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post #91 of 376 Old 02-20-2011, 08:40 PM - Thread Starter
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Okay, so does anyone have a basic design they'd like me to pass by our foamy friend?

I'm ready to go with this if you guys want it done.

I say we start with the 1D and see how it goes. If you guys can tell me how wide, and the heights of each "cell" or whatever, I'll try to get it to him in the next couple days.


I wonder if we can also use the inverse of the cut he makes? So if we need a 5" tall design, and he runs the machine down the middle of a 10" thick sheet.......can we use both sides of the cut?

A cheesy drawing would help out even more. But if you must just list the heights and stuff, maybe I can get member Radman to draw it out on the computer. he's pretty good at that.
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post #92 of 376 Old 02-20-2011, 09:27 PM
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Quote:
Originally Posted by Erich H View Post
Okay, so does anyone have a basic design they'd like me to pass by our foamy friend?

I'm ready to go with this if you guys want it done.

I say we start with the 1D and see how it goes. If you guys can tell me how wide, and the heights of each "cell" or whatever, I'll try to get it to him in the next couple days.


I wonder if we can also use the inverse of the cut he makes? So if we need a 5" tall design, and he runs the machine down the middle of a 10" thick sheet.......can we use both sides of the cut?

A cheesy drawing would help out even more. But if you must just list the heights and stuff, maybe I can get member Radman to draw it out on the computer. he's pretty good at that.
This one looks pretty good
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post #93 of 376 Old 02-20-2011, 09:52 PM - Thread Starter
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That's a 2D design. Plus, we're hoping to come up with something a little different and not really a copy.
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post #94 of 376 Old 02-20-2011, 09:59 PM
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Does the patent prevent others to copy for personal use also?

I am probably going to make some 2D diffusers, using a special knife for EPS as proposed by another poster in this thread. 1D is not bad either. May a mix of 1D and 2D diffusers?
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post #95 of 376 Old 02-20-2011, 10:02 PM
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I'll post a design tomorrow night if no one else has. Have a look at the qrdude program. Pretty easy to use. To answer your other question, yes you can use both sides of the cut. The other side is called the inverse panel and is actually quite necessary if you use a lot of diffusers on one wall to break up repetetive lobing.

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post #96 of 376 Old 02-21-2011, 08:01 AM
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I might be able to find some time to put together a few designs. Sketchup work?

The inverse is good, but you can't use the inverse and still have dividers.

There is one other possibility. It would be similar to Decware's kit. You could sell the cut wells and the buyer could then cut his own dividers from 1/8" hardboard. For 4" deep diffusers, you would end up shipping the entire 8" thick piece of styrofoam which has been cut. It would be a primary and inverse in each package. I think this would be a fine compromise. Very lightweight. Very easy to cut. The downside is it still requires some work by the user cutting strips of 4" wide hardboard with a circular or table saw. You could possibly get your wood cutting buddy to supply those strips as well though.

Decware kit using all wood:

http://www.decware.com/p1324.htm
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post #97 of 376 Old 02-21-2011, 08:27 AM - Thread Starter
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Could the 4" strips be foam as well?

It doesn't really matter if the inverse could be used or not, it was just a thought I had.

My guess is that the inverse could work, just not quite as good.
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post #98 of 376 Old 02-21-2011, 11:07 AM
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I had not thought of using thin foam strips as the dividers. I guess it depends on how tough they are. You could probably go up to 1/4" thick. From a diffusion standpoint material is pretty much a non-factor.

The hardboard option would make for a tougher product overall IMO without adding much weight or cost because it would only be the dividers. You could even integrate the strips into the packing scheme to protect the foam. It would also help to frame the piece when it is on the wall, helping it to protect it from getting gouged.

I do understand the cost and complexity would go up, but it could make for a far better product and still at a reasonable price.
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post #99 of 376 Old 02-21-2011, 11:19 AM - Thread Starter
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We can always figure it both ways. If you can draw something out, I'll send it tot he right people.
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post #100 of 376 Old 02-21-2011, 12:04 PM
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Timely thread, I'm doing my HT acoustics just now.
Once you guys decide on a design I'd be willing to join a "group buy" with (2) 2' x 4' and (2) 4' x 4' diffusers.
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post #101 of 376 Old 02-21-2011, 05:45 PM
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Erich, I've attached a SketchUp that I threw together. The dimensions with dividers is 19.25" x 19.25". It is a N17 + 4 1D QRD that is 4" deep. Well width is 1" with 1/8" dividers. Design frequency is 1294hz. It scatters as low as 647hz and diffuses as high as 6880hz.

