[SoCalWJS]

Awkward thread title, I know....

I have a question for anybody that might be able to shed light on it. The wife and I are considering purchasing a new home, with the thought that one of the rooms would eventually be altered slightly in order to become a true dedicated combined 2 Channel/HT room. The problem is that the solution would cost some decent $$$ (installing a new wall), but for right now the purchase is a real stretch, and there would be no extra money to start with, so I'm looking at a cheap ("free") temporary solution.

Assuming that the room would be "U-Shaped" (3 walls - front and both sides in a rectangular configuration.....)

If we made a rear wall out of bookshelves, filled with Blu rays, DVD's CD's and Vinyl, how would that work acoustically?

The bookshelves would be about 6' tall in a room with 10' ceilings. The shelves are not all solid wood (some would be solid wood, some would be out of particle board with thin plywood backing).

Could you consider this as a fairly solid wall within a specific frequency range? If so, what would the range be? (approximately)

(we're playing around with numbers and trying to make this work as our "last house")

[RDavidson]

Is it entirely necessary to have a back wall for HT? If you install rear surrounds in the ceiling, you sort of create an invisible acoustic boundary. Maybe I'm missing something? Or is maybe the goal is to contain / absorb sound and keep most of it in the HT area?

[JLM]

With enough "randomness" in the sizes of contents, how acoustically reflective they are, and how full the shelves are you would have a diffuser of sorts, good down to roughly 1,000 Hz.  Does the room need diffusion (most go more for absorption)?  More importantly from an acoustics standpoint is the size/shape of the room. 

I use tall bookcases on each side wall (roughly 5 foot width on one side and half that on the other) and try to randomly fill them with speakers on short wall in a 13 ft x 21 ft x 8 ft room.  With nearfield setup absorbing treatments have almost no effect.

[drummermitchell]

I had rear surrounds in just below my ceiling(8") and it was okay.
Ethan(RealTraps)mentioned a long time ago that theatres years ago used to do that to try and  create some ambiance as I believe it was prologic back then and the room was a lot bigger than are our rooms.
When I stumbled on that thread again about  4 months ago I tried the surrounds down below on stands.
What a major improvement that is,all front and back locked into basically a 380 degree.
Major movie involvement compared to before,I was quite shocked really.
As far as cd's and dvd's,books ect for diffusive properties I'm sure we get what we pay for for which totally relates to the sound we hear.
Just like my surrounds,what an upgrade that was and was free.
I do use RT diffusion on my back wall and am satisfied that I don't have to do anything else back there as also have the 2x2module bass traps on the floor/wall corners.
I'd never ever do ceiling mount surrounds again as having the tweets at ear level is a huge upgrade compared to ceiling mount.
Some times we have to take a chance and spend some coin or not to get that HUGE improvement we know is there if we do something about it,depends on our love for audio I suppose.
I'll try to squeeze  as much into it as I can or afford or listen to people that know about acoustics instead of all the chit chat.
Go to the source,plus you will save money for all the trials and errors and the end result will be satisfaction.
Time for a Kokannee .

[RDavidson]

What a major improvement that is,all front and back locked into basically a 380 degree.

  Whoa! 380 degrees? That's 20 degrees more than usual.
I'm gonna have to try this.
Sorry, I couldn't help myself.

[drummermitchell]

LOL,yes 20 more degrees.
Perhaps with the 29 degree Alberta sun today on the back deck and add a few more ice chilled Kokannees to the pot,
I'll stick to 380.
Really though the tweet/ear level surround compared to ceiling mount is truly a much more immersive sound field even at 360 .