Allen&Heath GLD-112 Reference Guide - Manual (Page 25)

GLD Touch Screen Reference V1.4 – Issue 1 25 ALLEN & HEATH
and relies on manual sweeping of the phase chain using
the ‘offset’ control.
Offset - Shifts the operating frequency range of the Phaser.
Maximum settings force the Phaser to operate in higher
frequencies. Lower Offset settings allow lower frequency
phase sweeps (more intense). In manual mode (Depth = 0)
the user can adjust the phase sound with this control.
Preset Name is displayed. Touch and scroll using the
screen Rotary for live update. This is a way of live
auditioning all library presets for this module (factory, user
and USB). You can also select and recall a particular preset
using the Library window.
Hypabass
A sub-harmonic synthesis unit used in the live sound
environment to generate infra and sub bass spectrum from
weaker bass programme. We initially emulated the
American analog classic, but implementation in DSP gave
us the ability to use more sophisticated techniques in the
sub harmonic generator and filtering stages. The result is
reduced distortion in the infra bass section and much better
independent control of the infra and sub bass spectrum,
essential for live PA use.
The module is stereo in stereo out (with software
normalised mono input if source is mono). The stereo
signal remains stereo throughout the signal path. There is
no mono’ing to produce either the infra or sub bass path.
• BEWARE - Extreme care is needed. Driving high infra
bass levels into insufficient speakers may lead to speaker
equipment damage.
Operation
‘Hypabass’ is a sub harmonic synthesis module. An LF
input de-emphasis/emphasis trim stage feeds the sub
harmonic generator creating low distortion, low frequency
spectrum below the source input spectrum. This sub
harmonic spectrum is then band-split into Infra Bass (18-
36Hz) and Sub Bass (36 Hz upwards). This allows Infra and
Sub bass to have separate level controls, essential for
controlling ‘Infra Bass’ and ‘Sub Bass’ preventing speaker
equipment damage, and dealing with resonant acoustics or
speaker resonance with exotic LF cabinet porting. Separate
Infra Bass and Sub Bass meters are provided. Each are
peak detected from both Left and Right signal paths and
presented on one meter.
UPPER FREQ CUT - Controls the upper bandwidth of the
sub bass harmonic spectrum. This setting depends greatly
on the sub bass speaker equipment and the original bass
content. Typically a low setting is common to prevent the
generated sub bass upper harmonics clashing with the
original bass content. Beyond mid position is only useful for
Lost Fundamental mode.
LF INPUT BOOST - This filter stage provides emphasis on
the input spectrum into the sub harmonic generator and
can be used as a global ‘more or less’ control once
everything else is setup.
INFRA BASS Mode - This is the default mode. Energy in
the Infra and Sub bass spectral regions is synthesised from
the input bass content. Using the independent level
controls the engineer can balance Infra and Sub bass.
• Avoid infra bass damaging equipment or sub bass
resonating. UPPER FREQ CUT needs to be kept low to
prevent the generated sub bass upper harmonics clashing
with the original bass content.
LOST FUNDAMENTAL Mode - These harmonics can be
output to a mid-range driver to create apparent bass energy
since these upper harmonics are musically related to the
original bass content. Useful for increasing bass perception
in music driving mid-range speaker systems. This turns the
Infra bass section off and modifies the output spectrum to
operate in the typical upper bass region. Using the Sub
level and UPPER FREQ CUT the engineer can manipulate
the output to contain harmonics that are above the input
bass spectrum.
Preset Name is displayed. Touch and scroll using the
screen Rotary for live update. This is a way of live
auditioning all library presets for this module (factory, user
and USB). You can also select and recall a particular preset
using the Library window.
Empty Rack
The GLD RackFX is a 'virtual outboard effects rack' with 8
slots. These can be loaded with different types of effects
units or left empty.
To load an effect – Touch the Library button and select an
FX type and preset from the lists. You can choose to view
the built-in Factory or User presets, or those found on a
USB key when plugged in. Touch Recall to load the FX unit.
To remove an effect – Touch the Library button and select
‘Empty Rack’ from the list. Touch Recall. The current FX will
be removed and the rack slot left empty.