Fbt 38591, Operating Manual

Page: 36 / 60

CONTROLS AND FUNCTIONS
IN-LINK: Balanced input / output sockets: «IN» allows to connect a pre-amplified signal such as that coming, for instance, from mixer output.
«LINK» allows to connect multiple speakers to the same signal.
PRESET: To choose among 8 presets each one corresponding to a system configuration, according to the number of speakers in use (see
PRESET section).
GND LIFT: Switch to isolate the chassis ground and the signal ground to avoid ground loops, which can cause hum problems.
ON: Indicates that the system is «ON».
AMPLITUDE SHADING : top speakers are generally configured with the HF LEVEL set at «+dB», whereas central ones are generally set at
«0dB» and bottom ones - closer to the audience - at «-dB». This serves to compensate for the atmospheric attenuation of acoustic waves,
which is significant at high frequencies. It is also used to avoid discomfort for those people in the audience standing close to the system,
which may be due to the extremely high energy of treble frequencies.
HP FILTER: This switch activates the low-cut filter which lets only the frequencies above the cut-off frequency pass at the output.
PEAK: When this led lights up it indicates that the signal is reaching saturation.
HF LEVEL: This control corresponds to a HIGH SHELVING filter, aimed to provide the system with a frequency response as even as
possible through the whole listening area. The HF LEVEL control is extremely useful, and can be used in two ways:
TOGETHER WITH THE PRESET : in small systems consisting of 2, 3 or 4 speakers per side, users can adjust the balance of tones by acting
on the HF LEVEL control while selecting one of the A-B-C presets.
LMT/PRT: If this led lights up there is a system malfunction due to an internal amplifier failure or to the intervention of current limiting circuits
against thermal overload.
4805 LA / 4820 LA
32