Getting creative, I was thinking cardboard could be used for the dividers. It doesn't get much cheaper or lighter. It should be effective at these frequencies and easy to bond to the styrofoam.

Frame it with some wood, wrap in acoustic cloth and nobody would know it was just styrofoam and cardboard behind there.

Edit: I could do something similar closer to 12" or 24". I could also reduce the well width some to hit a more regular dimension if that makes production easier.
LL
LL
LL

 

QRD N17+4 4in deep with inverse.zip 48.6435546875k . file
LL
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File Type: zip QRD N17+4 4in deep with inverse.zip (48.6 KB, 13 views)
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post #102 of 376 Old 02-21-2011, 07:46 PM - Thread Starter
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How would you insert the boards between the different heights of foam? It looks as if you have the boards going all the way to the bottom of the diffuser. If there was a thin gap cut between each height, I could look at getting some very thin planks cut that would slide right into those gaps. It would look better than cardboard.



If someone wanted to use that without the boards, would it work as a normal diffuser? Or do we need a different design for that? Some people might be interested in those as an easier alternative.
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post #103 of 376 Old 02-21-2011, 09:05 PM
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When all the details get worked out I'd be interested as well.
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post #104 of 376 Old 02-22-2011, 06:56 AM
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Quote:
Originally Posted by Erich H View Post

How would you insert the boards between the different heights of foam? It looks as if you have the boards going all the way to the bottom of the diffuser. If there was a thin gap cut between each height, I could look at getting some very thin planks cut that would slide right into those gaps. It would look better than cardboard.



If someone wanted to use that without the boards, would it work as a normal diffuser? Or do we need a different design for that? Some people might be interested in those as an easier alternative.

The way I designed it, each of those foam pieces is independent. The user would have to glue them together. The tricky part is the spaces where there is no foam.

It could be done where the foam has an extra ~1/2" of depth and wells like you mentioned are pre-cut into the foam with the user sliding material in for the dividers.

Basically the material used for the dividers doesn't matter significantly. So long as it is fairly rigid it will be reflective at the required frequencies and that is all that matters.

To get the modeled diffusion you need the dividers. I don't know how radical the difference is without them but they are required to work as designed. I'm sure there would be improvements in sound without the dividers so you could make it optional. I don't know of a way to design specifically without dividers.
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post #105 of 376 Old 02-22-2011, 12:28 PM
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You need to make some adjustments when designing to use inverse panels.

Here is the normal panel you are proposing...


All good so far.

Now for the inverse of that panel....


This is where it falls over. You need the fins to extend the full height as shown in the drawing. You will see that the build height will be 133mm as opposed to the 102mm for the normal panel.
When mounted, the faces of the normal and inverse panels will sit at different distances from the wall. For correct operation, they need to be the same distances, so you would have to pack behind the normal panel with 31mm spacers.

As you can see, the N17+4 pattern optimises the depth usage for the normal panel, but not for the inverse.

What you need to do is to share the optimisation between the two styles of panels.

If you're using QRDude for the designs, tick the option for "1D panel will be used in a sequence that includes it's inverse"


Now click the "Optimise" option.

QRDude switches to an N17+6 pattern. Set the deepest well to 100mm.


Switching to the inverse panel you get...


The inverse now has the same build depth as the normal panel.

Whilst the design frequency has gone up to 1523Hz, this is the best you can do with an N17 when you are constrained to a build depth of 100mm.

If you want to turn on Auto-optimise as follows...


... you can step through the different panel orders to see what design frequencies you can achieves at 100m depth for both panels
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post #106 of 376 Old 02-22-2011, 03:41 PM
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Quote:
Originally Posted by Collo View Post

You need to make some adjustments when designing to use inverse panels.

Here is the normal panel you are proposing...


All good so far.

Now for the inverse of that panel....


