GPX1200.4 - Receiver Crunch - Free user manual and instructions

Product type	4-channel amplifier receiver
Brand	Crunch
Model	GPX1200.4
RMS output power	4 x 80 W @ 4 Ohm / 4 x 150 W @ 2 Ohm
Max output power	4 x 160 W @ 4 Ohm / 4 x 300 W @ 2 Ohm
Speaker impedance (stereo)	2 – 8 Ohm
Frequency response	5 – 40 000 Hz (-3 dB)
Total harmonic distortion (THD)	< 0,5% (1 kHz)
Signal-to-noise ratio	> 90 dB
Input sensitivity	0,1 – 7 V
Input impedance	10 kOhm
Low-pass filter (CH3/4)	50 – 250 Hz @ 12 dB/Octave
High-pass filter (CH1/2 & CH3/4)	50 – 250 Hz @ 12 dB/Octave
Bass Boost (CH3/4)	Switchable 0 / 6 / 12 dB
Line output	Stereo, from CH1/2
Supply voltage	+12 V (9 – 15 V), negative ground
Fuse	2 x 20 A
Dimensions (W x H x D)	254 x 46 x 330 mm
Integrated protection	Yes, green LED (on) / red LED (fault), automatic shutdown

Frequently Asked Questions - GPX1200.4 Crunch

How to connect the amplifier to the car battery?

First, disconnect the negative terminal of the battery. Connect the power cable (+12 V) to the battery with an in-line fuse placed within 30 cm of the positive terminal. Connect the GND terminal of the amplifier to a clean chassis ground. Finally, connect the REMOTE wire to the remote output of the car stereo.

What to do if the protection LED lights up red?

This indicates a short circuit, too low impedance, or overheating. Check the speaker connections, the impedance (minimum 2 ohms per channel in stereo, 4 ohms in bridged mode) and make sure the amplifier is well ventilated. If the problem persists, let it cool down and check the battery voltage.

How to adjust the high-pass and low-pass filters?

Set the FILTER switch to HPF for high-pass, LPF for low-pass, or FULL for full-range. Adjust the crossover frequencies (50-250 Hz) according to the speakers: for a subwoofer, use LPF around 80-120 Hz; for satellites, use HPF around 125 Hz.

What is the minimum speaker impedance?

In 4-channel stereo mode, the minimum impedance is 2 ohms per channel. In bridged mode (2 channels), it is 4 ohms. Do not go below this to avoid triggering protection.

How to connect a subwoofer in bridged mode?

Use channels CH3 and CH4: connect the positive wire of the subwoofer to the positive terminal of CH3 and the negative wire to the negative terminal of CH4. Set the filter to LPF and the desired crossover frequency. The subwoofer impedance must be at least 4 ohms.

The amplifier does not turn on, what to check?

First check the power LED: if it does not light up, check the in-line fuse, the amplifier fuses (2x20A), the ground connection, and the voltage on the +12 V and REM terminals (must be between 9 and 15 V). Also check that the REM wire is properly connected to the car stereo.

How to avoid engine noise in the speakers?

Route the audio cables (RCA) away from the power cables. Make sure the grounds are clean and well connected. If the noise persists, add an extra ground wire between the battery and chassis, or use a noise filter.

How to use the Bass Boost function?

The Bass Boost (CH3/4) increases the low frequencies by 0, 6, or 12 dB. Use it moderately to avoid saturating the subwoofer. Excessive adjustment can damage the speakers.

Can I connect multiple amplifiers?

Yes, use the line output OUTPUT CH1/2 to connect another amplifier. This output transmits the stereo signal from the CH1/2 inputs. Make sure the power supply can handle the total power.

How to adjust input sensitivity (GAIN)?

Set the car stereo volume to about 75% of its maximum. Turn the GAIN potentiometer on the amplifier until you get a moderate sound level without distortion. Too much gain can introduce noise.

USER MANUAL GPX1200.4 Crunch

Please read the user's manual carefully before the installation and the first operation of the amplifier.

SPECIFICATIONS

Output Power RMS	4 x 80 W @ 4 Ohms4 x 150 W @ 2 Ohms
Output Power Max.	4 x 160 W @ 4 Ohms4 x 300 W @ 2 Ohms
Loudspeaker impedance (stereo)	2 – 8 Ohm
Frequency Response	5 – 40 000 Hz (-3 dB)
Total Harmonic Distortion	< 0,5 % (1 kHz)
Signal-to-Noise Ratio	>90 dB
Input Sensitivity	0,1 – 7 V
Input Impedance	10 kOhm
Lowpass Filter (CH3/4)	50 – 250 Hz @ 12 dB/Octave
Highpass Filter (CH1/2 & CH3/4)	50 – 250 Hz @ 12 dB/Octave
Bass Boost (CH3/4)	Switchable 0 / 6 / 12 dB
Line Output	Stereo, from CH1/2
Operating Voltage	+12 V (9 – 15 V), negative ground
Fuse Rating	2 x 20 A
Dimensions (B x H x L)	254 x 46 x 300/330 mm

