Crown POWER-TECH 3 Reference Manual page 15

Power-Tech Series Power Amplifiers
Maximum Power Specifications
Crown's maximum power specifications represent the largest amount of output power you can expect from your amplifier when it is driven to full
output under the given conditions. These specifications can be used to prevent loudspeaker and hearing damage.
The maximum power matrices include specifications for single cycle and 40-millisecond burst sine waves. Burst signals act like large transient
peaks that are present in common source signals. Loudspeakers can respond to a single cycle burst, so the single cycle burst specifications
should be used to help you protect your loudspeakers. In contrast, a 40-millisecond burst represents the typical response time of the human ear.
Your ear will not respond to the entire dynamic change of a burst that lasts less than 40 milliseconds.
The specifications are provided at 0.05% THD because this represents a low distortion condition. To help you operate your amplifier within these
tolerances, Crown's premium amplifiers include an input/output comparator that shows when the amplifier has exceeded 0.05% THD. Operating
the amplifier at levels higher than 0.05% THD can result in output power levels that are higher than those listed in the maximum power matrices.
Maximum Power Notes:
All maximum power specifications are based on 0.5% regulated AC mains with THD of less than 1.0% and an ambient room temperature of 70° F
(21° C). International units with multi-tap transformers are specified for the best-case transformer tap (normally 240 VAC, 60 Hz). Although it is an
unusual condition, your amplifier can function well with AC mains voltages up to 10% over the rated line voltage. With overvoltage conditions, your
amplifier may be capable of delivering instantaneous power levels up to 20% greater than the specifications in the matrix. Maximum power testing
conditions are very demanding and sometimes result in the activation of the amplifier's ODEP protection circuitry. In the following matrices, spaces
are left blank when ODEP limiting prevents the output power level from significantly exceeding the unit's minimum guaranteed specifications.
1. A single cycle sine wave is presented to the amplifier and monitored for nonlinear distortion. The average power during the burst is
reported. Loudspeakers must be able to withstand this level if they are to be safely used with this amplifier.
2. A 40-millisecond sine wave burst (10 percent duty cycle) is presented to the amplifier and monitored for nonlinear distortion. The average
power during the burst is reported. This power level is a measurement of the amplifier's maximum transient power that can be perceived
by the human ear.
Reference Manual
Fig. 4.4 Power-Tech 1 Maximum Power Matrix
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