Audio consoles - TvTechnology

Audio consoles

Learn how NBC handles 5.1 and stereo audio for the network's programming. An NBC engineer describes how presets, automation, snapshots and other tools make the audio engineer's job easier
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Presets, automation, snapshots and other tools make today’s audio engineer’s job easier. NBC Universal’s mixing engineer Fred Zeller uses a Calrec Alpha 100 in Studio 6A at Rockefeller Center.

In the mid 1990s, the professional audio console business was engrossed in the transition from analog to digital technology, keeping pace as recording studios and television networks and stations laid out the groundwork for a digital revolution of their own. Now, in 2005, looking back at the evolution of first- and second-generation digital mixing consoles, they have all but replaced analog consoles. Broadcasters are reaping the benefits of each and every development that these early digital mixers pioneered.

A winning combination

Today's console features are up, reliability is strong, and pricing is lower than the cost of their early ancestors from the 1990s. Research and development costs have been recuperated, the price of DSP is down, and suppliers are now concentrating on maximizing their investment by offering a family of similar and powerful products targeted at differentcustomers across many TV markets.

Console manufacturers may start a new product line focusing on the flagship model that can be fitted with the most channels and can have the largest physical footprint and an abundance of features. This product can cover all the bases for the most demanding broadcaster, but at a “network level,” cost may not be within reach of a market primarily composed of hundreds of TV stations with limited budgets.

Enter digital technology and manufacturing. The next logical step is to offer a scaled-down version of the already designed top-of-the-line model. This desk is designed around a smaller, less expensive control surface with similar features of the flagship in a more cost-effective, but limited, package. It benefits by using the same mixing engine while being targeted at a broader customer base. Although this version of the console may have fewer channels and features, it's still a win-win situation for the station and engineer.

Know your requirements

When selecting a smaller to mid-size console, the station profits from all the development gone into the flagship console. Often this means the customer gets identical hardware and gains an advantage from the technology, expertise and service of the high-end product at a lower cost.

The person tasked with ordering a new audio console first needs to collect some important information about the operation to be able to identify the right console to do the job.

The primary question often becomes: How many channels should the console handle? Because the console is digital, the number of faders necessary to access them becomes a second issue. Inputs can be running under the direct control of a fader or assigned to the “B” layer (or more) of the console, only tying up a fader input strip when an adjustment is required.

However, operators typically need instant access to a channel's level. Though digital technology makes it possible to run many channels of audio from an assignable and smaller control surface than from analog desks, there must be enough strips to access all necessary channels immediately, and layering should be reserved for less demanding sources.

Next, you need to determine how many outputs are needed. Start by considering the most demanding show your facility produces. Unlike adding additional input channels with a mini mixer for election night, it's difficult and often impossible to add unique outputs to the mix without a complicated add-on matrix. Mix-minuses for talent, clean feeds for control-room monitoring, in-house MATV feeds, and a main monaural mix, stereo, and even 5.1 channel program busses all require separate outputs. Some consoles offer a mix-minus per input channel as standard, and some use an assignable buss. Aux send outputs are available from the input strip and vary in quantity, usually between six to 10.

Getting the right mix of I/O interfaces can be a real challenge. Every signal that's connected to the digital audio console will need the proper format connection. A list of microphones, analog sources and destinations, AES digital sources and destinations, and monitor paths should be used to calculate the amount of necessary conversion frames required for each format. Costs can quickly add up when standard I/O frame packages are exceeded and another frame is required for only one or two leftover circuits.

Today's features are abundant

The added benefit of this type of interconnection is its built-in routing capabilities. Any source can be applied to any input and any input to any output. In some cases, inputs and outputs can be connected without the audio console in the circuit, potentially handling all the audio routing needs of the facility.

Digital consoles with today's lower-cost DSP chips offer a tremendous variety of features while using mature digital control and solid mixing engines. Consoles often provide easy-to-see TFT metering displays, but conventional LED bargraphs and mechanical VU meters are also available. TFT displays may offer more custom-izable information in less space with choice of scaling and ballistics. They not only monitor the signal but also can analyze it by showing EQ, dynamics and signal path information on an as-needed basis, whether the signal is mono, stereo or 5.1, from a choice of points in the circuit. Much of this is now standard on many consoles.

Inputs may be assigned as mono, stereo or 5.1 as well, all under the control of one fader or broken away to individual channels when discrete adjustment is required.

Processing functions are available on fixed, selectable or centralized controls. Each input strip will provide dedicated controls, and some may have assignable functions to a particular knob. A full array of control is available when an input can be interrogated and then sent to single or multiple master panels for fine-tuning.

Digital consoles often can provide a bank of as many as 100 memory snapshots. This provides the operator with the ability to electronically reconfigure the console for different shows or broadcasts with the push of a button. Changes can include router crosspoint and electronic scribble strip changes along with trim, bussing and processing configurations. If your facility needs to handle back-to-back shows, this feature is a real time-saver.

Digital reliability is solid

Remote microphone input panels that digitize the analog signal at the talent stage are available, eliminating the disadvantages of long analog cable runs. Taking it a step further, sophisticated multi-studio, multi-control room applications can benefit from networkable interfaces. This level of optional sophistication allows input and output sharing across multiple systems, surrendering conventional audio distribution to IT-based routing and connectivity. Moving from facility to facility and show to show can be near instantaneous and under the control of a single push-button.

Much of the DSP technology used for the audio mixing engine in today's consoles are redundant, fault-tolerant and/or self-healing, though this does vary. Software routines monitor the console's heartbeat and then command online resources to re-establish any failed paths almost instantaneously and without loss of audio. Many consoles will continue to pass mixed audio if the control system goes down.

On-board and remote diagnostics may be available. Many permit remote interrogation by the manufacturer to access critical console data logs that help facilitate local repair.

Look for components from faders to I/O and for DSP cards to be hot-swappable. This is key to effecting a speedy recovery while minimizing outage in the event of a problem. This is especially critical if other portions of the system are not completely fault-tolerant or redundant.

Today, console commands are typically carried out by dedicated and secure operating systems, with control surface re-sets taking seconds and full system re-booting usually at or under a half-minute. Look for redundancy here, but regardless, control surface resets should not affect the on-air output.

As the DTV transition continues, it's evident that sophisticated audio devices like consoles will become more IT-friendly. The ultimate benefactor is the TV station engineer. With the many features, functions and capabilities of today's digital consoles, engineers can more easily specify new mixer requirements, complete with a full set of digital features that meet their operations' needs, while staying within budget.

Jim Starzynski is principal engineer in advanced technology for NBC-Universal.