Pro-Ject Phono Box S3 B


Affordable phono stage utilising True Balanced connection



High End Features at an Affordable Price

The Phono Box S3 B is a phono preamplifier that offers a fully balanced design in a neat, small package. Pro-Ject have packed this tiny chassis to the brim with high-end features. One of those is their new True Balanced Connection. When used in combination with a Pro-Ject turntable with a 5-pin balanced output and 5P to XLR cable, you can achieve a totally balanced connection, minimising noise and delivering a breathtaking analogue signal.

Until now, balanced connections were exclusive to the RS range of products. The Phono Box S3 B brings those features to more affordable products.

Fully discrete and symmetrical gain stage

The new Phono Box S3 B gain stage uses a fully discrete layout. A discrete circuit is composed of disparate electronic components, and individual devices. The amplifier section is built of single parts and doesn‘t use any integrated circuits! That makes for an extended and more costly design process but results in the best sound quality. The fully symmetrical gain stage can optimise the signal-to-noise ratios, feeding the semi-passive, RIAA equalisation stage with a clean signal to work on.


  • Input impedance: 10, 50, 100, 1k, 47k ohms
  • Input capacitance: 50, 150, 300, 400 pF
  • Gain (+ 6dB using XLR Out sockets): 40, 45, 60, 65 dB
  • Signal / Noise ratio MM (40dB): 103dBV, 110dBV – ‘A’ weighted
  • Signal / Noise ratio MC (60dB): 85dBV, 90dBV – ‘A’ weighted
  • THD at 1 kHz: <0,001% MM, < 0,005% MC
  • THD (20Hz-20kHz): <0,008% MM, < 0,01% MC
  • RIAA-equalization curve accuracy: <0,3dB / 20Hz – 20kHz
  • Subsonic filter: at 20Hz with 18dB/octave
  • Input: 1x 5-pin mini XLR / 1x pair RCA phono sockets
  • Line-level output: 1x pair RCA, 1x pair XLR
  • Power supply DC: 18V/500mA
  • Power consumption: 18V/170mA DC, <0.5 W in standby
  • Dimensions: 206 x 55 x 153 (164 with sockets) mm (W x H x D)
  • Weight: 930g without power supply

Check out the brochure for more information – Pro-Ject Phono Box S3 B Brochure / Manual




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