I heard the one note bass!
I have been frustrated with the dillemma of too much reverb in my main room and no way to fix it without painting the place with absorbtion. Physics are tough to outsmart.
So I moved the stereo into my office as a gesture of surrender, grasping for sanity and an attempt to move forward. I suspected the Ushers would be a bit too much in the little 12 x 11 x9 room
, and sure enough they were. But mostly because of the one note bass, not so much the SPL, but that was a little too strong also, due to small closed field volume. But I was able to make some interesting observations about the bass anomalies.
I am set up along the longer wall (12) to best accomodate the door. I have 64 sq feet of 5" absorbtion on the rear wall, 32 sq feet on the left wall, the diy holy diffusor panel on the front wall between speakers. Plus stereofools 6" thick 2x4 FG panels in corners, and the 2 giant bass traps (cardboard boxes full of absorbtion) in the rear corners. I will be experimenting with placement of all this stuff, but it is in there now so results are probably at least 80% of potential.
Lots of fussing with speaker position yielded this which was just barely starting to give solid center image. It's just too damn close for these speakers which IME are not laser imagers anyway.
The modes start at 47Hz or so. But obviously the speakers are playing below that frequency. I hear the dreaded one note bass at every location in the room except smack dead center on all three dimensions. In the dead center of the room, bass is a little too loud, but tuneful and clear. Move a foot away in any direction and I can start to hear the smearing, echoish almost, layers of reflections graying up the music. It is really grungy indistinct energy. As I move farther away from the dead center, the grunge gets more smeared until it is many reflections all melted into one, making the sound of 99 Maxima playing Tupac full volume.
My question is about the frequencies below the modal region. Is there any chance for music down there, or is it just dead man's land, where no music can be had? The one note also seems to be triggered on notes above 47Hz. Maybe the modes are what I'm hearing. I've read that below modal frequencies it is just non-directional pressure.
I can fill all 12 wall corners of the room with large bass trap absorbtion. But I would like to know if this will cure the one note bass before I try it. How low frequencies can a 2x2 foot triangular wedge of solid cotton absorb? If not low enough for 47Hz, how to kill that mode? Tuned trap?
Having heard how the one note bass thing changes with position, I'm wondering if what is happening is that the wavelengths larger than room dimensions fold back on each other and create many pressure peaks in the room, which are perceived as the room dimension's wavelength, with all three wavelength of the major room dimensions smearing together like a low freq muddy chord.
I know that I can't apply absorption thick enough to affect even the first mode, requiring absorption 6 feet from the wall to reach quarter wave peak velocity of the reflection. So I'm starting to wonder if it's possible to make full range music in a small room. EQ can manage the bass level, and your head can be in the least reactive spot in the center, but that is not practical in a very small room.
Cool little freq/wavelength calc:
http://www.mcsquared.com/wavelength.htmWhat is the potential for massively treating the corners with absorbtion? Can the one note be effectively eliminated?
All opinions are very welcome!
pics:
Thanks
Rich