Room Size vs. Speakers

[wfo1955]

Okay, to start off with, I'm a dumb as*....flunked math. I don't understand the 1.x1.26x1.59. ratio mumbo jumbo. What do you multiply these by?

Here is my situation:...gotta' 40'x40'x14' walls to 16' center ceiling metal building=garage. Here is my 7.1 system:

Rf-63's, (couldn't afford the RF-83's) RC-64II, RT-12D, RS-62's and RB-81's. B&K Ref. II 7270 200wx7 amp, with an Integra DHC-40.2( pre/AV.

Essentially, I can construct any size room that will be accoustically representative of a kick-butt HT/Audio mancave. Gonna use a 65" or larger LED LCD TV on the wall. I figure about 6-8' away from the TV, and about 10-12' fro the second row(raised 12" floor to view over front row). All components are gonna be racked on each side of the TV. Since it is a metal building, I'm gonna stud up 6" walls, then(believe it or not) 8"x16" concrete walls, then either 6" or 12" studded interior walls. The concrete walls are for security, (I'm anal about theft, gonna have a gunsafe inside). Considering the racks and front speakers extend out 4-5' I I help to tell me how wide, how deep and how tall the cave should be. (I was thinkin' 'bout 20' wide and around 23'5" Long and 12'5" vaulted ceilings). I also need to know if vaulted ceilings are recommended. I've done a little research on accoustic ecoutrements, but thats down the road.

Please don't tell me to hire it done by a HT group, gotta save where I can.

As always, appreciate help from those that know....I'm scared as hell!

WFO1955

[Chris A]

(I was thinkin' 'bout 20' wide and around 23'5" Long and 12'5" vaulted ceilings)

The shortest dimension is the first one you use for Mr. Klipsch's calculations: in your case (as in most rooms) that is the height: you say ~12.5 feet tall.

The next dimension would be 1.4 --> 1.6 times that, so the next shortest dimension of the room should be (12.5 x 1.4 to 12.5 x 1.6), which is between 17.5 feet to 20 feet. You chose 20 feet...this is okay.

The next dimension should be 1.6 to 2.2 times the shortest dimension (12.5 x 1.4 to 12.5 x 2.4), which is 20 feet to 27.5 feet. You chose ~23.5 feet... this is okay.

Other dimension ratios of the room are also useful, but the ratios used above are sort of in the middle of the road, so I'd say you got a good eye for proportion. []

A vaulted ceiling is okay, but may require you to do a little more work when you get everything set up to move your speakers and listening position around to find the best places for each one. You might also need to do a little diffusion/absorption on the walls (curtains or absorption panels) or even on the ceiling to kill early reflections. The peak of the vaulted ceiling is a really nice place to put bass traps.

Higher ceilings are better than lower ones. A 12.5 foot ceiling is very nice.

Chris

[wfo1955]

Hey Chris, thanks a lot for explaining that, now it makes sense and I have some direction to go by.

WFO1955

[colterphoto1]

if you can get away with it, make the walls slightly NON parallel to each other, this will reduce standing waves in the room.

Ethan Winer has some excellent articles on room acoustics too, you might look them up.

Michael

[colterphoto1]

remember for THX purposes, a standard sized room is 3000 ft3. If you get a lot larger than that you need a lot more bass output. You lose that whole 'compression' feeling of the impact of the subs during action/adventure movies. One Forum member went so far as to install rubber bulb seal on doorways to his small home theater- that's really an experience!

[garyrc]

Since it is a metal building, I'm gonna stud up 6" walls, then(believe it or not) 8"x16" concrete walls, then either 6" or 12" studded interior walls. The concrete walls are for security, (I'm anal about theft, gonna have a gunsafe inside). Considering the racks and front speakers extend out 4-5' I I help to tell me how wide, how deep and how tall the cave should be. (I was thinkin' 'bout 20' wide and around 23'5" Long and 12'5" vaulted ceilings). I also need to know if vaulted ceilings are recommended. I've done a little research on accoustic ecoutrements, but thats down the road.

WFO1955

Not sure about your walls.

• The concrete wall plus one 6" studded wall may be enough for

  soundproofing, but if sound proofing is a concern, don't forget the

  ceiling!

• An article I saw called something like "10 myths of soundproofing"

  said that once you get two layers with an air space and each layer with

  its own studs and its own sole plate, adding more layers and airspaces

  can backfire. A good layer might be 5/8 sheetrock (nothing thinner, but

  reading your post leads me to believe that you would never go thin)

  over 3/4 voidless plywood, screwed and glued. with staggered seams.

  Each row of studs should be 2 x 6, with insulation between both sets of

  studs. I toyed with studs closer than 16" O.C., but several

  individuals/articles indicated that that would transmit more sound to the outside.

• Virtually nothing short of a concrete wall/floor, or something of

  equally high mass and rigidity will keep intensive bass from going

  outside to some degree. I used to have a room within a room, with a

  floating floor, and double walls with airspace, and the low bass went

  right through. It stopped the midrange and treble, though.

• If your room proportions are favorable (i.e., don't cause clumping of room modes), then very firm walls should give you more bass, and you will probably want it.. If the proportions are unfavorable, you may not want very firm walls (but certainly not floppy ones).
• Even though you are building a listening room rather than a

  studio, you may want to look at Jeff Cooper's book Building a Recording

  Studio. It is meant for DIY folk building rooms in their homes. It has

  many pages devoted to how much sound different wall and floor

  construction designs will block. The common block, sheet rock one on

  page 83 of the fifth edition may be an alternative to your concrete

  wall(?). He also reproduces a copy of Bolt's polygon graph which gives

  you a wide choice of room proportions (page 153, fifth edition). Cooper

  designed sound facilities for several of the little people, including

  Francis Ford Coppola, George Lucas, Steven Spielberg, and a few bands.

  Some people would deviate from Cooper by not using resilient material

  behind the wall surface nearest the sound, to make for firmer walls

  & firmer bass. The Bolt is also reproduced in Paul Klipsch's Dope

  From Hope somewhere ... I think it's in an article called something like

  "Distribution of Eigentons."

• If you get the idea that there is a lack of agreement and a little

  alchemy and acoustical mythology in some of the articles in the glossy

  audio and home theater magazines, I wouldn't be surprised.