Speaker Configurations; Digital Audio Connections - Lab.gruppen PLM series Operation Manual

Application Guide
▸ Absolute Noise Floor: -71.3 dBu
60.0
40.0
20.0
0.0
-20.0
-40.0
-60.0
-80.0
-100.0
-120.0
-140.0
Analog
Figure 10-6: Analog Input: Moderate Noise with Very High Output (Very High SPL)

10.5 Speaker Configurations

Connecting two speakers in parallel to a PLM power output presents a load to the amplifier which is half the
impedance of that presented by one speaker. Therefore, the current that two speakers will attempt to draw
from the output stage is double that for one speaker, and this higher current may be sufficient to cause the
Current Peak 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
configuration is adopted. Please ensure care is taken to match polarity correctly.
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 the amplifier section to deliver more than
its rated power.
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.

10.6 Digital Audio Connections

Whenever possible, it is preferable to connect a digital rather that analog input signal to the device. This is
particularly relevant if the source signal is already in the digital domain, such as the source from a digital
mixing console or digital distribution system. The primary cause of signal distortion and signal delay (latency)
is the digital-to-analog and analog-to-digital conversion process. Therefore, using digital inputs normally
provides higher quality audio with lower latency.
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PLM Series Operation Manual rev 1.1.9
AES Input Input Mixer Module In Module Out Amp Attenuation Analog Ref Amp Gain
Clip
Nominal
Noise
ISVPL Output