This is where it falls over. You need the fins to extend the full height as shown in the drawing. You will see that the build height will be 133mm as opposed to the 102mm for the normal panel.
When mounted, the faces of the normal and inverse panels will sit at different distances from the wall. For correct operation, they need to be the same distances, so you would have to pack behind the normal panel with 31mm spacers.

As you can see, the N17+4 pattern optimises the depth usage for the normal panel, but not for the inverse.

What you need to do is to share the optimisation between the two styles of panels.

If you're using QRDude for the designs, tick the option for "1D panel will be used in a sequence that includes it's inverse"


Now click the "Optimise" option.

QRDude switches to an N17+6 pattern. Set the deepest well to 100mm.


Switching to the inverse panel you get...


The inverse now has the same build depth as the normal panel.

Whilst the design frequency has gone up to 1523Hz, this is the best you can do with an N17 when you are constrained to a build depth of 100mm.

If you want to turn on Auto-optimise as follows...


... you can step through the different panel orders to see what design frequencies you can achieves at 100m depth for both panels

Thanks for catching that and thanks for the tool. I will readjust after Erich gets a better idea of feasibility. I think the SketchUp I made should give his styrofoam guy a good idea to get estimates from.
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post #107 of 376 Old 03-09-2011, 07:52 AM
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Is there any update/good news to share?

I'm ready to handle the small back wall area behind my 2nd row seats, either with thin/small absorber behind each section of seats or a DIY sound diffuser that works nearfield, since 2nd row ears are about 20" or so from rear wall.

I can hear a echo among the center channel and my rear wall back to my DW lamiante screen, it forms an echo chamber!

Rear wall with corner broadband bass treatments:


Side walls/ceiling treatments:
LH side ....................................RH side
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post #108 of 376 Old 04-09-2011, 05:08 PM
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Is this still being considered?
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post #109 of 376 Old 04-10-2011, 07:23 AM - Thread Starter
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Is this still being considered?

It is, I just have to get through another group buy right now. Once I get caught up, I'll be spending more time getting this idea figured out.
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post #110 of 376 Old 04-10-2011, 07:39 AM
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Eric, Count me in on wanting some of these with my new HT plans...side and back walls having some diffusers would work very well.

Also I know you are busy but any updates on the Pallet from Poland?

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post #111 of 376 Old 05-18-2011, 11:26 AM
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I'm most interested in a 1D design, so that's what I've concentrated on.

Here's a hybrid styro/wood design with one piece for all the styro of each diffuser section.
Attachment 212297
The main and inverse panels would be made from one block (for cheapness) and nested for shipping robustness. Maybe, depending on manufacturing method, you could even leave the divider blanks in and not de-nest the two pieces at all. The user would make or commission hardboard separators and glue them in, using a styro assembly jig (that I also designed) to keep the spacing right at the front. Also the depth is 5.5" so you can build a housing using 1x6 lumber (for one period or several together with a separator between the styro pieces). The whole thing (one period of the main panel) would look like this:
Attachment 212298
and I think that each side could be used as an individual diffuser or they could be used in periods with Barker code modulation.

Having slots cut into the frame for the separators would be ideal, but is much more work. I think that as long as glue coverage to the frame is good it would work fine without.

I already made dimensioned drawings if OP wants to quote this in a range of ordered lengths. I also found some guidance for the material from some experienced folks at a different forum and I'd be willing to work with your supplier to find something suitable.
LL
LL
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post #112 of 376 Old 07-22-2011, 07:04 PM
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Erich H, I know you have stuff going on with the SEOS packs and such but do you have any updates on this?
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post #113 of 376 Old 07-22-2011, 08:06 PM - Thread Starter
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I had a meeting today with the CNC company I used for cutting the last round of flat packs. Hoping they will cut about 7 more different designs. The designs are for other DIY speaker being discussed at the PE forum. Should be interesting to see 700+ flat packs if pricing goes well!

Anyway, I did give them a drawing of a shallow picture frame type 'open box' to get a price on. But it was designed to hold rigid fiberglass or rockwool. So it's really going to be an acoustic panel for absorbing, not diffusing.


This thread sort of died without us really figuring out a good way to go on this. I talked with a company that can cut pieces of styrofoam any way we would want (large or small). And I know the CNC company will do the same if it was out of wood panels. The problem is that I'm just not sure what people actually want.


