Rockford Fosgate 4-CHANNEL AMPLIFIER owner manual Information Cubed, Audio Graph - The PowerCube

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 Cubed

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 Impedance is displayed on the Z axis. Output Power, in watts, is listed on the left hand side for each impedance at each phase angle.

Audio Graph – The PowerCube

MODEL BEING	VOLTAGE FROM		x4 = STEREO		MANUFACTURERS
TESTED
		BATTERY	MONO = BRIDGED MONO*
					RATED OUTPUT
Amplifier: PUNCH 4040 14.4V x 4				Rated Power : 20W at 4 Ohms
Serial No: B1AB13A000016
Owner : ROCKFORD CORPORATION

I M P E D A N C E

8Ω *–60°	20 W
–30°	20 W	POWER
0°	19 W
		IN
30°
	20 W	{ WATTS
60°	20 W
4Ω *–60°	38 W
–30°	35 W
0°	35 W
30°	36 W
60°	38 W
2Ω *–60°	66 W
–30°	60 W
0°	58 W
30°	60 W	–60°(Cap)
60°	64 W
		0°
1Ω *–60°	100 W
–30°	87 W	PHASE{ANGLES
0°	84 W
30°	87 W	"MOTION OF
60°	100 W	SPEAKER"

*If a Bridged/Mono, test amplifier sees 1/2 impedance (2Ω

1Ω (Ind) +60°

test amp sees 1Ω )

OUTPUT VOLTAGE

AT THE RAILS100V (MOSFETS)

60V

20V

8Ω

4Ω

2Ω

{ Impedance

29