1. Introduction
The G-MARK GPH800 is an ultra-low noise, 8-channel high-power stereo headphone amplifier designed for studio and stage applications. It allows up to eight users to monitor an audio source simultaneously, each with independent volume control. Its robust design ensures high-fidelity analog circuitry, excellent dynamics, and low-distortion sound quality, making it ideal for distributing audio signals to multiple headphones without crosstalk.
2. Safety Information
- Ensure the power adapter used is the included 12V DC 2A adapter to prevent damage and ensure safe operation.
- Do not expose the device to rain or moisture to avoid electric shock.
- Do not open the casing; there are no user-serviceable parts inside. Refer all servicing to qualified personnel.
- Place the unit on a stable, flat surface away from heat sources and direct sunlight.
- Keep out of reach of children.
3. Package Contents
Please check the package for the following items:
- 1 x G-MARK GPH800 Headphone Amplifier
- 1 x 12V DC Power Adapter
4. Product Overview
The GPH800 features a compact and durable design with intuitive controls for easy operation.
Front Panel Controls and Connections:
- VOLUME 1-8 Knobs: Individual volume control for each of the 8 headphone channels.
- MUTE Buttons (1-8): Mute/unmute individual headphone channels.
- PHONES 1-8 Jacks: 3.5mm and 6.35mm (1/4") headphone output jacks for each channel.
- POWER Switch: Turns the unit on or off.
Rear Panel Controls and Connections:
- IN 2 (Stereo Input): Main audio input for the amplifier.
- MONO/ST Switch: Toggles between Mono and Stereo input modes.
- 1-8 MUTE Master Switch: Mutes/unmutes all 8 channels simultaneously.
- POWER INPUT (DC 12V): Connection for the included 12V DC power adapter.
5. Setup Instructions
- Power Connection: Connect the included 12V DC power adapter to the POWER INPUT jack on the rear panel of the GPH800. Plug the adapter into a suitable power outlet.
- Audio Input: Connect your audio source (e.g., mixer, audio interface, computer) to the IN 2 (Stereo Input) on the rear panel using a 1/4" TS or TRS cable.
- Mode Selection: Set the MONO/ST switch on the rear panel according to your audio source. Use 'ST' for stereo signals and 'MONO' for mono signals.
- Headphone Connection: Plug your headphones into any of the PHONES 1-8 output jacks on the front panel. The amplifier supports both 3.5mm and 6.35mm (1/4") headphone plugs without requiring adapters.
6. Operating Instructions
- Power On: Flip the POWER switch on the front panel to the 'ON' position. The power indicator light will illuminate.
- Master Mute (Optional): If you wish to mute all channels, use the 1-8 MUTE master switch on the rear panel.
- Individual Channel Mute: For each connected headphone, you can mute or unmute its output using the corresponding MUTE button on the front panel.
- Volume Adjustment: Adjust the VOLUME knob for each channel (VOLUME 1-8) to set the desired listening level for the connected headphones. Start with the volume low and gradually increase it to a comfortable level.
- Stereo/Mono Switching: If your audio source changes or you need to switch between stereo and mono monitoring, use the MONO/ST switch on the rear panel.
7. Maintenance
- Cleaning: Use a soft, dry cloth to clean the exterior of the unit. Do not use liquid cleaners or aerosols.
- Storage: When not in use for extended periods, disconnect the power adapter and store the unit in a cool, dry place.
- Ventilation: Ensure proper ventilation around the unit to prevent overheating. Do not block any ventilation openings.
8. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No power | Power adapter not connected or faulty; power switch off. | Ensure power adapter is securely connected and plugged into a live outlet. Check power switch is ON. |
| No sound from headphones | Headphones not connected properly; channel volume too low; channel muted; master mute engaged; audio source issue. | Check headphone connections. Increase individual channel volume. Ensure individual channel mute button is off. Check master mute switch. Verify audio source is playing and connected correctly. |
| Distorted sound | Input signal too high; headphone volume too high; faulty cable. | Reduce input signal level from the source. Lower individual headphone volume. Try a different audio input cable. |
| Sound only in one ear (mono source) | Stereo/Mono switch set to 'ST' for a mono input. | Set the MONO/ST switch to 'MONO'. |
9. Specifications
| Feature | Specification |
|---|---|
| Product Type | 8-channel headphone power amplifier |
| Model Number | GPH800 |
| Brand Name | G-MARK |
| Power Source | DC 12V 2A (External Adapter) |
| Built-in Battery | No |
| Inbox Adaptor | Yes |
| Output Interface | 3.5mm + 6.35mm (1/4") |
| Headphone Adapter Impedance | 16-600Ω |
| Input Signal Level | +22dB |
| Output Impedance | 47Ω |
| Maximum Gain | 20dB |
| Signal-To-Noise Ratio | >98dB |
| Output Power (per channel) | 16Ω/150mW*2, 32Ω/340mW*2, 64Ω/470mW*2, 150Ω/300mW*2, 300Ω/170mW*2, 600Ω/100mW*2 |
| Product Dimensions (L x W x H) | 280mm x 78mm x 25mm (11.02 x 3.07 x 0.98 inches) |
| Product Weight | Approx. 0.45 kg (0.99 lbs) |
| Package Weight | 0.859 kg (1.89 lbs) |
| Package Dimensions (L x W x H) | 32cm x 13cm x 10cm (12.6 x 5.1 x 3.9 inches) |
| Certification | CE, FCC, RoHS, WEEE |
10. User Tips
No specific user tips were available from reviews or Q&A at the time of manual creation. However, general best practices for audio equipment include:
- Always connect and disconnect cables when the unit is powered off to prevent pops or damage.
- Start with low volume settings on both the source and the amplifier, then gradually increase to avoid sudden loud sounds.
- Use high-quality audio cables for optimal sound transmission and to minimize noise.
11. Warranty and Support
For warranty information, technical support, or service inquiries, please contact the seller or manufacturer directly. Keep your purchase receipt as proof of purchase.