Neumann.Berlin KH 420, Operating Manual

Page: 22 / 42

20
| KH 420
Examples of sound pressure levels as a function of the input and output level of the KH 420:
Input signal
[dBu]
0
(0.775 V)
0
(0.775 V)
+4
(1.23 V)
−20
(77.5 mV)
INPUT GAIN control
B
[dB]
0 −15 −4 −15
OUTPUT LEVEL switch
A
[dB SPL] at 1 m
100 100 94 114
Sound pressure level
[dB SPL] at 1 m
100 85 94 79
Compensating for video delay (lip sync)
Signal processing in LCD, Plasma and LED screens, digital projectors with LCD or DLP
chips, and video processors used in broadcast centers delays the video signal.
The delay is disturbing when audio leads video by more than 20 ms or lags by more than
40 ms.
To compensate for the video signal delay, the audio signal can be delayed by up to
409.5 ms, which is 10.2 frames at 40 ms/frame or 12.3 frames at 33 ms/frame. The same
value should be used for all loudspeakers in the system.
Please consider the information on latency on page 21.
Compensating for listening distance differences (time-
of-flight)
Loudspeakers placed at different distances suffer from time-of-flight differences which
affects imaging. The delay resolution is small enough (0.1 ms) that the delay can be used
for time-of-flight adjustment (3.44 cm or 1 3/8" steps).
To compensate for the time-of-flight delay, the audio signal of the KH 420 can be delayed
by up to 409.5 ms, which is 140.87 m (462' 2"). Loudspeakers positioned closer to the
listening position should be delayed to be the same as the furthest loudspeaker from the
listening distance.
Example
Loudspeaker A listening distance: 1.50 m
Loudspeaker B listening distance: 1.65 m
Time-of-flight difference: 0.15 m
So loudspeaker A should be delayed by the time equivalent of 0.15 m which is 0.436 ms
(0.15 m / 3.44 cm x 0.1 ms). The nearest setting of the DELAY rotary switches
M
is 0.4 ms,
so set the 0.1 ms switch to position 4.
Please consider the information on latency on page 21.
If a video delay compensation has already been made, add the time-of-flight difference
(here: 0.4 ms) to the setting already made.
DIM 1 DIM 1 DIM 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 M M M M M M M M M M M M M M M M M M M M M M M M M M M M M M I I I I I I I I I I I I I I I I I I D D D D D D D D D D D D D D D D D D D D D D D D D D D
SIGNAL SELECT
DIGITAL DELAY
x 1.6 ms
x 25.6 ms
x 0.1 ms
ANALOG
ANALOG *
DIGITAL A+B
DIGITAL A+B
DIGITAL A
DIGITAL A
DIGITAL B
DIGITAL B
DELAYED
EN