ProJect Phono Box RS2 Preamplifier

Reference class phono preamplifier with unique impedance control

The Phono Box RS2 is the ultimate phono preamplifier of the highest class. It is fully balanced from the input to the output. Electronics are fully discrete, no op-amps are in use and it uses split passive RIAA and DECCA equalisation.

Discrete Circuitry

A discrete circuit is composed of electronic components which are disparate, individual devices, also called discrete components. These can be “passive” components, like resistors, capacitors and inductors, as well as “active” components, which in our case are transistors.

The opposite to this would be an integrated circuit, which uses operational amplifiers (Op-Amps) in the signal chain. Countless hours of listening tests and years of experience have shown us that even the very best Op-Amps do not tend to be so neutral, natural, dynamic or vivid. Standard phono pre-amplifiers with integrated circuits have a few tens or hundreds of components, but discrete designs will employ hundreds or thousands of components by comparison.

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

Fully Balanced

The Phono Box RS2 employs a true fully balanced design principle. Balanced transmissions consist of a hot and a cold (also called + and -) signal. Both the + and – signal chains effectively carry the same musical information. A true balanced amplifier can now extract the final musical information out the +/- signals and subtract, remove, all noise that could potentially be added along the transmission. In a true, fully balanced amplifier, like the Phono Box RS2, the + and – sections of both the left and right channel are treated individually, which doubles the amplifier sections by 2 as a result.

Split passive EQ

The Phono Box RS2 uses split passive equalisation for both of its RIAA and DECA curves. This is more costly to design and implement but ensures the most accurate representation of the ideal EQ curve. Split passive equalization allows for better impedance matching and lower deviation from the ideal RIAA or DECA curve.

Extreme cartridge loading options

No other phono-preamp in the world has such fine options of setting the gain like the Phono Box RS2. Very large ranges from 40dB (voltage amplification by 100x) up to 70dB (voltage amplification by 3690x) are possible.

Load impedance can be set continuously via potentiometer, a system invented by Pro-Ject Audio Systems. It allows you to seamlessly adjust the impedance during playback and immediately assess the impact of different loading options.

Cartridges, by nature, suffer from small imbalances between the left and right channels. To correct this the Phono Box RS2 introduces a new feature that is absolutely rare in this price category. A potentiometer allows you to adjust the exact centre of the sound stage in ranges of 2dB to the left or right.

Steel/aluminium chassis

The Phono Box RS2 has a steel chassis which is covered by screwed aluminium panels. This construction brings very good rigidity and splendid isolation against interferences.

Power Box RS2 Phono – linear power supply upgrade

An outboard power supply with linear construction is even better, because it can offer much cleaner power. When you want to manufacture such clean and really high-end power supplies, you have to use a transformer with a very low core saturation and preferably with shielding between primary and secondary windings. Obviously, such a transformer becomes larger than one would expect. Also, much more expensive.

That is why such a power supply requires a cabinet the size of the Phono Box RS2 itself. Our Power Box RS uni 1- & 4-way will be another step up for your Phono Box RS2 performance.

Product Features

• MM & MC capable
• Fully balanced, true dual mono design
• Fully discrete hardware design - NO Op-amps!
• Fully passive RIAA & DECCA equalisation
• Balanced XLR & unbalanced RCA In & Outputs
• Unique continuously variable input impedance loading and channel balance control to match every cartridge to 100% (adjustment even while playing)
• Superior low noise / low distortion
• Metal casing protects against vibration and interference