1.5.2 Gain Knob
The Gain Knob allows you to control the amount of gain
added to the input signal. The gain should be set as high
as possible without either seeing the peak indicator (*)
flash on the VU meter, hearing audible clipping or
distortion, or overloading the following stage in the signal
chain. For instance, your Mic Pre 4T can support outputs
up to +26dB, but most audio interfaces clip at +18dB.
The gain control would have to be set so as to not
overload the audio interface. Professional consoles are
capable of handling levels as high as +30dB in some
cases.
One common procedure for setting gain is to set the level
while the channel is muted. Turn up the gain until the
peak indicator (*) flashes during the loudest parts of the
performance. Then reduce the gain by 5 – 10dB.
Disengage the mute of the console or DAW and listen to
the signal. Note that many performers will sing or play
significantly harder and more energetically when they
believe they are recording compared to when they
believe that levels are being set.
If you are still showing peaking on the VU meter, but
the gain switch is turned down all the way, engage the
Pad button
to reduce gain by 20dB. This will not affect
the timbre of the audio, just the level.
1.5.3 Variable HPF (High-Pass Filter) Knob
Why do we need it?
In the old days (or even now if you can afford it!) we
recorded audio on magnetic tape, which isn’t good at
reproducing very low frequencies. When tracking at 30
IPS (Inches Per Second) frequencies below 40 Hz were
severely attenuated and, even at 15 IPS, frequencies
below 20 Hz were attenuated. Digital equipment, on the
other hand, happily records frequencies from 40 Hz all the
way down to DC.