Klein + Hummel 0810 Bedienungsanleitung Seite 22

Calibrating Phase
One way to calibrate the phase control is by simple physical measurements in the room. For example, if the
loudspeakers are positioned 1.5 m closer to the listening position than the subwoofer, the loudspeakers should
be delayed by 4.36 ms which is approximately the same as -135° at 80 Hz. Delaying a single subwoofer signal is
more practical than delaying all the main loudspeakers so use a -225° setting (achievable using the -180° and -
45° settings). It is recommended to keep the listening distance difference between the subwoofer's and the main
loudspeakers' within 2 m (6') of each other.
Another easy way to calibrate the phase control is to use the built in signal generator. Connect a loudspeaker to
the left output of the subwoofer, and turn on the signal generator. An 80 Hz tone will be heard from the
subwoofer and the loudspeaker connected to the left output. Now systematically use the two phase controls to
give values of 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°. Find setting that gives the lowest sound level at
the listening position. This can be measured using an acoustic measurement system or a sound level meter (set
to "C-weighted" and "Slow"), or by listening (requires a second person). This is the case when the subwoofer and
loudspeaker are completely out of phase so now flip the 0°/180° switch to its other setting. Finally, check the
result with the other loudspeakers in the system by connecting different loudspeakers to the left output socket.
It is possible that the same setting is not valid for all loudspeakers. A reason for this is the presence of reflections
in the room that cause cancellations around the 80 Hz region in either the loudspeakers, subwoofers, or both. The
solutions for this include moving the subwoofer and/or main loudspeakers, or applying acoustical treatment to
the source of the reflection.
Calibrating Absolute Level
Absolute acoustic level calibration for signal channels is generally achieved using a sound level meter set to
"C-weighted" and "Slow". Play a broadband pink noise test signal set to -18 dBFS (Europe) or -20 dBFS (USA) on
the console meters and measure the sound pressure level at the listening position. Then adjust each channel's
source level, not the loudspeakers and subwoofer(s)) so that the desired acoustical level is achieved:
The maximum acoustical output of the subwoofer is limited by the protection system. In general, larger
subwoofers can play louder and for longer periods than smaller subwoofers. If the protect light is regularly
illuminated, add more subwoofers to the system or change to a larger subwoofer, and then recalibrate.
Test Signals
To help calibrate the in-room response of subwoofers, some specially designed test signals have been designed.
They can be found at www.klein-hummel.com. Instructions for their use are included which supplement the
instructions written above.
Operating Manual O 810 / O 870
Calibrating the Phase Control
Application
Movie
Broadcast
Music Engineer's preference
SPL
85 dB(C)
79 dB(C)
English
Klein + Hummel
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