Room acoustics - yet again


I have the books and the theory of room acoustics for rectengular enclosed rooms. Any guidelines for irregular (ie partly-cathedral ceilings, multiple openings to the listening room) ? Or is it the usual measure-listen-change ? My problem is finding a reasonable starting spot and tewak from there.
ikarus

Showing 1 response by subaruguru

I too am blessed (!) with a very irregularly-shaped room(s):
a two-foot sofa-enclosed jog-out on the left wall, and a 45- angled fireplaced cut-back on the right, with large openings right-front (to entry hall) and behind me into another smaller library-roon. Add to this a 7 ft Steinway B, and an insistent wife...phew! Yet I heartily disagree with the stated view above that irregularity is completely unfortunate!
Staggering driver/boundary distances becomes almost automatic, and problematic bass modes are smoothed, too! The piano's depth required that I find reference speakers that had sufficient bass to be way out from the front wall (8-9 ft), had great WAF, and worked in the nearfield (as a 7.5 ft triangle is all I had left). Several 3-ways (esp Nautilus) couldn't cohere in the nearfield, and rear-firing woofers (Verity Audio Fidelios) sounded anemic. Fortunately I was able to find outstanding speakers that work exceptionally-well (Parsifal Encores, woofers front-firing).
The triangle evolved by trial and error acoustically. I used
soundstage development and tonal cues as guides, as I was unaware of software for irregular shapes. The resultant soundstage is VERY deep, yet triangular (piano angles back starting 1 ft behind the speaker plane; opening on right rear). Having non-parallel
sidewalls seems to be very beneficial, as I have very little
first-reflection anomoli. Measurements indicate surprisingly flat bass response: only a mild bump at 80 Hz... although it's a little hot at 6kHz because I toed in to widen the sweet-spot and reduce reflections.
My friend who is pres/owner of a prestigious acoustical consulting firm (ex-BB&N Acentec) was pleasantly surprised at the stage I was able to produce. His "very good!" proclamation says a lot.
His sole mod was to lean forward even closer (only 6.5 ft off the plane); interestingly the guys at Verity Audio had suggested pulling my chair forward a bit as well. Sitting
in a 7 ft triangle in a 14x24 space seems a bit close, but
the soundstage is easily as wide as the room, and sometimes
20-30 feet deep (the Alephs help here)! Apologies for my quasi-bragadocio, but I want to urge you to proceed with confidence and good cheer, knowing that the asymmetry can have benefits.
Maybe you needn't worry too much about software-assistance, either, but I would urge you to be VERY careful with speaker selection. To risk repeating: whereas many 3-ways will cohere reasonably given
sufficient distance, I certainly found that extra care was required when selecting for near-field use. Getting the modernistic N803 past my wife was a great initial coup, but what awful sound in the nearfield! I had also been warned by some at this site that "loading" a piano soundboard in the room was a big taboo, and that non-parallel sidewalls
would result in a non-rectangular stage, but I certainly experience NO ringing or resonant overhang from the Steinway (maybe it helps that it's horizontal?--an upright would be problematic?), and I don't really miss hearing the "back corners" of the stage, as often referred to. Sorry to not be concise, but I'm now a firm believer that a well-damped, asymmetric living room can make a wonderful listening room as well. Visiting friends and musicians are soon transfixed, exclaiming often "it's like he/she's right THERE!..." Truly gratifying. So don't sweat the software and trust your ears when selecting speakers carefully. Hope this helped. Good luck. Ernie