All Specifications are subject to change

IMPORTANT NOTES PRIOR TO INSTALLATION

• This device is only suited for a 12 volt system with negative ground.
• The radiated heat while operation requires sufficient air circulation at the place of installation. It is very important that the heat sink fins do not have contact with any metal parts or any surfaces which could impair air circulation. The amplifier may not be installed in small closed location or spaces without air circulation (e.g. spare wheel recess or below the vehicle carpeting). We recommend the installation in the vehicle's trunk. Ensure sufficient protection against vibrations, dust and dirt.
• Ensure that the input and output cables are sufficiently separated from the power supply cables. Otherwise interferences may occur.
• Ensure the accessibility of the fuse and the operating elements after installation.
• The reliability and performance of the amplifier depends on the quality of installation. Preferably consult an expert to install the system, particularly if you want to install several loudspeakers.

IMPORTANT!

Always observe the correct polarity of all connections!

INTERCONNECTION

POWER SUPPLY AND TURN-ON-CONNECTION

ATTENTION: Before you start with the installation, disconnect the ground connection from the vehicle's battery in order to prevent short circuits.

The power wiring which is usually installed in on-board car networks is not sufficient for a power amplifier's demands. Make sure that the power wires to GND and to the +12 V terminal has been sufficiently specified. A cable cross-section of at least 10 mm^2 must be used to connect the battery to the amplifier's terminals.

First connect the GND terminal of the amplifier to an appropriate ground connection at the chassis. To ensure a good connection, residue dirt and dust from the connection point. A loose connection may cause malfunctions or interferences noise and distortion.

Then connect the +12 V terminal of the amplifier with the battery by using an appropriate cable including an in-line fuse. This fuse should be located very close to the battery; for safety reasons not more than 30 cm away. Only insert the fuse when the installation, including the connection of the loudspeakers, has been accomplished.

Then connect the remote turn-on-wire from the head unit with the amplifier's REM terminal. A cable with a cross-section of 0.5mm^2 is adequate.

LOUDSPEAKER CONNECTIONS

• In 4-channel operation (i.e. one loudspeaker on each amplifier channel), the impedance must not be lower than 2 ohms for each speaker
• In bridging mode (two amplifier outputs combined) the impedance must not be lower than 4 ohms for the bridged output.
• Never connect loudspeaker cables with the ground of the chassis or the +12 V supply voltage.

If the amplifier is operated with a too low impedance or incorrectly used, the entire sound system may be damaged. This means a warranty void in such cases.

AUDIO SIGNAL CABLES

When installing the audio cables between the RCA outputs of the headunit and the RCA inputs of the amplifier, the audio and power supply cables should, if possible, not be routed along the same side of the vehicle. We recommend a separated installation, e.g. routing the power cable through the cable channel on the left side and the audio cables through the cable channel of the vehicle on the right side or vice versa. This prevents interferences due to crosstalk into the audio signal.

SIGNAL OUTPUTS TO CONNECT ADDITIONAL AMPLIFIERS

The input signal on the INPUT CH1/2 jacks (Fig. 1,5) will be routed in stereo to the output jacks OUTPUT CH1/2 (Fig. 1,6). Thus the OUTPUT jack allows the connection of a additional amplifier.

OPERATING ELEMENTS

INPUT SENSITIVITY CH1/2 & CH3/4

Turn the GAIN (Fig. 1,4 CH1/2 and fig. 1,8 CH3/4) controller of the amplifier to the MIN position. Then turn the volume controller of the headunit to 80 - 90% of its full setting. Now turn GAIN clockwise until you hear some distortion. Then turn back the GAIN slightly until you hear a cleaner sound.

VARIABLE HIGH PASS FILTER CH1/2 & CH3/4

If the amplifier is to be used for mid-range/tweeter loudspeakers, set the switches FILTER (Fig. 1,3 CH1/2 and fig. 1,11 CH3/4) to HPF. Then set the desired crossover frequency on the HPF controller (Fig.1,2 CH1/2 or fig. 1,12 CH3/4). Thus to that only the frequencies above the chosen crossover frequency will be amplified. This effectively minimizes distortions and overloads at lower frequencies. A good point to start is at 125 Hz.

If you use loudspeakers (>20 cm) set FILTER (Fig. 1,3 CH1/2 and fig. 1,11 CH3/4) to FULL. In this case, the HIGH PASS controllers (Fig.1,2 CH1/2 or fig. 1,12 CH3/4) are without function.

VARIABLE LOW PASS FILTER CH3/4

If the amplifier is used to drive a subwoofer, set the switch FILTER (Fig. 1,11 CH3/4) to „LPF“. Set the desired crossover frequency by using the controller (Fig. 1,10 CH3/4). Thus to that only the frequencies below the chosen crossover frequency will be amplified and the subwoofer plays more precised and efficient.

SWITCHABLE BASS BOOST CH3/4

By using the BASS BOOST switch (Fig.1,9 CH3/4) you are able to increase the bass level by 6 or 12 dB.

Attention: Use the BASS BOOST wisely!

PROTECTION CIRCUIT

The POWER/PROTECTION LED (Fig. 1,1) lights up green, if the amplifier is in operation.

