PLM Series Operation Manual rev 1.1.3
12. Application Guide
89
As can be seen to the left, the improvement in noise performance (at the cost of losing headroom and
compression features) is only 0.6 dB. It is therefore recommended
not
to try to optimize performance in this
manner.
When using analog inputs:
Figure 12.4a illustrate how to minimize absolute noise within the PLM, while limiting available SPL.
Parameter list:
Input clip: 12 dBu
Amp gain: 22 dB
SNR: 105.5 dB
Absolute Noise Floor = -71.5 dBu
SPL is limited to -8.9 dB relative to clip in this “minimum absolute noise level application”.
Figure 12.4b illustrate how to minimize absolute noise while achieving full power. In this illustration it can be
seen that there is no available headroom.
Parameter list:
Input clip: 12 dBu
Amp gain: 30.9 dB
SNR: 111.3 dB
Absolute Noise Floor = -68.4 dBu
Gain Structure: "Low SPL - Low Input" Application (Low noise with limited output)
-140,0
-120,0
-100,0
-80,0
-60,0
-40,0
-20,0
0,0
20,0
40,0
60,0
Analog
AES Input
Input Mixer
Module In
Module Out
Amp
Attenuation
Analog Ref
Amp Gain
ISVPL
Output
dB
/d
B
u
Clip
Nominal
Noise
Figure 12.4a: Minimizing noise
Gain Structure: "Low SPL - Low Input" Application (Low noise with limited output)
-140,0
-120,0
-100,0
-80,0
-60,0
-40,0
-20,0
0,0
20,0
40,0
60,0
80,0
Analog
AES Input
Input Mixer
Module In
Module Out
Amp
Attenuation
Analog Ref
Amp Gain
ISVPL
Output
dB
/d
B
u
Clip
Nominal
Noise
Figure 12.4b: Minimizing noise
