Not so long ago, at end of the previous century, nearly all professional loudspeakers, amplifiers and signal processors lived in separate boxes. All were connected by a proliferation of analog cables. And networks were strictly for computers.
However, starting in the mid-1990s, some amplifiers went to live inside the loudspeaker cabinets, and some signal processing (crossovers and limiters) had to go along for the ride.
About 10 years ago, smaller and more cost-efficient digital signal processing (DSP) circuits started migrating into loudspeakers, replacing their analog counterparts and—in some cases—introducing sophisticated room equalization and delay functions.
Around that same time, networking technology started moving into the loudspeaker boxes as well. At first only monitoring and control functions were networked, but soon multiple digital audio signals were piggybacked onto the same skinny CAT-5 cable, eliminating all analog signal connections.
Whew. It's getting crowded in there. It's also an intriguing trend, one that is opening options in both permanent church installations and in portable church scenarios. Let's survey the current landscape.
Group A: Local Control DSP
First we'll consider loudspeakers that have integrated digital signal processing (DSP) and employ only local, rear-panel adjustments, if any. Perhaps stating the obvious, all loudspeakers discussed here are of the self-powered variety, since DSP functions must be inserted before the power amplifier stage.
At the most basic level, the loudspeakers here (all groups) replace the analog crossover with DSP-generated filters for signal splitting. This particular function normally is not user-adjustable, since each pair of loudspeaker drivers (or trio if a three-way system) will have an optimum crossover frequency and slope that will deliver the best performance. The same DSP can be used to implement phase correction circuits that yield a more linear response, and this tuning procedure requires advanced laboratory gear to calibrate properly. The DSP can introduce small amounts of signal delay to time align the drivers to compensate for the physical difference in their acoustic centers. And finally, the DSP can be used to control limiting functions that keep the output section from overloading the drivers. All DSP-loaded loudspeakers will move these functions into the digital domain, but—as with analog designs—the sonic results may vary depending on the expertise put into the design and the quality of DSP chip employed.
Of course, once that DSP chip is in place, extra processing horsepower can be used for user-adjustable functions such as equalization, delay and (less commonly) special effects such as reverb and chorus. In this group, selection or adjustment is accomplished via rear panel knobs and switches. The EQ functions are generally limited, sometimes only offering pre-set boost and cut parameters tailored to different applications, such as or for voice vs. music reproduction, or for either FOH or monitor use in dual-use cabinets. (Monitor applications usually benefit from a bass roll-off.)
Proceeding alphabetically, in this group we have the latest generation of the Eurolive Series from Behringer, which employs DSP to handle the crossover, limiter and time-and-phase alignment duties. In the DVX HP series from dB Technologies, DSP is again applied to optimize response across all the same parameters, and two presets are offered for either flat (FOH) or monitor.
The DLM Series from Mackie utilizes internal DSP to optimize the performance of its “TruSource” technology, which is based around coaxial loudspeakers—where the high-frequency driver is placed in the center of the low-frequency woofer. In this case the DSP can provide more coherent alignment between the two than can be achieved with physical devices such as phase plugs. An integrated digital mixer (for the two input channels) with OLED display includes 16 presets for reverb, chorus and delay.
The K Series active loudspeakers from QSC use DSP for precise matching of low-frequency and high-frequency coverage; time, frequency and amplitude response; excursion limiting; and precise adaptive limiting to allow full power without clipping. In addition, rear-panel switches select EQ settings: flat or vocal boost on the HF side, and normal or deep on the lows. Similarly, in the D Line from RCF, an integrated DSP system manages crossover, equalization, soft limiter, compressor and dynamic bass boost.
THE TREND TOWARD PACKED BOXES HAS BEEN MORE OF AN EVOLUTION THAN A REVOLUTION.
Finally, Yamaha's DSR Series applies considerable DSP power in a digital crossover using high-order FIR filters and delay for precise system optimization, and also in a D-Contour multi-band dynamics processor, which monitors the instantaneous frequency envelope and adjusts compression for greater clarity at high power levels.
Group B: Basic Networking
When high-performance, self-powered loudspeakers emerged in the mid-1990s, many were targeted for demanding touring and installation applications where the cabinets would not be easily accessible. This raised user concerns. How can we be sure that those internal amplifiers, flown way up in the air, are working properly? And what if we want to mute one of them, or a group of them?
Thus, basic loudspeaker monitoring and control networks were born. The first was Meyer Sound's RMS, based on the Echelon LonWorks free topology networking solution for industrial monitoring and control. Here, robust reliability takes precedence over speed, since all the network has to do is report the status of performance parameters in the amplifier module to the host computer, and issue any mute/unmute commands. Everything is carried on a single twisted pair cable, and free topology allows great flexibility in connecting the loudspeaker nodes. When Renkus-Heinz started equipping its loudspeakers with amplifier modules, the company also adopted Echelon technology for its R-Control remote control and supervision network.
Several years later, by the time JBL introduced the DrivePack amplifier modules for several of its loudspeaker products, all the Harman Pro companies had committed to Ethernet-based networking solutions. Though somewhat trickier to set up and requiring costlier CAT-5 cables, this approach definitely opened the road for more speed and versatility. JBL now offers four different input module options for the DrivePack, three of which can connect to Harman's HiQnet for system configuration, control and monitoring. DrivePack can be fitted to loudspeakers in JBL's Vertec, VRX and VP lines.
Group 3: Networking Plus DSP
Here's where things get interesting. If you put your DSP in the box, connect the DSP to the network, and plug the network into a computer with a sophisticated graphical user interface (GUI)—suddenly it's a whole new ball game. Now user-adjustable options are no longer limited to a few presets. Using keyboard, mouse or touchscreen, you can freely manipulate parametric equalization curves, tweak limiters and set external delay times. In this situation, you're not simply fine-tuning what were formerly analog circuits inside the box. Now you're replacing a sophisticated, dedicated external loudspeaker processor. In sum, you've got one smart box.
Fitting neatly into this category is the StudioLive Active Integration (AI) Series from PreSonus. As with Mackie, here DSP is employed for fine-tuning the response of a coaxial driver set, but with a different twist: all loudspeakers are three-way, with a choice of bass drivers matched to a common coaxial mid-high unit. Some basic DSP presets are rear panel accessible, but the sophisticated capabilities listed above are available via the Ethernet for computer manipulation using SL Room Control software. Placing a Wi-Fi router on the network allows access to everything on an iPad.
If you outfit your JBL DrivePack with the DPDA input option, you get full network access to a host of BSS Omnidrive HD signal processing, including FIR/IIR digital filters and LevelMax multi-stage limiting.
Tannoy provides networked control of DSP in its VNET-enabled loudspeakers, such as those in the VQNet Series. VNET enables remote system tuning and continuous monitoring using the proprietary VNET software application.
Also in this category we find EAW's JFNT series of installation loudspeakers. When linked via the proprietary U-Net network computer running EAW Pilot software, [they] can access front-end DSP features that include level setting, 10-band parametric EQ and up to 1200 ms of delay.
Finally we have Line 6, a firm born in the world of DSP, now forging a unique identity with its stylish Stagesource Series of “intelligent” loudspeakers. Stagesource allows manual configuration of DSP, but it also uses accelerometers to sense horizontal or vertical orientation (setting a monitor EQ for horizontal) and a sensor for pole mounting, again adjusting DSP-generated EQ accordingly. Configuration and DSP settings of systems are implemented over the proprietary L6 Link network.
There are up-sides and down-sides to packing everything into the loudspeaker cabinet.
Group 3A: The Steerable Columns
We'll touch briefly on a sub-set of networked DSP loudspeakers, the beam-steering column arrays. All of these require both on-board DSP (and lots of it) to change beam vertical dispersion, aim the beams up or down, or split the beams in two. If you want more detail on these unique systems, they were covered extensively last year in Church Production Magazine, with the story available online (“Thin is In,” www.churchproduction.com/story/main/thin_is_in). Systems in this category include the Bosch Vari-Array, Duran Audio's Intellivox Series, EAW's DSA-250Z, Meyer Sound's CAL, the Iconyx line from Renkus-Heinz, and Tannoy's QFlex Series.
Group 4: Audio Joins the Net
Now we get to the point where digital takes total control. To this point, despite all the digital wonders, we've assumed that the loudspeakers still rely on a separate analog connection to carry the audio signal. However, a few of the above also offer the option to put the audio on the network, creating an all-digital signal path from the input of the mixing console to the output of the DSP circuits inside the loudspeaker. That's assuming the loudspeaker network is compatible with the mixing console network, and alas, that is not always a safe assumption.
So in this case, we'll look at the various networking options, and see whose loudspeakers will communicate on common grounds.
CobraNet is the long-established player in audio networking, and is dominant in many distributed sound applications. Here, JBL DrivePack's DCPN input option and Renkus-Heinz's RHAON networks carry CobraNet multi-channel audio.
CobraNet's latency can be problematic in some performance applications, which perhaps is why PreSonus chose a Dante network solution as an option (due late in 2013) for its StudioLive AI Series. Dante also can be used with Tannoy VNet-enabled loudspeakers via an external
Dante-VNet bridge.
The open-source AVB networking option is gathering steam, and Meyer Sound's CAL already has it on board. PreSonus has announced it also plans to introduce an AVB input option for StudioLive AI.
In the proprietary network department, EAW's U-Net can carry networked audio to properly equipped loudspeaker modules. And Behringer, in the newly announced IQ Series, has grafted its CAT-5-based Ultranet (first implemented in its personal monitoring system) into DSP-enabled loudspeakers, bringing this whole technology package into the sub-$1,000 price range.
They Built It, But Should You Come?
The trend toward packed boxes has been more an evolution than a revolution. There are up-sides and down-sides to packing everything into the loudspeaker cabinet. There are issues of accessibility of control, complexity for volunteer operators, and limited options for partial upgrading since it's all in one package. For these reasons and others, many highly respected manufacturers have opted to keep these functions outside the loudspeaker cabinets, though nearly all have merged both networking and DSP with the power amplifiers—often in proprietary combinations designed specifically to operate with the company's own loudspeakers.
Having more options is a good thing in any church tech planning. However, before exercising today's appealing “smart box option,” a bit more education on your part would be well advised.
