Pro-Ject Tube Box E phono preamplifier

The Pro-Ject Tube Box E is the "budget" version of the famous Pro-Ject Tube Box S2.

To offer it at an accessible price, the Austrian manufacturer has outsourced the production of this product to Asia.

Pro-Ject Tube Box E: Chassis

At first glance, the Pro-Ject Tube Box E phono preamplifier does not seem very different from its European predecessor.

However, a discerning eye immediately notices that the chassis has changed. Indeed, only the faceplate is made of aluminum; the rest of the chassis is steel. This naturally impacts the signal-to-noise ratio by providing less immunity against radio waves and various electromagnetic interference.

Furthermore, whether in the black or silver version, the tube guards are black, giving it a more "entry-level" look.

Pro-Ject Tube Box E: Front Panel and Settings

The front panel features a power button, as well as a button to engage the subsonic filter (20 Hz at 18 dB/octave).

There are also two switches on the front panel to select from 6 gain values (40, 43, 50, 53, 60, 63 dB).

Part of the gain is provided by ECC83/12AX7 tubes (one per channel). These are clearly budget versions, but they can be replaced with various models from different manufacturers to modify the preamplifier's sound signature and improve its performance.

Its adjustable gain, load, and capacitance values allow for a wide range of pairings with high-quality MM and MC cartridges. The Tube Box E is compatible with all Moving Magnet (MM) cartridges and the majority of Moving Coil (MC) cartridges.

The rear panel features the usual gold-plated RCA input/output connectors and a ground terminal.

Pro-Ject Tube Box E: Electronics

The internal architecture is simple but remains dual-mono, ensuring excellent stereo reproduction. The RIAA equalization is designed around a dual circuit: one part is active and the other is fully passive.

The Tube Box E is designed entirely around discrete components without the use of integrated circuits (Op-Amps).

The input stage is handled by "FET" transistors. All capacitors use polystyrene technology.

No electrolytic capacitors are used in the audio signal path. The Tube Box E is powered via an external power supply providing 18V DC. This allows the rectification and filtering circuits to be kept outside the device. However, several voltages are regulated and stabilized internally for different parts of the circuit.

Nevertheless, the specifications and measurements may suggest the use of lower-performance components compared to the Tube Box S2.

Pro-Ject Tube Box E: Review and Listening

The tonal quality and definition characteristic of the manufacturer's phono preamplifiers are present.

The Tube Box E offers a rich and nuanced sound, with warm midranges worthy of a higher-end tube phono stage.

However, the overall transparency and soundstage precision are below Pro-Ject's higher-tier models.

The tubes play their role perfectly here in terms of timbre without adding too much coloration.