Bass Trap Madness

miroslav

Cosmic Cowboy
As I mentioned in another thread...during the past week I was building some mega-bass traps for my studio.
These traps were built with the low-end in mind, rather than more typical broadband control (already have that)...so they are substantially beefier. I also wanted them to be portable, rather than wall/corner mounted...so they are finished on both sides, and can free-stand, and even be used for gobo-like purposes.

Each trap has 3 sheets of 2" OC 703 for a total of 6" of insulation in each trap, and the finished trap width is 7.5" with the wood mouldings.
Each 3-layer 703 sandwich has one sheet of OC 703 FRK, which has the aluminum/paper backing on one side, and its purpose for this build was to act as a membrane to further enhance the low-end trapping and less of the mids/highs by reflecting them on the one side of the trap... but since these are two-sided traps, they can also be turned around to the soft side that has the basic OC 703, which will do more broadband trapping.
So the traps have two ways they can be used, and due to the type of framing, they can stand alone or be stacked and configured in a variety of ways.
The point of this was mainly so I could move them into (behind) the mix position when I'm mixing...and move them out of the way when I'm not, since there is no way to permanently mount them there due to gear and some existing acoustic treatments....and I can also to use them in other areas of the studio as needed.

Along with that, I also wanted something different than the typical wrapped-around cushion look...and instead went with a more finished wood frame, with the cloth only on the front and back of the traps, and not on the sides.
Some folks like to cut holes in the wood frame sides when they are doing the wrap-around type, the idea being that you expose more of the insulation and get more out of it...but some tests that I've seen show that the extra side insulation area doesn't really add a whole lot to the traps functionality.

Anyway...I was going for some really nice looking traps, and here's some pics of the project and what I ended up with.

I started with 12' planks...8" x 3/4"...and then cut the individual pieces from them on my table saw . The 12' long planks were a bit awkward to work with until I made the first cut...but I managed to not fuck up any of the cuts. :D

BassTraps_01.jpg


From each 12' plank I first cut out the two long and two short sides for the traps. I had zero room for any errors since every square inch of the wood was going to be used for something.

BassTraps_02.jpg


Then from the cut pieces I ripped the moulding strips that would be on the finished traps.
I used 7 planks total...the 7th one was needed for the additional moulding strips, since I could only get one side worth of mouldings out of the cut pieces that I used for the sides and tops. Some basic math - 8" wide planks, (actual 7.25")...6" width needed for the sides/tops, which left about 1" for the moulding strips on one side of the trap, and the 7th plank gave me the mouldings for the other side of the traps....and of course, I had to account for what the table saw ate up.

BassTraps_03.jpg


I then assembled the basic sides/tops of the traps, using wood glue and screws on the outside, and I also added some 3" L-brackets on the inside to stiffen things up.

BassTraps_04.jpg


Then I did some light sanding, and staining, and I also gave them a light coat of satin finish polyurethane just to add a dull sheen to them, which I then buffed out with a scrubbie pad, as I didn't want a real shiny finished look.

BassTraps_05.jpg


I then repeated the whole process with the moulding strips. These actually took longer, due to the sanding, since the edges needed to be rounded off a bit on the each moulding strip for a nice look and feel.

BassTraps_06.jpg


Then I turned my attention to the 703 insulation.
I didn't want any fiberglass particles to ever be freed from the traps, so I wrapped each 3-layer 703 sandwich with a real thin, 0.4 mil plastic (basic painter's drop cloth), and taped up the seams, and I also reinforced the side corners with some extra tape, so the light plastic wouldn't rip on those L-brackets when I stuff the insulation into the frames.

BassTraps_07.jpg


This is how the 703 sandwich looked after wrapping. The very thin plastic seal will have basically zero effect on the bass trapping...while providing 100% sealing of the fiberglass. I just didn't want any fiberglass irritation in the studio, considering that the traps would be moved around a lot....and it certainly isn't something you want to be breathing in if you don't have to. Cloth alone might be OK for a mounted wall trap...though I would seal them too...as the fiberglass particles are small enough to push out through the porous cloth.

