Klein + Hummel
O 810 / O 870 Operating Manual Page 21 of 96
Version 01
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
Calibrating Absolute
Calibrating Absolute
Calibrating Absolute Level
Level
Level
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:
Application
Application
Application
Application
SPL
SPL
SPL
SPL
Movie
85 dB(C)
Broadcast
79 dB(C)
Music
Engineer’s preference
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
Test Signals
Test Signals
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.
Volume Control
Volume Control
Volume Control
Volume Control
One of the biggest problems in multichannel monitoring is controlling the replay level of the monitoring system.
When there is volume control available at source, the mixing console or surround sound processor controls the
level of the all the output signals from the device. The Volume Control switch should be set to “Disable” so that
the gain through the bass manager is fixed to 0 dB for all channels.
When volume control is not available at the source, it can be performed in the 7.1 High Definition Bass Manager™.
This is typical, for example, when stereo consoles are being used for multichannel work, or when CD players or
(processed) outputs from DVD players are directly connected to the subwoofer. In these cases, the Volume
Control switch should NOT be set to “Disable”, i.e. to the left. The system volume can then be controlled using a
hardware remote controller (the SRC 1 or SRC 2 from K+H), or by using RS-232 codes from an automation
system, for example Crestron or AMX.
The VOL stages are located at the main channel outputs of the 7.1 High Definition Bass Manager™ and the
subwoofer output. As a result they can be used for controlling the replay level of the entire system or for
remotely trimming individual loudspeaker levels. Consequently, they cannot be used to replicate signal SOLO or
SELECT type functions as seen in mixing consoles. However, it is possible to MUTE and SOLO one or more of the
loudspeaker outputs. This is useful when setting up the system – play some bassy material at high levels with all
the main loudspeakers muted (subwoofer is soloed) to find the source of rattles in the listening room. Using
subwoofer mute and bass management together gives some useful additional functionality:
