Specifications

13
EXAMPLE
You have a 70-volt transformer with taps labeled 1, 2, 4, and 8 watts. What power points will those
taps provide on a 25-volt line?
The table shows that 25 volts is 9 dB less than 70 volts. The chart confirms that the taps will provide
0.125, 0.25, 0.5, and 1 watt, respectively.
Using components with different line voltages
Sometimes it may be practical to use a transformer or loudspeaker/transformer combination with a different
voltage system from what it was originally intended. For example, a 70-volt transformer could be used in a 25-volt
system, although you would have to derate the power taps similarly. But never use a transformer with a higher
voltage than what it is designed for; i.e., you couldn’t use that same transformer on a 100- or 140-volt line.
To properly derate the transformer tap power levels, use the chart
at left. Locate the column with the voltage the transformer is
rated for, then locate the row with the system voltage you want
to use it in. The table will indicate the dB reduction to use with
the derating chart below.
0.001
0.01
0.1
1
10
100
0.1 1 10 100
-3
dB-3 dB
-6
dB-6 dB
-9
dB-9 dB
-12
dB-12 dB
-15
dB-15 dB
-18
dB-18 dB
Original Value of Power Tap, in watts
Derated Value of Power Tap, in watts