The Rane MA 3 is a three-channel amplifier designed to operate in commercial environments, such as paging, foreground music and background music distribution. Up to three optional 40 watt, 70.7 volt or 100 volt constant-voltage audio transformers may be installed inside the amplifier, eliminating the need for external wiring or transformer mounting.
The MA 3 uses a conventional linear power supply with toroidal transformer. This configuration minimizes the emissions associated with switching supplies and noisier transformer designs. The power supply features independent secondary supplies for each channel, minimizing load regulation interaction and crosstalk.
Thermal management is accomplished in the MA 3 with a sealed heat-tunnel design incorporating low velocity forced air and large aperture openings. This design minimizes the noise usually associated with forced air-cooling and eliminates the need for an air filter. Forced air-cooling allows the amplifier to operate reliably in harsh environments and avoid the buildup of heat in unventilated racks associated with passive convection cooling.
Dynamic protection circuitry completely safeguards each channel against over-voltage, under-voltage, overloads, transients from inductive loads, thermal runaway and instantaneous temperature peaks. Biasing is not allowed to occur when an under-voltage condition exists, reducing turn on and turn off transients. Fast-response limiters allow the MA 3 to tolerate up to 20dB of overdrive into 8 and 4 ohm loads while holding THD below 1 percent. This means no loss of speech intelligibility or harsh clipping, and greatly increases the dynamic range of the system without the use of external limiters.
The peak-responding, load-adaptive meters of the MA 3 accurately indicate the remaining headroom. The meters are helpful in setting system levels and indicating signal compression. Internally selectable 80Hz high-pass filters offer protection against over excursion of small bookshelf speakers and saturation of distribution transformers at low frequencies.