Q4 audio PTH 3 User Manual Download Page 6

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2. Setting up the amplifier

2.1 Installation

PTH series amplifiers are equipped with two cooling fans with
rear  to  front  airflow.    When  installing  the  amplifier,  allow  for
ample space behind the amplifier to ensure sufficient airflow,
especially  when  the  amplifier  is  operated  inside  a  rack
system.   This  enables  the  amplifier  to  get  rid  of  its  heat  and
avoids limiting or shut-off by the thermal protection circuit.

2.2 Mode switch

Before making any connections, you have to decide in which
mode you want to use your PTH amplifier. All PTH series
amplifiers are able to work in three operational modes which
can be selected by the mode switch (1) on the back panel.

DUAL

mode: in this mode both channels and their

corresponding in- and outputs work totally independent
from eachother. This is the mode for normal stereo (two-
channel) operation.

PARALLEL

(MONO) mode: in this mode, both inputs of

the  PTH  amplifier  are  internally  connected  in  parallel.
Using  the  input  1  gives  identical  signals  on  both
SPEAKER  OUT  1  and  2  outputs  (4  +  5)  with  the
possibility of individual volume control.

Warning:  this  mode  does  not  mean  that  the  outputs
of  both  channels  can  be  wired  in  parallel.  Never
attempt  to  wire  them  together!    This  will  damage  the
amplifier.

BRIDGE

mode: mono bridge mode allows to use the

amplifiers  full  output  capacity  for  one  single  monaural
channel. (See Chapter 5 for details).
This  configuration  is  recommended  to  produce  high
power  for  a  monaural  speaker  system,  e.g.  Bass

subwoofers.  In addition to that, any PTH amplifier working
in  BRIDGE  mode  can  be  directly  connected  to  an
unisolated  100V-line  (70V-line)  constant  voltage  sound
system.

2.3 Connections

All  input  and  output  sockets  are  on  the  rear  panel  of  the
amplifier.  The rear panel also holds the mains cord (2) and the
mode  switch  (1).    For  maximum  safety,  it  is  recommended  to
stick to the order given below when wiring the PA system.

2.3.1 Input connections

The  input  sockets  (3)  are  mixed  XLR/phone  jack  receptacles,
which  allow  the  use  of  microphone  or  instrument  cables  to
connect to the amplifier.  Whenever possible, use 2-conductor
microphone  cable  for  a  balanced  signal  transmission,  which
gives  the  best  results  and  the  lowest  noise.    The  inputs  are
wired in standard configuration with pin 1 as signal ground, pin
2 as signal "hot" and pin 3 as signal "cold".  You may also refer
to the input wiring diagram on the amplifier's back panel.  Two
'Direct  Out'  male  XLR  sockets  (7)  below  to  the  input  sockets
are  wired  in  parallel  to  the  inputs  and  provide  easy  linking  to
other amplifiers.

DUAL

mode: connect each channel input to the appropriate

output of the preceding audio device.

PARALLEL

mode: use

only

input 1

of the amplifier to obtain

identical signals on both speaker outputs 1 and 2. The output
levels can be adjusted individually by means of their
corresponding volume controls.

BRIDGE

mode: use

only input 1

. Both volume controls must

be used

simultaneously

for output level control. Under any

circumstance, keep both volume controls at the same value or
the amplifier will shut down during operation.

BRIDGED  MONO  OPERATION:  INPUT  SELECTOR  SWITCH  TO  BRIDGED
POSITION.  INPUT  SIGNAL  TO  CH.  1  ONLY.  CONNECT  SPKR  TO  1+  AND  1-  OF
BRIDGED  OUT  CONNECTOR.  MATCH  CH.  1 AND  CH.  2  GAINS  ON  THE  FRONT
PANEL AND REGULATE LEVEL WITH BOTH GAIN CONTROLS SIMULTANEOUSLY.

Input

1 = SIGNAL GROUND
2 =
3 = SIGNAL -

SPEAKER OUT 1

1+ = SIGNAL CH. 1
1 - = GROUND CH. 1
2+ = SIGNAL CH. 2

SPEAKER OUT 2

1+ = SIGNAL CH. 2
1 - = GROUND CH. 2

BRIDGED OUT

1+ = SIGNAL CH. 1
1 - = SIGNAL CH. 2
2+ = GROUND CH. 1

MODE

PARALLEL

DUAL

BRIDGED