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Discussion Starter · #1 ·
I am toying with the idea of making some bass traps like the ones on Jon Risch's website. I'm wondering if you have to have some sort of computer analyzer that will tell you where to put them, how many you need, and all that complicated stuff. Is it a bad idea to just make one or two and put them in a corner. Could I potentially harm the performance of the sub. Are there locations that generally do well for bass traps?
 

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The bass traps described in Jon Risch's site are of the broadband absorbtive type. That is, they are not tuned to a specific frequency as is the Helmholtz resonator type. In general they work best where they can "soak up" the most LF energy, generally in the corners where all three major room modes are active. If you have access to an RTA or similar instrumentation you can optimize the location. You are unlikely to do any harm with them.
 

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I've never heard the BFD, but my experience with parametric equalizers yields results which are grossly inferior to proper room treatments. And the Jon Risch bass traps are REALLY cheap!
 

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I have five of the Jon Risch bass traps in my listening room. I don't think I could live without them.


If you place them in the corners, it would be tough to harm your sound with them. Since they are broadband absorbers, if they are in the corners, they can only soak up spurious sound energy - regardless of the frequency, you probably don't want to hear any sound that's been to one of your room's corners and back.


I started by making just one trap, but as soon as I heard its effects, I had to build another. Once I heard the difference between one trap and two, I had to build more, and I have no regrets - improved sound every time. Despite having five, I will eventually build more as time allows.


-Tweak
 

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Discussion Starter · #8 ·
sounds good, how easy are they to make? I've never worked w/insulation before. What size did you guys get and what precautions do you take. Oh and what did the cost end up being for one bass trap? How long did it take etc...Thanks.
 

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While the bass traps are not easy to make, construction doesn't require any special skills. Because of the insulation, however, you will need a work space that is separate from your living space (basement, garage, outdoors, etc.). You will want to wear long sleeves, long pants, gloves, eye protection, and a dust mask. I also recommend taping the gloves to your sleeves - without doing this you are prone to exposing your wrists.


I started by building an 18" trap. As you can imagine, the larger the diameter, the lower the frequencies it will absorb. I had a nasty peak at 43Hz, so I built the largest trap I could fit in the corner. A 16" trap will supposedly absorb down to 80Hz. I didn't take any measurements after bulding just the first trap, but I can tell you that adding a second 18" trap along with three 14" traps sure helped smooth out the 43Hz bump. Since the traps only soak up spurious energy, I recommend building the largest ones you can reasonably fit in your room.


It took me between 3 and 4 hours to build each trap (the build time goes down with experience - your first one may take you an extra hour). You can also reduce build time a bit by making more than one at a time. When I built my first trap, I spent too much time cutting out the support circles - these do not need to be very precise at all - the overall shape should be round, but it does not have to be smooth or perfectly round. It does pay to spend time getting the wires tight and rattle free - minimize wire-wire contact, and use caulking or adhesive wherever there is either wire-wire or wire-wood contact.


Cost per trap should be around $30 or so. The materials you will need are: roll of fiberglass (6.5" thick, unbacked - $18), two sheets of .75" MDF ($7 for a 2x4 sheet), 4' hog fencing (the price will vary greatly - I think I got a 30' roll for about $30), 1" high loft polyester batting ($10 for a king size sheet), burlap or speaker grille cloth (can't recall the cost here, but fairly cheap), and adhesive (I recommend the classic Liquid Nails Construction adhesive (it's the stuff in the gold colored tubes and costs less than $2 per tube). I highly recommend obtaining a caulking gun if you don't already have one - that will make the adhesive cheaper to buy and much, much easier to apply. I believe I used 3 or 4 tubes of LN per trap. I did use the LN liberally - the fiberglass must be air tight - any leaks will greatly reduce the effectiveness of the finished trap.


Do note that some of the materials you buy will be enough for more than one trap (the fiberglass, hog fence, and poly batting fall in this category). Although I used burlap to cover my traps, I recommend using speaker grille cloth instead. Burlap is very dusty stuff, and it gives off a slight odor for a long, long time. I can't seem to keep my TV screen clean for more than a day since the burlap made it's way into my home (even though I thorougly vaccuumed the finished traps before bringing them inside) - I will be converting to grille cloth when I have time to do so.


I hope I answered all your questions. If not, just ask...


-Tweak
 
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