Quest Engineering QTA 1360P User Manual page 10

QTA 1360P/1480P
User Manual
For the benefit of those who want to calculate
the power of the system with a formula. See
below:
Determining power by calculating
total impedance
The alternative to counting the speaker taping
watts is to calculate the total impedance of
the line, which will also indicate the wattage
necessary to drive the system correctly.
The computational formula is voltage squared
divided by impedance:
Power = Voltage2 / Impedance
High impedance of speakers and output calculation table for 100Volt systems
8
Output
0.1W
0.5W
1W
2W
3W
5W
(100V plan) P = E x E / Z = 100x100 / Z = 10,000 / Z
P: Power(W), Z : Impedance (Ω), E : 100V(Designed voltage of a general-use amplifier)
User Manual
Q-Tech Commercial Series
QTA 1360P/1480P
Impedance Output
100KΩ 10W
20KΩ 15W
10KΩ 20W
5KΩ 25W
3.33KΩ 30W
2KΩ 35W
When the speaker line reaches its top voltage
of 70 Volts, the formula is:
Power = 5000 / Impedance
squared equals 5000).
To measure impedance a dedicated meter is
required. These use a 1k frequency to send an
alternating current through the transformer(s).
The resulting figure indicated by the meter's
dial can be cross referenced with the meter's
impedance chart to see what value should be
expected and the power that will be required.
Impedance Output
1KΩ 40W
667Ω 50W
500Ω 75W
400Ω 100W
333Ω 150W
286Ω 200W
(because 70
Impedance
250Ω
200Ω
133Ω
100Ω
66.7Ω
50Ω