Audio Artistry Beethoven loudspeaker system Measurements part 2
The individual responses of the panel's drive-units on the tweeter axis are shown in fig.5. The crossover between the twin midrange units and the tweeter can be seen at 2.2kHz; the midrange/woofer crossover is placed at 100Hz, but this is obscured by a rise in the midrange units' output at the bottom end of their range. The crossover's tonal shaping appears to compensate for this, which can be seen in fig.6, which shows the overall response of the Beethoven panel on the tweeter axis, equalized by the crossover and spliced to the nearfield response of the woofers with the crossover set to subwoofers on and off. The speaker is quite flat on-axis through the upper midrange and treble, but the apparent excess of energy in the bass is due to the fact that the nearfield measurement does not allow for the dipole cancellation typical of open-backed enclosures.
Fig.5 Audio Artistry Beethoven, anechoic responses on tweeter axis at 50" of tweeter, midrange units, and woofers, corrected for microphone response, with nearfield midrange and woofer responses plotted below 500Hz and 300Hz, respectively.
Fig.6 Audio Artistry Beethoven, anechoic response on tweeter axis at 50" with crossover EQ, averaged across 30 degrees horizontal window and corrected for microphone response, with the nearfield woofer response plotted below 300Hz.
The Beethoven panel's dipole design means its off-axis behavior will be very different from that of a normal monopole design. Fig.7 shows the differences in the response as the measuring microphone moved round to 135 degrees on either side of the tweeter axis. Other than in the mid-treble region, around the cursor position at 4616Hz, the speaker output falls off evenly across the band to the panel's sides. Below 2kHz, it reaches a minimum between 90 degrees and 100 degrees to the side. Vertically (fig.8), the response doesn't change much as long as the listener's ear is between the centers of the two midrange units (middle three traces), around 36"-45" from the floor.
Fig.7 Audio Artistry Beethoven, horizontal response family at 50", normalized to response on tweeter axis, from back to front: differences in response 135 degrees-5 degrees off-axis; reference response; differences in response 5 degrees-135 degrees off-axis.
Fig.8 Audio Artistry Beethoven, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 20 degrees-5 degrees above-axis; reference response; differences in response 5 degrees-10 degrees below-axis.