EgglestonWorks Andra loudspeaker Measurements part 2

Predicting how these three nearfield responses will sum at the listening position is difficult; shown to the left of fig.4 is my best guesstimate, with the acoustic phase and path-length differences taken into account. The Andra's output appears to peak up slightly at 70Hz, then slowly rolls off, reaching its -6dB point at a very low 22Hz. In-room, with the usual amount of low-frequency room gain, the Andra should easily extend to 20Hz at full level. Note that both the woofer and port have slight peaks at 200Hz; while these result in a slight peak in this frequency in the calculated farfield response, it should be subjectively inconsequential.

Fig.4 EgglestonWorks Andra, anechoic response on tweeter axis at 50", averaged across 30 degrees horizontal window and corrected for microphone response, with complex sum of midrange, woofer, and port responses plotted below 300Hz.

To the right of fig.4 is the Andra's farfield response, measured on its tweeter axis using the DRA Labs MLSSA system and averaged across a 30 degree horizontal window. The midrange trend in fig.4 is basically evenly balanced, but note the enormous measured suckout in the upper crossover region on this axis, centered on 3kHz. I must admit that I didn't find the Andra to be as free from coloration as WP did. I noted a slight degree of hollowness that made violin and viola, for example, sound a little as if played with mutes. However, this was much milder than I would have expected from this measured response.

The tweeter is 33" from the floor, which is on the low side. (Tom Norton's research has shown that a typical listener's ear in a typical chair is 36" high.) Fig.5 shows the Andra's response at different heights; it can be seen that the crossover-region suckout is worst on the tweeter axis. The broad overlap between the tweeter and twin midrange units does appear to make the speaker very sensitive to listening height. Perhaps the flattest measured response is obtained 10 degrees below the tweeter axis (the trace at the front of this graph). However, this represents a listener with his ear around 20" from the floor. By contrast, fig.6 shows the Andra's measured response 10 degrees above the tweeter axis, which represents a typical listener sitting in something like a director's chair. While there is still a lack of energy in the speaker's upper crossover region, it is much less severe than on the tweeter axis.

Fig.5 EgglestonWorks Andra, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 15 degrees-5 degrees above axis; response on HF axis; differences in response 5 degrees-10 degrees below axis.

Fig.6 EgglestonWorks Andra, anechoic response 10 degrees above tweeter axis at 50", averaged across 30 degrees horizontal window and corrected for microphone response, with complex sum of midrange, woofer, and port responses plotted below 300Hz.

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EgglestonWorks
435 S. Front St.
Memphis, TN 38103
(800) 290-5331
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