Someone pointed me to a Guy Kuo post one day that I can't find the link to right now. (I will post it as soon as I do find it) There is a really cool "trick" to use with your SPL meter and the Avia main speaker left/right phase test to help you locate where the sweet spot in your setup is. You might not even be sitting IN the sweet spot now. For all you know, you may have NEVER actually sat in the sweet spot of your own speaker setup. Do you know for certain where yours is? I can tell you where mine is, 91 inches from the left wall of my room.
Basically, set your SPL meter to fast response, play the L/R phase test (Avia - Main Speaker Setup), and slowly move your meter left and right of where you think the center of the image is. When you hit the sweet spot, the needle will sit at the normal SPL reading during the in phase portion of the test, and will deflect backwards 3 to 4 dB during the out of phase portion of the test. This deflection will be a very quick, very deliberate, backward needle swing. If your meter is set to slow response, it will mask this needle response. The meter will be in the exact spot where the two out of phase signals cancel each other out when you find the point of maximum backwards needle deflection (1/4" movements matter to get it spot on). If this point does not land in your listening position, use the L/R delay settings in your receiver to move the spot. You could also move your chair. A one foot change in either speaker delay setting moved the spot about 16 to 20 inches in my setup. Put in your favorite CD, sit with your head EXACTLY* where that backward needle deflection happens, lean back, close your eyes, and your Axioms will truely amaze you. You can visualize the studio or stage layout, hear singers breathing, fingertips sliding over strings, and in some cases, I swear I could hear toe tapping. I did this with Rush 2112 last night and swore I was in the studio.
You can use this same method with the left / center test to get that sweet spot in line with the l/r sweet spot. Once you get the 2 weet spots lined up, all of the surround modes sound better.
I almost forgot to mention that you should recalibrate the delay setting, phase, and gain of your sub after you find the sweet spot and before you do any serious testing of the results. Start by verify the sub distance setting, then set the phase. It is easiest if you can get someone to adjust the phase control on your sub while you sit in the sweet spot. This is going to sound silly, but once you are in the sweet spot of the main speakers, the phase setting on the sub works exactly like a "focus" control for the sound image. As the variable phase control on the sub is turned, you can hear the sounds of the drum kit coming from the sub "move" across the stage. The idea is to "line them up" with the drum sounds in the image created by the main speakers. You probably need to move the sub if yours doesn't have a variable phase control. (Thank you, SVS!) Finally, adjust the sub calibration with the phase adjusted correctly, and the meter stting exactly in the sweet spot.
* Your head needs to be in line with where the needle deflected, not in the exact point in 3D space where the meter was. Think of this spot as a "center line". It only works in 1 very narrow spot, 2-5" (yes, inches) wide. Put your nose right on this line, and adjust your head position to get your ears in the right spot.
I'd like someone who has never tried this to do so, and get back to me. I really can't wait to hear what you think. My bet is that you will have a whole new respect for the accuracy of your Axioms. If you are an auditioner, try putting the auditionee in that spot, crank up their favorite song on their favorite CD, leave the room (some folks might have a hard time closing their eyes and relaxing with other people watching). Come back 3 songs later, SOLD - I guarantee it. I've been debating moving this to a new post, but no, it belongs here. If you say "Ahhhh" now, you're going to be saying "Ahhh s$@t, why didn't I know this earlier?" after trying this one.
