Gain Structure - Lab.gruppen PLM 20K44 Operation Manual

10. Application Guide
10.2.2. Six PLM+ Series Devices with 100-120 V Mains Supply
If the mains supply is 115 V and the system requirement is 6 PLM+s, then the mains capacity would need to be
able to supply two 3 x 30 A circuits. There are two methods of achieving this:
1. Two racks, each with three 230 V version PLM+s and a 30 A three-phase mains supply. In the rack the PLM+s
are connected between the phases, i.e. one between phase 1 and 2, one between phase 2 and 3 and the last
between phase 3 and 1. Each 30 A mains breaker is shared between two PLM+s and the mains current is to
some extent canceled. This has the benefit that the three PLM+s don't have to draw the same current; one can be
allowed to draw a little more than the other two. The only limitation is that in combination they don't draw over 30 A.
2. Two racks, each with three 115 V version PLM+s and a 30 A three-phase mains supply. One phase is used for
each PLM+ within the rack. This has the benefit that each PLM+ has its own breaker, but they all have to operate
within the same limit of 30 A; therefore, more care must be taken to ensure that no breaker blows if different loads
are used.

10.3. Gain Structure

The PLM+ Series architecture provides gain adjustments at various points in the signal path and therefore enabling
various places for muting and level adjustment. Each mute or gain adjustment point serves a different purpose.
The signal flow diagrams in chapter 6 provide a useful reference for the signal path. The following sections describe
the various adjustment points, all of which are available via the Lake Controller software.
10.3.1. Input Headroom (Analog Inputs Only)
Input Headroom should be set to 12 dBu if the source can be limited to 12 dBu; otherwise it should be set to
26 dBu. This setting does not affect the other gain stages, or the overall noise floor; it allows control of the
appropriate headroom at the input stage only.
To adjust, navigate to I/O CONFIG > INPUT CONFIGURATION in the Lake Controller. Please refer to the Lake
Controller Operation Manual for further details.
10.3.2. Input Mixer
Input Mixer gains can remain at 0.00 dB for most configurations; if only one input channel is used per Module, the
other can be set to -INF.
To adjust, navigate to I/O CONFIG and tap the Input Mixer blocks for the Module in the Lake Controller. Please
refer to the Lake Controller Operation Manual for further details.
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PLM+ SERIES Operation Manual rev 1.0.0