GTQC Problem solving page
The output sounds distorted and noisy!
It may be that you have too much input gain and/or the output level control is turned back excessively.
To check that you have set up for the correct gain structure, apply the input signal to the input of the pre-
amplifier. Press the red “←” button on the compressor and also the green “bypass/in” button. Make sure
all the other compressor buttons are off.
Take your audio output from the compressor output XLR. Now, with the pre-amplifier level control at
maximum, rotate the pre-amplifier red gain knob clockwise until your input signal sends the VU into the
red region past 0VU. It should just be “kissing” this region of the scale.
You now have the gain set correctly for the source you are using.
I don’t get any output from the unit!
There are several things to check if you have no output from the unit…
If you are using the compressor and the pre-amplifier, make sure the red “←” button is pressed. Also,
make sure that the output level control for the pre-amplifier is at maximum.
Finally, the impedance switch on the rear of the pre-amplifier is designed to switch between 300Ω and
1200Ω input impedance. If this switch has been accidentally been moved to the center of its travel then
the microphone input XLR will be disconnected from the pre-amplifier.
I get bad hum when using the DI input!
This is because you are either getting a ground loop with the device you are connected to or, if a guitar, the
connecting cable is either not inserted properly at both ends or the pick-ups are getting interference from a
strong electro-magnetic field… like lamp dimmer pulses in the building wiring.
If the issue is a ground loop then make up a cable to connect the device to the microphone input XLR.
Connect the inner (signal) core to pin 2, and connect the shield to pin 3. Do not connect anything to pin 1.
Now, if the impedance switch is selected to 1200Ω, then the transformer-coupled input will isolate the
GTQ2 ground from the ground (or rather, lack of ground!) of the device you are amplifying.
There is also a possibility of a ground loop when using the pre-amplifier unbalanced output. Should this
occur... like if you connect it to an unbalanced guitar amplifier... then use a DI box with a transformer
input to isolate the ground of the GTQ2 from the grounding issues of the guitar amplifier.
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