Pro-ject Phono Box RS2

Fully symmetrical Dual Mono reference class phono preamplifier with unique impedance control

• Support for MM & MC cartridges
• Fully symmetrical and 100% dual mono design
• Fully discrete hardware design - NO operational amplifiers!
• Fully passive RIAA and DECCA equalization
• Symmetrical XLR and unsymmetrical RCA inputs and outputs
• Unique continuously adjustable input impedance loading and control Channel balance (adjustments can be made during playback)
• Extremely low noise and distortion levels
• Metal housing resistant to vibration and interference

The Phono Box RS2 is a top-of-the-line phono preamplifier. It is 100% symmetrical from input to output. The electronics are fully discrete, no operational amplifiers are used and it uses split passive RIAA and DECA equalization. Equalization must be handled and implemented very carefully and passive splitting is the most expensive, but also the only way to achieve the most accurate sound.

The RS2 Phono Box is equipped with the most advanced controls you will not find on any phono preamplifier in this price class! This is an incredibly powerful instrument for high-end enthusiasts and professionals who want to immerse themselves in all the settings and features the Phono Box RS2 has to offer. On the other hand, the top build quality, clean circuit board design and the technology used weighswill allow them to enjoy the turntable and all it has to offer without too much searching for the best settings. Purists can effortlessly enjoy the best sound, while professionals and technology enthusiasts will find their perfect high-tech phono preamp.

Discreet circuitry

Countless hours of listening tests and years of experience have shown us that even the best operational amplifiers can't be as neutral, natural, dynamic and lively. Standard phono preamps with integrated circuitry have dozens or hundreds of components, but a discrete design will use hundreds or thousands of components by comparison. This adds up to a lengthier and more expensive design process, but results in the best sound.

Fully symmetrical

The RS2 phono box uses a fully symmetrical design. A truly symmetrical amplifier can extract the resulting musical information from the +/- signals and subtract (remove) any noise that could potentially be added during transmission. The Phono Box RS2 preamplifier treats the + and - signals of the left and right channels individually, which in effect multiplies the need for an amplification section to 2. As a result, the Phono Box RS2 excels at suppressing unwanted noise, errors and interference and guarantees the best possible signal-to-noise ratio

Split passive equalization

The Phono Box RS2 uses split passive equalization for both its RIAA and DECA curves. It is more expensive to design and implement, but results in the most accurate representation of the ideal EQ curve. Split EQ allows for better impedance matching and less deviation from the ideal RIAA or DECA curve.

EXTREME ADJUSTMENT POSSIBILITIES

Gain

No other preamplifier in the world has the ability to adjust gain as finely as the Phono Box RS2. The range of adjustment is very large from 40 dB (100 x voltage gain) to 70 dB (3690 x voltage gain). You see a big gain increase between 40 dB and 70 dB, and therefore the phono preamplifier must be incredibly quiet (the fully symmetrical design brings many advantages here) to handle such high gain levels. The Phono Box RS2 handles this perfectly. You can configure it precisely for each cartridge, integrate it properly into the rest of your Hi-Fi system, and precisely match volume levels with other sources such as CD players or streaming devices.

Impedance

The load impedance can be adjusted continuously using a potentiometer - a system developed by Pro-Ject Audio Systems. The Phono Box RS2 allows you to continuously adjust the impedance during playback and instantly assess the impact of different adjustment options. It is a simple and extremely effective solution.

Channel balance function

Transmissions naturally suffer from a small imbalance between the left and right channels. The Phono Box RS2 preamplifier integrates a new feature that is very rare in this price range. The potentiometer allows you to adjust the exact center of the soundstage within a 2 dB range to the left or right. This function can be switched off to keep the signal path as short as possible in cases where its use is not necessary. Thus, there is virtually no MM or MC transmission for which the Phono Box RS2 will not find the ideal setting.

Power supply

The Phono Box RS2 is powered from an external adapter, which is rated at 20 V / 3 A. If you have an amplifier that has 3500 times the voltage gain and the input sensitivity is a few hundred microvolts (0.0001 volts), it will definitely need keep it as far away as possible from any sources of interference that may corrupt the vulnerable signal from the transceiver. Therefore, it is important to keep all parts that can radiate electromagnetic fields away from the amplifier. This is why Pro-Ject uses an external power supply.

LINKS

STEREOPHILE 9/2021 Review (EN)

TECHNICAL SPECIFICATIONS

• - Input impedance: fixed 47 kΩ, variable 10 - 1000 Ω
• - Switchable capacitance: 50, 100, 150, 200, 250, 300, 350 400 pF
• - MM Gain : RCA: 40, 43, 46, 50 dB (+6 dB when using XLR)
• - MC Gain: RCA: 60, 63, 66, 70 dB (+6 dB when using XLR)
• - Signal-to-noise ratio: MM (40 dB): 89 dB A-wt (10 mV); MC (60 dB): 79 dB A-wt (1 mV)
• - THD: < 0.0015% (MM 40 dB, 1 kHz); < 0.0024% (MC 60 dB, 1 kHz)
• - RIAA Accuracy: Within 0.4 dB / 20 Hz - 20 kHz
• - Subsonic Filter: At 20 Hz with 18 dB/octave
• - Input: RCA and XLR
• - Output: RCA and XLR
• - Power: 20 V / 3 A DC; 110 - 240 V, 50 / 60 Hz
• - Power consumption: Max. 350 mA DC
• - Dimensions W x H x D (Depth with connectors): 206 x 72 x 200 (230) mm
• - Weight: 1600 g without power supply