InterStudio Home PagePosition 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.
When measuring the overall response of a sound system, i.e. the interface between the speaker and the room (which will affect the apparent response of the speakers), the analyser should be placed at several listening positions to get a general picture of the performance of the system.
It is best to read the left and right speakers individually, then both together, to ensure they are summing correctly.
When setting graphic equalisers, avoid sharp dips and peaks, (unless a steep dip is required to reduce microphone feedback). 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. Smooth corrections giving a final response of 40Hz - 16kHz + 5dB are more practical and preferable to trying to achieve a totally flat response from 20Hz - 20kHz where the speaker units and amplifiers may run of headroom. On speech systems, a falling response below 100Hz, and a slight rise around the vocal harmonics at 8kHz may help to improve intelligibility. Similarly, with music systems, a slight rise (3-6dB) between 63Hz and 120Hz and another at around 10 kHz will help to improve the apparent "fidelity" of the system by stressing those frequencies where much of the energy occurs in music, and where most speaker systems are less efficient.
Speakers using compression drivers for the midrange tend to exhibit most distortion than cone drivers, especially at the diaphragm resonance around 1 kHz. A slight dip in response around this frequency tends to reduce "harshness" especially at high sound levels.
Start by setting the playback volume so that the 1 kHz reference on Track 1 reads 0dB on the Sound Check analysers meter. As the next 31 bands are played from 20Hz to 20kHz, readings can be taken from the meter, and the graph paper which has identical calibrations, can be marked to form a response curve.
The Sound Check disc is coded so that the announcements can be eliminated by pressing the "next track" facility found on most CD players. Using the facility, with practice, the 9.5 octaves covering the entire audio spectrum can be read with considerable speed.
Use the "store and repeat" (looping) function on your CD player or computer to repeat any track requiring special attention. For continuous playing of part of any one track, use the A-B facility found on most CD players.
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