A Ground Lift Switch; Principles Of The Hum Extractor Adjustment And Operation - iSP Technologies HUM EXTRACTOR +DECIMATOR G Owner's Manual

A GROUND LIFT switch is provided to avoid ground loops from redundant grounds in your
setup. When switched to LIFT this lifts the ground connections for both INPUT and OUTPUT
of channel 2.
Channel 2 should be connected after all preamplifier, equalization and compression which
allows the DECIMATOR to remove all gain noise present in the signal post gain functions.
This also allows the user to set the threshold to remove noise from the audio signal
without the need to change threshold settings when switching from high gain to a clean tone.
The diagram below shows the typical connections when using guitar pedals and a guitar
amplifier with a series effects loop. The guitar output is connected directly to the Guitar IN on
the HUM EXTRACTOR +DECIMATOR G, the Guitar OUT is connected to the input of all
pedals which can cause noise in the signal path, compression, overdrive, distortion etc. The
output of the pedal chain is connected to the input of a guitar amplifier and the series loop is
connected to the second channel of the HUM EXTRACTOR +DECIMATOR G. In this
configuration the HUM is eliminated in the signal between the guitar and the input of the pedal
chain and the DECIMATOR is in the signal path after the preamplifier of the guitar amplifier.
This allows the DECIMATOR to remove all noise introduced at any point in the signal path
and will not require any threshold change when switching from high gain to clean tones.
NOTE: when using longer time based effects like echo, delay and reverb it is best to insert
these effects after the output of channel 2 to avoid cutting off reverb tails or echo spillover.
Channel 2 can be inserted after the pedal chain if a series loop is not available in the setup.

Principles of the HUM EXTRACTOR adjustment and operation:

When set properly the HUM EXTRACTOR will remove line frequency HUM components and
the associated higher frequency harmonic hum components in the audio signal. Set the LINE
FREQUENCY switch for the required line frequency in use either 50 hertz or 60 hertz based