Measuring the Frequency Response Position the open CD case with the internal microphone facing the sound source and place it on a soft surface to avoid vibrations - a cushion makes an ideal stand. When measuring loudspeaker response, it is usual to place the microphone at a distance of 1 metre on axis from the tweeter. This is a sufficient distance to allow the various drivers to integrate, yet close enough to avoid unwanted room reflections. In large speaker stacks, the microphone should be placed at double the distance between the bass and HF units. It is best to read the left and right speakers individually, then both together, to ensure they are summing correctly.
Smooth curves are more musical.
A series of sharp changes may give a flatter response, but at the expense of phase linearity and imaging. The human ear is more forgiving than a microphone. On speech systems, a falling response below 100Hz, and a slight rise around the vocal harmonics at 8kHz may help to improve intelligibility. Speakers using compression drivers for the midrange tend to exhibit most distortion than cone drivers, especially at the diaphragm resonance around 1 kHz. Plotting a Response Curve Start by setting the playback volume so that the 1 kHz reference on Track 1 reads 0dB on the Sound Check analyser's meter.