Pro-Ject Power Box S3 PHONO silver

Two power supplies to replace, two wall wart adapters cluttering the countertop, two potential sources of electrical noise: the observation is the same for any vinyl setup made up of a turntable and a separate phono preamplifier. Pro-Ject’s Power Box S3 Phono combines the power supply for these two components into a single compact unit, with careful DC filtering and low-noise linear regulation.

A remote power supply, two dedicated outputs

The principle behind the Power Box S3 Phono is based on a simple idea: move the power supply away from sensitive audio circuits. By relocating the power source outside the turntable and phono preamplifier, electromagnetic interference that can affect the signal is reduced, especially the very low-level signals produced by a phono cartridge.

The unit provides two distinct voltages on two separate outputs: 15 V for the turntable and 18 V for the phono preamplifier, each regulated to ±0.5%. The maximum output current is 1000 mA, combined across both outputs. This fixed distribution matches the power standards of the relevant Pro-Ject ranges, which avoids any connection errors (the supplied cables are marked at both ends).

Careful DC filtering for a cleaner signal

The linear regulation used in the Power Box S3 Phono produces a more stable and cleaner direct current than the switching power supplies generally supplied with devices. The filtering circuit relies on low-ESR capacitors (low equivalent series resistance), which reduce residual ripple on the power lines.

In practice, the benefits are seen on two levels. On the turntable side, a more stable motor power supply promotes better rotational consistency, which limits micro speed variations (wow and flutter). On the phono preamplifier side, cleaner current lowers the noise floor of the amplification circuit, resulting in a quieter background and better intelligibility of fine details in the musical signal.

Compact aluminum construction

The enclosure measures 103 x 37 x 106 mm (W x H x D) and weighs 370 g excluding the power supply. The rigid aluminum chassis contributes to shielding against external interference. Two finishes are available, black or silver, to visually match the Pro-Ject ranges. A front-panel switch controls power on, and two LED indicators show the effective connection of each device (turntable and phono preamplifier).

The external power adapter (18 V / 1000 mA) connects to the rear of the Power Box S3 Phono. Two 42 cm power cables are included to connect the turntable and preamplifier. The original power supplies of the connected devices are then no longer needed: you go from two wall adapters to just one, which simplifies cabling behind the hi-fi cabinet.

Compatibility with Pro-Ject ranges

The Power Box S3 Phono is compatible with all Pro-Ject Phono Box preamplifiers powered at 18 V. The list is broad: Phono Box E, Phono Box S2, Phono Box S3 B, Phono Box DS2, Phono Box S2 Ultra, Phono Box ultra 500, Tube Box S2, Tube Box DS2, and many other models in the range.

On the turntable side, all Pro-Ject models powered by 15 V DC are supported, covering the Debut, Essential, Primary, E Line, T Line, Automat, Elemental, The Classic, S-Shape ranges, as well as the RPM and X Line series with the following restrictions.

The Power Box S3 Phono is not compatible with the X8, Xtension 9, Xtension 10, Xtension 12, RPM 9, RPM 10, Signature 10 and Signature 12 models. These turntables, positioned higher up in the Pro-Ject range, have current or voltage requirements that the S3 Phono does not cover. For these models, Pro-Ject recommends the Power Box RS2 Phono or the Power Box RS Uni TT, two higher-end linear power supplies equipped with an integrated toroidal transformer and capable of delivering higher current.

Technical specifications

Overview

• Type: filtered external power supply for turntable and phono preamp
• Function: dual-output power supply dedicated to a complete analog system
• Manufacturing: Europe
• Finish: black or silver

Electrical performance

• Regulation: low-noise linear voltage
• Filtering: high-performance DC circuit with Low ESR capacitors
• Interference reduction: remote power supply limiting electrical disturbances and audio signal pollution

Power supply and outputs

• Input power supply: 18 V / 1000 mA
• Outputs:
  • 1 x 15 V ±0.5%
  • 1 x 18 V ±0.5%
• Maximum output current: 1000 mA combined across both outputs
• Connectivity: dual power supply for turntable and phono preamp

Construction

• Chassis: rigid anti-interference aluminum
• Dimensions (W x H x D): 103 x 37 x 106 mm
• Weight: 370 g (excluding power supply)

Compatibility

• Compatible with:
  • all Pro-Ject 18 V Phono Box units
  • compatible Pro-Ject 15 V DC turntables
• Not compatible with:
  • X8
  • Xtension 9 / 10 / 12
  • RPM 9 / 10
  • Signature 10 / 12
• For these models, Pro-Ject recommends dedicated RS power supplies

Box contents

• Power Box S3 Phono
• Power supply unit
• 42 cm power cables for turntable and phono preamp
• User manual