Pro-Ject Tube Box DS3 B True Balanced Phono Preamplifier - Silver

A True Balanced Signal Path, Warmed by Tubes

The Pro-Ject Tube Box DS3 B is an MM/MC phono preamplifier built around two E88CC (6922) vacuum tubes in its input and gain stages. It's a hybrid design. That tube warmth pairs with a fully balanced, dual-mono circuit layout for genuine noise rejection.

This is the tube-based sibling of Pro-Ject's solid-state Phono Box DS3 B. Both share the same balanced architecture and continuously adjustable loading. The Tube Box trades some of the solid-state model's tighter noise and distortion figures for the character that comes with valve amplification.

A steel and aluminum chassis, assembled by hand in Europe, houses the whole circuit. It's available in silver or black, with optional magnetic wooden side panels sold separately.

Stepless Loading and Two Stored Setups

Gain switches across six levels: 40, 45, 50, 55, 60, and 65dB. An extra 6dB is available through the balanced XLR output. Resistive loading adjusts steplessly from 10 to 1,000 ohms via a front-panel potentiometer, or you can select a fixed 47 kOhms instead.

That stepless control lets you fine-tune loading in real time while a record plays. There's no switching between preset positions and guessing at what falls between them. Capacitance loading adds four more settings: 50, 150, 300, and 400pF.

You can connect two turntables at once, one through the balanced XLR input and one through unbalanced RCA. The DS3 B stores each input's settings separately, so switching between them doesn't mean redoing your setup.

RIAA accuracy is rated within ±0.5dB from 20Hz to 20kHz. Signal-to-noise ratio is rated above 87dBV A-weighted. Total harmonic distortion stays under 0.03%. A subsonic filter cuts at 18dB per octave below 20Hz.

It measures 206 by 70 by 194mm and weighs 1,560 grams. Power comes from an included 18V/1000mA external supply.

What Reviewers Are Saying

John Pickford reviewed the DS3 B for StereoNET in September 2024. He found "the Tube Box does indeed possess a rosy and inviting character" without sounding "thick-sounding or woolly."

He praised its "inherently musical nature," noting that it "brings out the best in your record collection, smoothing out the spikiness from poor recordings."

Ken Micallef reviewed it for AnalogPlanet in December 2024. Its performance, he wrote, "knocked me over with its sense of exhilaration, layering, pristine but sun-flecked treble." He also praised its "wide/large/tall soundstage that invigorated every record."

Micallef found that "the DS3 B played with clear-headed precision, with the pacing and timing of a more expensive unit."

Who Is This Preamp Best For?

• Listeners who want tube warmth with balanced connectivity. Two E88CC tubes bring genuine valve character to a fully balanced, dual-mono circuit.
• Owners of two turntables, or two tonearms on one deck. Balanced and unbalanced inputs run at once, each with its own stored settings.
• Owners of hard-to-match cartridges. Stepless loading from 10 to 1,000 ohms allows finer matching than fixed switch positions.
• Listeners who want proven, independently reviewed performance. Two named reviewers at established publications praised its musicality and soundstage.
• Not the right fit for anyone chasing the lowest possible noise floor. Pro-Ject's solid-state Phono Box DS3 B posts tighter distortion and noise figures than this tube-based model.

How Does It Connect to Your System?

Run a turntable's balanced cable into the 5-pin mini XLR input. If you're using a second turntable, run its unbalanced cable into the RCA input. Connect the DS3 B's RCA or XLR output to your amplifier or preamp.

Set the front-panel gain, loading, and capacitance controls to match each cartridge. Give the tubes a few minutes to warm up first. That warm-up time helps them settle into their best, most stable sound.

Pairs Well With

Building your system? Here are some great companions for the Pro-Ject Tube Box DS3 B:

• Turntables without a built-in phono stage
• Phono cartridges, MM or MC, matched to its stepless loading
• Preamplifiers with balanced XLR inputs

Frequently Asked Questions

How is this different from the Phono Box DS3 B?

The Phono Box DS3 B is a solid-state design with tighter noise and distortion specifications. The Tube Box DS3 B swaps in two E88CC vacuum tubes for a warmer character. It keeps the same balanced dual-mono architecture and stepless loading.

Can I use two turntables with this preamp?

Yes. One balanced XLR input and one unbalanced RCA input can be connected at the same time. The DS3 B remembers each input's settings separately.

How do I set the loading for my cartridge?

A front-panel potentiometer adjusts resistive loading steplessly from 10 to 1,000 ohms. You can dial it in while a record plays. A fixed 47 kOhm setting and four capacitance values are also available.

What's the warranty?

Pro-Ject and its dealers don't publish a specific warranty period for the Tube Box DS3 B. Check with your dealer for current coverage terms at the time of purchase.

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