **Reply #3 on:** 22 Aug 2011, 05:53 pm »

Quote from: neekomax on 22 Aug 2011, 03:55 am

3. Having a girlfriend who is down for this stuff is great. We use her table saw, by the way .

Your girlfriend has a table saw?? Does she have a sister?

neekomax · « **Reply #4 on:** 22 Aug 2011, 06:13 pm »

Quote from: S Clark on 22 Aug 2011, 05:53 pm

Your girlfriend has a table saw?? Does she have a sister?

Well, she does actually- 26 and very cute, but unfortunately that one doesn't come with any home improvement gear, as far as I know.

Hank · « **Reply #5 on:** 22 Aug 2011, 06:19 pm »

How about an unmarried Mom? Aunt?

neekomax · « **Reply #6 on:** 22 Aug 2011, 07:13 pm »

Tell you what... whoever can point me in the direction of some good material to make a skyline diffusor out of wins a date with a lovely, age appropriate woman who likes DIY projects.

srb · « **Reply #7 on:** 22 Aug 2011, 07:37 pm »

Quote from: neekomax on 22 Aug 2011, 07:13 pm

Tell you what... whoever can point me in the direction of some good material to make a skyline diffusor out of wins a date with a lovely, age appropriate woman who likes DIY projects.

Liking DIY projects is not enough. She must have her own plunge router and pneumatic brad nailer.

What is the average piece length? Although you're probably right about balsa being too expensive, I am curious while I am looking at a balsa source that has 2" X 2" at ~ $1.50/ft. I would like to avoid the toxic outgassing of most foam products.

Steve

neekomax · « **Reply #8 on:** 22 Aug 2011, 07:59 pm »

Quote from: srb on 22 Aug 2011, 07:37 pm

Liking DIY projects is not enough. She must have her own plunge router and pneumatic brad nailer.

Tall order, but we'll see...

Quote from: srb on 22 Aug 2011, 07:37 pm

What is the average piece length? Although you're probably right about balsa being too expensive, I am curious while I am looking at a balsa source that has 2" X 2" at ~ $1.50/ft. I would like to avoid the toxic outgassing of most foam products.

For a 2'x2' panel, the 2"x2" pieces are:

38 pieces - 1 7/8"
38 pieces - 3 3/4"
40 pieces - 5 5/8"
15 pieces - 7 1/2"

(This includes space for 13 blanks - 0").

This calls for 56 feet of 2"x2" material, if I'm not mistaken. So $84 using your balsa. That's about twice the price of the cedar we used. But half the weight, probably. Whaddya think?

steve k · « **Reply #9 on:** 22 Aug 2011, 08:15 pm »

I built a similar panel a few years back. It's a double panel (each 18" x 18") mounted on one piece of 1/2" plywood. Pieces were 1 1/2", 3" and 4 1/2" long with the shortest simply being the plywood backer panel. I used several 8 ft. lengths of 2X2 whitewood and glued the pieces in place with liquid nail, then finished the panel with clear, water-based polyurethane.

Believe it or not, I could actually hear the difference from the additional diffusion so it was worth it.

steve

neekomax · « **Reply #10 on:** 22 Aug 2011, 08:25 pm »

Cool

!

I was thinking of mounting it behind the LP, but maybe I should try between the speakers on the rear wall the way you have it as well?

srb · « **Reply #11 on:** 22 Aug 2011, 08:32 pm »

Quote from: neekomax on 22 Aug 2011, 07:59 pm

This calls for 56 feet of 2"x2" material, if I'm not mistaken. So $84 using your balsa. That's about twice the price of the cedar we used. But half the weight, probably. Whaddya think?

Thanks! Based on your sizes I come up with ~ 46 ft., but delivered I calculate $85.34 (12 - 2" X 2" X 48"@ $6.07 ea. + $12.50 shipping).
http://www.lonestar-balsa.com/Ordering/Order.php?PROD=5

It is definitely more expensive but it is a nice natural and very light material. Most modeling balsa I have seen is pretty smooth, but not sure how nice this stuff might or might not be. I would probably want to at least stain/seal it, but might be able to get away with only lightly sanding the one exposed end. Hmmm.....

Steve

neekomax · « **Reply #12 on:** 22 Aug 2011, 08:35 pm »

Lemme know if you do it, and thanks for the link! Might have to order that up...

richidoo · « **Reply #13 on:** 22 Aug 2011, 09:22 pm »

Neeko, you can use pink Owens Corning foam from Home Depot. It is light and rigid. If you cut it with hotwire the edges are sealed and pretty smooth, with saw less smooth, but shouldn't effect diffusion much, especially after painting it with thick latex paint. At least one commercial diffuser manufacturer uses that foam. In fact I'm sitting in front of one right now at my friend's house!

