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Pro-Ject Phono Box S3 B - True Balanced Phono Stage


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The new Pro-Ject Phono Box S3 B phono stage comes in a complete new casework. Due to the bigger case, Pro-Ject were able to bring new features into the S3 phono preamplifier. The new steel & aluminium chassis with full aluminium buttons brings great rigidity and isolation against interferences.

"B" Stands for Balanced

Connect your turntable with the 5-pin mini XLR cable & profit from the balanced signal path. Symmetrical, or balanced, transmissions consist of a hot and a cold (also called + and -) signal. Both signal chains effectively carry the same musical information.

A true balanced gain stage can now extract the final musical information out of the +/- signals and subtract, remove, all noise that could potentially be added along the transmission. As there are two separate signal chains, we also needed two individual amplifier sections.

Not only Balanced, also Discrete

The gain stage of the new Phono Box S3 B uses a fully discrete layout. A discrete circuit is composed of electronic components which are disparate, individual devices. The amplifier section is built out of single components and doesn't use any integrated circuits.

That makes for an extended and more costly design process, but results in the best sound quality.

Semi-Passive EQ

After treating the balanced +/- signals independently they are added back together and are processed by the semi-passive RIAA equalisation stage. By keeping the gain stage fully symmetrical, we can optimise the signal-to-noise ratios and keep interference to a minimum, giving the EQ section the best source to work its magic on.

For the balanced XLR outputs, a balancing stage generates a symmetrical signal, so you benefit from balanced signal transmissions again. The RCA are by nature single-ended and get their signals served directly by the RIAA EQ.

Cartridge Loading Options

Compared to the S2 Line, you are now able to set everything easily on the front plate. You can connect two turntables at the same time. Each input settings are stored in the memory. Large ranges from 40dB up to 65dB are possible. A fully balanced design makes all the difference here.

You can perfectly match it with a wide variety of cartridges and perfectly integrate it into the rest of your HiFi system, matching the volume levels accurately to other sources like CD players or streaming devices.

The loading options for MM and MC are designed so that the widest array of cartridges will work perfectly with the Phono Box S3 B. Ultra low values like 50 pF or 10 ohms allow you to account for special situations, for example sub-ideal higher capacitance cables.

Technical Specifications

  • 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-equalisation 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

Further Information

Pro-Ject Phono Box S3 B - User Manual

Pro-Ject Phono Box S3 B - Product Information


We offer Free Delivery on orders to the UK Mainland over £100.


Our staff are passionate about what they do and can provide advice and assistance on your purchase.


You can return any unwanted and unused item within 30 days and get a full refund.


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The products we use and sell are of the highest quality and we trust them wholeheartedly, but every now and again a product has a fault that is covered under the manufacturers warranty.

In the event of such an occurance please contact us via email at to proceed with the warranty process.

Below is a list of all the Manufacturers warranty timeframes with any special instructions for extended warranties:


  • 1 Year Standard Manufacturers Warranty


  • 5 Years standard Manufacturers Warranty


  • 5 Years with Installation by an Authorised Installer (Studio Incar is an Authorised Installer)
  • 1 Year if you are doing your own Installation
  • 2 Years if you register the product with the UK supplier


  • 2 Years standard Manufacturers warranty


    • 1 Year standard Manufacturers warranty
    • 2 Years if you register the product with the UK supplier


    • 90 Days Standard Manufacturers Warranty
    • 3 Years Extended Warranty - Product Registration within 30 days of Purchase


    • 6 Months standard Manufacturers warranty


    • 1 Year standard Manufacturers warranty

    Chord Company

    • Lifetime Warranty


    • 2 Years on Car Audio Products - No Extendable Warranty
    • 2 Years standard Warranty on Home Audio Products
    • up to 8 Years Extendable Warranty on Home Audio Products when you register at Dynaudio


    • 1 Year Standard Manufacturers Warranty
    • 2 Years Extended Warranty when registered with Focal


    • 2 Years Standard Manufacturers Warranty


    • 1 Year standard Manufacturers warranty
    • 2 Years if you register the product with the UK supplier

    HiFi Rose

    • 2 Years Standard Manufacturers Warranty

    iFi Audio

    • 1 Year Standard Manufacturers Warranty

    JL Audio

    • 1 Year for Speakers and Subwoofers
    • 2 Years for Amplifiers and Processors


    • 3 Years Standard Manufacturers Warranty


    • 1 Year Standard Manufacturers Warranty

    Peachtree Audio

    • 2 Years Standard Manufacturers Warranty
    • 3 Years Extended Warranty if Registered with Peachtree


    • 2 Years Standard Manufacturers Warranty
    • 3 Years Extended Warranty if Registered with Pro-Ject


    • 4 Years for Passive Loudspeakers
    • 1 Year for Active Loudspeakers / Subwoofers
    • 5 Years for Passive Loudspeakers if Registers with Q Acoustics
    • 2 Years for Active Loudspeakers / Subwoofers if Registered with Q Acoustics


    • 1 Year Standard Manufacturer Warranty


    • 1 Year Standard Manufacturer Warranty


    • 2 Years Standard Manufacturers Warranty
    • 3 Years Extended Warranty if registered with Wharfedale
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