The problem that I run into during the integration of a pair of stereo subwoofers using the Pre-8 is that all drivers’ relative sound levels, for both the main speakers and subs, are measured during the first step. Essentially, you place the measurement mic very close to each driver for left channels then repeat the process for the right. After all the driver measurements are collected for the left channels, graphic results are displayed of the response curve for each driver relative to each other. This in my case includes the left subwoofer sitting about five-feet behind the left main speaker and the same is on the right side as well. This seems to work well for drivers on, or nearly on the same plane, but for the subwoofer that I just took a near-field measurement, five feet (1.5m) behind my main speaker, is not going to have the same relative sound-level when measured at the plane of the main speaker.
In DEQX-Cal, used for legacy DEQX processors, you could match the level of your subwoofer to your main speakers by matching the subwoofer curve amplitude to the main speaker’s curve as measured from the sweet spot, but this was a manual process. You could also match impulse response of your subs to each other then both to the impulse response to your main speakers in order to set the correct delay. It appears now that subwoofer time alignment as well as time alignment of all drivers is performed automatically in step two with a provision to override (in distance).
But how could step two possibly set the subwoofer’s relative loudness when relative levels are set in step one and the subwoofer is substantially on different plane than the main speakers?
For me when I perform driver measurements in step one and close-mic my subs, the final outcome is low bass "lite". As a kluge, which actually returned fairly good results, I made step-one measurements of the main speakers, in my case at 16" (40cm) then moved the mic along the same plane as I measured my main speakers to where the mic was directly in front of my sub and still on the same plane as my main speaker. This placed the measurement mic about 66" away from the front of the sub and I then took the measurement. I also limited the lower speaker correction (but not room correction) to 200Hz crossing over at 60Hz12dB/oct since the Apogee woofer panels go very low. The bass is pretty damn good now, but I know this couldn’t be best way.
Always open to suggestions.
