Lab.gruppen PLM 20000Q - Manual (Page 96)

90
Application Guide
PLM Series Operation Manual rev 1.2.3
10.4.3.2 Analog Input Gain Structure Examples
Figure 10-4 illustrates how to minimize absolute noise while limiting the available SPL.
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 example
-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 10-4: Analog: Low Noise with Limited Output (Low Input / Low SPL)
Figure 10-5 illustrates how to minimize absolute noise while achieving full power. In this illustration it can be
seen that there is no available headroom.
▸ Input Clip: 12 dBu
▸ Amp Gain: 30.9 dB
▸ SNR: 111.3 dB
▸ Absolute Noise Floor: -68.4 dBu
-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 10-5: Analog: Low Noise with Full Output Power (Low Input / High SPL)