10
VA and Power Factor (cont.)
This means that the true power being delivered to the
subwoofers is 5000 X 78% = 3900 Watts. Now he can
use this tool to make changes to his box tuning, or even
something as small as rounding the corners inside the
box or the port itself can move the power factor around.
Typically the power factor will be the highest around the
port tuning frequency of a ported enclosure. In the case
illustrated here, the user could find the subwoofer's
tuning frequency by using
Impedance Mode (page 11).
Then make adjustments to the tuning frequency by
playing with the port, placement, bracing, damping,
stuffing, etc. to try to increase the Power Factor at the
frequency used in competitions for most efficient transfer
of power from the amplifier to the subwoofers.
How to measure VA and Power Factor
1. Power on the AMM-1 by pressing the ON button
2. Unit will power up, display internal battery condition,
and then land on the DC Voltage Screen.
3. Press the MODE button three times (or hold down)
to get to the VA & Power Factor screen.
4. Shut off AC source (amplifier)
5. Disconnect one of the wires from the load of interest
(subwoofer)
6. Run the either the negative or positive speaker wire
through the hole on the center of the AMM-1, and
reconnect the wire to the load. (Doesn't matter
which one, but only use ONE of them)
7. Connect the voltage harness to the banana jacks
and then to the amplifier speaker outputs (+) and (-)
8. Power up AC current source (amplifier) and apply a
signal with a tone generator or tone CD.
9. The AMM-1 will display the VA and the Power Factor
