I've made 3 types of traps. Rigid FG and cotton panel traps. Helped a friend with tube traps up to 20" inches diameter from pipe insulation. Some half filled with rock wool. I've also made membrane traps, using 1/8 and 1/4 hardboard as membranes.
The latter was the most effective with bass and didn't affect higher frequencies as much but were difficult to build and the least understood. To work their best, they should be solidly mounted with some air space behind them. They are often mounted diagonally across corners to maximize the air space behind them, without extending into the room and that air space will extend the maximum depth as well as the total effectiveness of the design. The total size and the material of the membranes is a big part of the equation and, in reality, it seemed that increasing air space beyond a minimum had reducing benefit. A membrane effective at 50Hz would be 4 times the area of the same material for 100Hz. Darn square root function.
I seriously doubt that tubes traps internally reverberate any frequecies inside 1" thick FG. It's just that they include an air space, making that 1" more effective. Maybe, some additional benefit when that air space is 1/4 the wave length but that's based more on total thickness of the material. A 4" FG panel placed diagonally across a corner would have the same benefit but with the added thickness. However, my results were even better with two panels, and twice the area parallel to the corner walls. Almost 1.414 times better.
http://www.soundonsound.com/sos/aug98/articles/practicalacoustic.html
What I call "membranes", they call "panels" and what we have called "panels", they call "mid and high absorbers". Realistic numbers, for a change.
It isn't a question of one type being better than another. It's just suitability. |
That's organ PIPE :-) no offense to my Catholic friends. |
Thanks Neil and Dan,
I did get your email :) Appreciated much:)
I did leave my tube traps fully covered:( I will remove half of the outside covering and also seal all my seams better too..
Take care
Mike |
Ah, that's probably the reason for the suggestion to use some type of plastic sheeting around 1/2 the diameter. Supposedly, you can tune the amount of reflection by turning the tube trap. I did that on some of my traps but I have to admit I was not able to find much of a difference. Probably because I didn't use a sheeting that worked as well as some others. |
I think that you guys are describing a Helmholtz resonator? If this is the case - Helmholtz resonators are tuned towards very specific frequencies. The application is completely different to a panel - a resonator only removes the frequency it is tuned to, whereas panels remove a wider band of frequencies. The frequency band and the level of attenuation depends on the thickness of the panel, the density of the material, and how far it is placed away from reflective surfaces. |
Dan (LOL) I sent Mike Jon Rische's site and another DIY site as well. Your interpretation BTW is incorrect (as far as all the info I've read anyway). "half open" in the context of tube traps , means that half of the exterior curved surface has to be wrapped or covered. And the other half of the surface, the fiberglas is exposed.
If you've ever seen an ASC tube trap, they are marked as to which half is which so the user can orient them as desired -- meaning that if you turn the open side toward the wall, they absorb mostly bass, but little HF. The tube interior should be left open to provide a resonant chamber which dissipates the bass energy (sort of like an organ pope in reverse ;-) |
Don't know what Nsgarch replied, but his description makes perfect sense to me in light of Jon Risch's tube trap recipe. Half solid, half open means to me that if you look at the tube from one end then 1/2 the diameter is filled with material and the other half is open space. The idea is that the waves are "trapped" for a certain length of time and more slowly released back into the room. This would help bass bumps in certain frequency ranges. The diameter of the tubes determines how low of a frequency will be affected by the tube trap. I can't remember the exact numbers but I think that a trap of 16" diameter is good down to a couple hundred hertz. I've heard from Ethan Weiner that placement of bass traps may not be all that critical, they just need to be in the room. But I would encourage folks to investigate that since I may have taken his words out of context.
I have no idea if tube traps are better than panel traps for bass. I do know that GIK has a good reputation and loyal following. As does Real Traps.
I use a combination of 12 tube bass traps and 5 panels, all DIY. I've also recently added some second hand treatments from Eighth Nerve for corner treatments. I've found that any one treatment method alone does not do much. When several treatments are used together the results are much, much better.
One issue with all of this is that some traps and absorption devices may also affect frequency ranges that you may not necessarily want them to. I'm sure the pro's know how to get this pretty close in a room but the rest of us are left with plain old trial and error. |
Mike I've sent you an email. There are many DIY tube trap sites you can find searching Google. |
Nsgarch you said:
"my understanding is that tube traps eliminate excess bass energy by 'trapping' it within a (half open - half solid) tube."
I have made Tube traps out of Large 12" pipe insulation (made of rigid fiberglass, 6 ft tall sealed all seems and top and bottom openings.. Never put anything inside of them. Made four smaller ones too, but didn't really make much difference...
What do you mean by half solid, half open? one end left open, i understand that..but one half made solid? how do i make it solid? Fill it full of insulation?
Maybe this is why my traps don't seem to work, i didn't make em right?
Thanks
Mike |
Dave, my understanding is that tube traps eliminate excess bass energy by 'trapping' it within a (half open - half solid) tube. The energy then dissapates as it resonates up and down the tube -- sort of an organ pipe in reverse. Panels do not work that way. |
02-10-08: Nsgarch
"Dave, please share your source for that information"
I don't recall where, or if, I read it at any one source. I have known it for a very long time? Any pro acoustical site that provides "a lot" of free acoustics reading material should have good info if you dig around...start at (Realtraps) and (Rives). Also, the Audioasylum (acoustics forum).
Nothing magnetic going on with sound trapping. It's a surface area thing. A larger target, will absorb more than a smaller target.
Dave |
Well, the interesting thing is that I didn't actually get to see or use the software -- I posted a thread in the audio asylum about my trouble, and this fellow in Singapore replied with all these subsidiary questions and requests for photos and everything. I thought he was planning to hire someone to break into my house, or something.
And then, about a week later, I get this e-mail from him with this very professional looking CAD diagram, that says: Place four 16" tubes exactly here, here, here, and here. Then place three 13" tubes exactly here, here, and here. I had no idea that different diameters, different shapes, even different heights made such a big difference -- but according to this guy (and his program) they apparently do.
I'll go back through the threads and try to find the guy. I think at least some of our correspondence was by private e-mail, so those might be easier to find -- or else gone altogether, which is the other thing that happens to e-mail. |
Dog_or_man, I'm in a similar situation--I'm trying to decide how to treat my room with panels or tube traps. I wasn't aware of a software program that determined the ideal size of the tube traps. Can you tell me what you're using or point me to a web site. Many thanks, Mark |
Dave, please share your source for that information. |
A good panel trap absorbs more bass than a good tube trap...surface area.
Dave |
Panels are OK but they won't manage bass as well as tube traps. |
Try inexpensive tubes, round is better the flat. It is the squareness of rooms that create the standing waves. |
