Acoutical Diffuser construction advice - Router Forums
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post #1 of 57 (permalink) Old 11-10-2016, 11:40 AM Thread Starter
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Default Acoutical Diffuser construction advice

Hey guys, my main interest is currently in Home Theater & I am in the process of building my own HT. I have the plans for the "Leanfusor," but not being an expert in wood working, I thought I would ask here for advice. Seems like a very nice forum (vertiscope owns Hometheatershack.com where I spend most of my time).

I guess I need advice on the best way to complete the build. Can't post links yet, but this is the URL. You should be able to copy it and paste it into your address bar. Let me know if it doesn't work.

arqen.com/wp-content/gallery/sound-diffusers/sound-diffuser-calage1-w700.jpg

I'm thinking I can build the endplates (maybe 2 more for along the length at intervals for stability). in the correct shape & attach 2"x4"'s to them I think I could router the 2"x4"s before attaching them, but I don't know if that is the best way to go about it. Thus the need for this thread.

I help people with time/money saving HT advice all the time, because I know so much about it. I figure you guys are the go to woodworking guru's so any advice on any equipment that I would need & the best way to go about it would be greatly appreciated.

Thanks in advance
Quenten

Last edited by Tonto1; 11-10-2016 at 11:51 AM.
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post #2 of 57 (permalink) Old 11-10-2016, 11:57 AM
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Hi Quenten and welcome. Here is the working link http://arqen.com/wp-content/gallery/...lage1-w700.jpg . The first example could easily be built in a few minutes on a table saw. I see you don't have one but it can be done a bit more slowly with a circ saw and a straightedge to guide it. Easiest but not the prettiest would be making it out of a sheet of plywood or mdf.

The second example is much more efficient as the illustration shows but would require a router. Even better if the router were mounted in a table but not absolutely necessary. The profiles can be done with beading bits. But there is an alternative to that too but a little more pricey. You could just buy ready made dowel rods and glue them to something resembling the first illustration. You can hold them in place with masking tape while the glue dries, maybe only a few pieces at a time. That would achieve the same effect as machining all those curves on individual pieces and gluing them together anyway as there is no other way to combine all those profiles.

Something in between the two would be much cheaper and much easier where you take the first profile and replace the flat strips added to the base pieces and replace them with dowels. You get rid of the hard flat edges that way. You could also cut dowels in half and do that which would be cheaper again and eliminate the traps that would be formed at the back sides of the dowels but you need a table saw for that.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #3 of 57 (permalink) Old 11-10-2016, 04:45 PM Thread Starter
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Hey C-Chuck, thanks for the quick reply. I posted those pictures too fast this morning & didn't really mean that design. This is the one I am thinking about.

http://arqen.com/wp-content/media/ac...al-588x315.jpg

Same dementions, no rounded tops! The problem is all those wells of different depths. This design should be a bit simpler. I was thinking I could use plywood & lumber for the basic design. That would be easy. I also thought the easiest plan would be 2x4's on top of the basic frame which I could router ahead of time.
I hadn't considered using my Circular Saw with a guide. The Milwaukee would be fast and certainly has the power for the job (15 amps). Faster than a router, I don't know. There would be many cuts with the circular saw...unless there is a special blade for that purpose (cutting grooves). If there is, that would be ideal. But that is why I came here. I felt you guys no just about everything about tools & woodworking. I think I remember in high school seeing a table saw with a dado blade that cut grooves. Does that sound right? Anyway, this is the basic plan for 1 of the 7 panels which when completed would hang side by side on a French cleat. I'm thinking I would make them 6 ft long. These are the instructions he sent me. I have the depths of each well on another email. I will look them up.


Quote:
Hi Quenten
Everyone seems to love fractal diffusers, but to most of us they look ridiculously hard to build. I've tried to break it down for you with this modular fractal stepped diffuser.
I'd like to introduce you to my favorite diffuser design: the Leanfracal. You may have seen it featured on the Arqen.com homepage, or read about it in my diffuser design thesis (where it's known as A1-Frac).

Click "Display Images" to see me (señor Leanfractal).

The Leanfractal is my personal favorite because you can mount it using the same profiled modulations that are given for the Leanfuser. Mounted this way it can perform better than my other fractal diffuser design, the Stepfractal (B2-Frac).

The Leanfractal is also simpler to build! It's a straightforward extension to the Leanfuser. In fact, you can build an array of Leanfuser panels first, then upgrade them later to Leanfractal panels.

Here's how to build it:

Step 1: Build Leanfuser modules according to the A1-LF fabrication drawings I sent you earlier. If you can't find this document, see my older email titled "Here are the free DIY diffuser blueprints you requested".

