distribution provides the engineer and technician with
a simple means of matching a number of loudspeakers
to an amplifier. To use this method:
this reduces to:
(2)
2. Add the power required for the individual
speakers and select and amplifier with a rated
power output equal to or greater than this total.
3. Select 70.7-volt transformer having primary
wattage taps as determined in step 1.*
4. Wire the selected primaries in parallel across
the 70.7-volt line
1 watt requires 5000 ohm primary
2 watt requires 2500 ohm primary
5 watt requires 1000 ohm primary
10 watt requires 500 ohm primary
Once the primary taps have been determined,
continue on through step 4 and 5 as outlined above.
When selecting transformer primary taps, use the next
highest available value above the computed value. A
mismatch of 25% is generally considered permissible.
Example: Required
the tap which matches the voice coil inpedance.
Two 10 watt speakers with 8 ohm voice coils
(use one transformer at this location).
following formulas may be used to determine
the proper taps in step 3.
(use 30-watt amplifier or other amplifier
capable of handling at least 26 watts).
(Amplifier output voltage)2
Impedance.
Desired speaker power
ohms(use 1000 ohm transformer)
ohms
(1)
in watts and the secondaries marked in ohms.
