Does Shape Make A Difference

[George Bellefontaine]

I thought I read somewhere that rectangle rooms are challenging for good sound. My room isn't exactly rectangle, it's actually 12 feet wide at the front of the room where the screen is, then widens on the left wall where there is an entrance to the outer basement and a doorway to upstairs.The back wall is 15 feet wide and the overall length of the room is 18.5 feet. I have always had pretty good sound in this room. There is carpeting on the floor and the chairs are plush,so I don't seem to get any kind of echoes.Then I got to wondering, since I don't have anything to compare with, is the shape of the room really good or bad. Any ideas ?




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[JonMarsh]

Hi George,

It's not easy to fully conceptualize your room shape from the description, but it sounds reasonalbe, and having none parallel walls does reduce/spread out the room modal frequencies.

A rectangle, with proper setup and location of speakers, listeners, etc., can be made to work very well. Other shapes, like a trapezoid (especially with a ceiling rising from front to back, as does mine) will help with some issues.

Unfortunately, room setup is one of the most commonly neglected issues fo system setup, and strongly affects the perceived performance up to about 300-400 Hz. There are a number of techniques that can be used with great success, even by someone without measuring equipment. There's even some very good, reasonably priced software to help with room design, and speaker and listner placement, such as RPG Accoutics Room Optimizer. (under $100; one of the most effective "tweaks" you can make to a system, in terms of bang for the bucks).

Some good sites to check out include

http://www.rpginc.com

http://www.cardas.com

look in the guide section, and room setup.

Regards,

Jon




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[George Bellefontaine]

Thanks,Jon.




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[Susan]

Neat! I downloaded the demo of the Room Optimizer..when they send me the serial number I'll take a look! Great info! Thanks!
Susan

[Lex]

I think square is actually the worst, right Jon?

I have cathedral ceiling peaking from front to back, several openings, some non square wall effects, and I really like the sound in my room, even if the meter did say it had some nulls and peaks. Oh well, can't have it all.

I haven't addressed accoustic treatments, if you saw the room, you would know it wouldnt be to easy to address.

Oh, you can see the room, it's on my website.




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[JonMarsh]

Yeah Lex, when it comes to room acoustics or speaker enclosures, square is DEFINITELY not where it's at!

There are always some tradeoffs between decorating, esthetics, and room treatments. But check out RPG's site; they do a lot of architectural acoustics- and report on some of their projects- you'd be amazed at how attractive some of them are.

Regards,

Jon




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[Bob]

I can attest to the effect of shape on the acoustics of our systems. When I built my HT I didn't realize that room shape mattered and only addressed sound proofing. My room is very square, 22x22. I had terrible problems with bass management and tried several treatments. Then one day I went into a local audio store where they had a small octangular room with inexpensive speakers and components but, with great sound. The salesman said it was an experiment and was designed by Theil. I then went home and put my four bookshelves in the corners so they angled from the side walls to the back or front walls. Bass improved. Then about a year latter I saw the PS Audio website and how they were building corner bookshelves raised up to make bass traps and thereby creating an octangular room. I have since copied that design. Very inexpensive treatment and a very, very, big improvement. No more standing waves. I would reccomend that anybody with bass management problems take a look at the PS Audio site. It is a heck of a lot cheaper than buying some type of eq device. Looks more pleasing than panels on the walls, and works great.