I can have the CNC guys cut angled grooves in 2 boards that act as the top and bottom of a diffuser. Then the end user can simply slide the slats into place. I just don't know the mathematics behind it. The 'open box' design I dropped off today could be modified to work as a diffuser. Or we go back to the foam idea.

I'm willing to try either method, but the smart guys would have to join in to help me figure out what's actually needed.
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post #114 of 376 Old 08-18-2011, 12:54 PM
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Quote:
Originally Posted by Erich H View Post

I had a meeting today with the CNC company I used for cutting the last round of flat packs. Hoping they will cut about 7 more different designs. The designs are for other DIY speaker being discussed at the PE forum. Should be interesting to see 700+ flat packs if pricing goes well!

Anyway, I did give them a drawing of a shallow picture frame type 'open box' to get a price on. But it was designed to hold rigid fiberglass or rockwool. So it's really going to be an acoustic panel for absorbing, not diffusing.


This thread sort of died without us really figuring out a good way to go on this. I talked with a company that can cut pieces of styrofoam any way we would want (large or small). And I know the CNC company will do the same if it was out of wood panels. The problem is that I'm just not sure what people actually want.


I can have the CNC guys cut angled grooves in 2 boards that act as the top and bottom of a diffuser. Then the end user can simply slide the slats into place. I just don't know the mathematics behind it. The 'open box' design I dropped off today could be modified to work as a diffuser. Or we go back to the foam idea.

I'm willing to try either method, but the smart guys would have to join in to help me figure out what's actually needed.

sorry, just joining the thread

i would be interested in this.
the issue ive had (thinking about most optimal, efficient way to build 1D QRDs of high-order) is aligning the well dividers and keeping them straight.

cutting slits into the top/bottom such that you can 'slide in' the well dividers would be absolutely wonderful.

you could then slide in a piece of foam/insulation to prevent resonation within the wells, and then a single piece of wood on top (to suffice as the well bottom) -- and then glue the gaps and move on to the next well.

much like this design:

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post #115 of 376 Old 08-18-2011, 03:31 PM
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the issue ive had (thinking about most optimal, efficient way to build 1D QRDs of high-order) is aligning the well dividers and keeping them straight.

cutting slits into the top/bottom such that you can 'slide in' the well dividers would be absolutely wonderful.

you could then slide in a piece of foam/insulation to prevent resonation within the wells, and then a single piece of wood on top (to suffice as the well bottom) -- and then glue the gaps and move on to the next well.

I say, why bother with the pieces at the bottom of the wells, use the styro for that if you consider it sufficiently reflective (as do some of the GS guys).

Also, there are two routes to go with the well dividers, either the slots in the top and bottom of the frame (more expensive I believe - or at least more work), or else a slot in the styro at the bottom and an assembly aid (jig) to hold the slats at the right place at the top. Put the frame around the styro, put the slats in place with glue to the styro, apply beads of glue where they meet the frame, put the jig(s) in place, and have a beer while it dries. The assembly aid would be kind of like this slat separator Ethan uses but extend out to the end of the frame. It could be made cheaply by the styro cutting company. It could be removed after assembly or left in to hold the slats in the right position and possibly damp them from resonating.
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post #116 of 376 Old 08-19-2011, 06:01 AM
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Quote:
Originally Posted by aackthpt View Post
I say, why bother with the pieces at the bottom of the wells, use the styro for that if you consider it sufficiently reflective (as do some of the GS guys).

Also, there are two routes to go with the well dividers, either the slots in the top and bottom of the frame (more expensive I believe - or at least more work), or else a slot in the styro at the bottom and an assembly aid (jig) to hold the slats at the right place at the top. Put the frame around the styro, put the slats in place with glue to the styro, apply beads of glue where they meet the frame, put the jig(s) in place, and have a beer while it dries. The assembly aid would be kind of like this slat separator Ethan uses but extend out to the end of the frame. It could be made cheaply by the styro cutting company. It could be removed after assembly or left in to hold the slats in the right position and possibly damp them from resonating.
ah, yes! the slat separator is a great idea.

looking at the well depth layout, it would be possible to glue the well dividers directly to the adjacent well's foam, except for wells which have max or close to max well depth (as the well blocks would be too short to get lateral support against the well dividers)

maybe for those wells (where well depth is a max), you could put some wood spacers at the bottom (at the very top and bottom vertical places within the bottom of the well) just to give the well divider something to attach to.

time for another recce' at home depot and lowe's over my lunch break
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post #117 of 376 Old 08-19-2011, 02:51 PM
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Quote:
Originally Posted by localhost127 View Post

maybe for those wells (where well depth is a max), you could put some wood spacers at the bottom (at the very top and bottom vertical places within the bottom of the well) just to give the well divider something to attach to.