Step 2: Build the small fractal cells. Details about them are given in the FAQ here. One way to make them is on a milling machine, like Schaap has done here and here. If all you have to work with is a Dremel, a 5/16 Dremel router goes just deep enough to cut the middle fractal groove in Schaap's version of the design. In this case you would also need a Dremel router table which is inexpensive.

Step 3: Mount the fractal cells onto the Leanfuser modules. You now have Leanfractal panels!

Click "Display Images" to see Leanfractal panel assemply

Step 4: Mount your Leanfractal panels using the same profiled modulations recommended for the Leanfuser (To learn how to mount 5 or 7 panels, see the last pages of the A1-LF fabrication drawings document). If you want to instead mount 3, 4 or 6 panels, see the FAQ.

Click "Display Images" to see Leanfractal array (Profiled Modulation 2)

And that's it!

FYI, I'm using the words 'modules' and 'panels' interchangeably. In earlier work I always called them modules but 'panels' is more intuitive to most of us.

Also, keep in mind that all diffusers will exhibit a small amount of absorption. In general, the rougher the surface, the more absorptive, so fractal diffusers tend to be more absorptive than their non-fractal siblings. Some absorption is inevitable but to minimize it, varnish the surface of your diffuser to make the material as reflective as possible.

Tim Perry
Acoustic Designer
Arqen.com
I am open to all suggestions, but just like everybody, I'd like to consider the cheapest solution while maintaining quality.

Last edited by Cherryville Chuck; 11-10-2016 at 07:50 PM.
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post #4 of 57 (permalink) Old 11-10-2016, 04:53 PM Thread Starter
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Wow, I just typed a long reply, clicked post & it disappeared! I'm at work now, will see about rewriting it later. That's for the quick reply Cherryville Chuck!

The jist of it was:

1) Build the basic frame, router the groves in a 2x4 & glue/screw them on.
2) Use my Milwaukee to cut the grooves (is there a special blade the it could use to make wider cuts?
3) Would a table saw with a dado blade cut the grooves?

Thanks for all your advice.
Quenten
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post #5 of 57 (permalink) Old 11-10-2016, 06:25 PM
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Welcome to the forum Quenten

I'm sorry I don't have any advice , but HT is one of my favorite subjects ,so I will be watching your build closely if you share it with us .

I know a guy that designs home theatre rooms in his new homes , and I know he mentioned the ceiling was not level in order to suppress standing waves .
These diffusers your making seem a little differant from the way I'd approach it , but will be interested to see how you make out

I don’t always insulate , but when I do .
Ok ,I never insulate

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post #6 of 57 (permalink) Old 11-10-2016, 08:03 PM
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Ok Quenten, I fixed the link. First, that build is a layered build. The outside pieces are are attached to one piece of panel board. The middle part of the base has been built up with layers of something and I really don't recommend dimension lumber for this as it tends to warp, cup, and bow with changes in humidity and temperature. The individual profiled pieces are attached to that and it depends on the scale of the size as what they could or should be made of. Yes they can be profiled with a dado set on a saw. They could also be cut with a router and a straight bit with an edge guide on a router or on a router table but this method is slow and there is a lot of wear and tear on the router and bit. Best overall method is to use both. Get close with the table saw to remove the bulk of the waste and then finish with a light cut with a router to get a better finish. Depending of the size of the pieces you might also be able to build that from mouldings available at your local hardware store and then all you have to do is cut it to length.

By the way, I have physics in my education and the 1/2 round dowels will do a better job of dispersal. The distribution pattern (reflection i.e.) will be almost totally random.
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post #7 of 57 (permalink) Old 11-10-2016, 08:11 PM
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Charles I thought the same thing . Not liking the idea of flat surfaces in the equation

I don’t always insulate , but when I do .
Ok ,I never insulate
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post #8 of 57 (permalink) Old 11-10-2016, 10:36 PM
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Half round molding should be relatively easy to find - Home Depot carries 1" x 1/2" x 12' long polystyrene molding as well as various sizes of wood half round.
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post #9 of 57 (permalink) Old 11-11-2016, 12:52 AM
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Welcome to the forum Quenten.

Ross,
Rockhampton, Queensland, Australia


Enjoy the knowledge of others that can be found within.

‘Members are requested to add a first name in their profile as we are a very friendly bunch here'.
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post #10 of 57 (permalink) Old 11-11-2016, 02:23 AM
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Back when I was a HI Fi nut (60's to 90's), any wood surfaces were a complete no no. Thick carpet and curtains with fabric furniture was the answer. I knew several people who papered their walls with carpet tiles.
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