1. Introduction
The Pro-Ject Tube Box S2 is a high-quality phono preamplifier designed to enhance the audio signal from your turntable. It features a discrete circuit design without operational amplifiers (OpAmps) and utilizes two ECC83 tubes, which can be interchanged to customize the sound. This unit is compatible with both Moving Magnet (MM) and Moving Coil (MC) cartridges, offering versatile connectivity and sound adjustment options. Its robust aluminum and metal sandwich casing provides effective protection against vibrations and electromagnetic interference, ensuring a clean audio signal.
2. Safety Instructions
- Always connect the power adapter to the unit last.
- Ensure the unit is placed on a stable, level surface to prevent accidental falls.
- Do not expose the unit to moisture, rain, or extreme temperatures.
- Avoid placing the unit near heat sources such as radiators or other heat-producing appliances.
- Disconnect the power adapter from the wall outlet during lightning storms or when unused for extended periods.
- Do not attempt to open or service the unit yourself. Refer all servicing to qualified personnel.
3. Package Contents
Please check that your package contains the following items:
- Pro-Ject Tube Box S2 Phono Preamplifier
- Power Adapter
- User Manual
4. Product Overview
The Tube Box S2 features a compact design with clearly labeled inputs, outputs, and controls.
Front Panel
Image: Front view of the Pro-Ject Tube Box S2. This image displays the unit's front panel with its two prominent vacuum tubes, indicating its tube-based amplification.
- Gain Selector: Adjusts the amplification level for different cartridge types.
- Subsonic Filter Switch: Activates or deactivates the subsonic filter to remove unwanted low-frequency rumble.
Rear Panel
Image: Rear view of the Pro-Ject Tube Box S2. This image highlights the rear connections, including the gold-plated RCA input and output jacks, the ground screw, and the 18V DC power input.
- RCA Inputs (In): Connect your turntable's RCA cables here.
- RCA Outputs (Out): Connect these to your amplifier's line-level input.
- Ground Screw: Connect your turntable's ground wire here to minimize hum.
- 18V DC Power Input: Connect the supplied power adapter.
- Impedance/Capacitance DIP Switches: Located on the underside of the unit, these switches allow fine-tuning of input impedance and capacitance to match your cartridge.
5. Setup
Follow these steps to connect your Tube Box S2 to your audio system:
- Placement: Position the Tube Box S2 on a stable surface, away from strong electromagnetic fields and heat sources.
- Turntable Connection: Connect the RCA output cables from your turntable to the RCA Inputs (In) on the rear of the Tube Box S2.
- Ground Connection: Connect your turntable's ground wire to the Ground Screw on the Tube Box S2.
- Amplifier Connection: Connect the RCA Outputs (Out) of the Tube Box S2 to a line-level input on your amplifier (e.g., AUX, CD, Tuner). Do not connect to your amplifier's Phono input, as this unit is a phono preamplifier itself.
- Power Connection: Connect the supplied 18V DC power adapter to the 18V DC Power Input on the Tube Box S2, then plug the adapter into a wall outlet.
System Integration Example
Image: The Pro-Ject Tube Box S2 shown as part of a complete hi-fi system, illustrating its position between a turntable and an amplifier.
Cartridge Settings (Gain, Impedance, Capacitance)
The Tube Box S2 offers adjustable settings to optimize performance for various MM and MC cartridges. These settings are crucial for achieving the best sound quality.
- Gain: Use the front panel selector to choose the appropriate gain setting for your cartridge. MM cartridges typically require lower gain (e.g., 40dB), while MC cartridges require higher gain (e.g., 60dB). Consult your cartridge's specifications for the recommended gain.
- Impedance & Capacitance: These are adjusted via DIP switches located on the underside of the unit. Refer to your cartridge's specifications for the recommended load impedance and capacitance. For high-output MC cartridges, the fixed 47kOhm setting is often suitable.
6. Operating Instructions
- Power On: Once all connections are secure, plug the power adapter into the wall outlet. The unit will power on automatically.
- Select Input on Amplifier: Choose the corresponding line-level input on your amplifier where the Tube Box S2 is connected.
- Play Record: Start playing a record on your turntable.
- Adjust Volume: Control the overall volume using your amplifier.
- Subsonic Filter: If you experience excessive low-frequency rumble or woofer pumping, activate the subsonic filter using the front panel switch. This helps to remove infrasonic frequencies that can cause distortion.
7. Maintenance
Cleaning
To clean the unit, use a soft, dry cloth. Do not use abrasive cleaners or solvents, as they may damage the finish.
Tube Replacement
The ECC83 tubes in the Tube Box S2 are designed to be interchangeable, allowing for sound customization. If a tube needs replacement due to wear or for sonic experimentation, ensure the unit is powered off and unplugged before carefully removing and inserting new tubes. Handle tubes by their base to avoid damage.
8. Troubleshooting
If you encounter issues, refer to the following common problems and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| No sound | Incorrect connections, power off, wrong amplifier input. | Check all RCA and ground connections. Ensure power adapter is plugged in. Select correct line-level input on amplifier. |
| Humming or buzzing sound | Ground loop, ungrounded turntable, interference. | Ensure turntable ground wire is securely connected to the Tube Box S2. Try moving the unit away from other electronic devices. |
| Distorted or weak sound | Incorrect gain setting, impedance/capacitance mismatch, worn tubes. | Adjust gain to match cartridge. Check DIP switch settings for impedance/capacitance. Consider replacing tubes if they are old. |
| Excessive bass rumble | Infrasonic frequencies from warped records or turntable rumble. | Activate the subsonic filter on the front panel. |
9. Specifications
- Manufacturer: Pro-Ject
- Model: Pro-Ject Tube Box S2
- Number of Channels: 2
- Output Power: 10 Watts
- Maximum Supply Voltage: 18 Volts
- Mounting Type: Surface Mount
- Material: Aluminum/Metal casing
- Components Included: Tube Box S2
- Item Weight: 2.12 pounds (approx. 0.96 kg)
- Country of Origin: Austria
- Compliance: CE
10. Warranty Information
Pro-Ject offers a 25-year spare parts warranty for this product. For specific warranty terms and conditions, please refer to the documentation provided with your purchase or contact your local Pro-Ject dealer. Keep your proof of purchase for warranty claims.
11. Support
For further assistance, technical support, or service inquiries, please contact your authorized Pro-Ject dealer or visit the official Pro-Ject Audio Systems website. You can find contact information and additional resources there.
