Hsu Subs and Audyssey Distance Measurements

[bluesky636]

I am a user of Audyssey MultEQ. Part of the process of setting up MultEQ involves the measurement of the sub distance to the first microphone measurement point. In all cases with my VTF-2 Mk 3 sub, Audyssey calculates a sub to mic distance of 9.5 feet vs a tape measure distance of 12.5 feet from the mic to the center of the sub speaker. The crossover on the sub is bypassed and polarity is set to "0". I have the sub set up for maximum extension. I follow the the Audyssey Setup Guide as outlined in http://www.avsforum.com/avs-vb/showpost.php?p=14456895&postcount=5701 (http://www.avsforum.com/avs-vb/showpost.php?p=14456895&postcount=5701). As per the Guide I use a mic stand with a boom arm to hold the Audyssey mic. There are no vibrations transmitted to the mic. Several other Hsu owner's have commented on similar distance errors as noted in the dedicated Audyssey thread (http://www.avsforum.com/avs-vb/showthread.php?t=795421 (http://www.avsforum.com/avs-vb/showthread.php?t=795421)). We would appreciate any insight you can give as to why Hsu subs seem to measure closer than the actual physical distance. Thanks.

Bill