MSP 3400C
PRELIMINARY DATA SHEET
7.1.21. Equalizer Loudspeaker Channel
Different sound sources (e.g. Terrestrial channels, SAT
channels or SCART) fairly often don’t have the same
volume level. Advertisement during movies as well has
mostly a different (higher) volume level, than the movie
itself. The Automatic Volume Correction (AVC) solves
this problem and equalizes the volume levels.
Band 1 (below 120 Hz)
Band 2 (Center: 500 Hz)
Band 3 (Center: 1.5 kHz)
Band 4 (Center: 5 kHz)
Band 5 (above 10kHz)
+12 dB
0021
0022
0023
0024
0025
H
hex
hex
hex
hex
hex
H
H
The absolute value of the incoming signal is fed into a
filter with 16ms attack time and selectable decay time.
The decay time must be adjusted as shown in the table
above. This attack/decay filter block works similar to a
peak hold function. The volume correction value with it’s
quasi continuous step width is calculated using the at-
tack/decay filter output.
H
H
0110 0000
0101 1000
60
hex
hex
+11 dB
58
+1 dB
0000 1000
0000 0001
08
hex
The Automatic Volume Correction works with an internal
reference level of –18 dBFS. This means, input signals
with a volume level of –18 dBFS will not be affected by
the AVC. If the input signals vary in a range of –24 dB to
0 dB the AVC compensates this.
+1/8 dB
0 dB
01
00
hex
0000 0000
RESET
hex
–1/8 dB
–1 dB
1111 1111
1111 1000
FF
F8
Example: A static input signal of 1 kHz on Scart has an
output level as shown in the table below.
hex
hex
Scart Input
0dbr = 2 Vrms
Volume
Correc-
tion
Main Output
0dBr = 1.4 Vrms
–11dB
1010 1000
1010 0000
A8
A0
hex
–12 dB
hex
0 dBr
–18 dB
–12 dB
–6 dB
–18 dBr
–18 dBr
–18 dBr
–18 dBr
–18 dBr
–24 dBr
With positive equalizer settings, internal overflow may
occur even with overall volume less than 0 dB. This will
leadtoaclippedoutputsignal. Therefore, itisnotrecom-
mended to set equalizer bands to a value that, in con-
junction with volume, would result in an overall positive
gain.
–6 dBr
–12 dBr
–18 dBr
–24 dBr
–30 dBr
–0 dB
+ 6 dB
+ 6 dB
Equalizer must not be used simultaneously with Bass
and Treble (Mode Tone Control must be set to FF to use
the Equalizer).
Loudspeaker Volume = 73h = 0 dBFS
Scart Prescale = 20h i.e. 2.0 Vrms = 0dBFS
7.1.22. Automatic Volume Correction (AVC)
To reset the internal variables, the AVC should be
switched off and on during any channel or source
change. For standard applications, the recommended
decay time is 4sec.
AVC
on/off
0029hex
[15:12]
AVC
off and Reset
of int. variables
0000
RESET
0hex
AVC
on
1000
8hex
Note: AVC should not be used in any Dolby Prologic
modes, except PANORAMA, where no other than the
loudspeaker output is active.
AVC
Decay Time
0029hex
[11:8]
8 sec (long)
1000
0100
0010
0001
8hex
4hex
2hex
1hex
4 sec (middle)
2 sec (short)
20 ms (very short)
MICRONAS INTERMETALL
39
MICRONAS [ MICRONAS ]
