GPX750.1D - Receiver Crunch - Free user manual and instructions

Product type	Class D Monoblock Amplifier
Brand	Crunch
Model	GPX750.1D
RMS Output Power	1 x 200 W @ 4 Ω, 1 x 300 W @ 2 Ω, 1 x 375 W @ 1 Ω
Max Output Power	1 x 400 W @ 4 Ω, 1 x 600 W @ 2 Ω, 1 x 750 W @ 1 Ω
Speaker Impedance	1 – 8 Ω
Frequency Response	4 – 150 Hz (-3 dB)
Total Harmonic Distortion	< 0.02 % (80 Hz)
Signal-to-Noise Ratio	> 114 dB
Input Sensitivity	HI LEVEL: 1 – 10 V, INPUT: 0.1 – 3 V
Input Impedance	20 kΩ
Low Pass Filter	40 – 150 Hz @ 12 dB/octave
Sub Sonic Filter	10 – 35 Hz @ 12 dB/octave
Bass Boost	0 – 12 dB @ 40 Hz
Phase Shift	0 – 180°
High Level Inputs	Yes, via included cable connector
Auto Turn-on Function	Yes, via high level inputs
Power Supply	+12 V (9 – 15 V), negative ground
Fuse	2 x 30 A
Dimensions (W x H x D)	254 x 46 x 205 mm
Protection	Short circuit, overheating, undervoltage

Frequently Asked Questions - GPX750.1D Crunch

How to connect the amplifier?

Before installation, disconnect the negative battery terminal. First connect the amplifier's GND terminal to the vehicle chassis (clean the surface). Connect the +12 V terminal to the battery via an inline fuse (within 30 cm of the battery). Then, connect the REM terminal to the remote output of your head unit. Finally, connect the audio cables (RCA or high level) and speakers respecting the impedance.

What minimum speaker impedance?

The total impedance must not be lower than 1 ohm. Using a lower impedance can damage the amplifier and void the warranty.

How to adjust the low pass filter?

Use the LOW PASS potentiometer (Fig. 1,4) to adjust the cutoff frequency between 40 and 150 Hz. This sends only low frequencies to the subwoofer.

The protection LED turns red, what to do?

A red LED indicates a short circuit, overheating, or too low impedance. Check speaker connections, amplifier ventilation, and impedance. Let the device cool down before restarting.

How to use auto turn-on?

Auto turn-on works via the high level inputs (HI LEVEL). The amplifier detects a voltage of 6 V on these inputs when the source is turned on. In this case, the REM connection is not necessary. Note: this works with most modern sources.

Can I connect two subwoofers?

Yes, in a 1 channel mono / 2 subwoofers configuration (Fig. 4). Connect one subwoofer to the amplifier's positive and negative terminals, and the second in parallel or series depending on desired impedance. Ensure the final impedance remains between 1 and 8 Ω.

How to adjust the input level?

Set your head unit to half volume, then turn the LEVEL INPUT potentiometer (Fig. 1,7) until you achieve a moderate sound level. This optimizes the signal-to-noise ratio.

What to do in case of engine noise in the sound?

Keep audio cables (RCA) away from power cables. Check ground connections: they must be clean and solid. You can add a second ground wire between the battery and chassis. If noise persists, test without other devices between the source and amplifier.

Where to install the amplifier in the car?

Choose a dry, ventilated, and vibration-protected location. Do not install it in an enclosed space (like the spare tire well). The trunk is ideal. Make sure the cooling channels are not obstructed.

What type of power cable to use?

Use a cable with sufficient gauge for the length (see the table on page 31 of the manual). Generally, a 4 mm² or larger cable is recommended to handle the fuse current (2 x 30 A). The REM cable can be 0.5 mm².

USER MANUAL GPX750.1D Crunch

Exterior view of a black CRUNCH 750 watt power supply unit with attached electrical connector (no readable text beyond branding)

GPX750.1D

MONO CLASS D SUBWOOFER AMPLIFIER

BEDIENUNGSANLEITUNG

USER'S MANUAL

MODE D'EMPLOI

MANUALE D'USO

MANUAL DE USO

INHALTSVERZEICHNIS TABLE OF CONTENT TABLE DES MATIÈRES SOMMARIO INDICE

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

SPECIFICATIONS	GPX750.1D
Output Power RMS	1 x 200 W @ 4 Ohms1 x 300 W @ 2 Ohms1 x 375 W @ 1 Ohm
Output Power Max	1 x 400 W @ 4 Ohms1 x 600 W @ 2 Ohms1 x 750 W @ 1 Ohm
Loudspeaker impedance	1 – 8 Ohm
Frequency Response	4 – 150 Hz (-3 dB)
Total Harmonic Distortion	< 0,02 % (80 Hz)
Signal-to-Noise Ratio	> 114 dB
Input Sensitivity	HI LEVEL: 1 – 10 VINPUT: 0,1 – 3 V
Input Impedance	20 kOhm
Lowpass Filter	40 – 150 Hz @ 12 dB/Octave
Subsonic Filter	10 – 35 Hz @ 12 dB/Octave
Bass Boost	0 – 12 dB @ 40 Hz
Phase Shift	0 – 180°
High LEVEL INPUTs	Via enclosed Cable Jack
Auto Turn On	Only via High Level Inputs
Operating Voltage	+12 V (9 – 15 V), negative ground
Fuse Rating	2 x 30 A
Dimensions (B x H x L)	254 x 46 x 205 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.