Actually, I already modified the design once I started thinking about it more so that each slat has a minimum amount of "embedment" into the styro. So there won't be any slats without a firm position like the one I posted earlier in the thread would have. The downside to this method is that it reduces the acoustical depth of the diffuser (compared to the physical depth) and therefore increases the low frequency limit of the diffuser.

Your method would work just as well and retain more diffuser depth but require you to cut a few more pieces. If I were going to do that method I would cut four pieces (for the top and bottom of the full-depth wells of the diffuser I showed) of the separator material, the pieces being the width of the well and the depth of the full-depth wells. Then during assembly just tack one at the top and bottom of each of the full-depth wells using the brads that my staple gun shoots - but you could use screws, staples, glue and a spreader clamp, whatever.
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post #118 of 376 Old 08-20-2011, 06:00 AM
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Quote:
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sorry, just joining the thread

i would be interested in this.
the issue ive had (thinking about most optimal, efficient way to build 1D QRDs of high-order) is aligning the well dividers and keeping them straight.

cutting slits into the top/bottom such that you can 'slide in' the well dividers would be absolutely wonderful.

you could then slide in a piece of foam/insulation to prevent resonation within the wells, and then a single piece of wood on top (to suffice as the well bottom) -- and then glue the gaps and move on to the next well.

much like this design:

I like the way this one looks.

How about this for an idea:
  1. Using 1/2" ply, cut 4 frame pieces with dado slots for the dividers in the top and bottom
  2. cut pieces of 1/8" ply that fit between the dividers
  3. cut 3 strips that span width-wise behind the panel (used to back the spacers)
  4. cut small spacer blocks from cheap 2x material that can be used to set the depths of each 1/8" ply strip

Assembly:
  1. Glue the 4 outer frame pieces.
  2. Slide in and glue the dividers.
  3. Glue the 3 strips behind the frame.
  4. Place the correct depth spacers into each well and glue...there are three per well
  5. Place each 1/8" well strip into on top of the spacers and glue

I'll put together a sketchup which will show this better.

This should be very easy for a CNC shop to cut. It will also be very easy to pack. It might not be as light or cheap as sytrofoam, but I think I'd prefer wood. It will be easily stainable or paintable. I think it should be more durable as well. Since it will only use thin strips and spacers instead of full depth styrofoam, the boxes for shipping should be smaller too.

Edit: I just reread what I quoted and it is pretty much the same, but I don't think the foam is needed. Three small spacer blocks would be easier.
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post #119 of 376 Old 08-20-2011, 06:18 AM - Thread Starter
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I can definitely get them to cut flat packs for those. The ones that control the depth of each section could be slid into grooves as well. Basically built the unit from left to right, then cap the top.

That and the styrofoam difusser was planned, I just don't know the angles or depths to make the stuff. But if it can be figured out, I will certainly have them do it. Not a problem at all. They're in the process of working through about 500 flat pack speaker boxes for the DIY guys right now.
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post #120 of 376 Old 08-20-2011, 06:45 AM
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Quote:
Originally Posted by Erich H View Post
I can definitely get them to cut flat packs for those. The ones that control the depth of each section could be slid into grooves as well. Basically built the unit from left to right, then cap the top.

That and the styrofoam difusser was planned, I just don't know the angles or depths to make the stuff. But if it can be figured out, I will certainly have them do it. Not a problem at all. They're in the process of working through about 500 flat pack speaker boxes for the DIY guys right now.
I'll submit what I think will work best. It might be a little bit before I have time. (day or two)

I really think the wood version will be better unless its cost is huge in comparison. I could see the styrofoam version taking a beating over the years. The wood should last a very long time and look better anyway.

The wood should ship in a much smaller box too. Something like a 48" x 5" x 5" tube like what golf clubs ship in. The foam version would have to be much wider.
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