Pro-Ject Tube Box S2 Phono Preamplifier
Category: other
A Little Tube Warmth for Your Vinyl
The Pro-Ject Tube Box S2 is an MM/MC phono preamplifier built around a pair of real vacuum tubes. It is a different approach from the solid-state Phono Box line, aimed at listeners who want some tube character in the sound.
Two ECC83 (12AX7A) tubes handle the gain stage. They're user-replaceable, so you can swap in a different tube later to tune the sound to your taste, a hobby vinyl people call tube rolling.
This is a more affordable sibling to Pro-Ject's Tube Box DS2, which steps up to a larger hybrid design in a different chassis. The S2 keeps things simpler, with a single pair of RCA connections for both input and output.
Dialed In for Your Exact Cartridge
Gain switches across five levels: 40dB, 43dB, 50dB, 60dB, and 63dB. That covers everything from a moving magnet to a moving coil, and the step you need is usually printed on the cartridge box.
Input impedance switches between 10, 100, 1,000, and 2,000 ohms for moving coil cartridges, plus a fixed 47 kOhm setting for high-output MC and MM cartridges. Input capacitance switches across six steps from 47pF to 587pF.
A subsonic filter cuts rumble below 20Hz at 18dB per octave, useful on a warped record or a turntable prone to footfall. Signal-to-noise ratio reaches 77dBA, with THD rated under 0.0025%.
It measures 103 by 73 by 131mm and weighs 410 grams without its included 18V power supply. An outboard Accu Box S2 battery supply is available as a separate upgrade.
What Reviewers Are Saying
Caleb Attaway reviewed the Tube Box S2 for Analog Planet in March 2020. Comparing it to a built-in phono stage, he found "a little better bass, maybe a bit more defined detail," along with a "little wider soundstage presentation."
Rick Coste reviewed it for The Joy of Vinyl in May 2023, describing its sound as "warm, captivating, and detailed." He also praised its "excellent instrument separation and impressively quiet background."
Who Is This Preamp Best For?
- Anyone curious about tube sound. Its two ECC83 tubes bring a warmer character than a typical solid-state phono stage.
- Listeners who enjoy tinkering. User-replaceable tubes let you experiment with different tube types down the road.
- Owners of both MM and MC cartridges. Switchable gain and loading cover either type.
- Shoppers who want proven, independently reviewed sound quality. Multiple named reviewers praised its warmth and detail.
- You are happy to change a tube every few years — the pair of ECC83s wear the way all valves do, and swapping them is the same job as changing a bulb. A solid-state phono stage asks nothing of you at all.
How Does It Connect to Your System?
Run your turntable's phono cable into the Tube Box S2's RCA input, then connect its RCA output to a line-level input on your amplifier or receiver.
Set the rear switches for gain, loading, and capacitance to match your cartridge before you start listening. Give the tubes a few minutes to warm up for their best sound.
Pairs Well With
Building your system? Here are some great companions for the Pro-Ject Tube Box S2:
- Turntables without a built-in phono stage
- Phono cartridges, MM or MC, matched to its switchable gain
- Interconnect cables to connect its output to your amp
- Turntables whose own phono stage you would rather bypass
Frequently Asked Questions
What tubes does it use?
Two ECC83 (12AX7A) tubes. They're user-replaceable, so you can swap in a different tube as they wear out or to experiment with the sound.
How is this different from the Tube Box DS2?
The DS2 is a pricier, larger model in a different chassis. The S2 covers the same MM/MC ground in a simpler, more affordable package.
Can I use this with a moving coil cartridge?
Yes. Its 60dB and 63dB gain settings, along with lower loading options, are built with moving coil cartridges in mind.
How often do the tubes need replacing?
There is no fixed interval. A pair of ECC83s runs for years of normal listening, and you will hear when one is tiring long before it stops.
What's the warranty?
Pro-Ject covers the Tube Box S2 with a two-year warranty, extendable to three years with product registration.
See It in Action
This Does Not Compute puts the Tube Box S2 through a full review:
HIFI Daydreaming compares it against a Rega phono stage:
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Learn More
Want to learn more about tube versus solid-state phono stages, matching a preamp to your cartridge, or getting the most from your vinyl collection? Visit our Learning Center for guides, tips, and expert advice.
