Description
About the Pro-Ject Tube Box S3 B Phono Pre-amplifier
The Pro-Ject Tube Box S3 B Phono Pre-amplifier has flexible cartridge settings which include four gain levels, five impedance options and four capacitance settings. Importantly, these controls are conveniently located on the front panel. Therefore, you can correctly match a wide range of MM, high-output MC and low-output MC cartridges.
The Tube Box S3 B also supports Pro-Ject’s True Balanced connection system. A compatible turntable can connect through the balanced five-pin mini-XLR input, while balanced XLR outputs provide a low-noise connection to a suitable amplifier.
Standard RCA input and output connections are also included. Better still, the Tube Box S3 B can accommodate two turntables at once and store separate settings for each input.
What We Think
The Tube Box S3 B sits in a particularly useful position within Pro-Ject’s phono-stage range. It offers more flexibility than a basic MM/MC pre-amplifier, while remaining considerably more compact and affordable than many high-end valve designs.
The pair of ECC83 valves adds the warmth, dimensionality and smoothness that many listeners want from a tube phono stage. However, this is not simply a pair of valves added for appearance. Pro-Ject uses a fully symmetrical and discrete gain section supported by dual-mono construction.
Cartridge matching is another major strength. The 40dB and 45dB settings suit many moving-magnet and high-output moving-coil cartridges. Meanwhile, 60dB and 65dB gain settings provide the additional amplification required by many low-output MC designs.
Its balanced connectivity is especially attractive for a compatible Pro-Ject turntable and moving-coil cartridge. A balanced phono connection can reject noise picked up by the cable before the signal reaches the phono stage. This matters because a cartridge produces an extremely low-level signal.
We recommend the Tube Box S3 B for vinyl listeners who want genuine valve character, flexible cartridge matching and a clear upgrade path into balanced analogue playback.
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The Pro-Ject Tube Box S3 B Phono Pre-amplifier Is Ideal For:
- Vinyl listeners wanting genuine valve character
- Moving-magnet and moving-coil cartridges
- Compatible Pro-Ject True Balanced turntables
- Low-output MC cartridge upgrades
- Systems requiring balanced XLR outputs
- Owners running two turntables or tonearms
- Listeners who want front-panel cartridge adjustment
- Integrated amplifiers without a built-in phono stage
- Upgrading from an entry-level external phono pre-amplifier
- Compact premium hi-fi systems
- Listeners wanting replaceable valves
- Systems affected by low-level phono noise
EISA Product Award
Yes, you can use the Pro-Ject Tube Box S3 B as a single-ended MM/MC phono preamplifier – and you’ll like it. But it truly comes to life in a balanced configuration. A fully symmetrical, discrete gain stage is complemented by balanced 5-pin mini-XLR and XLR connections, delivering exceptionally low noise without the overly warm character often associated with tube designs.
Front-panel controls make it easy to adjust gain and loading for both MM and MC cartridges, ensuring compatibility with an exceptionally wide range of pickups. Versatile, attractively priced, and above all wonderfully musical, the Tube Box S3 B once again demonstrates Pro-Ject’s ability to deliver outstanding value. +read more
Frequently Asked Questions
- What does the Pro-Ject Tube Box S3 B do?
The Tube Box S3 B amplifies the extremely low-level signal produced by a turntable cartridge. It also applies the required RIAA equalisation before sending a standard line-level signal to an integrated amplifier, pre-amplifier or active speaker system. - Does the Tube Box S3 B work with moving-magnet and moving-coil cartridges?
Yes. It supports MM, high-output MC and many low-output MC cartridges. Four gain settings, five impedance settings and four capacitance options allow it to be configured for a wide range of cartridge specifications. - What do the ECC83 valves add to the sound?
ECC83 valves are often associated with a smooth top end, dimensional midrange and spacious presentation. However, the final sound also depends on the turntable, cartridge, records, amplifier and speakers. The Tube Box S3 B is designed to combine valve character with low noise and strong detail retrieval. - Can the valves be replaced?
Yes. The two ECC83 or 12AX7 valves are replaceable. Replacement should be carried out carefully with the unit disconnected from power and allowed to cool fully. A suitable matched pair is recommended, and Rapallo can advise on compatible replacements. - What does the “B” in Tube Box S3 B mean?
The “B” identifies the model’s balanced connectivity. It has a balanced five-pin mini-XLR input and stereo XLR outputs, supported by a fully symmetrical internal gain stage. - Can I use the Tube Box S3 B with a normal RCA turntable cable?
Yes. It includes a conventional stereo RCA phono input and ground terminal. Therefore, it can be used with most turntables, including models that do not support Pro-Ject’s True Balanced connection system. - Do I need a Pro-Ject turntable to use it?
No. Any suitable turntable can connect through the RCA input. However, using the five-pin mini-XLR balanced input requires a turntable with compatible wiring and the correct Pro-Ject True Balanced phono cable. - Do I need a moving-coil cartridge for balanced operation?
Pro-Ject primarily recommends its True Balanced connection system with suitable moving-coil cartridges. Cartridge construction and turntable wiring must both be compatible. Rapallo can check the complete turntable, cartridge and cable combination before purchase. - Can two turntables be connected at the same time?
Yes. One turntable can connect through the RCA input and another through the five-pin mini-XLR input. The front-panel input control switches between them, and the phono stage remembers the settings allocated to each input. - How do I choose the correct gain setting?
Gain should be matched to the cartridge’s output voltage. Most moving-magnet cartridges suit 40dB or 45dB. Meanwhile, many low-output moving-coil cartridges require 60dB or 65dB. The XLR outputs add 6dB, which should be considered during setup. - What impedance should I select for my cartridge?
Most moving-magnet cartridges use 47k ohms. Moving-coil cartridges can require 10, 50, 100 or 1,000 ohms depending on the manufacturer’s recommendation and system preference. Start with the cartridge manufacturer’s specified range before making careful listening comparisons. - What does the capacitance setting change?
Input capacitance mainly affects the frequency response of moving-magnet cartridges. The total loading includes the phono stage, tonearm wiring and phono cable. The 50, 150, 300 and 400pF settings help achieve a closer match to the cartridge manufacturer’s recommendation. - What does the subsonic filter do?
The filter reduces unwanted energy below the audible bass range. This can be caused by warped records, footfall, tonearm resonance or acoustic feedback. It can help prevent excessive woofer movement without significantly affecting normal musical bass. - Can the XLR and RCA outputs be used at the same time?
Pro-Ject provides both output formats, but simultaneous operation is not clearly confirmed in its published information. For the most predictable performance, use the output type required by the connected amplifier and confirm any dual-output application with Rapallo.
Key Features
Two Replaceable ECC83 Valves
The Tube Box S3 B uses two ECC83 valves, also known as 12AX7 tubes. They help create a smooth, spacious and engaging presentation while remaining replaceable when they eventually reach the end of their service life.
Moving-Magnet and Moving-Coil Support
Four gain settings and multiple loading options allow the phono stage to work with MM, high-output MC and many low-output MC cartridges. Therefore, the Tube Box S3 B can remain in the system through future cartridge upgrades.
Fully Symmetrical Gain Stage
Pro-Ject uses separate positive and negative signal paths within the balanced amplification circuit. This fully symmetrical design is intended to improve noise rejection, stereo separation and low-level detail.
Fully Discrete Circuitry
The gain stage uses individual components rather than relying entirely on integrated operational amplifiers. This gives Pro-Ject greater control over the circuit’s electrical and sonic behaviour.
Dual-Mono Design
The left and right channels use separate amplification paths. As a result, channel interaction is reduced and stereo separation can be improved.
True Balanced Mini-XLR Input
A five-pin mini-XLR input accepts a compatible Pro-Ject True Balanced phono cable. When used with a suitable turntable and moving-coil cartridge, this maintains the balanced cartridge signal into the phono stage.
Balanced XLR Outputs
A pair of full-sized XLR outputs provides a balanced line-level connection to a compatible integrated amplifier or pre-amplifier. The XLR outputs also provide 6dB more output than the stated base gain settings.
Conventional RCA Connections
Standard RCA phono input and line output connections are included. Therefore, the Tube Box S3 B remains compatible with conventional turntables and amplifiers that do not offer balanced connections.
Two Turntable Inputs
The RCA and mini-XLR connections can accommodate two turntables or tonearm configurations. You could, for example, connect an MM-equipped turntable through RCA and an MC-equipped balanced turntable through mini-XLR.
Input Memory
The Tube Box S3 B remembers the cartridge settings assigned to each input. Consequently, switching between two connected turntables does not require every setting to be entered again.
Four Gain Settings
Selectable gain levels of 40dB, 45dB, 60dB and 65dB cover a broad range of cartridge output levels. The balanced XLR outputs add a further 6dB.
Five Impedance Settings
Selectable input impedance values include 10, 50, 100, 1,000 and 47,000 ohms. The lower settings are primarily intended for moving-coil cartridges, while 47k ohms is standard for most moving-magnet designs.
Four Capacitance Settings
Selectable capacitance values of 50, 150, 300 and 400pF help optimise the electrical match with moving-magnet cartridges and the connected phono cable.
Front-Panel Adjustment
Gain, impedance, capacitance, input selection and the subsonic filter can all be controlled from the front panel. This is more convenient than opening the case or changing small switches underneath the unit.
Switchable Subsonic Filter
The filter operates at 20Hz with an 18dB-per-octave slope. It helps reduce very low-frequency energy caused by record warps, tonearm movement or structural vibration.
Semi-Passive RIAA Equalisation
The carefully implemented RIAA circuit restores the tonal balance applied during record mastering. Pro-Ject specifies RIAA accuracy within 0.4dB from 20Hz to 20kHz.
Aluminium and Steel Construction
The rigid metal enclosure protects the sensitive phono circuitry from physical damage and electromagnetic interference. It also matches other compact Pro-Ject Box Design components. The Tube Box S3 B is designed and manufactured in Europe. It is available in black or silver to match different systems.
Suggested System Match
The Tube Box S3 B is a natural match for Pro-Ject turntables equipped for True Balanced operation. Models such as the Debut PRO B, X1 B, X2 B and X8 can form the basis of a balanced analogue system when fitted with the correct cartridge and cable.
A moving-coil cartridge offers the most straightforward route to Pro-Ject’s True Balanced system. The Ortofon Quintet range, Pro-Ject Pick it MC cartridges and suitable MC models from Audio-Technica can all be considered. However, the gain and loading settings must be selected for the exact cartridge.
Conventional RCA operation remains fully supported. Therefore, the Tube Box S3 B can also partner turntables from Technics, Rega, VPI and other manufacturers. It will work with popular MM cartridges such as the Ortofon 2M range and Audio-Technica VM series.
For the cleanest complete signal path, connect the XLR outputs to an amplifier with genuine balanced inputs. However, its RCA outputs still deliver the Tube Box S3 B’s valve-based character when used with a conventional integrated amplifier.
Specifications
Brand: Pro-Ject Audio Systems
Model: Tube Box S3 B
Product Type: Balanced valve phono pre-amplifier
Cartridge Compatibility: Moving magnet and moving coil
Circuit Design: Fully symmetrical and discrete gain stage
Channel Construction: Dual mono
RIAA Equalisation: Semi-passive
Valve Complement: 2 × ECC83 / 12AX7
Replaceable Valves: Yes
Gain Settings: 40, 45, 60 and 65dB
Additional Gain Through XLR Outputs: 6dB
Effective XLR Gain Settings: 46, 51, 66 and 71dB
Input Impedance: 10, 50, 100, 1,000 and 47,000 ohms
Input Capacitance: 50, 150, 300 and 400pF
Balanced Phono Input: 1 × five-pin mini-XLR
Unbalanced Phono Input: 1 × stereo RCA
Balanced Line Output: 1 × stereo XLR
Unbalanced Line Output: 1 × stereo RCA
Simultaneously Connected Turntables: Up to two, one per input type
Input Setting Memory: Yes
Subsonic Filter: Switchable
Subsonic Filter Frequency: 20Hz
Subsonic Filter Slope: 18dB per octave
MM Signal-to-Noise Ratio at 40dB: 97dBV; 105dBV A-weighted
MC Signal-to-Noise Ratio at 60dB: 83dBV; 88dBV A-weighted
MM THD at 1kHz: Less than 0.005%
MC THD at 1kHz: Less than 0.01%
MM THD, 20Hz–20kHz: Less than 0.1%
MC THD, 20Hz–20kHz: Less than 0.03%
RIAA Accuracy: Better than 0.4dB from 20Hz to 20kHz
Ground Terminal: Yes
Front-Panel Controls: Power, input, impedance, capacitance, gain and subsonic filter
Enclosure: Steel and aluminium
External Power Supply: 18V DC / 1,000mA
Power Consumption: 18V / 800mA DC
Standby Consumption: Less than 0.5W
Dimensions: 206mm W × 81mm H × 153mm D
Depth Including Sockets: 164mm
Weight: 1.01kg without power supply
Available Finishes: Black and silver
Country of Manufacture: Made in Europe
Included Accessories: External power supply and documentation, subject to market package
Specifications are based on Pro-Ject’s published product information and may change by production revision or market.
Why Buy From Rapallo
✔ Expert MM and MC cartridge matching
✔ Advice on Pro-Ject True Balanced compatibility
✔ Help selecting the correct mini-XLR phono cable
✔ Gain, impedance and capacitance setup assistance
✔ Turntable, cartridge and amplifier system matching
✔ Guidance when upgrading from an integrated phono stage
✔ Balanced and conventional RCA connection advice
✔ New Zealand-based sales and product support
✔ Secure nationwide delivery options
✔ Complete turntable setup and installation options
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