Norman Varney

Bill, I don't know what microphone you are using, but now that I see a photo of your testing procedure, I'm hoping it's an omni and suggest that you aim it straight up (at ear height) in order to capture the front/back and sides of the room effectively.

If you want to excite all the room modes, the woofer should be located in a tri-corner, rather than a bi-corner. Also, I would place the microphone at your specific sitting position ear height, because that's the relevant height. Rather than taking so many measurements, simply look at your RTA (slow, flat, 1/12 octave) and mark the smoothest response on your line while running pink noise. Discovering optimum speaker placement will be more subjective in that, not only do you have room modes to deal with (likely, you'll no longer be contending with at least f1 & f2 axial nodes with your new speaker position), but also soundstage (speaker separation) and tonality (speaker toe-in) compromises. Eventually, you'll end up working down to fractions of an inch regarding placement of both speakers and listening positions by trusting your ears with familiar recordings. With final aiming of the speakers, use a laser pointer and measure its position on the rear wall. This will offer great accuracy for matching.

Being my profession, I know that acoustics is usually the last thing people think about when discussing audio, and yet, it is the most important because it has the most impact on the audio experience. Here are a few basic things to consider: There is a hierarchy to playback systems: 1. Physical set up 2. Calibration 3. Acoustics 4. Equipment Achieving optimal room acoustics is a matter of controlling noise and vibrations, room modes, first order reflections and reverberation times in a linear fashion. Regarding your set up, like your speakers, it is beneficial to locate the listener away from the wall to avoid reflections and modes. Without understanding your specific room characteristics, I will just generalize that for a typical (not too live, not too dead) residential room it's a good idea to address the low frequencies (room modes) first, then the first order reflections for each speaker at all six locations, then address the remaining reverberation times. Regarding interior acoustic treatments, there are three tools; absorption, reflection and diffusion. The common room treatments, especially the DIY kind, deal only with absorption, and only address about 500 Hz. (essentially Middle A on a piano) and up. This approach typically leaves the room sounding too dead in the mids and highs, and slow and muddy below. Knowing how much, of what, where, is one of the ways acoustical engineers can turn the audio experience from ho-hum into WOW!