Pro-Ject Phono Box S3 B Phono Stage

The Pro-Ject Phono Box S3 B is a versatile MM and MC phono stage designed for high-quality vinyl playback, combining extensive cartridge adjustment with Pro-Ject's True Balanced Connection technology. With both conventional RCA and balanced connections, it can be used with a wide range of turntables while also allowing compatible systems to maintain a balanced signal path from the cartridge.

At the heart of the Phono Box S3 B is a fully symmetrical and discrete gain stage with a dual-mono design. Rather than using conventional operational amplifiers in the gain stage, Pro-Ject uses individual electronic components to create a low-noise circuit designed to preserve the delicate signal generated by a phono cartridge. Semi-passive RIAA equalisation provides accurate signal processing across the audible frequency range.

The Phono Box S3 B offers extensive adjustment for both Moving Magnet (MM) and Moving Coil (MC) cartridges. Five impedance settings of 10, 50, 100, 1,000 and 47,000 Ohms, four capacitance settings of 50, 150, 300 and 400pF, and four base gain settings of 40, 45, 60 and 65dB make it possible to optimise the phono stage for a broad selection of cartridges.

For compatible turntables and cartridges, a 5-pin mini-XLR balanced phono input enables Pro-Ject's True Balanced connection system. The Phono Box S3 B also provides a pair of balanced XLR outputs, with XLR operation adding 6dB to the selected gain level. Standard RCA phono input and RCA line-level output connections remain available for conventional turntable and amplifier setups.

A switchable 20Hz subsonic filter with an 18dB/octave slope helps reduce unwanted low-frequency information caused by warped records and other sources. Front-mounted controls make cartridge loading and gain adjustments easy to access, while the steel chassis and aluminium outer panels provide a rigid enclosure designed to help protect the sensitive internal circuitry from interference.

With MM and MC compatibility, adjustable cartridge loading, balanced XLR connectivity and a discrete dual-mono circuit design, the Pro-Ject Phono Box S3 B is a flexible phono preamplifier for vinyl enthusiasts looking to get more performance from their turntable and cartridge.

Specifications

• Product Type – True Balanced MM/MC Phono Stage
• Cartridge Compatibility – Moving Magnet (MM) & Moving Coil (MC)
• Circuit Design – Fully Symmetrical & Discrete
• Channel Design – Dual Mono
• Equalisation – Semi-Passive RIAA
• Input Impedance – 10 / 50 / 100 / 1,000 / 47,000 Ohms
• Input Capacitance – 50 / 150 / 300 / 400pF
• Gain – RCA Output – 40 / 45 / 60 / 65dB
• Gain – XLR Output – 46 / 51 / 66 / 71dB
• Signal-to-Noise Ratio – MM (40dB) – 103dBV / 110dBV A-Weighted
• Signal-to-Noise Ratio – MC (60dB) – 85dBV / 90dBV A-Weighted
• THD at 1kHz – MM – <0.001%
• THD at 1kHz – MC – <0.005%
• THD (20Hz–20kHz) – MM – <0.008%
• THD (20Hz–20kHz) – MC – <0.01%
• RIAA Accuracy – <0.3dB, 20Hz–20kHz
• Subsonic Filter – 20Hz at 18dB/Octave
• Unbalanced Input – 1 × Stereo RCA Phono
• Balanced Input – 1 × 5-Pin Mini-XLR
• Unbalanced Output – 1 × Stereo RCA
• Balanced Output – 1 × Stereo XLR
• Power Supply – 18V / 500mA DC
• Power Consumption – 18V / 170mA DC
• Standby Consumption – <0.5W
• Dimensions (W × H × D) – 206 × 55 × 153mm (164mm including sockets)
• Weight – 0.93kg

Key Features

• Moving Magnet and Moving Coil cartridge compatibility
• Pro-Ject True Balanced Connection technology
• 5-pin mini-XLR balanced phono input
• Balanced stereo XLR outputs
• Standard RCA input and output
• Fully symmetrical discrete gain stage
• Dual-mono circuit design
• Semi-passive RIAA equalisation
• Five selectable impedance settings
• Four selectable capacitance settings
• Four base gain settings
• Additional 6dB gain when using XLR outputs
• Switchable 20Hz subsonic filter
• Front-panel cartridge loading and gain controls
• Steel chassis with aluminium outer panels
• External power supply
• Made in Europe

What's in the Box

• Pro-Ject Phono Box S3 B Phono Stage
• 18V / 500mA DC Power Supply
• Product Documentation

Available Finishes

• Black
• Silver