JBL System Design Using the GTQ360 and GTQ240, Controls and Connectors, Speaker Requirements

LINE LEVEL			PREAMP
GR1	INPUT	GR1	OUTPUTS
	GR2		GR2
L
R

SPEAKER LEVEL INPUTS

+R – GR2 – L+

+ – – +

R GR1 L

L	SPEAKER OUTPUTS (BRIDGED: R+ TO L–)				R
	GR1	R	L	GR2
+		+	+		+	FUSE	FUSE
						30A	30A

			30A	30A
–	–	–	–

REM POWER

IN/OUTMUTE

BATT(+)GND

BASS EQ	MODE
OFF ON
	F
R	ST L+R

CROSSOVER
SPEAKER	PREAMP
H	F
L	L

GROUP 1

H

MIN MAX

GAIN

INPUT	BASS EQ		MODE		CROSSOVER
GR1 GR2	OFF ON				SPEAKER		PREAMP
				F		H F		H
		R	ST L+R		L		L
					CROSSOVER DESIGNATIONS				MIN MAX
					F = FLAT (BYPASS)				GAIN
					L = LOW PASS
					H = HIGH PASS
					GROUP 2

1 2

3

4 9

56

78

14 13 12 11 10

15 14 13 12 11 10

2.2 Controls and Connectors

1.Preamp-Level Input Connector – Use these connectors for line-level (preamp) inputs to the amplifier.

2.Preamp-Level Output Connector – Use these outputs to send signal to additional amplifiers.

3.Speaker-Level Input Connector – Use this connector for speaker-level input sig- nals. A wire harness is supplied for use with this connector. This input also includes JBL’s Common Sense input cir- cuitry which turns the amplifier on as soon as the high-powered head unit con- nected to this input is turned on.

4.Speaker Output Connectors – Connect speaker wiring to these connectors. See wiring directions for more information.

5., 6., 7., 8. Power Connector – Connection for power wires REM IN/OUT and Mute. See wiring directions for infor- mation on proper connections.

9.Fuses – GTQ240: 30A ATC type. GTQ360: 2 x 30A ATC type.

10.Gain Controls – Use these controls to adjust the gain of the amplifier channel group. See the “Adjusting the Gain” sec- tion for tips on proper setup.

11.Preamp Crossover Switches – These switches control the built-in crossovers that are directed to the preamp-output connectors. Set the switch to F (flat) for full-band operation for that group. Set the switch to L (low) to activate the low-pass filter on the pre-amp output group (for subwoofer use or to use in conjunction with a high-pass filtered input signal to create a band-pass crossover for a midrange or midbass driver). Set the switch to High-Pass to activate the high- pass filter for use with satellite speakers or tweeters on the pre-amp output group.

12.Speaker Crossover Switches – These switches control the built-in crossovers that are connected to each group's power amplifier circuitry. Set the switch to F (flat) for full band operation on a group. Set this switch to L (low) to activate the low-pass filter on the selected amplifier group for subwoofer use or to use in con- junction with a high-pass filtered input signal to create a band-pass crossover (for a midrange or midbass driver). Set the switch to H (high) to activate the high- pass filter for use with satellite speakers or tweeters on an amplifier group.

13.Mode Switches – These switches are used to set the input mode for both pre- amp and speaker-level inputs. Set the switch to ST(ereo) for normal operation on the group using individual left and right inputs. Set this switch to R to drive both the left and right outputs with only a single input on the right jack. Set the switch to L+R to sum the left and right inputs for a mono output on the group. These switches do not affect the preamp ouputs.

14.Bass EQ Switch – These switches acti- vate a built-in Bass Boost circuit used to increase low-bass output on the selected group. These switches do not affect the preamp outputs.

15.Group 2 Input Switch – This switch is used to select which inputs will drive Group 2 of the amplifier. Put the switch in position “GR 1” to allow Group 2 to be driven by the Group 1 inputs. Put the switch in the “GR 2” position to drive Group 2 with the Group 2 inputs.

Power Indicator LED (on amp chassis top) – LED steadily illuminates for normal operation. LED blinks when protection circuitry or muting is engaged.

3.System Design Using the GTQ360 and GTQ240

3.1 Speaker Requirements

When used in the non-bridged mode, a group-channel of the GTQ360 or GTQ240 can easily drive two 2-ohm speaker loads. When only one speaker is connected to the left and right outputs of a group, virtu- ally any conventional speaker may be used. Although the amplifier will not be damaged, load impedances lower than 2 ohms will eventually cause the amplifier to overheat, activating the protection cir- cuits and causing the unit to shut off until it cools down sufficiently.

When a group is in bridged mode, the combined impedance of the speaker (or speakers) connected to the bridged chan- nels should be at least 4 ohms. Sustained operation of the unit in bridged mode with less than 4 ohms will likely cause overheating.

The GTQ360 or GTQ240 must not be used with speakers that have either one of their input terminals wired to the frame of the speaker or to the chassis of the vehicle.

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