Your project reminded me of these BBC articles, which I think about trying someday, but lots of work. You are an inspiration!!

http://downloads.bbc.co.uk/rd/pubs/reports/1990-15.pdf
http://downloads.bbc.co.uk/rd/pubs/reports/1995-01.pdf
http://www.pmerecords.com/Diffusor.cfm

neekomax · « **Reply #14 on:** 22 Aug 2011, 09:30 pm »

Quote from: richidoo on 22 Aug 2011, 09:22 pm

Neeko, you can use pink Owens Corning foam from Home Depot. It is light and rigid. If you cut it with hotwire the edges are sealed and pretty smooth, with saw less smooth, but shouldn't effect diffusion much, especially after painting it with thick latex paint. At least one commercial diffuser manufacturer uses that foam. In fact I'm sitting in front of one right now at my friend's house!

Your project reminded me of these BBC articles, which I think about trying someday, but lots of work. You are an inspiration!!

http://downloads.bbc.co.uk/rd/pubs/reports/1990-15.pdf
http://downloads.bbc.co.uk/rd/pubs/reports/1995-01.pdf
http://www.pmerecords.com/Diffusor.cfm

Thanks richidoo... I think I saw the pink Owens Corning foam at Home Depot. Didn't use it because we weren't sure that it could be painted without dissolving it, and didn't want pink outcome. You're saying latex paint works with it? You bought a diffuser that is made out of that? Is it painted? Photo maybe?

srb · « **Reply #15 on:** 22 Aug 2011, 09:39 pm »

Okay, back to foam. What sort of effect do you think a diffusor built with varying lengths of foam tubing might produce? Specifically I am thinking about something like this pipe wrap insulation tubing, that has a 3/4" hole with 1/2" wall thickness for an overall diameter of 1-3/4"?

It's a nice dark grey color, smooth and would only require easy length cuts. And it is only $1.18 per 6 ft. length.

Another idea might be solid "pool noodles". Although usually in bright colors, they are also available in white. Solid with no center hole, 2-1/2" thick and about $3.00 / 5 ft. length.

Steve

neekomax · « **Reply #16 on:** 22 Aug 2011, 09:51 pm »

Quote from: srb on 22 Aug 2011, 09:39 pm

Okay, back to foam. What sort of effect do you think a diffusor built with varying lengths of foam tubing might produce? Specifically I am thinking about something like this pipe wrap insulation tubing, that has a 3/4" hole with 1/2" wall thickness for an overall diameter of 1-3/4"?

It's a nice dark grey color, smooth and would only require easy length cuts. And it is only $1.18 per 6 ft. length.

Steve

No idea how a different shape would affect the functionality of a diffusor. Any acoustic engineers watching this thread care to comment?

The price is right on that stuff, and I bet it would be very easy to work with. It also looks very much like this stuff that I got from some packaging, which I think would be perfect if I could find a place to buy it in quantity:

srb · « **Reply #17 on:** 22 Aug 2011, 10:18 pm »

Quote from: neekomax on 22 Aug 2011, 09:51 pm

It also looks very much like this stuff that I got from some packaging, which I think would be perfect if I could find a place to buy it in quantity:

That looks like something similar to MicroCell closed cell foam. It's available from a number of foam vendors, but I haven't found precut 2" X 2" pieces yet. Most vendors can custom cut with professional cutting rigs to get super smooth cuts. An example would be 2" MicroCell from Foam Express, sold in sheets:

Full Sheet 2" X 48" X 72" $89.85
Half Sheet 2" X 24" X 72" $47.85
Quarter Sheet 2" X 24" X 36" $30.85

Will have to inquire how much the cuts would be.

Steve

neekomax · « **Reply #18 on:** 22 Aug 2011, 10:59 pm »

Looks like a half sheet would more than enough for around 50' of 2"x2", right? I think I would get a full sheet and see about making a big, lightweight panel.

Good find...

srb · « **Reply #19 on:** 22 Aug 2011, 11:13 pm »

Quote from: neekomax on 22 Aug 2011, 10:59 pm

Looks like a half sheet would more than enough for around 50' of 2"x2", right? I think I would get a full sheet and see about making a big, lightweight panel.

Half sheet would give you 72' and full sheet 144' of 2" x 2". They probably use a hot blade or wire with little to no waste or shrinkage. Although it could probably be done on a lightweight foam backing, I would probably use 1/4" plywood or 1/4" foam core art board wrapped in 3/4" X 1-1/2" hardwood trim for aesthetics on my 2' X 4' panel.

Steve

Steve