MEASUREMENTS

I used DRA Labs’ MLSSA system and a calibrated DPA 4006 microphone to measure the Acora SRB’s frequency response in the farfield, and an Earthworks QTC-40 mike for the nearfield and in-room responses. My initial measurements were performed on one of the original samples auditioned by Julie Mullins, serial number TIB0010. After Acora found out that the first samples had been incorrectly assembled with the tweeters wired in the wrong polarity, which resulted in a massive suckout in the crossover region, they submitted new samples. I performed a complete set of measurements on serial number TIB0021. Except where noted, all the following comments apply to the new sample.

Acora specifies the SRB’s sensitivity as 86.5dB/W/m; my estimate was within experimental error of this, at 85.9dB(B)/2.83V/m. Although the is close to 4 ohms for much of the audioband and drops to 2.54 ohms between 120Hz and 130Hz. As is often the case, this loudspeaker will work best with amplifiers that are comfortable driving loads below 4 ohms.