If your audio room is quite long and fairly narrow, this tip applies to you. If your audio room also has a peaked ceiling that runs the length of the space, then this tip is basically your personal guide to listening pleasure.
The following writeup was extracted from a forum discussion on Audiokarma.org. The entire discussion can be found here.
Straight from the mental reservoir of TubeTrap inventor and ASC President, Art Noxon, PE, please enjoy this week’s HiFi acoustic tip!
Something to Consider…
“Many years ago I got a call from Mark Levinson. At the time was hauling around and promoting his Cello speaker system packed into a truck load of TubeTraps, enough to quell the temper of any room he was trying to use for a speaker demo. His herculean effort succeeded. But, back to the phone call. He said his nightmare room had been for some time those long skinny rooms. But he finally figured out how to set them up and needed to share his discovery with me. I’m positive he won’t mind my sharing it with you. By the way, your hunch is correct…..
He discovered he could set the speaker listener footprint up in the middle of the long wall. As you noted, this left two roaring volumes of room outside of the listening zone, one to the left and right. Side walls were so far away no side wall reflection control was needed. But between the speakers both on the front wall and the back walls a lot of acoustics (TubeTraps back then) had to be set in place. He needed to dry up the full bandwidth front to rear “flutter” echo (bass and treble) so the sound tracking inside the listening zone would be fast and clear. He needed good musical articulation, now called musical C50 clarity (see ASC MATT test). The reverb roar to either side of the listening zone (stereo reverberation) was calmed down by adding some full range bass absorption and treble diffusion (TubeTraps) in the 4 corners, along with anything else, lamp shades, vases, cabinets etc… that can diffuse treble.
Anyway, I’ve done the same thing many times and always with great success. Oh yes, I didn’t hear anything in the discussion about the carpet, might have glossed over it, always apply thick Persian-like carpet on listening footprint, from back of speakers to at least under front legs of listening chair.
Bad news……In this room we have something extra to consider. The rear surface of the huge angled cathedral ceiling is acting like a second back wall, stacked up on top of the lower back wall and tipped in to reflect a second rear wall bounce directly back into the lower front wall corner. Outside of some edge of the reflection hitting the listener in the back of the head, there will be a lot of full bandwidth acoustics intercepting the bounce back on the front wall so at least the rear wall bounce won’t return back and forth. If it did it would be a lower front wall/floor corner bounce that returns back to tipped in upper back wall (ceiling) full bandwidth “flutter echo”.
A listening room with great gear ….but no real speaker yet, an interesting position to be in. You have so much room, try a big dipole, Magniplaner does very well and no subwoofer is needed with their new double wide model. Of course, Martin Logan is always a contender but they have converted their product line into hybrids, woofer with dipole on top. Planers play most music really well but not loud, explosive rock and roll. Subs and other dynamic speakers under a tall peaked hall type of room end up with a lot of vertical, floor to ceiling peak, bass reverb buildup which is hard to get out from underneath of or get rid of. Dipoles do not play sound vertically or laterally, in the plane of speaker, only perpendicular to the plane of the speaker. They don’t stimulate the dreaded vertical mode of this room or any room. Alternatively keep a dynamic woofer in your sound system and add huge bass traps into the peak of the room in the middle, above the listening zone to help tone down the vertical reverb buildup.
Well, thanks for hanging out and imagining the voice of the room with me.”