Rockford Fosgate Punch Owner's Manual page 32

A 4 ohm speaker may experience a drop in impedance 4-
6 times lower than its nominal (printed) impedance. A
speaker will also create phase shifts in the signal that is
passed through it. These phase shifts happen because
a speaker is an inductor (voice coil) and a capacitor
(compliance of the surround/spider), as well as a resistor
(voice coil wire).
To simulate a speaker the Audio Graph PowerCube
measures output power into 20 different loads. It tests at
8 ohms, 4 ohms, 2 ohms and 1 ohm. Each of these
impedances is also tested at -60°, -30°, 0°, +30° and
+60° phase angles. These different impedances and
phase angles represent the shifts in impedance and
phase that can occur in a typical loudspeaker.
Information
The data acquired in the testing procedure is then graphed
in the form of a 3-dimensional cube, hence the name
PowerCube.
The Phase Angle is expressed on the horizontal axis, the
Output Voltage is presented on the vertical axis and the
lmpedance is displayed on the Z axis. Output Power, in
watts, is listed on the left hand side for each impedance
at each phase angle.
MODEL BEING
TESTED
VOLTAGE FROM BATTERY
I
Amplifier: PUNCH 4040 14 4V x
Serial No B1AB13A000016
Owner : ROCKFORD CORPORATION
20W
- 3 0 " 20 W
19W
20 W
6 0 ' 20 W
36 W
-30"
35 W
35 w
30" 3 6 W
38W
60 W
58W
100W
87W
84W
67W
Cubed
Audio Graph -The PowerCube
X4=STEREO MONO=BRIDGED MONO
29
MANUFACTURERS
RATED OUTPUT
Rated Power: 2OW at 4 0hms