iLive Reference Guide – Firmware
Part 2 - 39
AP6526-2 iss.4
Hypabass
A sub-harmonic synthesis unit classically 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.
Note
-
BEWARE
- Extreme care is needed. Driving high infra bass levels into
insufficient speakers may lead to speaker equipment damage.
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.
Note
- 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.
Beware Infra
Lost Fundamental