BassTraps_08.jpg


Once the 703 was sealed, I was able to take the rest of my trap building inside, and I ended up finishing them off right in the studio....starting with a layer of polyester felt.
I was going to just use the Guilford of Maine FR701 fabric at first, but decided that I didn't want to see the 703 foil or the yellow fiberglass peeking through the GOM fabric pores...so the black felt took care of that, and also provided a light "cushion" to the 703 FRK side, so that there wouldn't be too hard a reflection of mids/highs, but I would still get the effect of the FRK membrane on the lows.

BassTraps_09.jpg


After the polyester felt came the Guilford of Maine FR701 fabric, which I wanted for both the fabric quality and the final look. Yeah, it cost more, but like I said, I wanted really nice looking traps, and not something that would look like stuffed sofa cushions. Both the poly felt and the GOM fabric were each stapled to the edge if the frame...same process on both sides of each trap.

BassTraps_10.jpg


I then stared on the moulding strips that would cover the stapled edges and give the traps their finished look. I made sure to put down a nice bead of wood glue, both for the moulding strips and also to seal the seams of the GOM fabric so the threads would not ever come unraveled on the cut fabric.

BassTraps_11.jpg


I then screwed down the side mouldings using the same type of screws that I used to assemble the sides of the traps. They are GRK Star Drive Trim-Head Finish/Trim screws that can sink in like a finishing nail, but have the better grip of a screw, and they look really nice with the brass color on these traps. Since I was also using the wood glue, I didn't need to go nuts with a lot of screws per moulding.

BassTraps_12.jpg


Same thing on the top/bottom mouldings...same thing on both sides of each trap.

BassTraps_13.jpg


These are the 6 finished traps, and TBH, I was quite impressed with how well they came out, and the fact that I didn't have any major fuck-up from start to finish...and everything came together the way I had envisioned it in my mind and how the math/measurements were computed. Nothing wasted.

BassTraps_14.jpg


These are certainly not for everyone, and they took some time, and they are not the cheapest way to go if you just want to do quick, basic wrapped-around traps for the walls...but I did some shopping around for ready-made traps, and this size of trap, with this thickness, using 703 and 703 FRK, not to mention the finished wood look...would have cost me 2-3 times more ready-made...but I also didn't even see anyone that had anything that looked like these.
Most everyone sells the same old wrapped-around stuff, that has no back side, as it's meant to be mounted against a wall or corner.
So in the end...I'm quite happy with the results, and glad I went the DIY route.

I'll be testing them out this weekend and doing some measurements with and without, and trying them in different positions and configurations in my studio...though I expect they will perform as intended, since I did a bit of research on how best to build them for my purpose.
 
:o I'm primarily amazed at the amount of guitars on the bottom picture :o

Really well made, I love the darker finish makes the wood look much more classy. Do the plastic wrappings not reflect the real high frequencies? 'cause I worry about escaping fibers from my bass traps which I finished with just cotton. I might redo them in your style some day...
 
That looks fantastic Miro. Get some players in there to record music. I want to hear how it sounds.
 
Last edited:
Thanks guys!

Do the plastic wrappings not reflect the real high frequencies? 'cause I worry about escaping fibers from my bass traps which I finished with just cotton. I might redo them in your style some day...

It's very thin plastic cloth....0.4 mil...and they even have 0.3 in the paint isles at your hardware store, but for some reason it only comes in bulk rolls...way more than you need. I found the .4 in a smaller roll, and went with that.

If you take a piece of the plastic, wrap it over a mic...and then go record anything you want, you will see that it has no, noticeable effect, though maybe if it's something very delicate with lots of very high-end content, there might be the smallest effect.
I also have the layer of felt over the plastic-covered insulation sheets...so that takes care of any high-frequency reflection...and everything else will just blast right through the thin plastic. :)

If you're using fiberglass, it is exceptionally irritating if you get it on your skin or breathe it in...though TBH, I would cover even rock-wool or those "safe" types of insulation, because they ALL shed their fibers, and having any kind of fibers coming out of the traps only means it will end up in the studio. I mean...even lots of cotton fibers can be annoying...like have you ever cleaned the screen from you clothes dryer, and watched all those tiny lint particles just fly all over the place...and they probably made you sneeze. :D
 
The other option to combat fibres is to use polyester sound deadener, the dense acoustic stuff, you do not even have to cover it. There are also wool products that are designed for acoustics. Does cost more, but no fibres.

Alan.
 
Back
Top