Review: The Hazelrigg Industries VDI Vacuum Tube Direct Box Delivers High-Quality Acoustic Guitar Sound

The Hazelrigg Industries VDI Vacuum Tube–Based Direct Box cuts no corners in pursuit of the best possible sound for acoustic guitar.

The role of a direct box, or DI, is often underappreciated, even though it can have a significant impact on amplified sound. A DI provides an interface between your guitar’s pickup, which usually has a high-impedance unbalanced output, and a PA system that expects a balanced low-impedance signal. While a budget DI may be all many guitarists need, others appreciate the very finest.

Hazelrigg VDI Direct Box Front
Hazelrigg VDI Direct Box rear panel

D.W. Fearn has been making boutique pro-audio equipment, primarily for the recording market, since 1993, and is known for his ultra-high-quality, hand-built products. Several decades ago, Fearn introduced the VT-1/F, a massive 15-pound tube-and-transformer-based DI, which quickly became legendary for its sound quality and was adopted by many well-known touring acts.


Fearn’s designs are now made by Hazelrigg Industries. The company’s latest offering is the VDI, a smaller, single-channel DI that shares most of the circuitry of its predecessor. Built like a tank from 1/4-inch-thick steel, the VDI weighs in at six pounds. As with the VT-1/F, it cuts no corners in pursuit of the best possible sound. The active AC-powered DI pairs a custom Jensen transformer with a pair of hand-selected 6072/12AY7 tubes and achieves a frequency response of +/- 0.2dB from 10Hz to 20kHz, while staying within 3dB all the way from 0.5Hz to 90kHz. Features are minimal, consisting of a power switch, ground lift, 1/4-inch input, and both 1/4-inch and XLR outputs. The input impedance is 1MΩ, ideal for most acoustic pickups, while the output impedance is the usual 150 ohms.

acoustic guitar amplification essentials - everything you need to know about amplifying your acoustic guitar

The feeling I got while playing through the VDI was of unlimited headroom, like driving a high-powered car that responds to your actions effortlessly. The sound was clean and clear, with that undefinable appeal of an all-analog tube circuit, making playing with a pickup a more enjoyable experience. The VDI is not for the faint of heart. Its hefty size and weight—not to mention its $1,350 price tag—make it clear that this is a fully professional, industrial-strength affair. At a time when cheap electronics are pervasive, it’s a pleasure to experience a product designed with quality as its singular goal.

This article originally appeared in the March/April 2022 issue of Acoustic Guitar magazine.

Doug Young
Doug Young

Doug Young is a fingerstyle instrumental guitarist, writer, and recording engineer. He is the author of Acoustic Guitar Amplification Essentials.

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