The POWER/PROTECTION LED (Fig. 1,1) lights up red, when the amplifier is overheated, or a short circuit occurs resp. a too low impedance load is connected to the speaker outputs. If this events, the internal built-in protection circuit shuts down the amplifier automatically. The amplifier should work again properly after you have solved the problems.

FIGURES (P. 28-30)

CONNECTIONS AND CONTROLLERS (FIG. 1)

(1) Power-/Protection-LED
(2) High pass filter controller CH1/2
(3) Selector FULL / HPF (High pass) CH1/2
(4) Gain level controller CH1/2
(5) Audio signal inputs CH1/2
(6) Audio signal outputs to run additional amplifiers
(7) Audio signal inputs CH3/4
(8) Gain level controller CH3/4
(9) Bass Boost selector CH3/4
(10) Lowpass filter controller CH3/4
(11) Selector FULL / HPF (High pass) / LPF (Low pass) CH3/4
(12) High pass filter controller CH3/4

POWER SUPPLY AND TURN ON CONNECTION (FIG. 2)

(1) GND terminal for the ground
(2) REM terminal for the turn on connection
(3) +12 V terminal for the positive-connection of the battery
(4) Vehicle's battery
(5) In-Line Fuse (not included in the scope of delivery)
(6) Turn on wire from the head unit or the electrical antenna
(7) Fuse(s)

4-CHANNEL OPERATION STEREO (FIG. 3)

If you want to run the amplifier with the 4 line output channels* from the head unit to drive 4 loudspeakers, in stereo connect the following setup:

(1) To the head unit, line output left FRONT CH1
(2) To the head unit, line output right FRONT CH2
(3) To the head unit, line output left REAR CH3
(4) To the head unit, line output right REAR CH4
(5) Loudspeaker left REAR CH3
(6) Loudspeaker right REAR CH4
(7) Loudspeaker left FRONT CH1
(8) Loudspeaker right FRONT CH2

3-CHANNEL OPERATION STEREO & MONO (FIG. 4)

If you want to run the amplifier with the 4 line output channels* the head unit to drive a pair of loudspeakers and a subwoofer, connect the following setup:

(1) To the head unit, line output left FRONT CH1
(2) To the head unit, line output right FRONT CH2
(3) To the head unit, line output left REAR CH3 or subwoofer output
(4) To the head unit, line output right REAR CH4 or subwoofer output
(5) Loudspeaker left FRONT CH1
(6) Loudspeaker right FRONT CH2
(7) Subwoofer

* If your head unit only have 2 output channels, use commercially available Y-adapters for splitting the signal. But then the FADER function of the head unit does not work anymore.

TROUBLESHOOTING

If you are having problems after installation follow the Troubleshooting procedures below.

Procedure 1:

Check Amplifier for proper connections.

POWER/PROTECTION LED lights up green. In this case skip to Step 3, if not continue.

1. Check in-line fuse on battery positive cable. Replace if necessary.
2. Check fuse(s) on amplifier. Replace if necessary.
3. Verify that Ground connection is connected to clean metal on the vehicle's chassis. Repair/replace if necessary.
4. Verify there is 9 to 16 Volts present at the positive battery and remote turn-on cable. Verify quality connections for both cables at amplifier, stereo, and battery/fuse holder. Repair/replace if necessary.

Procedure 2:

POWER/PROTECTION LED lights up red.

1. If the LED lights up red it is a sign of a possible short in the speaker connections. Check for proper speaker connections and use an ohm meter to check for possible shorts in the speaker wiring. Too low speaker impedance may also cause PROTECTION to light. This can also be a sign of driving the amplifier at very high power gains without adequate airflow around the amplifier. Shut off the system and allow amplifier to cool. Check that the vehicle charging system is maintaining proper voltage. If the previous items do not solve the problem, a fault may be in the amplifier. In this case you should contact your dealer.

Procedure 3:

Check Amplifier for audio output.

1. Verify good RCA input connections at stereo and amplifier. Check entire length of cables for kinks, splices, etc. Test RCA inputs for AC volts with stereo on. Repair/replace if necessary.

Procedure 4:

Check Amplifier for a popping noise while turning on.

1. Disconnect input signal to amplifier and turn amplifier on and off.
2. If the noise is eliminated, connect the REMOTE lead of amplifier to source unit with a delay turn-on module.

Procedure 5:

Check Amplifier if you experience excess Engine Noise.

1. Route all signal carrying wires (RCA, Speaker cables) away from power and ground wires.

OR

1. Bypass any and all electrical components between the head unit and the amplifier(s). Connect stereo directly to input of amplifier. If noise goes away the unit being bypassed is the cause of the noise.

OR

1. Remove existing ground wires for all electrical components. Reground wires to different locations. Verify that grounding location is clean, shiny metal free of paint, rust etc.

OR

1. Add secondary ground cable from negative battery terminal to the chassis metal or engine block of vehicle.

OR

1. Have alternator and battery load tested by your mechanic. Verify good working order of vehicle electrical system including distributor, spark plugs, spark plug wires, voltage regulator etc.

© Audio Design GmbH, All Rights Reserved