APA’s new power and DSP platforms have been designed to interact intelligently and adapt to prevailing conditions, protecting drivers and significantly enhancing performance of all loudspeaker systems.
By including studio-quality analog-to-digital converters at the outputs as well as the inputs, real-time audio currents and voltages presented at the loudspeaker terminals can be fed back into the DSP in addition to processing the incoming audio, allowing the amplifier to adapt and correct its performance continuously.
The tight coupling of the power supply’s behavior through real-time monitoring of the mains supply, as well as over ten temperature sense points, means that the amplifier can adjust its power consumption and output drive to ensure that maximum permissible power is always available.
“We’ve included the same A-to-D converters that we use in the DS8000D [XTA’s Audio Distribution System], which allows us to monitor the outgoing audio voltages and currents to the same degree of accuracy as we do when digitizing incoming analog audio prior to processing,” explains XTA technical director John Austin. “These outgoing signals can 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 utilized 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 an efficient power supply and generous energy storage reservoirs, result in an amplifier that is adept at converting input mains power into output loudspeaker power with less wasted heat (system efficiency is 80 percent), while also being able to offer better sustained peak power at low frequencies. A quick start mode, and a low power stand-by mode (with a power consumption of under 0.75W) mean reduced running costs.
According to XTA technical brand manager Waring Hayes, “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 first model - the APA-4E8 - features four channels of power totaling 20 kW peak output into four ohms, and continuous power available of 3,400 watts per channel into four ohms. Four audio inputs allow all four amplifier channels to be individually utilized if required with a full suite of XTA DSP, including dynamic EQ, FIR (and phase linearization) and classic IIR filtering, mix matrix and the manufacturer’s famously transparent limiters and soft knee compressors.
“What with all the feedback from the PSU and mains monitoring and all the temperature sensors everywhere, the DSP really is at the center of things in the amplifier, and far from being bolted on to the front end - it’s more an engine management system than a speaker management system,” Hayes notes.
The APA-4E8 can route audio from analog, AES or network sources with automatic fallback. USB and internal SD cards offer additional audio choices for playback of emergency evacuation messages, and quick upload of presets or download of performance logging data. The APA series also includes extensive GPIO and remote control covered by Ethernet, USB and RS485.
Housed in a 2RU chassis and weighing 28.2 pounds (12.8 kg), the APA-4E8 is outfitted with a front panel interface with a large color LCD, which, in combination with innovative user selectable metrics and tricolor multimode panel metering, offers reassuring feedback of the amplifier status from any distance.
New remote software written to run natively on both the Windows and Mac platforms is available and operable via an Ethernet or USB Connection.