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Tubes vs. Panels?

A few months ago I started a thread in another forum about room treatments, and another forum member (after viewing digital photos of the room, a bird's eye sketch, and asking lots of questions) sent me back a computer-generated printout showing the placement of four 16" diameter bass traps that stood four feet high, and three additional 13" bass traps that stood 42" high.

I can fit all of that stuff in my room, but I'd really rather not.

Then, yesterday, in a different discussion, someone else sent me a link to an outfit called GIK Acoustics, which offers free-standing panels among other things.

My question: given that the panels probably won't work as well as the specific thing the computer wanted me to make, does everyone think they'll still work *reasonably* well? I could buy them relatively inexpensively and not have to reconfigure the whole room.
dog_or_man
amfibius
282 posts
 
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.
nrgy22
14 posts
 
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
ngjockey
1,042 posts
 
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.
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