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 sufficient cable cross section (see page 31, fig. 6) 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 (see page 31, fig. 6) including an in-line fuse. This fuse should be located very close to the battery; for safety reasons not more than 30 cm away.

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 CONNECTION

• The total impedance must not be lower than 1 ohm.
• 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 head unit and the RCA inputs of the amplifier (Fig. 1,8), 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.

HIGH LEVEL INPUTS & AUTO TURN ON

The high level inputs under HI LEVEL INPUT (Fig. 5) are suitable to connect the device input with speaker wires, if your head unit is not equipped with pre-amplifier RCA outputs. Extend therefore every regarding speaker cable from your head unit with appropriate speaker cables from your car audio retailer to the mounting location of the amplifier. Then connect the each matching loudspeaker cable with the cables of the included HI LEVEL INPUT connector.

CAUTION: Never use the high level inputs and the RCA inputs at the same time. This may damage the device seriously.

The amplifier detects a voltage rise (6 Volts) with a so called "DC Offset" over the connected input signal on the high level inputs under HI LEVEL INPUT (Fig. 5) when the head unit will be switched on. Hence, the amplifier will also be turned on. As soon as the head unit will be turned off, the amplifier turns also automatically off. In this case the turn-on connection REM (Fig. 2,2) is not needed.

NOTE: The Auto Turn On function usually works with 90% of all head units, because they are equipped with "High Power"-outputs. Only with a few older and head units the Auto Turn On function is not working.

INPUT SENSITIVITY

Turn the LEVEL INPUT (Fig. 1,7) controller of the amplifier to the MIN position. Then turn the volume controller of the head unit to 80 - 90% of its full setting. Now turn LEVEL INPUT clockwise until you hear some distortion. Then turn back the LEVEL INPUT slightly until you hear a cleaner sound.

VARIABLE SUBSONIC FILTER

With the SUB SONIC controller (Fig. 1,5) you can adjust the lower crossover frequency, to filter the very low frequencies to relieve the subwoofer or to generate a bandpass signal. If you don't want to use this function, turn the controller (Fig. 1,5) to the very left to the 10Hz position.

VARIABLE LOW PASS FILTER

Set the desired crossover frequency by using the controller LOW PASS (Fig. 1,4). Thus to that only the frequencies below the chosen crossover frequency will be amplified and the subwoofer plays more precisely and efficient.

VARIABLE BASS BOOST

By using the BASS BOOST controller (Fig. 1,3) you are able to increase the bass enhancement from 0 to 12 dB. ATTENTION: Use the BASS BOOST wisely!

The PHASE SHIFT controller (Fig. 1,6) allows to adjust the phase between 0^ and 180^ to match the output signal with the vehicle's interior acoustic.

With the included bass level cable remote controller you are able to adjust the bass level e.g. out of the driver's seat. Connect the remote controller and the REMOTE connector (Fig. 1,2) with the enclosed cable.

FIGURES (P. 28-31)

CONNECTIONS AND CONTROLLERS (FIG. 1)

(1) Power-/Protection-LED
(2) Connector for the included bass level remote controller
(3) LOW PASS controller
(4) BASS BOOST controller
(5) SUB SONIC controller
(6) PHASE SHIFT controller
(7) LEVEL INPUT controller
(8) LINE INPUT L/R

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) Inline Fuse (not included in the scope of delivery)
(6) Turn on wire from the head unit or the electrical antenna
(7) Fuses

1-CHANNEL OPERATION MONO / 1 x SUBWOOFER (FIG. 3)

If you want to run the amplifier with the 2 line output channels from the head unit to drive a subwoofer, connect the following setup:

(1) Bass level remote controller
(2) To the head unit, line output left or subwoofer output
(3) To the head unit, line output right or subwoofer output
(4) Subwoofer (1 - 8 Ω)

1-CHANNEL OPERATION MONO / 2 x SUBWOOFERS (FIG. 4)

If you want to run the amplifier with the 2 line output channels from the head unit to drive two subwoofers, connect the following setup:

(1) Bass level remote controller
(2) To the head unit, line output rear left or subwoofer output
(3) To the head unit, line output rear right or subwoofer output
(4) Subwoofer 1 (2 - 8 Ω)
(5) Subwoofer 2 (2 - 8 Ω)

IMPORTANT!

Always observe the correct polarity of all connections!

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 respective 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.

TROUBLESHOOTING

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

Procedure 1:

Check Amplifier for proper connections.

Verify that POWER/PROTECTION LED lights up green. If this is the 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 PROTECT lights up red, this 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.

CONTROLLO REMOTO DAL LIVELLO DEI BASSI

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