UK - After several years of investment in R&D resources, more than doubling the department's engineering staff, and following on from research projects into loudspeaker protection and adaptive protection, the APA Series makes its PLASA debut this year.

The completely new power and DSP platforms have been designed to interact intelligently and adapt to prevailing conditions, protecting drivers, and significantly enhancing performance from all speaker systems.

Waring Hayes, XTA's technical brand manager explains why this is at the centre of the design ethos for APA. "It's not so difficult to add a DSP module to an existing amplifier design in the form of a plug-in card, but to provide the level of monitoring and feedback within the amplifier that we wanted - that took a little longer!"

The tight coupling of the power supply's behaviour through real time monitoring of the mains supply, as well as over 20 temperature sense points means that the amplifier can adjust its power consumption and output drive to ensure that maximum permissible power is always available.

John Austin, XTA's technical director reveals a little of the magic that makes the APA so special: "The A to D converters strategically positioned at the outputs allow us to monitor the outgoing audio voltages and currents to the same degree of incredible accuracy as we do when digitising incoming analogue audio prior to processing. These outgoing signals are then be fed back into the DSP (responsible for all the user adjustable EQ and protection) so that it can make adjustments to ensure that any connected speaker driver is being utilised to the best of its abilities, without undue stress to the driver, or the amp for that matter."

The Class D amplifier design, combined with a highly efficient power supply and generous energy storage reservoirs result in an amplifier that not only is better at converting input mains power into output speaker power with less wasted heat (system efficiency is 80<), but is also able to offer better sustained peak power at low frequencies - where you need it most. A quick start mode, and an ultra low power stand-by mode (with a power consumption of under 0.75W) mean reduced running costs in all circumstances.

The first model - the APA-4E8 - features four channels of power totalling 20kW peak output into 4R, and continuous power available of 3400W per channel into 4R. Four audio inputs allow all four amplifier channels to be individually utilised if required, with a full suite of XTA's world renowned DSP including dynamic EQ, FIR (and phase linearisation) and classic IIR filtering, mix matrix and our famously transparent limiters, and soft knee compressors.

The APA can route audio from analogue, AES or network sources (AVB/Dante) with automatic fallback. USB and internal flash memory offer additional audio choices for playback of emergency evac messages, and quick upload of presets or download of performance logging data. The APA also includes extensive GPIO and remote control covered by Ethernet, USB and RS485.

Hayes continues, "The APA is a sociable beast - unused DSP resources can be routed onto the network for extra processing power where you need it, lending a helping hand to more basic amplifiers. The devices can also periodically email you (through the XTA APA Server) with a status report just to let you know all is well, and be set up to contact you should there be any alarm conditions you might need to know about - problems with mains power, speaker faults, filter blockages, tampering - basically anything that would impact performance of your system."

The elegant front panel interface has a large colour LCD which, in combination with innovative user selectable metrics and tricolour multimode panel metering, offers reassuring feedback of the amplifier status from any distance. The APA-4E8 is a 2U design and weighs 15.0kg. New multi-user remote software, via an Ethernet or USB connection, and


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