Pro-Ject Phono Box S3 B Phonostage
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Pro-Ject Phono Box S3 B PhonostagePro-Ject Phono Box S3 B PhonostagePro-Ject Phono Box S3 B PhonostagePro-Ject Phono Box S3 B Phonostage

Pro-Ject Phono Box S3 B Phonostage

  (1 Review)

True Balanced Connections

£290.83 Exc. VAT |  |

Pro-Ject Phono Box S3 B MC Phonostage

The Phono Box S3 B is a compact, affordable moving magnet and moving coil phono stage with dual-mono layout, discrete circuitry and balanced inputs and outputs. With its spacious, minimalist design layout, it is easily customisable to suit any connected cartridge, and offers unrivalled value for money and performance when connected to any matching analogue hi-fi system.

The Pro-Ject design team took the decision to employ fully symmetrical and discrete circuitry in the gain stage of the Phono Box S3 B. Discrete circuits involve no operational amplifiers (op-amps), and the result is a more neutral, natural, dynamic, and vivid sound. They are more complicated to put together and involve a greater variety of components, but the result when utilised in a well-organised electrical layout is a true high-end sound.

The Phono Box S3 B is extensively customisable so suit the moving magnet or moving coil cartridge it is connected to. With five Impedance (Ω), four Capacitance (pF) and four Gain options on offer, there are very few cartridges this box of tricks cannot accommodate.

As the Phono Box S3 B is equipped with both balanced inputs and outputs, it is also part of Pro-Ject’s True Balanced Connections concept. By connecting to a turntable with a moving coil cartridge and using one of Pro-Ject’s balanced connection cables, your analogue system can benefit from increased dynamics, less noise and improved signal-to-noise ratios. Going true balanced is like hearing parts of your music that were not there before.

This requires engineering that has never been seen at this price point and opens up iconic mid-level turntables, such as the Debut Pro, to the benefits of True Balanced Connections.

Elsewhere in the Phono Box S3 B design, the semi-passive RIAA equalisation stage is optimised for absolute accuracy and signal integrity. Depending on the outputs you are using, this stage is then either directly fed to the output stage (when using RCA outputs) or is connected to a balancing stage for onward balanced connections.

The Phono Box S3 B is finished in a steel chassis, covered by silver or black aluminium panels, for extreme rigidity and good electrical isolation. The neat minimalist aesthetic allows for good spacing between controls on the front panel and connections on the back panel, despite its smaller size. It also features an external power adapter, to keep the sensitive internal signals free from any interferences.

True Balanced Connections

The interconnect cable between a record player and a phono stage is prone to pick up noise on the way. That noise and interference can stem from a lot of unavoidable sources, such as household applicances, wi-fi and bluetooth devices, other power cables and audio amplifiers. Unshielded (i.e. RCA) interconnects can amplify the picked-up noise and make it audible through your speakers, interfering with the pure musical signal.

Balanced (typically XLR) cable connections double the wires carrying the musical signal – with one side inverted. In this case noise still gets picked up by both wires, but with one side reversed. When the signals are re-joined at the phono stage, the picked-up noise is cancelled out by the opposing signals. The benefit of this is a louder, cleaner musical signal that has doubled in size with almost no remaining noise.

Key Features:

  •     NEW 5-pin mini XLR balanced input
  •     NEW balanced XLR outputs
  •     NEW fully symmetrical & discrete gain stage
  •     NEW easy settings adjustment on the faceplate
  •     MM & MC capable
  •     Dual mono design
  •     Semi-passive RIAA equalization
  •     Superior low noise / low distortion
  •     Aluminium casing protects against interference
  •     Available in silver or black
  •     Made in Europe

Input impedance:

10, 50, 100, 1k, 47k ohms

Input capacitance:

50, 150, 300, 400 pF

Gain (+ 6dB using XLR Out):

40, 45, 60, 65 dB

SNR MM (40dB):

103dBV, 110dBV - ‚A‘ weighted

SNR 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


1x 5-pin mini XLR / 1x pair RCA phono sockets

Line-level output:

1x pair RCA, 1x pair XLR

Power supply DC:


Power consumption:

18V/170mA DC, <0.5 W in standby


206 x 55 x 153 (164 with sockets) mm


930g without power supply

Average Rating (1 Review):  
Write a Review and share your opinions!

Stunning phono stage
14 August 2022  | 

I bought this after reading Ken Kessler's review in Septembers hi-fi news. Its to replace my aging Cambridge Azur 640p I use on my vintage Pioneer PL12D turntable fitted with an AT VM95SH cartridge (over kill, maybe) Once hooked up it was very apparent from the start this was something special. It was like removing ear plugs and hearing the music as it should be. Everything sounds right, base is deep and controlled, midrange is spacious and engaging and treble is sweet and detailed without being foreword or harsh. It was wired single ended from the PL12 D and balanced XLR to the pre amp. After 4 or so hours of listening I decided to experiment and swap it with my Musical Fidelity MX-VYNL fitted to my Gyrodec SE with SME IV and Ortofon cadenza black cartridge and in fully balanced mode. This is when I got the shock of my life, wow the S3 B wipes the floor with the MX-VYNL. It really does, It makes the MX-VYNL sound flat and dull by comparison. I could not believe what I was hearing, I was honestly taken aback at what I was listening to, and at half the price of the MX-VYNL The S3 B has to be the best phono stage this side of a grand. So much so I decided to leave the S3 B connected to my Gyrodec and let it run in for a good few days and I can only imagine it will get even better, and it'll probably stay there as its that good. The range of adjustments on the S3 B are spot on and the subsonic filter is handy to have. Swapping between XLR and RCA operation is easy as the switch is on the front. The only down side is that it does not have a mono button but I can live with that. This is an excellent and affordable balanced phono stage.

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