The entire audio system was supplied by Brazilian rental company Gabisom, which has provided audio for the last 13 editions of Rock in Rio, including those in Lisbon, Madrid and Las Vegas.
Sound designer and FOH system engineer for the World Stage at the Rio de Janeiro event was Gabisom's Peter Racy.
"The world stage was loaded with a massive PA system, which comprised 126 line-array elements, as well as 50 flown subs and 32 ground subs," says Peter. "There were several artists who opted to rent a DiGiCo SD7, including Rod Stewart, Seal and AH-A, while several others brought in their own."
The system was set-up in an unusual manner, with each of the four main hangs consisting of three columns of flown cabinets: the innermost column, called band, was dedicated to a full band mix (drums, bass, guitars etc.); the middle column was a flown sub array, normally linked to the inner column to work as a four-way system for the band mix; whilst the outermost column of each hang was dedicated to vocals, or any other element featured in the mix.
"The purpose of splitting the mix in this way was to allow maximum headroom for featured elements, while not having to compete with a full band mix for that headroom," explains Peter. "This concept frees up headroom in the mixing desk's summing amps and the busses in the system processors, the power amplifiers and in the speaker components themselves.
"The net result is a massive amount of power and high definition audio. Of course, many guest engineers are not prepared for this and prefer to run the system in either a conventional way, or in another of many possible configurations."
In order to offer this flexibility, with a choice of several different ways to drive the numerous sub-systems, the routing can become quite complex. This is where the SD7 steps in as the master console to solve the equation.
"All the desks used for mixing bands, were fed into the SD7," Peter continues. "Here, we were able to easily route each input (typically six inputs from each desk) to any of the sub-systems, add or subtract gain as requested and create a down mix of the band and vocal mixes to be fed to delays, front fills, press, broadcast etc.
"Additionally, we had SD-Racks on either side of the stage connected to the SD7 master desk via an Optocore loop, which transmitted the digital drive lines directly to the power amplifier inputs, ensuring a clean and robust feed to the amplifiers. As a result, our operation became much more reliable, flexible and precise."
(Jim Evans)
