Alex, the rear speakers should have no effect on the listening window curve. The measurements taken for that can vary, but typically they're anechoic measurements taken on axis and about 10 degrees above and below axis and possibly 10, 20 and 30 degrees to left and right of axis. So, those frontal response measurements should not reflect(pun intended)the contribution of the rear speakers, which would be absorbed by the anechoic chamber wedges.

The sound power curve is significantly affected, since that's an attempt to measure omnidirectional output at numerous angles(Dr. Toole speaks of using 70), front, back, up, down, side to side. This is sometimes done using a "typical" listening room rather than an anechoic chamber, but an anechoic chamber can also be used for an omnidirectional measurement by varying the position of the speaker so that a large number of angles to the microphone are taken into account and an omnidirectional result is obtained from direct measurements, despite the reflections being absorbed.

In general, the closer the sound power curve is to the listening window curve, the more nearly omnidirectional is the speaker. Looking at both graphs, the LFR appears to have an edge in that respect, although it isn't known if the measurement conditions differed.

Note that the anechoic chamber bass measurements aren't accurate below about 80Hz(because of the size of the wedges)and so the 70Hz flat LFR number may not be fairly compared to the 35Hz flat Model T number. Possibly one or both of the measurements have had a calibration adjustment applied to the lowest bass numbers to increase their accuracy.

Incidentally, I will say that looking at the all black Axiom drivers that Tanner shows on one model, they strike me as being more attractive than the present Axiom standard issue, and something that might be considered for adoption in Axiom models.

Edit: Fred, the above reply might partially answer your question. It appears that if they spin the speaker around to a large number of angles in the chamber(e.g., 70 per Dr.Toole), they consider this result to be in adequately close agreement with live listening room numbers.






Last edited by JohnK; 05/21/12 02:19 AM.

-----------------------------------

Enjoy the music, not the equipment.