Gain Settings - Lab.gruppen PLM series Quick Start Manual

6.5 Gain Settings

The architecture of the PLM Series provides gain adjustments at a number of points in the signal flow path.
Thus, there are many places in which one can adjust the levels in the PLM. Each point serves a different
purpose.
More detailed information on gain settings can be found in the PLM Operation Manual section 8.1.
The following can be used as guidelines for adjustment of the gain settings, from input to output. The block
signal flow diagram below can also be used as a reference to help in understanding the signal path through
the PLM's architecture:
Input headroom (Analog Inputs)
As a rule, this should be set to 12 dBu if the source is (or can be) limited to 12 dBu; otherwise it should be at
26 dBu. This setting has no direct influence on the rest of the gain stages in the PLM, or on the overall noise
floor. The PLM's variable input gain is strictly meant to provide the appropriate headroom at the input stage.
(Adjust in I/O Config window, Input Configuration, left side.)
Input mixer
This setting should be left at "0" for most setups. If only one input channel is used, the other can be set to
"- inf". (Adjust in I/O Config, module pane.)
Module output gain (Levels)
Two points of gain level adjustments are provided per Module output. They are used to balance the mutual
gain between frequency bands in a multi-way set up, and can be described as follows:
- Manufacturer gain: This is "hidden" within the module file and is set by the creator of the file. As such, it
is not user editable.
- User gain: This is editable by a user. The module file (part of the Fingerprint) contains a default value for
this as well as the manufacturer gain. If the manufacturer gain is set to a non-zero value, then the default
user gain is zero dB so that the user can easily see any changes that have been made to this setting. It
should normally not need to be adjusted by the user.
Output gain (Levels)
One adjustment is provided per output channel in the module to balance the mutual gain between frequency
bands in a multi-way set up. Generally, this setting is derived from the LoadLibrary Fingerprint data within
the PLM preset. As such, it should not need to be adjusted further. (Adjust in I/O Config, module pane.)
Attenuator
One adjustment is provided per output channel in the PLM. This control replaces the traditional knob found
on conventional amplifiers. It should typically be left at 0 dB during use. (Adjust in Lab.gruppen Info, Status
tab)
Amp Gain
Corresponds to the gain that you would have available in a conventional system if the amplifier section was
outside the PLM.
It should retain the same settings as in the module file that is loaded. The limiter and output gain
PLM Series Quick Start and Field Reference Guide rev 1.0.6
6. Quick Start Tutorial
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