[maddogpilot]

First off, thanks to all -- have been lurking for a very long time, now am finally starting my "real" HT project. Have run into an audio/room design problem though. My basement room measures about 15 feet wide by 18 long. Due to structural requirements I must retain a room pillar within the room (7 inches square, floor to ceiling) about 5 feet from the front screen; the pillar is offset from the side wall by 3 1/2 feet. (I cannot "header" this thing away due to an already low 7 1/3 foot ceiling height). Also -- I have in the opposite rear corner of the room a large soffit area about 30x30 inches which will extend from the floor to at least 4 feet off the floor (like a big box stuck there in the corner).


Planning right now on 3-4 seats on a sofa on a riser in the rear row and 2-3 seats in the front row, with a likely setback for the front primary seats of about 10 1/2 feet from the screen. Planning on a ceiling mounted projector of some kind, with all audio/video equipment racked out of the room itself.


My questions are these:


1. Should I shift the front screen (planned for about a 100 inch diagonal) away from the pillar (L/R) -- or otherwise can I make the pillar acoustically invisible by adjusting its shape from square to something else?


2. Should L/R speaker placement avoid a line-of-sight block to the primary seats?


3. For the rear soffit -- would it be better to finish it with an area at the top to mount one of the rear surrounds, or just finish the soffit to the ceiling?


Many thanks for the ideas.

 

[Brucer]

Longer wavelengths (relative to the size of the pillar) will bend around without creating much of a problem. It's the smaller wavelengths (higher frequencies) that might be of some concern here. [1130ft/sec / 7" = 1937hz and up].


In this case, 'angle of incidence = angle of reflection', so perhaps a round column would prove less objectionable. The good news is that most all acoustic absorptive materials (foam / fiberglass etc.) have higher absorption coefficients with increasing frequency.


See here for explaination on diffractions and 'much, much more.

http://hyperphysics.phy-astr.gsu.edu...iffrac.html#c1

 

[maddogpilot]

So, with the pillar close to the front of the soundstage, should I plan on covering the pillar with an absorbing material such as cloth -- or make the pillar reflective? Will a rounded pillar serve my purposes better than a square one?


Thanks !!!

 

[JustPatrick]

Is it possible to turn the theater around 180 degrees? Make the front the back and the back the front? That way you could place the seating around the pillar. Maybe give people you don't like the obstructed view?

 

[maddogpilot]

Thanks for the idea I'll CAD it out!


Gary

 

[Terry Montlick]

I wouldn't worry too much about the pillar. Technically, if you were to make it round, it would be more acoustically transparent because it would diffuse high frequencies rather than reflect them.


The main thing for good acoustics in a HT is to add sufficient absorption over a broad range of frequencies. This uniformly reduces reverberation so your room doesn't ruin the sound as it travels from speakers to ears.


Regards,

Terry