Obi-Wan zenabI
Active member
My PVC Helmholtz Invention (?) *edited*
Ok, I've nearly completed the sheetrocking of my 20 x 30 foot studio space. I'm using it for playing, recording, listening to LPs, etc. No seprate control room or anything.
I wanted to build some kind of diffusors for the back wall, out of scrap wood or whatever, you know, stacked on end at random lengths to get a skyline thing going. Then I read this description of the Helmholtz resonator:
http://www.saecollege.de/reference_material/index.html
*edit* the link to the SAE site does not work.... so here it is cut and pasted:
QUOTE: "LOW - MID ABSORBERS
If you look at the absorption coefficients of various materials you will notice that some of the fibreglass products absorb low-mid frequencies very efficiently as does a panel absorber with a fibreboard panel instead of a plywood panel. But the best low mid absorber (and the best looking) is the helmholtz resonator - often called a slat resonator.
THE HELMHOLTZ RESONATOR
The helmholtz resonator (named after a Mr Helmholtz who discovered it) can best be demonstrated by taking a normal soft drink bottle and blowing over the mouth of the bottle - a note is produced. Now place some cotton wool in the bottle and try again. You will notice the note has reduced- well not really, the note is produced but the wool absorbs the resonance and turn the sound energy into heat! Imagine, if you lined a whole wall with bottles of various sizes, all filled with insulation material. You would now have a low-mid (200 - 500Hz depending on the bottle size) absorbing wall that as well as absorbing the low mids would also reflect or diffuse the high frequencies. I haven't tried it yet but it would be worth trying if you are short of cash because bottles are cheap. The Romans used to do it using clay jars which they placed around their theatres." END QUOTE
I got thinking that instead of diffusion, I could glue different lengths of pvc pipe (heck, even different diameters) on the end, maybe with some insulation at the bottom.
Would this work as an abosrber? Could it also have some diffusive qualities to give the room some air?
PS if you use this idea and make a great deal of money, a few beers would be an acceptable payment...
Ok, I've nearly completed the sheetrocking of my 20 x 30 foot studio space. I'm using it for playing, recording, listening to LPs, etc. No seprate control room or anything.
I wanted to build some kind of diffusors for the back wall, out of scrap wood or whatever, you know, stacked on end at random lengths to get a skyline thing going. Then I read this description of the Helmholtz resonator:
http://www.saecollege.de/reference_material/index.html
*edit* the link to the SAE site does not work.... so here it is cut and pasted:
QUOTE: "LOW - MID ABSORBERS
If you look at the absorption coefficients of various materials you will notice that some of the fibreglass products absorb low-mid frequencies very efficiently as does a panel absorber with a fibreboard panel instead of a plywood panel. But the best low mid absorber (and the best looking) is the helmholtz resonator - often called a slat resonator.
THE HELMHOLTZ RESONATOR
The helmholtz resonator (named after a Mr Helmholtz who discovered it) can best be demonstrated by taking a normal soft drink bottle and blowing over the mouth of the bottle - a note is produced. Now place some cotton wool in the bottle and try again. You will notice the note has reduced- well not really, the note is produced but the wool absorbs the resonance and turn the sound energy into heat! Imagine, if you lined a whole wall with bottles of various sizes, all filled with insulation material. You would now have a low-mid (200 - 500Hz depending on the bottle size) absorbing wall that as well as absorbing the low mids would also reflect or diffuse the high frequencies. I haven't tried it yet but it would be worth trying if you are short of cash because bottles are cheap. The Romans used to do it using clay jars which they placed around their theatres." END QUOTE
I got thinking that instead of diffusion, I could glue different lengths of pvc pipe (heck, even different diameters) on the end, maybe with some insulation at the bottom.
Would this work as an abosrber? Could it also have some diffusive qualities to give the room some air?
PS if you use this idea and make a great deal of money, a few beers would be an acceptable payment...
Last edited: