About the Pro-Ject Phono Box S3 B

Product highlights:
- compatible with moving magnet and moving coil phono cartridges
- discrete audio circuitry in a full dual mono configuration for optimal channel separation and clarity
- true balanced gain stage for reduced channel noise and enhanced detail when using compatible turntables with balanced output
- subsonic filter reduces low-frequency rumble and wasted amplifier power (18dB/octave at 20 Hz)
- steel and aluminum chassis shields audio circuitry from vibration and electromagnetic interference
Performance specs:
- input impedance: 10, 50, 100, 1k, or 47k ohms
- capacitance settings: 50pF, 150pF, 300pF, or 400pF
- gain settings: 40dB, 45dB, 60dB, and 65dB
- RIAA response accuracy: 0.3dB (20-20,000 Hz)
- THD (20-20,000 Hz): 0.008% (MM); 0.01% (MC)
- signal-to-noise ratio: 103 dBV (MM); 85 dBV (MC)
Connections:
- unbalanced stereo RCA input and output
- 5-pin mini XLR balanced stereo input
- pair of standard XLR balanced outputs
- 12-volt trigger input and output
Dimensions and warranty:
- 8-1/8"W x 2-3/16"H x 7-1/8"D
- weight: 2.05 lbs.
- warranty: 2 years
- MFR # 9120097829283
- Item # 252PHS3BBK
What's in the box:
Pro-Ject Phono Box S3 B owner's manual
If you need assistance accessing this owner's manual, please give us a call.- Phono (MM/MC) pre-amplifier
- AC power adapter (with attached 4' DC cord)
- 3 AC power plug iinserts (US/EU/UK)
- Instructions For Use
More details on the Pro-Ject Phono Box S3 B

Features & specs
Features | ||
---|---|---|
Cartridge Type | MM, MC | |
Subsonic Filter | Yes | |
Cartridge Loading | Selectable | |
Adjustable Resistance Load | Yes | |
Adjustable Capacitance Load | Yes | |
Vacuum Tube | No | |
Connections | ||
RCA Inputs | 1 Pair | |
XLR Inputs | No | |
RCA Output | 1 Pair | |
XLR Output | Yes | |
USB Output | No | |
3.5mm Output | No | |
Optical Output | No | |
Coaxial Output | No | |
Specs | ||
Signal-to-noise Ratio (MM) | 103 | |
Signal-to-noise Ratio (MC) | 85 |
Product Research
Features
True Balanced Design: The Pro-Ject Phono Box S3 B features a "True Balanced Design" that can now extract the final musical information out of the audio signals, plus subtract and remove all noise that could potentially be added along the transmission. It features a fully discrete & symmetrical gain stage with balanced input and outputs for dynamic and detailed sound from your vinyl record collection.
- Fully Discrete Gain Stage: 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 differing, individual devices. The amplifier section is built out of single components and doesn't use any integrated circuits for better results when it comes to sound quality.
- Semi-Passive EQ: After treating the balanced audio signals independently, they are added back together and are processed by the semi-passive RIAA equalization stage. By keeping the gain stage fully symmetrical, the Phono Box S3 B can optimize the signal-to-noise ratio and keep interference to a minimum. For the balanced XLR outputs, a balancing stage generates a symmetrical signal, so you benefit from balanced signal transmissions again.
Note: The Phono Box S3 B is compatible with MM (moving magnet) and MC (moving coil) cartridges. However, due to the internal wiring of MM cartridges, you'll need to upgrade your turntable with an MC cartridge to access the entirety of that balanced audio signal.
Balanced & Unbalanced Connectivity: The Pro-Ject Phono Box S3 B is outfitted with balanced (XLR) and unbalanced (RCA) connection. There is stereo unbalanced RCA input, plus a 5-pin mini XLR balanced stereo input to connect to your turntable. There is also a stereo unbalanced RCA output, as well as a XLR balanced stereo output to connect to the corresponding unbalanced or balanced line-level input of your integrated amplifier or AV receiver. By utilizing phono preamp's 5-pin mini XLR input and stereo XLR outputs, you'll enjoy the benefits of a balanced signal path.
Note: A 5-pin mini XLR to stereo RCA cable (sold separately) is required to make connection between the Phono Box S3 B's 5-pin mini XLR input and the stereo RCA output of your turntable.
Control Settings: The Phono Box S3 B features various control settings to perfectly match the Phono Box S3 B to a wide variety of phono cartridges, making sure your turntable sounds it best.
- Gain Levels: The phono preamp's gain level (40/45/60/65dB) can be adjusted to match the level of your MM/MC turntable.
- Input Impedance/Capacitance: You can adjust the phono preamp's input impedance (10/50/100/1k/47k Ohms) and input capacitance (50/150/300/400 pF) to the setting that best suits your turntable.
- Subsonic Filter: A switchable subsonic filter prevents your amplifier and speakers of ultra low rumble below 20Hz (-18dB).
Note: You can connect a up to two turntables simultaneously (one via balanced and one via unbalanced), with all the control settings and parameters for each input stored in the phono box's memory.
Ground Terminal: The phono preamp also has a turntable ground, in case your turntable has a separate ground lead. This provides shielding to the tone-arm and the sensitive circuitry in the turntable.
External Power Supply: The Phono Box S3 B is powered by an external AC adapter in order to keep all the parts which can radiate electromagnetic fields out of the phono preamp's amplifier range.
All Metal Case: The Phono Box S3 B's steel & aluminum case offers very high rigidity and isolation against outside interferences, which is essential for phono applications. The front-panel push button controls are also made from aluminum. The Phono Box S3 B is available in a black or silver finish.
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Customer Q&A
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Using with a MC cart. & the sound is much better than it was with the Bellari tube preamp it replaced. Very happy with this purchase.
John from Modesto, CA