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Project Audio S3B Phono Pre-amp

Regular price $589.99

Taxes calculated at checkout.

 order now for jun/jul delivery


The Phono Box S3 B is an entry-level phono preamplifier that offers a fully balanced design in a neat, small package. We’ve packed this tiny chassis to the brim with high-end features. One of those is our new True Balanced Connection. At Pro-Ject, balanced connections were exclusive to our RS range of products until now. The Phono Box S3 B brings those features to an incredible new entry level.

True High-End For the New Entry-Level

Our Phono Box S3 B comes in complete new casework. The bigger size enabled us to bring a completely new feature set that was never seen before in this price range. The new steel & aluminium case also offers very high rigidity and isolation against outside interferences, which is essential for the new technology inside. Connect up to two turntables simultaneously – all parameters for each input get stored in the memory. You can perfectly match the Phono Box S3 B to a wide variety of cartridges. Use the gain setting to accurately match the output to other sources like CD players or streaming devices. Ultra-low values like 50 pF or 10 ohms allow you to account for all situations.

Balanced By Nature

Cartridges are balanced signal transducers by nature! Due to the internal wiring of MM cartridges, you'll need to upgrade your turntable with an MC cartridge to access the entirety of that balanced signal. Together with our new True Balanced Connection cables you'll be able to access high-end features that were previously only available on the most expensive of phono stages. And the best of all: any Pro-Ject turntable with RCA, miniXLR or 5P outputs can do it!


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 optimize 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

Audiofi is your Project Audio S3B dealer, we ship free in Canada