7
The 'SIGNAL OUTPUT' section on the back panel is provided with Speak-on connectors
(11).
To operate the amplifier on BRIDGED mode, place the 'OP. MODE' switch (8) to the
“BRIDGED” position. The correspondent Led on the front panel will shine. The input signal must be
connected to the channel I “BRIDGED INPUT” connector while the output signal will be present on
the central Speak-on connector labelled as “BRIDGED”. Remember that the BRIDGE mode is not
available on the PAM2000/2600 models.
The phase shifter used for BRIDGED mode is electronic and is placed in the input circuit,
thus lessening the distortion and increasing the phase margin. When operating on BRIDGED
mode, the signal input is made through channel I input and the corresponding input attenuator is
operative while the one of the other channel is not.
The cable between the amplifier outputs and the loudspeakers must be of good quality,
enough section and as short as possible. This is very important when the distance is long and the
load is low (4-8
Ω
). We recommend a section of 2.5mm
2
or more for distances up to 10m and a
section of 4 or 6mm
2
for longer distances. An easy way to known the required section, assuming a
4% loss, is:
Length in meters
Section in mm
2
=
Loudspeaker impedance in
Ω
4. OPERATION
4.1. Starting up
To start up the amplifier turn on the 'POWER' switch (7). It will shine together with the two
red 'PROTECT' leds (5). After a while, the loudspeaker protection relays will close and the
PROTECT leds will be off.
It is very important to start the audio chain in the following order: sound signals , mixer,
equalizers or active filters and, finally, power amplifiers. To stop the chain follow the inverse order.
4.2. Input attenuators
They are based on step-rotative potentiometers placed on the front panel (1). The
attenuators make possible to use loudspeakers of less power than the amplifier in a safe way,
without damaging them by a missuse of the preamplifier and/or mixer volume.
4.3. Status indicators / Protections
4.3.a) Signal presence indicators 'SIGNAL' (3)
They show the presence of a sign al at the amplifier inputs. They shine when the input level
is greater than -40dBV.
4.3.b) Protection indicators 'PROTECT' (5)
They show that the output relays are open and, in consequence, there is no signal on the
amplifier outputs.
They can be lit in the following cases:
