Klein + Hummel O 810 - Calibrating the Acoustical Controls

Klein + Hummel
O 810 / O 870 Operating Manual Page 19 of 96 Version 01
• The Parametric
ParametricParametric
Parametric Equalizer
EqualizerEqualizer
Equalizer is a single stage PEQ filter with gain
gaingain
gain (+4…-12 dB), frequency
frequencyfrequency
frequency (20…120 Hz) and Q
QQ
Q
(1…8) controls designed to control nonlinearities seen below 120 Hz – see graph above. These nonlinearities
can come from boosts caused by constructive interference or strong room modes. It is possible to bypass the
parametric equalizer using the bypass
bypassbypass
bypass switch.
• The Subwoofer Phase
Subwoofer PhaseSubwoofer Phase
Subwoofer Phase controls consist of a 0°
0°0°
0° / -
--
-180°
180°180°
180° switch and 0°
0°0°
0° / -
--
-45°
45°45°
45° / -
--
-90°
90°90°
90° / -
--
-135°
135°135°
135° switch. This applies a
very short delay (45° at 80 Hz = 1.56 ms) to the subwoofer output, and gives a positional resolution of 0.54
m (1’ 9”). These controls are used to acoustically realign the subwoofer with the main loudspeakers when
they are positioned at different distances from the listening position.
• The subwoofer’s output level is controlled using the Subwoofer Gain
Subwoofer GainSubwoofer Gain
Subwoofer Gain controls. This consist of a finely
graduated Input Gain
Input GainInput Gain
Input Gain (+2 to -12 dB) potentiometer and a coarse Output Level
Output LevelOutput Level
Output Level (100 or 114 dB SPL at 1 m)
switch. This allows the subwoofer to be matched to a wide range of equipment outputs whilst maintaining
the desired acoustical output. It can also compensate for level differences due to acoustical loading and the
distance of the subwoofer from the listening position compared to the main loudspeakers. The default
settings are “0 dB” and “100 dB SPL at 1m”. This gives an output level of 100 dB SPL at 1m when the input
signal is 0 dBu (0.775 V). The most sensitive setting (most acoustical output for a given input voltage) is “2
dB” and “114 dB SPL at 1m”, and the least sensitive setting is “-12 dB” and “100 dB SPL at 1m”.
Acoustic output level [dB SPL] of the loudspeaker at 1m
Acoustic output level [dB SPL] of the loudspeaker at 1mAcoustic output level [dB SPL] of the loudspeaker at 1m
Acoustic output level [dB SPL] of the loudspeaker at 1m
when input signal is 0 dBu
when input signal is 0 dBuwhen input signal is 0 dBu
when input signal is 0 dBu
Input Gain
Input Gain Input Gain
Input Gain
Potentiometer [dB]
Potentiometer [dB]Potentiometer [dB]
Potentiometer [dB]
Output Level switch = “100 dB”
Output Level switch = “100 dB”Output Level switch = “100 dB”
Output Level switch = “100 dB” Output Level switch = “114 dB”
Output Level switch = “114 dB”Output Level switch = “114 dB”
Output Level switch = “114 dB”
-12 dB 88 102
-10 dB 90 104
-8 dB 92 106
-6 dB 94 108
-4 dB 96 110
-2 dB 98 112
0 dB 100 (default) 114
2 dB 102 116
Below are some examples of how to calculate the output level:
Input signal [dBu] 0 (0.775 V) +4 (1.23 V) +6 (1.55 V) +16 (4.89 V)
Input gain setting [dB] 0 0 0 0
Output level setting [dB SPL] 100 100 100 100
Sound Output of Loudspeaker
[dB SPL at 1m] 100 104 106 116
In Europe, 0 dBu is -18 dBFS (EBU standard R68). In the US, +4 dBu is -20 dBFS (SMPTE standard RP155).
These dBu values should equate to 85 dB SPL at the listening position. It is typical in the broadcast industry
to use a reference level of 79 dB SPL at the listening position. Near field loudspeakers can be as close as 1 m
from the listening position, whereas loudspeakers in a Dolby certified movie mixing room should be at least 5
m from the listening position. In the examples below, it is assumed that the listener is inside the room radius
and thus the sound field decays according to 20 log
10
(r), however this may not always be the case.
Input signal [dBu] 0 (0.775 V) +4 (1.23 V)
Input level setting [dB] -1 -5
Output level setting [dB SPL] 100 100
Listening distance [m] (dB change) 5 m (-14 dB) 5 m (-14 dB)
Loudspeaker Output Level [dB SPL] 85 85
Maximum input signal before clipping 17 dBu 17 dBu
The maximum input level that the input stage can accept is +17 dBu (5.5 V).
Calibrating the Acoustical Controls
Calibrating the Acoustical ControlsCalibrating the Acoustical Controls
Calibrating the Acoustical Controls
Calibrating Main Loudspeakers
Calibrating Main LoudspeakersCalibrating Main Loudspeakers
Calibrating Main Loudspeakers
Firstly, calibrate each main loudspeaker’s response (preferably using an acoustical measurement system) to the
one of the following target responses: