Published in August 2006

Digital Dominance In Consoles
By Jerrold Stevens, CTS

Advantages and more solutions.


The Mackie TT24 digital live console in a permanent installation at the 7 Cedars Casino in Sequim, WA.

     The vibrations in air that comprise audio may be an analog world, but over the last 10 years the stuff between the microphone and the loudspeaker quickly has become the domain of 1s and 0s. Certainly, there are some sonic advantages of high quality analog circuitry, but well designed digital hardware and software offer tremendous advantages and solutions for the sound reinforcement system designer and the end user. There always will be a place for analog, but digital signal processors have become the dominant format these days, so it’s not unreasonable to expect the same could happen with the mixing console in the not too distant future.

Similar Functionality, But…
     Digital consoles offer much of the same functionality of their analog predecessors. Basic functions such as input pre-amp, equalization, signal routing and sub grouping all are implemented. But on-board digital processors provide many more functions not generally possible in the analog console. This is where digital consoles offer some great benefits to the live mixing venue.
    Most digital console models offer full dynamics processing on all inputs and outputs, and some provide multiple channels of effects processing including reverberation, delay, chorus, etc., eliminating the need for racks of outboard processing and patchbays. Some even provide loudspeaker management processing at their outputs. In addition, a couple offer on-board sound measurement systems; just plug your reference mic into the console and analysis is available at the touch of a button.
    Typically, these consoles offer high I/O counts for their footprint. Control surfaces as small as 3'x3' can allow full control of as many as 96 inputs with 20-plus outputs. Much smaller control booth space is required, reducing “seat kill” in the audience chamber and thus allowing an increase in potential revenue to the owner. It also minimizes the visual impact on the venue and distraction to the patrons near the control position.


Storage Benefits
     Digital consoles offer the enormous benefit of storing all settings within the console as a preset or scene that can be recalled instantly, just as lighting systems have been doing for years. Mixes for repeating performances now can be programmed per song or scene and recalled as the program progresses, improving the consistency of mixes from performance to performance. Some allow synchronizing of the mix to SMPTE and/or MIDI Time Code for complete show control, thereby allowing the operator to concentrate on tweaking the mix of each scene as needed.
     This scene storage capability also works well for multi-act performances where each act can do its sound check and store it for instant recall through the show. This works well for churches with multiple services on Sunday morning, using a praise band and worship team in the early contemporary service and a traditional service with orchestra and choir following right behind.
     Digital consoles come in three basic “form factors”: all-in-one, modular (separate audio devices and control surface) and hybrids.
     • All-in-one models (Figure 1) are designed to be “drop-in” replacements for analog consoles with all inputs, outputs and signal processing in the console itself. This is ideal for the existing venue that would like to replace its analog board with minimal changes to infrastructure.
     • Hybrid form models (Figure 2) include some quantity of I/O and all audio processing within the console, but allow for additional I/O via remote located devices. These typically are remote controlled microphone pre-amps with A/D converters that send some form of digital audio to the console and a remote control signal. This could be AES digital audio transport with an RS422 control line.
    Some transport digital audio over Cat5, coax or fiber via EtherSound, CobraNet or some proprietary transport. This form lends itself pretty well to fixed installations because it reduces the quantity of wiring and infrastructure required for the mixing system. The cable count and necessary conduit size for AES wiring can be half that of analog wiring, and infrastructure for Cat5 or fiber cabling can be as little as a couple of ¾" conduits.

Figure 1

 

Figure 2


Additional Models
     Still other models base all I/O and the audio mixing engine in remote-located hardware of various forms with a control surface linked via Cat5 or coax (Figure 3). No audio actually passes through the control surface, only control signals passing between the control surface and its connected hardware. This provides quite a bit of flexibility in system configuration.
    Input hardware containing mic preamps and digital converters can be located on or near the stage to minimize analog cable length with additional input hardware located at the control surface for local inputs of wireless microphone receivers, playback decks and outboard signal processors. Output devices can be located at the amplifier racks and the stage, as required for the venue. Once again, infrastructure demands are reduced to a few small conduits between hardware locations.
    The modular and hybrid hardware forms also allow easy signal splitting in the digital domain. Some provide this through multiple on-board digital audio outputs. Others allow multiple control surfaces to be connected to the mixing engine with each controlling different sets of outputs. Most models can provide splits via third-party digital audio splitters. This can result in a significant reduction in overall project cost when compared to analog audio splitters and the associated infrastructure, not to mention the benefits of splitting signals in the digital domain.

Figure 3


Resistance to Digital
     With all this advanced functionality and flexibility, one would think the professional audio world would embrace the digital console eagerly. However, there has been resistance for some good reasons. One, the earlier-mentioned user interface issues limit their use to those venues where only in-house staff will be operating the console. The staff can take the time to learn to use the console and put its many benefits to good use. Typical “road-houses” where visiting engineers will be operating the consoles each night probably will have to provide a tech rider friendly analog desk or face the cost of renting analog for most acts.
    Initial digital console offerings seemed to focus on the production environment rather than live sound reinforcement. Those early models required the user to spend some time learning how to operate the console before getting to the mix. Their functionality worked reasonably well as long as the operator didn’t have to access some key control quickly. This limited their use in the “live” environment.
    Smaller footprint, higher channel counts and additional signal processing control requirements forced console designers to design control surfaces with a few physical controls, including faders, rotary encoders, joysticks and push-buttons, that serve multiple channels and other parameters. They usually included some sort of graphic display in the form of LCD panels and touchscreens. These operational features required the user to access sets of channels via “layers,” and to adjust some parameter in one location while viewing the results in a different location.




Allen & Heath’s iLive is that company’s entry into the digital console market.

More Attention to Ergonomics
     Recently, we have seen manufacturers focus much more of their design attention to the ergonomics of the control surface and graphical user interface (GUI). Multiple color LCD displays with integral or adjacent encoders are showing up on many recent models. Designers have minimized the number of steps required to access any control during the mix. Some even have taken the extra step of programming encoders and the parameter they are controlling to respond just like their analog counterparts.
    Another reason for user resistance is the sound character of a given digital console vs. a comparable analog console. Certainly, the microphone pre-amp and the equalizer sections contribute to the sound character of certain highly regarded analog desks. Frequently, this can be attributed to certain distortion characteristics of these analog circuits when they are driven hard. Clipping in the digital domain is anything but “pleasing,” and the somewhat “benign” nature of the digital signal path and processing algorithms can send some users running back to their trusty old analog axes.
    Some digital console models lend themselves well to incorporating third-party mic preamps and digital converters. This allows users to “customize” the sound of the console to their personal preferences. Some manufacturers also have announced the support of software “plug-ins” that are so prevalent in software-based digital audio workstations. This allows users to select their favorite reverberation, EQ or dynamics processing, getting the sound for which they are looking.




Yamaha's DM2000 digital console allows instant changeover
from contemporary service to traditional service at the
Asbury United Methodist Church in Tulsa, OK.



'Holy Grail'
     Although the user interface and sound may be the “Holy Grail” of the digital console, let’s not forget the world of possibilities digital processing brings us. This writer was a keyboard salesman in a music store back in the early days of MIDI. During a visit from the rep for a popular manufacturer of keyboards and MIDI sequencers, we began to debate the merits of various hardware and software sequencers available at that time. He made the comment that there was a limited number of things you could edit in MIDI. I told him that was true, but there were a million ways to manipulate MIDI data. For example, sequencers allowed the user to change he note number or velocity value of a single note, but the more powerful sequencers allowed values of multiple notes to be manipulated at the same time. One quite useful function allowed one to define a range of velocity values for a given track, resulting in the MIDI equivalent of compression and/or other forms of dynamics processing.

Massive Impact
     The exponential development of processing power in the computer world will have a massive impact on our little industry, as well. Who knows what process some clever software designer could develop in how we manage mixes that would allow us to concentrate more of our energy on the art of mixing rather than the science of the knobs?
    Who says a parametric filter must behave like the analog filter it emulates? As with most processing currently in the digital domain, it simply emulates something familiar. What other signal processes are possible in the digital domain that simply could not be done in the analog world?
     It is said the only things in life that are guaranteed are death, taxes and change. We should not limit ourselves to “the way we have always done things” for the sake of user acceptance. The real beauty of the digital format is that the “analog feel” configuration can be provided for first-time users, but then the advanced stuff can be implemented as the user’s comfort level and knowledge develops!
     So, are digital consoles ready for prime time? I suggest that, for many applications, they are. They certainly have garnered a significant portion of the touring market, and we have seen them showing up in more and more installed systems.
    Some further development in the user interface and sound character will accelerate the transition for sure, and new ways of managing signals will have their impact, as well. But the day an analog fader jockey can walk up to a digital desk, intuitively begin mixing and get the character of sound he expects is the day digital consoles will begin rapidly replacing analog.

Jerrold Stevens, CTS, is a senior consultant and project manager for PMK Consultants, LLC. He is a regular instructor for the NSCA and a member of InfoComm International’s Professional Education and Training Committee (PETC).



Alex Cooper

The $350,000 Midas XL8: A First

Editor’s Note: At Musikmesse/Prolight + Sound, held in Frankfurt, Germany, at the end of March, Telex introduced the Midas XL8, the result of a three-year program to develop its first digital console. Was the goal when the project was first proposed to build a product with a $350,000 price tag? Did the XL8 evolve from that, or was the final product basically what was proposed at the outset? We spoke with Alex Cooper, director of console development, for the answers to these questions, and to learn more.

    Alex Cooper: The initial concept was to replace our Flagship XL4 console, which was then eight years old, with a digital “equivalent.” When the XL4 was designed, the initial concept was to build the ultimate live sound console, so the XL8 used the same design brief; but obviously, the market had moved on and the resulting product specification was quite different.
     We did our market research, and from that, decided the scale of the console: input, output, buss counts, etc. We also looked at the technical issues and confirmed that we would have to take some extraordinary measures to ensure the audio quality, control feel and system latency were up to “analog” standards.
    The cost of these measures was not fully known then, but we had a good idea and thus the final product cost is no surprise to us. Obviously, there was some evolution during the design process, but this was minimal and basically the XL8 you see today is not too far removed from the initial concept specifications. Most of the changes were in the fine detail: control placement, screen position, etc.

What Sets the XL8 Apart?
     Sound & Communications: What sets the XL8 apart from other upper-end consoles?
    AC: It’s important to note that XL8 is not just another digital console, but an integrated audio control and distribution system, requiring only the addition of mics, amps and speakers to provide a complete audio system.
    The design approach is typically Midas. We do not spend much time looking at the competition. We take customers’ problems and develop solutions that meet their requirements and our own performance quality benchmarks. We also spend a lot of time critiquing our previous designs, and thus our solutions tend to have individual style, character and flare within the marketplace, while retaining continuity (and continuous improvement) within the Midas product family. This approach results in many differences from other high-end consoles. First, the audio quality is everything you would expect plus a whole lot more. We look at issues such as what happens if you overload the audio. Traditionally, digital systems are not tolerant of this situation and sound terrible if you accidentally overdrive them. The XL8 is different and is well behaved like the best of analog consoles under this condition.
    We also take care to time-align all signals within the mix to eliminate comb filtering effects that plague many other digital mix systems, and also sound terrible. Even so, the system latency remains extremely low at under 2mS for monitor configurations.
    The performance of the digital controlled mic amplifiers and DSP EQ is modeled carefully to sound like Midas analog consoles, and the digital dynamics and effects processing incorporate new developments that provided unparalleled sonic control and creativity.
    Second, the control surface is unique. Its layout and operation are based on extensive research into how users operate conventional consoles and, as a result, the design remains conventional enough to be familiar and yet incorporates many physiological-based ergonomic innovations.
    The XL8 control center has three major dedicated subsections: inputs, mix area and outputs, that are juxtapositioned according to familiar analog norms.


From left: Simon Harrison, R&D director; Karl Brant, service manager; John Oakley, managing director; Alex Cooper, director of console development; David Cooper, sales and marketing director; Richard Ferriday, Midas and Klark Teknik brand development manager

‘VCA Centric’
    A “VCA centric” channel-selection mechanism clusters channels into musical groups and recalls them to the control surface with a single button push. This provides an intuitive alternative to conventional numeric-based paging systems.
    There are no dual-function controls and all control subsections are recognizable instantly from their position and layout, so there is no need to read the panel labels or indicators to confirm their function.
    Five high-resolution, daylight-visible screens employ advanced graphic quantization techniques to provide ultimate quality status feedback, including comprehensive (not paged) metering for all primary signal paths. They also can be switched to monitor external sources, and one of them can utilize an internal KVM switch to remotely control external equipment.
    Third, the console borrows another analog hardware trait in its approach to reliability. The XL8 is modular and uses this to good effect to limit the extent of any single failure within the system, while N+1 and dual redundant backup topologies are standard for all critical elements such as the DSP and network interconnections.
    S&C: How does the XL8 control and network with products outside IRISNet (i.e., CobraNet and Ethernet)? Please address integrated open-architecture AES50 digital audio distribution.
    AC: XL8 interfaces audio on single-channel balanced analog (3-pin XLR), dual-channel digital AES EBU (3-pin XLR) and 24-channel bidirectional digital AES50 (on XLR-cased Cat5 connectors). The AES50 also carries internal Ethernet control data, and the console system incorporates the means to “tunnel” external Ethernet seamlessly from the stage to FOH position. When this is used in conjunction with the surface KVM switching, the “control center” can be used to control up to three external computers as well as the XL8 console system. CobraNet and other interfaces will be made available according to customer demand.
    S&C: To which market segment is the XL8 directed?
    AC: The XL8 is aimed at the very high end of concert sound touring, plus theater, house of worship and other fixed installations. The modular nature of the system and the ability to distribute components around a building make it very attractive for fixed installation.
     Much of the cabling expense traditionally associated with larger installs is reduced dramatically because audio multi-cores are replaced with Cat5, Cat6 or fiber for longer runs of more than 330 feet. The comprehensive automation systems allow instantaneous scene recall that can be used for anything from control of complex theater shows to room function change; from corporate conferencing to music performance, for example.
     S&C: What’s next from Midas (Telex) in the way of digital consoles?
    AC: Other products are planned at lower price points, but will be positioned carefully in order to complement, but not compete with, XL8. Midas consoles are a major investment for our customers and we do not want to undermine the value of this. If we replaced consoles every three or four years, the value of previous-generation consoles would drop dramatically. Thus, it always has been our policy to design for the long term.


The Midas XL8 handled FOH duties in the Agora Tent in
Frankfurt, Germany, where it was introduced in Prolight + Sound.



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