Specifications
Page 13
D-45 / D-75A Power Amplifiers
Crown specifications are guaranteed for three years.
In an effort to provide you with as much information as possible about the power-producing capabilities of your amplifier, we have created the
following power matrix. The specifications found in these tables are for 120 VAC, 60 Hz North American units and are guaranteed for
three
years. Some spaces in the matrix are left blank because we do not provide this same guarantee for those conditions—however, your amplifier
will perform well under
all conditions listed in the table.
Power Specifications
When measuring power, 0.1% THD appears to be the industry standard for distortion. The maximum average power shown in the power
matrix is measured when THD rises to 0.1% so you can easily compare Crown specifications to those of other manufacturers. But this high
level of distortion actually allows for some clipping which is undesirable. The burst power specifications in the power matrix are measured at
0.05% THD which is not a clipped condition. Crown has chosen to provide these specifications with the hope that other manufacturers will
also start providing specifications that correspond to the way amplifiers should be used in the real world—without clipped output.
Many manufacturers publish power specifications with a tolerance of ±1 dB or worse. That means their amplifier can deviate more than 20%
in output! A 100 watt amplifier would meet their specification if it only produced 79.4 watts. Other manufacturers qualify their specs by saying
they are “typical,” “subject to manufacturing tolerances,” “single channel driven” or that they are specified with “fuses bypassed.” Each of these
statements effectively removes any performance guarantee. We take a different approach at Crown—our published specifications are
guar-
anteed
for three years. Further, because our “in-house” specs are more stringent than our published specs,
every
Crown amplifier will
exceed
its published specs. We believe you should get what you pay for.
Fig. 4.1 D-45 Power Matrix
Fig. 4.2 D-75A Power Matrix
Notes:
All power matrix specifications are based on a 0.1% regulated 120 VAC, 60 Hz power mains and an ambient room temperature of 70° F (21° C).
1. Continuous power in the context of Federal Trade Commission testing is understood to be a minimum of five minutes of operation. Harmonic distortion is measured at the RMS
sum total as a percentage of the fundamental output voltage. This applies for all wattages greater than 0.25 watts.
2. A 1 kHz sine wave is presented to the amplifier and the output monitored for nonlinear distortion. The level is increased until the THD reaches 0.1%. At this level the average
power per channel is reported.
3. 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.
4. A 40 millisecond burst or a two cycle sine wave (whichever is of greater duration) is used and the power computed as the average power during the burst. The duty cycle of
this test is 10 percent. This power level is a measure of how loud an amplifier is as perceived by the human ear.
5. EIA standard RS-490 (both channels driven).