The amount of power required to cover the area to the 1,000 foot perimeter was swiftly determined. According to the company’s V.P. and Director of Marketing, Ralph Morris, “We rate our standard arena system as adequate for 10,000 people in an outdoor situation. That’s a 6,000 watt system. We use that formula and add in multiples thereof. Of course, it’s only a rule of thumb because the sound doesn’t just go out so far and then stop. But the formula works.”
Some days before the concert it became apparent that the attendance would almost certainly surpass the 200,000 mark and appropriately the capability of the reinforcement system was upgraded. An additional array of speakers was added on towers at the 1,000 foot mark. These speakers were faced outward and fed through an 859 millisecond delay.
All the basic hardware used by Tycobrahe was designed and built by them and carried their brand name. The company began manufacturing its own equipment when it recognized the need for a specialized sound refinforcing mixer. The specifications established by their engineering team called for a mixer that was simple and straightforward, highly ruggedized and portable.
The Tycobrahe Model MX24-4 input mixer has stereo main and monitor outputs, with separate panpots on each input. It was designed solely for sound reinforcement and can accommodate the “screaming microphone levels which would clip the inputs on most studio consoles.”
View from the mixing tower, looking toward the stage.
Each input has 3 band equalizers with 3 selectable frequencies in each band. There is no EQ on the outputs so that inexperienced, or overzealous mixers cannot get into too much trouble with a single EQ control.
Overall EQ is available for the monitor mix, but those controls are included in the monitor power amp circuitry. Dual band limiters are in the outputs of the mixer which limits about a half a dB from the clipping point of the power amps. They are similar to Altec dual band limiters, with a crossover frequency of 250 Hz. 250 was chosen because that frequency is just about the dividing point between vocals and bass.
Dual band limiting is necessary, according to chief engineer Jim Gamble, to prevent pumping the midrange and highs during those very heavy bass parts.
The amplifiers used at the Jam were also Tycobrahe products, their 2,000 Watt BFA 2000 bi-amplifiers. Like the mixers, the amplifiers were designed specifically for location sound reinforcement applications. The low frequency section of the amp delivers 1,500 Watts, and the high frequency channel delivers 500 Watts. The crossover frequency is at 800 Hz. The units are packaged in a rugged portable case, and are mounted in drawers for easy access