1. Introduction
The Pro-Ject Phono Box RS is a high-performance phono preamplifier designed for both Moving Magnet (MM) and Moving Coil (MC) cartridges. It offers extensive adjustability for input impedance, capacitance, and gain, allowing for precise matching with a wide range of cartridges. This manual provides essential information for the proper setup, operation, and maintenance of your Phono Box RS.
2. Safety Instructions
- Always connect the power adapter to the unit last, after all other audio connections have been made.
- Ensure the power supply voltage matches the requirements specified on the unit.
- Do not expose the unit to rain or moisture.
- Avoid placing the unit near heat sources such as radiators, heat registers, stoves, or other heat-producing apparatus.
- Do not block any ventilation openings.
- Disconnect the unit from the power outlet during lightning storms or when unused for long periods.
- Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
3. Package Contents
Please check that your package contains the following items:
- Pro-Ject Phono Box RS unit
- Power supply unit (18V DC)
- User Manual
4. Product Overview
4.1 Front Panel Controls
The front panel of the Phono Box RS features controls for adjusting various parameters to optimize performance with your phono cartridge.
Image: Front view of the Pro-Ject Phono Box RS, highlighting the impedance selector and control switches.
- Power Button: Toggles the unit on and off.
- Impedance Selector: A rotary knob allowing adjustment of input impedance from 10 Ohm to 1,200 Ohm for MC cartridges.
- Mute Switch: Mutes the audio output.
- Gain Switches: Adjusts the input gain (e.g., 40 dB, 50 dB, 60 dB) for both RCA and XLR outputs.
- Equalization Switches: Selects between RIAA and DECCA equalization curves.
- Subsonic Filter Switch: Activates or deactivates the 20 Hz, 12 dB/octave subsonic filter.
4.2 Rear Panel Connections
The rear panel provides all necessary audio input and output connections, along with the power input.
Image: Rear panel connections, including RCA and XLR inputs/outputs.
- Audio Inputs: One stereo RCA input and one stereo XLR input for connecting your turntable.
- Audio Outputs: Stereo RCA and stereo XLR outputs for connecting to your amplifier or receiver.
- Ground Terminal: For connecting the ground wire from your turntable to minimize hum.
- 18V DC Power Input: Connects to the supplied external power supply.
5. Setup
Follow these steps to set up your Pro-Ject Phono Box RS:
- Placement: Place the Phono Box RS on a stable, level surface away from strong electromagnetic fields and heat sources.
- Turntable Connection:
- Connect the RCA or XLR output cables from your turntable to the corresponding input on the Phono Box RS.
- Connect the ground wire from your turntable to the ground terminal on the Phono Box RS.
- Amplifier Connection: Connect the RCA or XLR output from the Phono Box RS to a line-level input (e.g., 'Aux', 'CD', 'Line In') on your amplifier or receiver. Do NOT connect it to another phono input.
- Power Connection: Connect the supplied 18V DC power supply to the '18V DC' input on the rear of the Phono Box RS, then plug the power supply into a wall outlet.
- Initial Settings: Before playing music, ensure the Mute switch is engaged.
6. Operating Instructions
The Phono Box RS offers extensive customization to match your cartridge and listening preferences.
6.1 Cartridge Type Selection (MM/MC)
The Phono Box RS automatically detects the cartridge type based on the impedance and gain settings. For MM cartridges, typically use higher capacitance and lower gain. For MC cartridges, adjust impedance and gain as needed.
6.2 Adjusting Input Impedance (MC Cartridges)
For Moving Coil (MC) cartridges, use the front panel rotary knob to adjust the input impedance. Start with the manufacturer's recommended impedance for your cartridge. Common settings range from 10 Ohm to 1,200 Ohm. Experiment to find the best sound for your system.
6.3 Adjusting Input Capacitance (MM Cartridges)
For Moving Magnet (MM) cartridges, the input capacitance can be adjusted. The unit offers options such as 100pF, 200pF, 300pF, 420pF, 520pF/47k ohm. Refer to your MM cartridge's specifications for the recommended capacitance. The 47k ohm setting is standard for MM cartridges.
6.4 Gain Setting
Use the gain switches to match the output level of your cartridge to your amplifier's input sensitivity. Options typically include 40 dB, 50 dB, and 60 dB. Higher gain is generally used for lower output MC cartridges.
6.5 Equalization Curve
The Phono Box RS supports both RIAA and DECCA equalization curves. RIAA is the standard for most modern records. Select DECCA only if you are playing older records specifically mastered with the DECCA curve.
6.6 Subsonic Filter
Activate the subsonic filter (20 Hz, 12 dB/octave) if you experience excessive low-frequency rumble or woofer pumping, which can be caused by warped records or turntable vibrations. This filter helps to remove inaudible low-frequency noise without affecting the musical content.
7. Maintenance
To ensure the longevity and optimal performance of your Phono Box RS, follow these maintenance guidelines:
- Cleaning: Use a soft, dry cloth to clean the exterior of the unit. Do not use liquid cleaners or solvents, as they may damage the finish.
- Ventilation: Ensure that the ventilation openings are not obstructed to prevent overheating.
- Storage: If storing the unit for an extended period, disconnect it from the power supply and store it in a cool, dry place.
8. Troubleshooting
If you encounter issues with your Phono Box RS, consult the following table before contacting support.
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound | Unit not powered on; Mute engaged; Incorrect connections; Amplifier input not selected. | Check power connection and switch; Disengage Mute; Verify all audio cables are correctly connected; Select correct input on amplifier. |
| Humming or buzzing noise | Ground wire not connected; Ground loop; Nearby electrical interference; Faulty cables. | Ensure turntable ground wire is connected to Phono Box RS; Try different power outlets; Move unit away from other electronics; Replace audio cables. |
| Distorted sound | Incorrect gain setting; Incorrect impedance/capacitance; Damaged cartridge/stylus. | Adjust gain to appropriate level for your cartridge; Verify impedance/capacitance settings match your cartridge; Inspect cartridge and stylus for damage. |
| Sound too quiet or too loud | Incorrect gain setting. | Adjust the gain switches on the front panel to match your cartridge output and amplifier input sensitivity. |
9. Specifications
Technical specifications for the Pro-Ject Phono Box RS:
- Audio Inputs: 1 Stereo RCA, 1 Stereo XLR
- Adjustable Input Impedance: 10 Ohm to 1,200 Ohm
- Input Capacitance Options: 100pF, 200pF, 300pF, 420pF, 520pF/47k ohm
- Fixed Input Impedance: 10 Ohm (for specific configurations)
- Input Gain (with XLR): 40 dB, 50dB (B), 60dB (A)
- Subsonic Filter: 20 Hz, 12 dB/octave
- Power Supply: Dual 18 V/250 mA DC
- Power Usage: 150 mA DC, Less than 1W in Standby
- Dimensions (WHD): 8.1" x 2.9" x 7.9" (206 x 72 x 200 mm)
- Product Weight: 4.4 lb (2 kg)
Internal Components
Image: Internal view of the Phono Box RS circuit board.
10. Warranty and Support
Pro-Ject products are manufactured to the highest standards and undergo strict quality control. In the unlikely event of a defect, please refer to the warranty terms provided with your purchase documentation. For technical support or service inquiries, please contact your authorized Pro-Ject dealer or distributor. Keep your proof of purchase for warranty claims.
