8
HELIX BOARD 12 PLUS
Channel Controls
18. Low Cut Filter (75 Hz)
This button, located on channels 1 through
to 4, will activate a low-cut / high-pass
filter that reduces all frequencies below
75 Hz at 18 dB per Octave, helping to
remove any unwanted ground noise or
stage rumble.
19. Mic / Line Gain Control
This controls the sensitivity of the input signal of the Microphone
/ Line input. The gain should be adjusted to a level that allows
the maximum use of the audio, while still maintaining the quality
of the feed, based on the channel setup instructions. This can
be accomplished by adjusting it to a level that will allow the peak
indicator occasionally illuminate. All 4 mono channels feature
this control.
20. High Frequency Control
This control is used to give a shelving boost or cut of ±15 dB to high
frequency (12 kHz) sounds. This will adjust the amount of treble
included in the audio of the channel, adding strength and crispness
to sounds such as guitars, cymbals, and synthesizers.
21. Middle Frequency Control
This control is used to provide a peaking style of boost and cut
to the level of middle frequency (2.5 kHz) sounds at a range of
±15 dB. Changing middle frequencies of an audio feed can be
rather difficult when used in a professional audio mix, as it is
often more desirable to cut middle frequency sounds rather than
boost them, thereby soothing overly harsh vocal and instrument
sounds in the audio.
22. Low Frequency Control
This control is used to give a shelving boost or cut of ±15 dB to
low frequency (80 Hz) sounds. This will adjust the amount of bass
included in the audio of the channel, and bring more warmth and
punch to drums and bass guitars.
23. USB Pre/Post Switch
This switch is used to change the signal of the corresponding
channel that is sent to the Computer via the USB interface between
that of a pre-EQ, pre-fader, pre-low cut to that of a post-EQ, post-
fader, post-low cut. In the uppermost position, the channel will be
pre, and in the lower position post.
24. AUX 1 (Monitor) Control
This control allows the user to send the corresponding signal
to the AUX 1 output, which can be used in conjunction with an
amplifier and studio or stage monitors, or simply as an auxiliary
output for any means required. The control is pre-fader, therefore
any changes made to the corresponding channel level control do
not affect the AUX 1 send signal.
25. AUX 2 (Effects) Control
This control alters the signal level that is sent to the AUX 2 (or
EFX) send output, which can be used in conjunction with external
signal processors (this signal of which can be returned to mixer via
the AUX return input, or any stereo input channel), or simply as an
auxiliary output for any means required. This control is post-fader,
therefore any changes made to the corresponding channel level
control are also applied to the EFX signal. The EFX send signal
is also sent to the built-in effect processor for providing effects to
the main output and AUX 1 send, as required.
26. Pan / Balance Controls
This alternates the degree or level of audio that the left and right
side of the main mix should receive. On mono channels, this
control will adjust the level that the left and right should receive
(pan), where as on a stereo channel, adjusting the BAL control will
attenuate the left or right audio signals accordingly (balance).
27. Mute / ALT 3-4
This handy little button is basically a typical mute button – effectively
stopping any signal received by the channel from being sent to
the Main L/R or AUX 2 send mixing buses – however it does so
much more. Pushing this button routes the channel’s signal away
from the Main L/R and to its own “Alternate” stereo output (Alt
3-4), where the signal can be used at will. If you wish to use it to
connect an amplifier and speakers, or simply patch it through to
an unused input channel, you can easily do so.
28. Peak Indicator
This LED indicator will illuminate when the device hits high peaks,
6 dB before overload occurs. It is best to adjust the gain of the
channel so that the PEAK indicator lights up on intervals only. This
will ensure a greater dynamic range of audio. This LED will light
up while the Mute button is pushed in.
29. Level Control
This rotary control will alter the signal level that is sent from the
corresponding channel to the Main or Alt. 3-4 mixing bus.
