General.

The AXYS^® PB800 is a multi channel power amplifier that is intended for use in distributed 70V/100V professional Audio installations. The unit is composed of a high power switch mode supply, eight separate power amplifiers and a 2-in, 8-out digital signal processor unit. The unit is accommodated in a 3 HE 19" rack enclosure.

Amplifiers.

The full complementary class AB amplifiers are equipped with rugged industrial power mosfet devices capable of handling large currents without risk of failure. The large phase margin within the feedback loop keeps the amplifiers stable under any load condition.

Power Supply.

The AXYS^® PB800 is equipped with a high-power switch mode power supply. The power supply is specially designed for audio applications, featuring soft knee over current protection and very high peak power capability. Active power factor correction keeps the mains harmonics at low levels while increasing the input voltage range from 90V to 270V without interruption or manual changeover. A low-power stand-by switch mode auxiliary supply enables shut down of the main supply under network control.

Signal Processing Unit.

A digital signal processor unit controls the amplifier units. The board contains 2 analog audio inputs and 8 analog outputs. A digital AES/EBU input is optional. The digital processing is performed by a 32 bit floating point DSP. The DSP software provides various functions in order to attenuate, delay, equalize, filter, compress or limit the separate audio signals for all individual output channels, or perform special algorithms necessary for dedicated active array control. All software is stored in non-volatile memory, enabling the unit to start up and operate autonomous without host control unit. Audio AD and DA conversion is performed by high performance 18bit 50Ksample converters. A dedicated DLC (dynamic level control) circuit prevents the AD converter input from being overdriven.

Related Links:
::: AXYS® WinControl - DSP control software :::
::: Datasheet download page :::

Inputs and Outputs.

All power-amplifier outputs are equipped with high-grade toroidal output transformers to provide 100V/70V/ 50V outputs. Two 50V windings can be put in series in order to combine two amplifier channels to one channel with double power rating. All loudspeaker terminals are protected by means of gas discharge devices against voltage spikes. Both inputs are transformer insulated and can be adapted to interface at 0dBV level or 100V input.

Network.

The RISC also manages the network functionality of the device. This network is based on a RS485 full duplex party-line hardware platform in which each PB800 has its own address. By using a host PC, the user can monitor all surveillance related parameters, send "one line" control commands or upload new DSP code or process settings to any combination of addresses. All surveillance related and DSP related software inside the PB800 is stored in non-volatile RAM, restoring the last settings automatically after power up.

Surveillance.

The surveillance routines are performed by a RISC (reduced instruction set computer) which is located on the processor board. It monitors a large amount of surveillance related parameters. These include: pilot tone detection on both inputs, load monitoring on each output, temperatures of heat sink and ambient, amplifier functionality, fan speed, ambient noise sensing microphone presence and DSP status. The RISC software enables the PB800 to take “intelligent” autonomous decisions such as switching to a second input channel in case a pilot tone is lost, or acoustical output level adaptation the to the ambient noise level without any central intervention. All possible reported failures can be mapped onto a dedicated failure relay.