I used DRA Labs’ MLSSA system, a calibrated DPA 4006 microphone, and an Earthworks microphone preamplifier to measure the Q Acoustics Concept 50’s frequency response in the farfield. I used an Earthworks QTC-40 mike for the nearfield and in-room responses and Dayton Audio’s DATS V2 system to measure the impedance magnitude and electrical phase angle.
Q Acoustics specifies the Concept 50’s anechoic sensitivity as 90.5dB/W/m. My estimate was somewhat lower, at 88.1dB/2.83V/m. The Concept 50’s impedance is specified as 6 ohms, with a minimum value of 3.6 ohms. The impedance magnitude (fig.1. solid trace) varied between 6 ohms and 10 ohms over most of the audioband, with lies close to 3 ohms at 53Hz, between 96Hz and 262Hz, and between 1.6kHz and 4kHz, with a minimum value of 2.18 ohms at 2.58kHz. As long as the partnering amplifier is comfortable driving 4 ohms, the Concept 50 won’t present it with any drive problems.
