1. Introduction
The Fosi Audio PH04 is a compact 4-channel stereo headphone amplifier designed for studio and stage applications. It allows up to four individuals to monitor a single audio source simultaneously, each with independent volume control. This device is compatible with both 3.5mm and 6.35mm headphones (with an adapter for 6.35mm). Its robust design and high-quality components ensure clear audio performance even at high volume levels.
2. What's in the Box
- Fosi Audio PH04 Headphone Amplifier x1
- 12V DC Power Adapter x1
- User Manual x1
3. Product Overview
The Fosi Audio PH04 features a durable metal enclosure and a straightforward design for ease of use. It includes a power switch and individual volume controls for each of its four channels.
Front and Rear Panel Layout
The front panel houses the power button, power indicator LED, and four independent volume control knobs for channels 1 through 4. The rear panel includes the audio input and four headphone output jacks, along with the DC 12V power input.
The PH04 is designed with a 3.5mm headphone output, eliminating the need for a 6.35mm to 3.5mm adapter for most common headphones. It also includes a dedicated power switch for convenient operation.
Compact and Durable Design
The amplifier features an ultra-compact design, making it suitable for various setups without occupying much space. Its heavy-duty metal enclosure ensures durability and protection for the internal components.
4. Setup Instructions
- Connect Power: Plug the provided 12V DC power adapter into the DC 12V input jack on the rear panel of the PH04. Connect the adapter to a power outlet.
- Connect Audio Source: Connect your audio source (e.g., mixer, computer, audio interface) to the 3.5mm INPUT jack on the rear panel using an appropriate audio cable.
- Connect Headphones: Plug your headphones into any of the four 3.5mm HEADPHONE JACK outputs on the rear panel. If using 6.35mm headphones, ensure you have a compatible 3.5mm to 6.35mm adapter.
- Power On: Press the POWER button on the front panel. The power indicator LED will illuminate, indicating the unit is active.
Visual Setup Guide
5. Operating Instructions
- Adjust Master Volume (Source): Ensure the volume level from your audio source is set appropriately, typically at a moderate level to avoid clipping.
- Individual Channel Volume Control: Each of the four headphone outputs has an independent volume control knob (CH 1, CH 2, CH 3, CH 4) on the front panel. Rotate the corresponding knob clockwise to increase the volume for that specific headphone channel, and counter-clockwise to decrease it.
- Monitoring: Connect your headphones and adjust the individual channel volume to your desired listening level. The PH04 maintains high sonic quality across all channels.
Operation Demonstration
6. Maintenance
- Cleaning: Use a soft, dry cloth to clean the exterior of the unit. Avoid using harsh chemicals or abrasive materials.
- Storage: When not in use for extended periods, store the amplifier in a cool, dry place away from direct sunlight and extreme temperatures.
- Cable Management: Ensure all cables are connected securely and are not under undue strain. Avoid bending cables sharply.
- Ventilation: Do not block the ventilation openings (if any) on the unit to prevent overheating.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound from headphones |
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| Distortion or poor sound quality |
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| Only one channel has sound |
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| Humming or buzzing noise |
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8. Specifications
- Brand: Fosi Audio
- Model Number: PH04
- Input: 3.5mm Stereo Audio
- Outputs: 4 x 3.5mm Headphone Jacks
- Power Supply: 12V DC (included)
- Enclosure Material: Metal
- Item Weight: 0.38 Pounds
- Compatible Devices: Headphones
- Connectivity Technology: Wired
9. Warranty & Support
Warranty Information
The Fosi Audio PH04 comes with an 18-month manufacturer warranty. Please retain your proof of purchase for warranty claims.
Customer Support
For technical assistance, troubleshooting, or warranty inquiries, please contact Fosi Audio customer support through their official website or the retailer where the product was purchased. Refer to the contact information provided in your product packaging or on the Fosi Audio website.
