Where did you find the DIY projects?
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the Jon Risch site is very good for these. However, you do need to make a bunch of them. When room modes are excited a few placed in the corners will not make a very big difference. I often hear people tell me--these traps don't work. Well, they do, but room modes are compounded by the surface area of wall(s) and thus need a large portion of the wall covered to relieve the pressure that is causing the problem.
For problematic rooms like mine ( highly reverberant) commercial tube traps work extremely well. I doubt that any other treatment would work as well. The traps need to go from floor to ceiling, and all of the corners and first reflection points need to be treated. Also, any extended reflective surfaces.
Its not a sightly solution, but highly effective.
One problem with many tube traps in a room is that they will eventually tip the frequency balance, typically leaning out the midrange.
I just completed a full range trap/system. My ideas came from the designer of RealTraps.com. Actually, search for bass trap on the web and you will find the first site Ethan Winer used before he started realtraps.
I made 3 different traps. Two low bass traps, two midbass traps and 2 mid/high traps. mine started with his ideas but I made them a little different. No way would my wife let me hang them on the walls. I made free standing boxes about 4 feet tall. My base boxes unlike Ethan's have insulation for the faces so that I could place them around the room to get mid/highs. Therefore, all of my boxes are good for mid high as well.
My system is not optimal since I am not treating all walls. BUT, the improvement is amazing. I have JmLab mini-utopias with VTL tube gear. I just moved into a new house and to my horror the new living room made my system sound like a boom-box. REALLY muddy. Now the bottom end is so much tighter. Second I am using the strictly mid/high boxes on the front and rear walls. The soundstage is great-while the speakers just fade away. I made them look like art-well a little like art anyway.
My placement is as follows. One low and one mid bass trap behind the speakers and in the corner. That is one side a low the other a mid. Then a box next to the speaker along the walls to kill specular reflections. One gets a low the other a mid. Last, The back wall gets a larger, 4'by 4' mid/high and another I place one between the speakers. My rear wall is about ten feet back so that one is not too dramatic of a difference. The one between the speakers really pulls the stereo image out. Since my panels are free standing I move this one around since my speakers are on either side of a fireplace.
Sorry, this was rather long but this type of works very well even if you cannot cover all the walls. The physics theory is sound and in pracitice it can make a huge difference.
I made some traps to tame the highs behind my Martin-Logan SL3's. I got 6 swimming pool noodes and covered them with material from the company that supplies tube traps (silent source - link from the tube traps page) - the noodles are bubblegum pink. I then attached 3 tubes to the wall behind each speaker with velcro, spacing them about an inch and a half apart. I have fournd that they smooth out the strings on symphonic works - they sound more rounded and fuller. I think I need to add at least one or two noodles behnid each speaker. Next project is corner traps...gotta find something better than chicken wire, though. I was thinking of noodles placed in a ring. secured to top and bottom wood end caps using dowels, and stuffing fibreglass in-between, then using the same material as before to make a tube sock. Any thoughts ?
Rives, your company makes the PARC room correction processor. Would it not be better to be proactive and prevent the room resonance in the first place with a room correction processor. The problem that I see with tube traps is that they not only attenuate the resonant mode frequency but all other frequencies in that range as well. The spike is still there, but the problem now is that the surrounding frequencies have been attenuated too much. Tube traps need to be more frequency selective, and that's not going to happen. Doesn't the PARC attenuate only the frequencies that cause the bass boom and leave the others untouched? To me it would make more sense avoiding room resonance in the first place by having a correct room dimension, constructing walls with ASC iso-wall damp material, using a room correction processor, etc.
Redwoodgarden: You are correct. My order of best possible scenarios are as follows:
1. A room with good modal spacing--thus no prominent modes to create a problem. No need for traps, resonators, or electrical correction.
2. A room with a built in Helmhotz resonator that is specifically tuned to the right frequency (this is far more difficult to do than most people would imagine and can actually create a new set of resonance problems that most people don't even recognize--but if done correctly it works very well).
3. An analog parametric compensation device that can very specifically tune to the problem frequency(s) and not corrupt other parts of the signal. This is exactly why we designed the PARC.
4. Broadband attenuation through a pressure relief (bass traps). This can work if the problem is not very severe and is naturally a low Q factor (broad band). It does not work well if it is a high Q factor and needs high attenuation. Hihg Q > 2.5 and high attenuation would be > 5 dB.
We designed the PARC because most rooms are not designed with proper modal spacing and have bass boom. It quickly becomes the only practical way to deal with the problem. We also spent a tremendous amount of time insuring that it was transparent and did not cloud the signal in any way. If anyone heard the demonstrations we had at CES it was remarkable and I'm very pleased both with the results we achieved and with the response we got. It is a fully progammable unit that can adjust the frequency, Q (width of attenutation), and amount of attenution. You can read more about it at PARC