[maddogpilot]

Room pillar audio interference?

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.



__________________

One day it will be done . . .

 

[jlmclemore]

Can you reverse the room layout putting the screen on the wall with the soffit? If so, you could possibly build a matching soffit in the other corner and set your front speakers on them (assuming you don't have floor standers).


Just a thought....


John

 

[AFryia]

Can you rotate the room layout (seats and screen) say 15 degrees putting the screen partially toward the corner. This will help keep the post out of your peripheral view. also leaves space behind the screen for anything built-in.

 

[maddogpilot]

I'll look at reversing the room -- interesting idea -- but at first glance it looks like reversing the room layout won't work (unfortunately) due to room entry location and lack of an area to rack the gear.


Tilting the room -- I had thought of this but am worried about uneven sound diffraction in the room if L/R sound is off-angle. So, am leaning toward sliding the screen/soundstage slightly to one side to move the pillar absolutely out of line of sound for the back row. This would leave my L speaker about 1 1/2 feet from the left wall, and the R speaker about 4 feet from the right wall.


Appreciate the thoughts outside of the lines though!! After a lot of watching, it seems that is the best thing about these forums!


Thanks...

 

[Vince_B]

What material is the pillar (i.e. could something stronger and smaller be substituted?) Also, is the 3.5' the clearance between the pillar or the total obstruction into the room?


If you reverse the room will it put the pillar right next to some of the

seating positions? In answer to your question, it will be very detrimental to the sound if the pillar obstructs line of sight to a speaker. Also I would definitely avoid having it anywhere between the main L-R pair as it will contribute to the soundstage. Have you considered building out the front wall (not the 5' to the column, but) enough to have a perfed screen and put the front 3 speakers behind it. That would hide your speakers and compress the installation left to right. Or just get skinny L-R speakers. Maybe a combination of this and moving a bit (say a foot) to one side would give satisfaction.


Being a foot or more to one side will not be a problem in a room that size, especially if you're going to treat the room acoustically. Also when you wrap the post it's getting wider anyway...

 

[maddogpilot]

The pillar is 3.4 feet sideways intruding into the room, with a offset (at this point) about 5 feet from the front where the screen will be mounted. Pillar change is unlikely due to fact that it currently holds up my main floor and roof structure (over my living room and its B&W803s...) -- but will consult with contractor on this, many thanks....


As far as a screen offset to the front, when I ran the viewing angle calculators, with my size room, any reduction in length of room will result in the loss of the rear row of seats, so can't see a way out there. It would be nice though to have the speakers flush mounted to the screen -- and will re-run the calculator to look at this -- but am very leery of a greater than 45 degree viewing angle for the front row of seats (see following page)


( http://www.myhometheater.homestead.c...alculator.html )


Luckily, I am using Paradigm 120s with a width of 9 inches. So, this means I can put the speakers quite close to the screen and still maintain some offset from the side walls.


Tomorrow will re-CAD the room 180 degrees out, as well as looking at a small side offset with the room as it is now. Also, I had a recommendation from the speaker forum to "round" the pillar to reduce reflection also. I think this just may work out...


THANKS>>>

 

[outlier2]

I had a similar pillar problem. I fixed it by having an engineered steel I-beam put in with a stronger post moved to the outer wall of the HT. Costs are around $700-$2000 US including an engineering report estimating load bearings. Worth every penny to get rid of that damn post!

 

[maddogpilot]

Just to close this thread out...I ended up hiring an engineer. The report was that the pillar absolutely could not be removed - in fact I had to replace the existing wall with a header to support both the load above and provide sideways shear protection for the home. Oh well.


So, I hired a designer, flipped the room and am now well into the destruction and rebuild of the room itself. Will end up with a 92" screen size for two tiers of seating. Side note for all you pillar-challenged people out there -- the Berkline seats are well suited to situations like mine because of the limited amount of clearance required for their use.


thanks for the comments!