SPL Iron V2 Two-Channel Tube Mastering Compressor (Black/Silver) - Manual (Page 11)

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General Information General Information
Ground Lift switch to avoid ground loops
On the rear panel of the IRON mastering compressor (see details on page 13) is also a
“GND LIFT” (Ground Lift) switch to avoid any ground loops. Ground loops take place when
gear connected in the same network have different potentials.
The GND LIFT switch disconnects the equipment ground from the service ground to avoid
such problems. The Ground Lift function is activated (= equipment ground disconnected)
when the switch is depressed.
Tube Warm-Up
IRON includes several tubes in the signal path. We recommend you to warm up the tubes
of the IRON about 30 minutes before processing any audio material with it. The sound
and compression characteristics of the IRON compressor might change especially within
the first 15 minutes after powering on.
Suggestions for setting the compressor
The operation of the IRON strongly depends on the input signal. Normally the following
start values are a good starting point:
Attack: Position 2 or 3 (clockwise from “fast”)
Release: Position 1 or 2 (clockwise from “fast”)
Rectifier: LED
Side Chain EQs: Off
Tube Bias: Low
Threshold: 20
If you switch through the different rectifiers, you have to adjust the other parameters. The
remaining rectifier circuits tend to provide faster/slower time values. When the program
material stays the same, slower/longer time values should be chosen and/or the thresh-
old should be raised.
Especially when it comes to group applications, the high bias setting can be interesting.