26. EFX Control
This control alters the signal level that is sent to the EFX
send (AUX 2) output and the built-in digital effect proces-
sor. The EFX send signal can be used in conjunction with
external signal processors (this signal of which can be
returned to mixer via the AUX return input), or simply as
an additional auxiliary output.
27. 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, the PAN 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).
28. On Button and Indicator
This turns the channel on, allowing the user to use the feed
from the channel’s inputs to supply the MAIN L/R, GROUP
1/2, AUX and EFX buses. The corresponding indicator will
be illuminated when turned on.
29. 1-2 and L-R Buttons
These handy buttons allow you to decide the audio path
of the corresponding channel. Pushing the “1/2” button
allows the signal to be sent to the Group 1/2 mix, where
the “L-R” allows it to be sent to the Main L/R mix.
30. Peak Indicator
This LED indicator will illuminate
when the channel hits high peaks,
6 dB before overload occurs. It is
best to adjust the channel level
control so as to allow the PEAK
indicator to light up on regular
intervals only. This will ensure a
greater dynamic range of audio.
This indicator also doubles as a
Solo indicator, when the SOLO
button is engaged.
31. Solo Button
The Solo button is pushed to allow the signal of a corre-
sponding channel to be sent to the Control Room / Phones
control (pre or post fader, depending on the properties
selected by the pre / post button, located by the Control
Room / Phones control), for use with either headphones
or studio monitors. This also allows easier setting of the
input gain and tracking of audio by sound engineers. The
Peak indicator above the Solo button also doubles as a
Peak Indicator, illuminating when the signal reaches high
peaks.
32. Channel Level Control (Fader)
This control will alter the signal level that is sent from
the corresponding channel to the corresponding mixing
buses.
Channel Controls
20. Low Cult Filter (75 Hz)
This button will activate a high-pass fi l-
ter that reduces all frequencies below
75 Hz at 18 dB per Octave, helping to
remove any unwanted ground noise or
stage rumble.
21. Gain Control
This controls the sensitivity of the input signal of the Line/
Microphone input. The gain should be adjusted to a level
that allows the maximum use of the audio, while still main-
taining the quality of the feed. This can be accomplished
by adjusting it to a level that will allow the peak indicator
occasionally illuminate.
22. 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.
23. Middle Frequency Control
This control is used to provide a peak-
ing style of boost and cut to the level
of middle frequency sounds at a range
of ±15 dB. These mixers also provide a
sweep control, allowing you to select a
center frequency between 100 Hz and
8 kHz. Changing middle frequencies
of an audio feed can be rather diffi cult
when used in a professional audio mix,
as it is usually more desirable to cut
middle frequency sounds rather than
boost them, soothing overly harsh vocal
and instrument sounds in the audio.
The stereo channels of the Helix Board
17 mixer feature a High-Mid and Low-Mid control instead
of the typical controls described above. They provide a
peaking style of boost and cut to middle frequencies, where
the frequencies are set at 3 kHz and 800 Hz (High-Mid is
set at 3 kHz and Low-Mid is set at 800 Hz).
24. 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.
25. AUX Control
This control alters the signal level that is being sent to the
auxiliary 1 mixing bus, the signal of which is suitable for
connecting stage monitors, allowing artists to listen to the
music that is being played. Also included is a Pre/Post
button (for AUX 1), which alternates the feed to the AUX
mixing bus between a post and pre-fader feed.
8
HELIX BOARD 17
