Operation Manual

10. Application Guide
PLM+ SERIES Operation Manual rev 3.0.4
81
The improvement in noise performance (at the cost of losing headroom and compression features) is only 0.6 dB;
it is therefore not recommended to optimize performance in this manner.
10.3.3.2. 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
Table 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
Table 10.5: Analog: Low Noise with Full Output Power (Low Input / High SPL)
-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 A mp Attenuation Analog Ref Amp Gain ISVPL Output
dB/dBu
Clip
Nominal
Nois e
-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 ISV PL Output
dB/dBu
Clip
Nominal
Nois e
10. Application Guide
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PLM+ SERIES Operation Manual rev 3.0.4
Figure 10.6 illustrates how moderate noise with extreme SPL can be achieved. SPL is extremely high in this
example as maximum headroom is available at the input and within the processing stage. This makes it possible to
increase the average SPL by utilizing internal compression capabilities.
• Input Clip: 0 dBFS
• Amp Gain: 35 dB
• SNR: 114.2 dB
• Absolute Noise Floor: -71.3 dBu
-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/dBu
Clip
Nominal
Nois e
Table 10.6: Analog Input: Moderate Noise with Very High Output (Very High SPL)
10.4. Speaker Configurations
impedance of that presented by one speaker. Therefore, the current that two speakers will attempt to draw from
Limiter to become active. The more speakers connected to an output in parallel, the lower the impedance and the
higher the current draw.
Multiple loudspeakers may be driven by a PLM+ power output more satisfactorily if a series-parallel wiring
When using series-parallel wiring, the nominal impedance is the same as with one speaker; however, the principle
of power sharing still applies, and it is not possible to get t
NOTE: Nominal loads as low as 2 ohms are supported by the PLM+. However, a 2 ohm nominal load
has impedance dips at its resonances below 2 ohms; in such cases it is likely that the resulting higher
current will cause CPL to activate.
10. Application Guide
82
PLM+ SERIES Operation Manual rev 3.0.4