Calrec Audio's Alpha and Sigma

Since 1993, Game Creek Video has provided mobile units for a wide variety of customer needs. Its trucks and engineers have covered major sporting events such as the World Series, the Super Bowl and the Kentucky Derby. It also has provided mobile facilities for entertainment customers such as HBO's coverage of the Rolling Stones at Madison Square Garden and CBS's coverage of ̶Celine Dion: Live in Las Vegas.”

We currently operate 17 units: four HD mobile trucks, five SD units, one analog unit, and seven B units for tapes, graphics and office space. In addition, we recently began building a four-unit HD truck, commissioned to provide FOX Sports with facilities to cover NFL and NASCAR events.

Lots of inputs required

From an audio perspective, these trucks must handle an increasingly large number of incoming feeds. As with any large sporting event, it is essential to have an audio console that can handle feeds from a variety of sources — everything from microphones positioned along the track or on the field to announcers, effects from instant replays and secondary announcer boxes.

All of these sources must be processed in real time, which makes it crucial to choose an audio console that can process this large number of sources simultaneously. The console also must be user-friendly and intuitive for operators.

The result was the demand for a console that could manage a large number of channels, including a variety of at least 160 stereo channels, plus roughly 150 other channels, all with full EQ and dynamics.

The need for surround capability

Surround sound is an increasingly important component of HD production. In a major sports production, it is not unusual to need up to 70 full 5.1 channels. Another important need is the ability for each channel to feed every bus at the same time, without restrictions. When mixing a big event, an operator doesn't have time to worry about a console's bussing capabilities.

With these requirements in mind, we installed Calrec Audio systems into our new HD trucks — a 96-fader digital Alpha into one and a 64-fader Sigma into the other. The Alpha will be used for the main audio for both NASCAR races and NFL games, while the Sigma will be mainly used as a support unit for the effects submix for NASCAR.

We chose the Alpha and Sigma because of their ability to process a lot of power in a package that could fit into the size requirements of mobile production units. Both feature Calrec's new Bluefin high-density signal processing system, which provides more than double the processing in less physical space, for roughly the cost of the previous technology. Bluefin provides 480 equivalent mono signal paths on the Alpha, and the capability for 78 full 5.1 surround sound channels on just one DSP card. It also provides EQ and dynamics, along with four main outputs, 48 multitrack outputs and 20 aux feeds.

Our new Alpha and Sigma boards both include spill panels, which offer fine adjustment of every leg of the surround channel. Calrec makes up a surround channel using two stereo channels for the L/R and LS/RS legs, and two mono channels for center and LFE. These are allocated from the available mono and stereo channels when the surround channel is assigned.

This method of building a surround channel gives us more control of the balance and width of the signal. Using stereo channels allows adjustment of the front and rear width of the surround signal. It also ensures that during adjustment, the overall balance of the surround channel is not upset, which could happen when adjusting a surround channel with six monos. In addition, it gives us more flexibility and confidence if we need to manipulate the signal on the fly; we can isolate any particular element and adjust each one. For example, we could isolate the center channel and adjust the EQ if necessary.

Fitting it all in

When planning a truck, space is at a premium. Therefore, the amount of space Bluefin saves is an advantage. Bluefin is designed to operate on just two cards, one of which is a spare to guarantee 100 percent redundancy. The cards can be located in the existing digital I/O rack. This removes the need for a DSP rack, saving us seven units of space in our equipment room and making the truck lighter.

It is reassuring to have full redundancy across all system-critical points; most of our work is live to air, and our trucks can take a pounding. Whatever manufacturers tell you, components can always fail. As an operator, full redundancy gives us absolute confidence.

Both the Alpha and the Sigma operate independently from the PC. In fact, the PC can actually be switched off, and the desks will still process audio and provide full control.

We already use Calrec consoles in three HD units: a Sigma in the Freedom, and Alphas in both the Patriot and Yankee Clipper. Because the consoles are based on the same basic user interface, it simplifies operation for experienced users and also makes training for new operators a snap.

Installation of the consoles into the trucks was easy. Calrec does an enormous amount of pre-planning, including at the point of installation, so it's really just a plug-and-play operation.

By Pat Sullivan is president of Game Creek Video.