XTA Electronics introduced our guest in early 2005, and it quickly became one of the most interesting digital audio management systems for any type of installation, from stereo rigs made up of just a pair of compact cabinets to more complex events with delays, more than 3-way systems, and so on. Versatility and functionality. In the words of Andrew Grayland, co-founder and director of XTA, “it is a system that brings analog people together with digital technology, and that is what we have always done at XTA.” Like all XTA products, the DP428 is the perfect solution for any audio installation. Renowned artists such as Eric Clapton, the Rolling Stones and U2 have tested and verified the effectiveness of this gear over the years, and it is also an essential part of installations as complex and complete as the Olympic Games, the Grammy Awards and even the Super Bowl. What better résumé is there?
Flexible
The DP428 was designed to deliver high sound quality, with the highest possible specs, at an unprecedented level of performance. At every stage of the process the audio signal goes through in this digital audio management system, the company’s engineers have lavished attention on audio quality, which was the most important premise throughout R&D. The board design, the choice of components with far-from-critical tolerance margins, and even the finishing all contribute to this difference.
On the technical side, the DP428 offers a 4x8 matrix, with crossover filter slopes of up to 48 dB, along with a complete range of EQ tools to solve virtually any audio problem. It has four inputs, each with its own gain control, 28-band graphic EQ, eight filters and independent delay. Added to that are eight outputs, each with its own gain control, polarity switch, delay, high-pass and low-pass filters and up to nine filters.
Each input can be routed to any combination of outputs, and all inputs and outputs can be phase-adjusted in 2-degree steps. The crossover filters are available in two types, with slopes of 6, 12, 18, 24 and 48 dB. For added versatility, a two-stage RMS and Clip/D-max limiter is included.
The DP428 supports internal sample rates of up to 96 kHz (external up to 192 kHz). It is perfect for AES/EBU digital input signals.
All of it can be controlled from the small but generous LED display on the front panel, complemented by the LED meter bank that shows input and output signal levels. Easy to use, any beginner will find the working interface a perfect ally, intuitive and clear. But anyone who wants more control, more speed and more precision can opt for the AudioCore remote-control software for PC. With it we also control the entire input and output routing system, but through simple screens (much more convenient than the unit’s own LCD), as well as the EQ curves (faster and easier to adjust).
Another feature of our guest is that it can network up to 128 DSP428 units and control them centrally through this software, AudioCore, using simple XLR cables. For those who want even more, there is the Walkabout kit, which lets you adjust the system from a PC through a wireless interface, ideal, for example, for listening to the results while sitting comfortably in any seat in the auditorium, or for improving the accuracy of the setup across the entire listening area with just a network-capable laptop. What more could we ask for?
With this launch, XTA expands its audio management series to as many as 4 different models: the DP448 (4 inputs and 8 outputs), DP446 (4 inputs and 6 outputs), DP444 (4 inputs and 4 outputs) and DP424 (2 inputs and 4 outputs); the DP428 that we analyze in these pages, renamed DP448 since then, is the one with the highest input and output capability. In this way XTA meets the demands of professionals with solutions that deliver top performance, flexibility and ease of use.
Part of the secret of the series lies, unquestionably, in its ability to process a signal in the digital domain at really high sample rates, which allows far more precise processing and a high-quality output signal. As we have already mentioned, our guest carries high-performance 24-bit converters on both the inputs and the outputs, at 96 kHz, which yields a bandwidth reaching 30 kHz and a dynamic range exceeding 116 dB. With its four balanced inputs and eight balanced outputs, our guest achieves truly impressive flexibility. How would you like to have up to four monitors set up as 2-way?
Once the input signal has been digitized (let’s see anyone try to take any “analog” potential away from the system here), it can be equalized with 28 bands, with the option of adding a second, fully parametric 8-band EQ. The next step is the crossover, with adjustable slopes between 6 and 24 dB per octave. I should mention some of its possibilities, such as notch filters, bandpass filters, elliptic filters and variable-Q curves. This is without doubt not just a crossover and nothing more, but something far more complex and tremendously versatile. Think about its 4 inputs and 8 outputs, but don’t limit yourself to the easy options; think of a free-form web of possibilities. We can take 1 input and split it into 8 outputs (unlikely, given today’s systems), or, more commonly, use 2 of the inputs (stereo) and go for a set of 4 outputs per input (a 4-way stereo configuration), all the way to the one mentioned above: 4 independent inputs with 4 equally independent outputs, but 2-way.
The ability to use the digital inputs adds extra performance at a time when digital consoles are starting to become popular, even at live events. The AES/EBU industry standard included in this unit makes it possible to work with digital inputs and, at the same time, get digital outputs. As when working in analog, all digital input signals can be resampled from 32 kHz up to 192 kHz, although at the output we will always have a 96 kHz signal.
Software
If you think that controlling this unit from the simple LCD on its front panel could be tedious, you’re in luck. The AudioCore software is the perfect solution for any user, and I doubt anyone will abandon it once they notice how easy, fast and simple the program is to use. This exclusive XTA program allows not only control of the unit but also monitoring of it. As I mentioned before, with a simple cable or the optional Walkabout wireless system, we will have all the adjustment parameters, absolutely all of them, on our PC (a laptop or, even better, as they themselves say on their website, a tablet PC) in a series of graphic screens of tremendous visual power. It is very well suited to tuning a fixed installation with surgical precision, for example. The installer can set up the sound system to what is surely perfection, saving that configuration to removable media as a safeguard and even preventing bad hands (and unfortunately there are many) from spoiling the hours of previous adjustment.
But it is surely also handy live, from the simplest setup to the most complex. Being able to “see” what we are doing (for example, the frequency filters or the graphic EQ), even on a 15" LCD screen, is a real luxury when our goal is, without a doubt, to deliver the best possible sound quality. The program only runs on Windows. The connection between the PC and the unit is made through a 9-pin serial connector (there are USB converters for laptops that lack this connection). The connection between additional units is made through the RS485 communication standard, which uses conventional XLR cables. For extra flexibility there is a serial-to-Ethernet bridge, which lets you control the units over any standard Ethernet connection (TCP/IP). It sounds crazy, but can you imagine controlling a DP428 from the comfort of your living room sofa? It would be possible.
Conclusion
Now that we know our guest’s features, if there is anyone who still doesn’t know what it is for, they simply don’t know active sound systems. Many audio companies have several loudspeaker systems in their warehouse (active and passive, it makes no difference), and they will find in this DP428 (or any unit in the series) a perfect ally, not only for pooling and getting the most out of their gear (they can use the same amp rack for different cabinets; all that’s needed is to recall the corresponding preset), but also for achieving a precise and appropriate tuning. The bolder will be able to pay attention to new aspects during their live shows: phase problems, acoustics and others can be “solved” with some of the parameters this XTA lets you control. In any case, a perfect ally for those who still take sound seriously. I recommend it.
