Proel HPX series - Manual (Page 13)

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GENERAL INFORMATION
Thank you for having chosen a PROEL product. HPX is a new series of PROEL power amplifiers designed to provide to
entertainers and audio professionals quality performance and maximum portability at a very affordable price.
Combining rock-solid CLASS AB and CLASS H power stages to extremely efficient SWITCH MODE power supplies, the
HPX amplifiers delivers from 900W to 2800W of pure power to your speaker system, providing clear and defined highs
together with extremely punchy lows. All the models feature a true 2-ohm operation, providing a cost effective power
solution for the most demanding sound reinforcement applications.
Thanks to the SMPS light-weight technology and to the efficient cooling systems, the HPX come in a very compact and
portable package, yet sturdy enough to provide the maximum protection and durability over the years.
A built-in selectable LPN (Low-Pass Notch) filter enhances the amplifier response at the low frequencies, providing an
increased punch while protecting the speakers from over-excursion and increasing the headroom.
The front panel, with very comfortable die-cast handles and removable dust filters, features a comprehensive set of
LED indicators together with detented level controls. The connections includes XLR, 1/4" JACK and RCA for the inputs,
SPEAKON and binding post for the outputs.
SETUP AND RACK MOUNTING
All HPX amplifiers will mount in two units of a standard 19" (48.3cm) rack (the front panel is provided of four mounting
holes). HPX amplifiers use a forced-air cooling system to mantain a low operating temperature. Drawn by an internal fan,
cold air enters through the slots in the front panel and flows over and through internal components, then the hot air gets
out from the rear panel slots (as shown on figure 1). The HPX amplifiers drive the fan using a variable-speed DC circuit,
which is controlled by sensing the heat sink temperature. The fan speed will increase only when the temperature of either
heat sink requires it, which keeps fan noise to a minimum and helps cut dust accumulation inside.
NOTE: In order to prevent the dust accumulation inside the amplifier, the two air vents on front panel have a dust filter.
Each time these filters are dirty (it depends on enviroment conditions) you have to remove the air slots using a phillips
screwdriver (as shown on figure 2) and clean the dust filter using compressed air or a soft brush.
Under extreme thermal load, the fan will force a very large volume of air through the heat sinks. If the amplifier overheats,
another sensing circuit shuts down the amplifier to cut off power until it cools to a safe temperature.
IMPORTANT: The exhaust hot air is forced out through the rear of the chassis (see figure). ABSOLUTELY DO NOT
OBSTRUCT THE FRONT AND REAR OPENINGS and always let them free from cables or other materials.
If the amplifier is rack mounted, make sure the exhaust air can flow without resistance from front to back side of the rack.
Therefore we suggest to use only rack stands with front and back cover completely removed (Proel KR10AD as example
for fixed installation or Proel CR series for touring use). In this case amplifiers may be stacked directly on top of each
other (no space needed between units), starting from the bottom of the rack.
We advise against the use of rack with closed backs (or close to a back wall), but if you can do otherwise, we suggest to
leave at least one standard rack space of opening between every two amplifiers and to make sure there is enough space
at the rear of the amplifiers to allow the air to escape (at least 15 cm or 6 inch).
FRONT PANEL (FIG.4)
1. Cooling vent
Removable cooling vent: always keep it clean from dust.
2. Power indicator
Yellow LED: when lighted indicates AC power is available.
3. Power switch
Amplifier is "ON" when the switch is in the "I" position.
4. ON indicator
Green LED: when lighted indicates that the amplifier has been turned on.
5. Level control Channel 1
Rotary detented level control: in STEREO and PARALLEL operation it attenuates the level of the signal sent to the channel
1 of the amplifier, while in BRIDGE operation it operates as single control to attenuate the level of the signal sent to both
the channels.
The attenuation ranges from “∞” fully closed (the signal is completely attenuated) to “0” fully open, nominal level (the
signal is not attenuated in any way, so is fed to the amplifier channel at the same level at which it arrives on input).
6. Level control Channel 2
Rotary detented level control: in STEREO and PARALLEL operation it attenuates the level of the signal sent to the channel
2 of the amplifier. In BRIDGE operation it doesn't work.
The attenuation ranges from “∞” fully closed (the signal is completely attenuated) to “0” fully open, nominal level (the
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