User manual

2-2 E-PAC (V02) User Manual
IMPORTANT!
WARNING!
2.2. Power amplifier
The single channel power amplifier of the E-PAC maintains high linearity
throughout it’s operational range even into adverse loads. With fast
response to, and recovery from overload conditions, stability and
accurate performance is guaranteed. A two stage power supply keeps
the losses through heat emission low.
The E-PAC can deliver 200 W continuous sine wave output power into
a 16 ohm load or 300 W into an 8 ohm load. Selecting low impedance
mode (LO IMP DIP switch) enables the E-PAC to deliver an output
power of 150 W into 4 ohms. These values apply to continuous
operation for a minimum of 30 minutes at a maximum ambient
temperature of 24°C (75°F).
An E-PAC will normally be operated with speech or music programme,
complex signals where the average power requirement is below peak
power. The E-PAC will continue to operate indefinitely even where the
signal has very a low peak to RMS ratio (Crest factor, see section 2.13.),
provided the device is installed to enable the heat generated to be
adequately dissipated.
2.3. Cooling
The aluminium enclosure acts as a heat sink for the E-PAC power ampli-
fier; it is therefore convection-cooled. To prolong the life of components
inside the E-PAC, a small fan intakes cooling air into the front of the E-
PAC through an opening on the rear panel. The fan is very quiet and
runs continuously as long as the E-PAC is running or in mute.
When operating and installing the E-PAC, make sure enough air can
flow around the enclosure. Never cover or block the intake opening on
the rear panel or the exit opening on the front panel. Also refer to Sec-
tion 2.11., Installation.
Do not touch the heat sink. During operation the cooling fins of the heat
sink on the enclosure of the E-PAC can reach temperatures of 80°C
(176°F). The front and rear panels do not form part of the heat sink
and can be touched at any time.
2.4. Protective circuits
The E-PAC contains many integrated protective functions. If over
temperature occurs, the device switches to mute. After it has
cooled down, the output stage cuts in automatically. The output
current limiter (SOA watchdog) prevents damage to the output
stage that could occur from a short-circuit or incorrect cabling.
The mains power connection is protected by a fuse (see Section
2.8.).
A mains inrush current limiter provides a „soft start“ and enables
several E-PACs to be powered up at the same time without
overloading the mains power supply. The maximum current drain
during the power up phase is 10 A (peak).