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Below are some examples of how to calculate the output level:
Input signal [dBu]
Input gain setting [dB]
Output level setting [dB SPL]
Sound Output of Loudspeaker
[dB SPL at 1m]
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
Input signal [dBu]
Input level setting [dB]
Output level setting [dB SPL]
Listening distance [m] (dB change)
Loudspeaker Output Level [dB SPL]
Maximum input signal before clipping
The maximum input level that the input stage can accept is +17 dBu (5.5 V).
Calibrating the Acoustical Controls
Calibrating Main Loudspeakers
Firstly, calibrate each main loudspeaker's response (preferably using an acoustical measurement system) to the
one of the following target responses:
• In studio applications, the response of each loudspeaker at the listening position should be flat.
• In movie applications, the response of each loudspeaker should be one of the X-curve shapes, depending on
the size of the room (see ANSI/SMPTE 202M).
• In home applications, the response of each loudspeaker should be set for subjective audio quality. This is not
necessarily a flat response, but generally, with time, a gently downward sloping response with increasing
frequency is often preferred.
Next, all the loudspeakers in the system should have the same level at the listening position. This is often
measured using a pink noise signal and a sound level meter set to "C-weighted" and "slow", although it is
possible to do this by careful listening.
Calibrating Subwoofer In-room Response
For each subwoofer the following settings are recommended as a good starting point for further adjustment:
Loudspeaker Location
In a corner
Next to or flush mounted in a solid wall
Next to or flush mounted in a soft wall
Free standing in an untreated room
Free standing in a well-treated room
* The level setting depends on the level settings of the main loudspeakers. The value show assumes that the
main loudspeakers are set to "0 dB" and "100 dB SPL at 1 m", or equivalent in loudspeakers with differently
labeled controls.
** The use of the parametric equalizer very much depends on the acoustical conditions of the room so no
standard recommendation can be made here.
Operating Manual O 810 / O 870
All manuals and user guides at all-guides.com
0 (0.775 V)
0
100
100
Acoustical Controls
+4 (1.23 V)
+6 (1.55 V)
0
0
100
100
104
106
(r), however this may not always be the case.
10
0 (0.775 V)
+4 (1.23 V)
-1
-5
100
100
5 m (-14 dB)
5 m (-14 dB)
85
85
17 dBu
17 dBu
Level *
Low Cut
Parametric
-8 dB
-4 dB
-4 dB
-2 dB
-2 dB
0 dB
-2 dB
0 dB
0 dB
0 dB
English
Klein + Hummel
+16 (4.89 V)
0
100
116
**
**
**
**
**
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