Room thirds

I think this short series on how to make loudspeakers disappear through proper setup may have run its course and I have other topics I am anxious to write about, so this will be the last in the series. In yesterday's post we discovered how much the wall behind the loudspeaker effects the sound. Lower frequencies are exaggerated (because they wrap around the speaker and reflected back into the room) while treble frequencies are left intact - creating a weird tonal balance shift that pushes the sound forward of the loudspeakers. As we pull the speaker pair away from the rear wall the image recedes, first inline with the speakers themselves, then behind the loudspeakers as we get close to the magic 'third of the room'. If we pull them too far into the room the image becomes diffuse, distant and unnatural. Getting just the right balance by minimizing room reflections helps a stereo pair of loudspeakers image properly. I have mentioned in the past the image should come from behind the loudspeakers, never in front. You can now see why that idea makes sense. If the image your speaker pair projects is trapped in the speakers or out in front, it's typically due to an over-exaggerated lower midrange due to back wall reflections; which is why you need to pull them away from the wall behind them for best sound. Reading the last few day's posts will explain in good detail how you can prove this to yourself. There are speakers designed to be against the rear wall, several British ones come to mind. These achieve proper tonal balance because in a room without walls, they have reduced lower frequency response. In other words, they depend on the rear wall to fill in the frequencies they have been purposefully left short of. I do not personally hold this design in high regard for several reasons: our walls are not uniform and their effects are unpredictable even in the best case. Any reasonably designed loudspeaker pair can disappear in the room with proper setup. If yours achieves this, no need to fret. If not, read over the work I have invested over the last few days for help. Tomorrow I will tell you all about the new crossover for the IRSV in Music Room One.