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Pro-Ject Phono Box S3 B – S Series Balanced Audiophile Phono Preamplifier

The new Pro-Ject Phono Box S3 B can justifiably be called a small sensation, because for the first time Pro-Ject Audio Systems presents a phono preamplifier of the Pro-Ject Box Design S3 Series, which has a so-called dual-mono construction as well as a symmetrically designed output stage. With this solution, vinyl lovers get a phono preamplifier at a particularly attractive price that allows for a completely symmetrical set-up with the corresponding turntables and thus guarantees the best possible results.

Pro-Ject Phono Box S3 B – A lot of features at a low price

The Pro-Ject Box Design S Series has always been regarded as the product line of electronic components from Pro-Ject Audio Systems, which completely correspond to the philosophy followed by Pro-Ject Audio Systems from the very beginning, according to which solutions are developed which deliver the best possible results at the smallest possible price, in order to be able to inspire a particularly broad customer base with hi-fi and thus listening at a high level.

The new Pro-Ject Phono Box S3 B is a prime example of this, because, as already described, it offers features for which you had to pay much more in the past.

Dual Mono Construction and Balanced Output Stage

The focus of the new Pro-Ject Phono Box S3 B is to serve as an optimal tool for record players and to guarantee the best possible quality in signal processing. For this purpose, the developers used a so-called dual mono construction, and even more, the output stages are designed symmetrically.

In addition to the usual input in this class in the form of a pair of cinch sockets, the new Pro-Ject Phono Box S3 B also offers a so-called 5-pin mini XLR connection, thus making it possible to connect drives symmetrically.

On the output side, there are not only RCA sockets for an unbalanced connection, but also XLR sockets for a balanced connection to amplifier systems.

The Pro-Ject Phono Box S3 B is the first balanced phono preamplifier in this price range. The manufacturer himself speaks of a True Balanced Connection.

What are the benefits of a balanced phono preamplifier?

If you connect a record player to a phono preamplifier with a balanced connection, such as an XLR cable or a 5-pin mini-XLR cable, you benefit from a completely balanced signal path. Balanced transmissions consist of a “hot” and a “cold” signal, also known as + and -. Both signal chains effectively carry the same musical information.

A balanced amplification stage can now extract the musical information from the +/- signals and remove any noise that may have been added by interference of any kind during the transmission. Since there are two separate signal chains, you also need two individual amplifier sections to benefit from these advantages. All in all, this results in a reproduction with particularly low noise, lowest distortion and highest detail and dynamics, and thus an accurate reproduction of vinyl.

Discreet construction

The Pro-Ject Phono Box S3 B has a discrete construction, i.e. integrated circuits are deliberately omitted. This, of course, requires more effort, but, according to Pro-Ject Audio Systems, results in the best sound quality.

Pro Ject Phono Box S3 B 06Pro Ject Phono Box S3 B 05
Foto © Pro-Ject Audio Systems | Pro-Ject Phono Box S3 B

Semi-passive equaliser

After the balanced signal transmission, the signals are added together in the Pro-Ject Phono Box S3 B and processed by the semi-passive RIAA equalisation stage. By keeping the gain stage completely balanced, the signal-to-noise ratio can be optimised and interference kept to a minimum, according to the manufacturer. For the balanced XLR outputs, a balancing stage generates a balanced signal, so that one again benefits from balanced signal transmissions. The RCA connectors, on the other hand, are single-ended and receive their signals directly from the RIAA EQ.

Particularly flexible adaptation to different pick-up systems

Another unique feature of the new Pro-Ject Phono Box S3 B is the wide range of options for adapting it to different pick-up systems.

All relevant parameters can be set directly from the front panel, and the Pro-Ject Phono Box S3 B is of course equally suitable for MM and MC cartridges.

The input impedance can be selected between 10 Ohm, 50 Ohm, 100 Ohm as well as 1 kOhm and 47 kOhm, the input impedance can be 50, 150, 300 and 400 pF. The gain can be selected between 40, 45, 60 and 65 dB, with an additional 6 dB for the balanced output via XLR.

If desired, a subsonic filter can be activated at 20 Hz with 18 dB/octave to eliminate low-frequency interference signals.

Foto © Pro-Ject Audio Systems | Pro-Ject Phono Box S3 B
Foto © Pro-Ject Audio Systems | Pro-Ject Phono Box S3 B

New form factor of the Pro-Ject Box Design S3 Series

The new Pro-Ject Phono Box S3 B comes with a solid, high-quality aluminium housing, which is available in either silver or black anodised finish. With dimensions of 206 x 55 x 153 mm, or 164 mm including the connections at the rear, Pro-Ject Audio Systems also uses the new form factor of the Pro-Ject Box Design S3 Series.

Finally, it should be mentioned that the power supply is in the form of an 18 V 500 mA plug-in power supply unit, so that users can upgrade without any problems.

It should also be mentioned that the new Pro-Ject Phono Box S3 B is of course manufactured in Europe.

Prices and availability

The new Pro-Ject Phono Box S3 B should be available from specialist dealers from now on. As described, you can choose between silver or black, and in both cases the recommended retail price is listed at € 399.

Getting to the point

Until now, you had to dig a little deeper into your pocket for a symmetrically designed phono preamplifier with a discrete construction and all the options to optimally adapt it to MM or MC cartridge systems. The new Pro-Ject Phono Box S3 B is supposed to offer all this at a particularly attractive price. Pro-Ject Audio Systems even calls it a symmetrically designed, audiophile phono preamplifier. Considering the price of the new Pro-Ject Phono Box S3 B and its features, it is indeed a sensation. The Pro-Ject Phono Box S3 B is probably unique on the market.

Price€ 399,-
ManufacturerPro-Ject Audio Systems a division of Audio Tuning Vertriebs GmbH
Distribution AustriaAudio Tuning Vertriebs GmbH
Distribution GermanyAudio Trade Hi-Fi Vertriebsgesellschaft mbH
Distribution SwitzerlandLakeside Audio
More about this manufacturer at HiFi BLOG
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Michael Holzinger

Michael Holzinger, founder and editor-in-chief of HiFi BLOG and, has been working for years as a journalist in the fields of IT, photography, telecommunications and consumer electronics.

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