I just finished up what turned out to be quite an investment in time... haven't had a chance to fully install & test them, yet, but hopefully will this week.
I'm a home theater guy with 12X17X8 dedicated room - 7.1 surround. I wanted to add in some trapping for some boomy bass. But I also wanted to tackle the back wall (which has 2 side-by-side windows) about 4 feet behind the primary seating position. Not ideal - but it is what it is.
I originally
posted here, looking for some diffuser help. After some discussion, my take was that the distance between the primary seating and the back wall wasn't ideal for traditional diffusion... to make this short, a
back-and-forth with Boggy led me to design my own modified binary slat diffuser with absorption. The overall impact won't be as robust as a traditional diffuser, yes... but it's better than nothing!. It's total size is 6'X5' - 2" thick 703 insulation - and it is rigged to hang from the ceiling in front of the windows.
In terms of the bass traps, because of the size of the room, wall constraints, and the current placement of speakers and built-in component cubbies (many of which have wires run to them through the walls, etc., I tried to make the traps as tall and thick as possible to fit within my room. They definitely ended up being a custom creation - trying to get as much as I could out of them. I created four corner traps that are 54" tall and 24" wide - 8" thick 705 insulation, one corner trap that is 33" X 24" - 8" thick 705 insulation, and one wall mounted trap that is 48"X24" - 4 inch thick 703 insulation.
Now, I know that there are minimalists out there that don't believe in heavy framing for their traps. From a performance standpoint, the less frame the better... and from a cost/time standpoint they are DEFINITELY WAY EASIER TO MAKE! But, I wanted something that was going to look good without sacrificing too much performance... so I spent quite a bit of time and money making frames.
My supplies are fairly straight forward. I found a
distributor in Maryland that sold JohnsManville 703 insulation board and Knauf Ecose 705 insulation board. The primary wood I used was Pine #1 (I did use Pine #2 for the base of the frames and for the sides that aren't visible). If you ever plan on using/staining this kind of wood, plan on many MANY many hours of sanding and prepping the wood. Otherwise, your efforts will be for not. For the slat diffuser I purchased furring strips. And, of course, loaded up on tons of other supplies, countersink drill bits, screws, block sanders, stapes, brad nails, wood glue, sand paper and stain and material (Cloth) and finishing strips. In terms of tools, I relied heavily on: a drill (with a 3 1/2" hole saw bit), a power miter saw, an orbital sander, a jig saw, a Dremel (sanding and wood removal attachments), a pneumatic nail gun (both finish nailer and brad nailer), a staple gun, and a cabinet making Bessy Clamps. Honestly, making these without those core tools would be almost impossible.
For the cloth, I purchased "utility speaker cloth," burlap, and quilting cloth (which is nice because it is relatively thin like muslin BUT comes in lengths of 108" and can be purchased in a multitude of colors)... all at JoAnne Fabrics. Just as a word to the wise, if you're in the market for cloth, search the net for coupons for JoAnn Fabrics. I purchased all of my cloth with 50% off coupons... which saved me a ton of $.
For the bass trap frames, I opted to drill 3"+ holes into the framing... for those of you interested in doing this... there are several things you should know. First off... you need a solid drill with a ton torque. A cheap cordless drill will suffer and a low amp will flame out and die (believe me, it happened to me)... I suggest a good 9 amp or better drill (
this is the one I used). Secondly, the drill and the hole saw bit make a nice hole, but they are rough on the wood and the resulting holes require a lot of sanding (note, MDF board might not have this problem... I chose pine though, because I wasn't comfortable using MDF due to some of its carcinogenic properties... especially when it is airborne with dust particles... also I've read it can smoke and release fumes when heavily drilled). I used various dremel sanding bits and then leaned on a randomly orbiting sander to finish off the smoothing of the outer rim of each hole. Talk about time consuming (and very tedious work!). If you're wondering how many holes I drilled... this board says it all:
Here are a few photos of the frames during assembly. You can see I counter sunk exterior screws... and added some bracing on the inside.
Here's a shot of the slats after being sanded and one round of staining...
For the bass traps, I stapled the cloth onto the face, trimmed, and then attached finishing strips with a brad nailer (and wood glue). The holes were covered by stapling material on the inside of the frame. I used a lot of staples on the inside to make sure the material wouldn't slip when I inserted the tight-fitting rigid insulation.
Also, for the traps going in the back of my HT room, I faced them with kraft paper (front top and sides)... to attach the craft paper I used a spray rubber cement that the insulation contractor sold me. Very sticky stuff!
Here's some shots of the finished frames...
Once the frames were finished and the insulation was installed, I covered the backs with cloth and tight fitting burlap. Here's some shots at the finished product (again, lots of staples):
As for the modified, slat diffuser... I made the frame (note, instead of wood screws I used heavier hex-bolts)... then stretched material over furring strips that I brad nailed to the inside of the frame... Here is a pict looking at the back of the frame. This will give you an idea of how I stretched the fabric and affixed it to the frame by pinning it between a furring strip and the frame. I used an adjustable slide ruler to make sure the depth of the furring strip was uniform over the whole frame. Once installed, the material was placed in such away that it gave me about 2 1/4" of space on the backside (room for insulation) and about 3/4" space on the front for the slats and finishing touches!
On the backside of the material, I installed two 2 1/2" thick furring strips (notched to fit around the firing strips holding the material) horizontally... spaced about 2 feet apart. I don't have a photo of them... but they were installed to help hold the insulation AND to give me a place to nail the slats in the middle. In terms of sequencing for the slats, I used a
binary sequence that Boggy provided in another thread to dictate the distribution of slats on the diffuser.
The furring strips holding the material and the two larger firing strips running horizontally across the mid section of the frame gave me 4 solid points attach the slats with a brad nailer. Here's the finished frame without insulation...
Adding 703 insulation in the back (behind the material) was straight forward. It bulges just enough to touch the backside of the slats. This is hanging from the ceiling about 3 1/2 feet behind the primary seating position. This is a really bad picture that does it no justice... but here is a crummy shot. It actually looks very warm and inviting... and isn't as intrusive as it appears in the photo.
Anyhow, those are the finished products born from some discussions on gearslutz. Perfect? By no means. But, once I have the time to measure and calibrate, I'm hoping that I will be one step closer to sonic goodness!