Like many here I have built "stuff" w/o proper knowledge, then sometimes decided to try and fix it afterward.
DIRTFT, yes I know, if we all knew then what we are aware of now....
Take my 2nd row seat riser, I built that 3 years ago, way before I even heard of HT acoustics/bass traps etc.
Not that I know much technical analysis - I have read the book "Master Handbook of Acoustics" twice, so I'm aware of the need to address it for HT usage for proper sound quality (RT60/delay time) and reducing bass "boominess". But I don't live/walk it like the experts.
I'm trying to retrofit that riser into a Broadband bass trap and also improve the walking ergonomics of it by making is 7' deep instead of 5'6" deep.
7' deep will allow the rear seats some more space from the rear wall, and people can walk in front of the seats reclined w/o tripping over them while still on the riser. (yes, that happened already, so before carpeting I need to fix that)
I've read these threads:
pls review riser bass trap
Riser as Bass Trap- Still in or out?
Riser as Broad Band Bass Trap
And saw this article Dennis Erskine wrote and someone posted links too:
The marked up picts is my plan:
The riser is currently filled with pink insulation, this morning I removed the top.
Upon all this being done I will put 30lb roof felt under the complete unit / floor and also add a 2nd sheet of 3/4" OSB on top of the 1st sheet, separated by 30lb roof felt.
Yes, my 2 x 8's run the width of the room, not the length of the room - not correct to the article Dennis wrote, so now I have to cut slots in them for the bass to breathe and be absorbed by the insulation, or just the rear chamber is "active".
The volume of my chamber will then be not individual like the riser in Dennis's article, rather much more. I sure there is mathematical relationship to volume and frequency, just like 1/4 wavelength is a "magic" length when you want to address some frequency response. (It's been 25 years since my MSME and vibration analysis).
I'm open to comments/suggestions, and appreciate any/all.
I have speaker grille cloth to put under the vents so the pink is not visible/getting into living space.
Edited by mtbdudex - 1/23/14 at 6:20am