Apex C center channel measurements

How the Apex C was measured in room, and what the curves showed.

Speaker height

30" from the floor to the center of the tweeter

Microphone distance

65" from the speaker

Horizontal

on tweeter axis (mic 30" high) and 45° off axis, left to right

Vertical

15° (mic over 48" high), 30° (over 68") and 45° (at the 8 ft ceiling)

Horizontal

For the measurements the speaker was placed 30" off the floor to the center of the tweeter, which allows for some floor reflections in the measurements. The microphone was set 30" off the floor at a distance of 65" for the on-axis measurement, then moved to 45 degrees off axis horizontally.

Off axis, the sensitivity falls off slowly across the board. In the midrange area this comes from the two midrange drivers overlapping. Notice the small amount of upper-end roll-off from the tweeter: less than 5 dB at 20 kHz at 45 degrees off axis.

Vertical

The in-room vertical measurements go up to 45 degrees, up and down. They were done with the speaker in the same location, 30" off the floor, moving the microphone in a true curve that kept the 65" distance for the 15, 30 and 45 degree tests: at 15 degrees with the microphone over 48" off the floor, at 30 degrees over 68", and at 45 degrees at the ceiling height of 8 feet.

On axis and at 15 degrees off axis vertically, the response is very flat out past 20 kHz.

Neither the 30 nor the 45 degree vertical measurement really matters in the real world, because no one listens to speakers from this high or this low. The most important measurement is the off-axis horizontal one.