Parallel Wiring
(+)
2 ohms | | |
Nominal | 4 ohms | 4 ohms |
Impedance | | |
(–)
Series Wiring
(+)
4 ohms
8ohms Nominal Impedance
(–)
4 ohms
3.2 Signal Sources
The low-level preamp outputs of any radio/tape deck, CD player, or preamp/ equalizer so equipped can drive the GTQ360 or GTQ240. The gain controls of the amplifier are used to match its input sensitivity to the output voltage of the source. This matching is important to keep noise low and is explained in the “Adjusting the Gain” section of this manual.
Thanks to Universal Interface Circuitry, the GTQ360 or GTQ240 can also be con- nected to power amplifiers, radios or equalizers that are equipped with only speaker outputs by connecting them through the speaker-level input connec- tor. Inside the GTQ360 and GTQ240, the speaker-level and preamp-level inputs are connected through a mixing circuit, which allows them to be used simultaneously. Therefore a low-level source, such as a CD player equipped with a volume con- trol, may be connected to the preamp- level inputs at the same time as a pow- ered radio/tape unit is connected to the speaker-level inputs. This provides a high- er performance alternative to an FM mod- ulator connection when you wish to add CD capability to a factory cassette stereo. Switching from one source to the other is as simple as turning the desired source on and turning the undesired one off — no additional switches or relay connec- tions are needed.
4. Wiring
4.1 Wiring
Proper wiring of the GTQ amplifiers and the associated components is extremely important for proper performance and long-term reliability. Using the proper type of wire is very important.
Route the wiring through the car carefully. Do not allow wires to lay against sharp sheet metal edges or any other surfaces that might wear away or cut through the insulation of the wire. Use insulated strain reliefs, rubber grommets and plastic tub- ing to protect the wires whenever they are run through sheet metal panels or are placed where they might be pulled or damaged.
4.2 Ground Wire
•Proper grounding is extremely impor- tant. Use a heat- and oil-resistant stranded copper automotive wire equivalent to the size used for the +12V connection. Crimp or solder and insulate any wire-to-wire connections. Keep the ground wire as short as possible. A ground wire must be solidly connected to a major sheet-metal structure of the vehicle such as a panel near the amp-mounting location. Scrape all paint and primer off the sheet metal at the grounding point to ensure a good electrical connection. Attach the wire to the grounding point with a nut, bolt and star washer. The high current demanded by high-powered amplifiers requires a more secure ground than the typical sheet-metal screw will provide. Coat the connection with silicon sealant for better long-term reliability.
4.3 Remote-In/Out Connection
•The remote power control system turns the GTQ amplifier off when not in use to prevent discharging of the vehicle’s bat- tery. Because the JBL GTQ amplifiers include Common Sense 2-way turn-on, when using the speaker-level inputs with a head unit that includes a BTL power amp it is not necessary to connect the remote wire. The amplifier will automati- cally activate whenever you turn on the head unit. If you are using the line-level inputs, or the speaker-level inputs with a head unit that does not have a BTL power amp, use the following remote wire con- nections.
•Using the REM-IN feature – When +12 volts is applied to the remote IN/OUT ter- minal the amplifier is turned on. A red LED on the top panel of the amplifier will illuminate to indicate the amplifier is on. If the head unit has a +12 volt automatic antenna or amplifier remote activation wire, connect it to the REM-IN/OUT con- nector on the GTQ amplifier. When the amplifier is turned on, there is a time delay of several seconds (longer in cold weather) before the amplifier will produce sound. This eliminates the chance of annoying noises produced by the radio or signal processors being amplified and passed to the speakers when the system is first activated.
•Some head units have no automatic antenna or power amp activation wire. Others have automatic antenna wires that are “on” only when the radio is used but not when a tape is played. In such cases, connect the remote-in turn-on terminal to an unused accessory terminal in the fuse block, or any other +12 volt source that is turned on and off with the vehicle’s igni- tion switch. The remote on/off system
