Register description: Sound Terminal compatibility
STA380BW
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DocID024543 Rev 1
7.11
Dynamic control registers (addr 0x12 - 0x15)
7.11.1
Limiter 1 attack/release rate
7.11.2
Limiter 1 attack/release threshold
7.11.3
Limiter 2 attack/release rate
7.11.4
Limiter 2 attack/release threshold
The STA380BW includes two independent limiter blocks (not to be mistaken with the
STCompressor
TM
, for further details about this feature please refer to
purpose of the limiters is to automatically reduce the dynamic range of a recording to
prevent the outputs from clipping in anticlipping mode or to actively reduce the dynamic
range for a better listening environment such as a nighttime listening mode which is often
needed for DVDs. The two modes are selected via the DRC bit in
. Each channel can be mapped to either limiter or not mapped,
meaning that the channel will clip when 0 dBfs is exceeded. Each limiter looks at the
present value of each channel that is mapped to it, selects the maximum absolute value of
all these channels, performs the limiting algorithm on that value, and then, if needed, adjusts
the gain of the mapped channels in unison.
The limiter attack thresholds are determined by the LxAT registers if the EATHx[7] bits are
set to 0, else the thresholds are determined by EATHx[6:0]. It is recommended in
anticlipping mode to set this to 0 dBfs, which corresponds to the maximum unclipped output
power of an FFX amplifier. Since gain can be added digitally within the STA380BW, it is
possible to exceed 0 dBfs or any other LxAT setting. When this occurs, the limiter, when
active, automatically starts reducing the gain. The rate at which the gain is reduced when
the attack threshold is exceeded is dependent upon the attack rate register setting for that
limiter. Gain reduction occurs on a peak-detect algorithm. Setting the EATHx[7] bits to 1
selects the anticlipping mode.
The limiter release thresholds are determined by the LxRT registers if the ERTHx[7] bits are
set to 0, else the thresholds are determined by ERTHx[6:0]. Settings the ERTHx[7] bits to 1
D7
D6
D5
D4
D3
D2
D1
D0
L1A3
L1A2
L1A1
L1A0
L1R3
L1R2
L1R1
L1R0
0
1
1
0
1
0
1
0
D7
D6
D5
D4
D3
D2
D1
D0
L1AT3
L1AT2
L1AT1
L1AT0
L1RT3
L1RT2
L1RT1
L1RT0
0
1
1
0
1
0
0
1
D7
D6
D5
D4
D3
D2
D1
D0
L2A3
L2A2
L2A1
L2A0
L2R3
L2R2
L2R1
L2R0
0
1
1
0
1
0
1
0
D7
D6
D5
D4
D3
D2
D1
D0
L2AT3
L2AT2
L2AT1
L2AT0
L2RT3
L2RT2
L2RT1
L2RT0
0
1
1
0
1
0
0
1
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