Pro-Ject Tube Box S3 B – Balanced Tube Phono Preamplifier (MM/MC)

The Pro-Ject Tube Box S3 B is a high-performance phono preamplifier that brings true tube warmth and balanced connectivity to vinyl playback. With replaceable ECC83 tubes, a fully discrete gain stage, and flexible loading options for MM and MC cartridges, it is designed to satisfy both audiophiles and everyday vinyl enthusiasts.

B-Stock unit: This is an open-box / customer-returned unit. It has been inspected and tested by Soundium and is fully functional — the same Tube Box S3 B (Black) at a reduced price. Only one unit available.

Key Features

• Balanced design: 5-pin mini XLR balanced input and balanced XLR outputs for superior channel separation and noise rejection.
• Fully discrete gain stage: Symmetrical circuitry ensures clean, transparent amplification without op-amps.
• Replaceable tube stage: Uses two ECC83 (12AX7) tubes, giving you the option to roll tubes for sonic tailoring.
• Front-panel controls: Easy gain, impedance, capacitance, and subsonic filter adjustments accessible from the faceplate.
• RIAA precision: Semi-passive equalization with accuracy within ±0.4 dB from 20 Hz–20 kHz.
• Premium construction: Rigid aluminium chassis shields the delicate circuitry from electromagnetic interference.

Customer Benefits

The Tube Box S3 B gives vinyl lovers the flexibility of both RCA and balanced connections, letting you integrate it into a wide range of hi-fi setups. Its discrete dual-mono tube design ensures musical warmth, refined clarity, and low noise, while the adjustable settings let you match it precisely to your cartridge. Compact, elegant, and powerful, it’s an ideal upgrade for serious analog playback.

Quick Specs

• Tubes: 2 × ECC83 (12AX7)
• Input Impedance: 10, 50, 100, 1k, 47k Ω
• Input Capacitance: 50, 150, 300, 400 pF
• Gain: 40, 45, 60, 65 dB (+6 dB with XLR out)
• SNR (MM): 97 dBV (40 dB), 105 dBV A-weighted
• SNR (MC): 83 dBV (60 dB), 88 dBV A-weighted
• THD @ 1 kHz: <0.005% (MM), <0.01% (MC)
• THD (20 Hz–20 kHz): <0.1% (MM), <0.03% (MC)
• RIAA Accuracy: ±0.4 dB (20 Hz–20 kHz)
• Subsonic Filter: 20 Hz, 18 dB/octave
• Inputs: 1 × 5-pin mini XLR, 1 × pair RCA
• Outputs: 1 × pair RCA, 1 × pair XLR
• Power Supply: 18 V / 1000 mA DC
• Power Consumption: 18 V / 800 mA (operating), <0.5 W (standby)
• Dimensions (W × H × D): 20.6 × 8.1 × 15.3 cm (16.4 cm with sockets)
• Weight: 1.01 kg (without PSU)

What’s in the Box

• Pro-Ject Tube Box S3 B preamplifier (B-Stock)
• External 18 V / 1000 mA DC power supply
• User manual

Use Cases / Ideal For

Perfect for vinyl enthusiasts who want to experience tube warmth with the flexibility of balanced outputs. Ideal for medium to high-end hi-fi systems where noise rejection, cartridge matching, and musicality are priorities.

Compatibility

Supports both moving magnet (MM) and moving coil (MC) cartridges. Connects easily with integrated amplifiers, stereo receivers, or dedicated preamps via RCA or XLR. Compact enough to suit desktops or hi-fi racks.

Pros & Cons

✅ Pros:

• Balanced inputs and outputs for noise-free performance
• Front-panel adjustment makes setup easy
• Replaceable tubes allow for sound customization
• Compact yet feature-rich design

⚠️ Cons:

• Requires external PSU
• RCA and XLR limited to line-level (no digital output)

The Pro-Ject Tube Box S3 B is a refined step into balanced tube phono amplification—compact, versatile, and sonically engaging, it brings your vinyl collection to life with Soundium.