A Series Active Monitor Speakers
Date printed: 29.02.00 Service E4/23
4.4.2.7 A3: Polarity Check
• Place the measurement microphone at a distance of 10 cm from the baffle
and exactly in the center of the woofer.
Steps Generator Measurement
No. Description Id Value Test pos. Type Value Limits
1 System polarity G1 –14 dBV (255 mV
RMS
)/120 Hz/sine wave P1* Phase 0° ±20°
*Note: Without compensation, the microphone Brüel & Kjær BK4133+2639 is inverting
4.4.2.8 A3: Overall Phase Check
• Place the measurement microphone again on-axis, according to 4.4.2.4,
distance 0.806 m;
• Set the phasemeter propagation delay time to 2.91 ms (corresponding to a
distance of 1 m);
• Set balanced generator to 255 mVRMS (i.e. –11.8 dBV or –9.7 dBu);
• Plot a phase sweep 20 Hz…20 kHz according to the graph below;
• If the result is above the tolerance, increase the microphone distance, or if
the result is below the tolerance, decrease the microphone distance, and re-
peat the phase sweep.
100
1 k
–
180
–
135
–
90
–45
0
45
90
135
180
20 k10 k20 50 200 500 2 k 5 k
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