4DI DI BOX

True All-Tube Signal Path: Each channel uses a premium vacuum tube circuit based on the legendary D.W. Fearn VT-I/F design for deep, rich analog tone.

Four Independent DI Channels: Perfect for handling multiple instruments simultaneously in studios, live sound setups, or houses of worship.

Instrument-Level Inputs Front & Rear: Locking 1/4'' inputs on the front and mirrored pass-through jacks on the rear provide flexible routing options.

Transformer-Balanced Mic-Level XLR Outputs: Delivers warm, low-noise, mic-level signals designed to match 150-ohm professional preamps.

Massive Headroom and Detail: Captures full dynamic range from electric bass, guitar, synths, and acoustic instruments with pickups - without harshness.

Ground Lift Per Channel: Each input has its own locking ground lift switch with LED status to help eliminate hum and buzz in complex setups.

Built for the Stage and Studio: Housed in a rugged all-steel 2U rack chassis, designed for professional use under demanding conditions.

Handcrafted in the USA: Carefully assembled and tested by hand to ensure consistency and sonic excellence.

General Overview

4-channel all-triode vacuum tube direct injection (DI) box

Based on D.W. Fearn's classic VT-I/F design

Part of Hazelrigg Industries' Solution Series (with VNE, VLC, VEC, and VDI)

Designed for use in studios, live FOH, and houses of worship

Handcrafted in the USA with premium-grade components

Audio Circuitry

Pure analog vacuum tube signal path using selected 6072 or 12AY7 triodes

Each channel features independent DI circuitry

Custom Jensen transformer-balanced mic-level output

Cathode-follower output stage with capacitive coupling for optimum isolation

Input impedance: 1 M ohm

Output impedance: Matches 150 ozhm mic inputs

Input and Output Specifications

Inputs: 4 front-panel locking 1/4 in mono instrument jacks

Pass-through: 4 rear-panel 1/4 in parallel input/thru jacks

Outputs: 4 rear-panel gold-plated XLR mic-level balanced outputs (pin 2 hot)

Gain: -10 dB

Max input level: 2.3 V peak-to-peak (1% THD)

Frequency response: 10 Hz - 20 kHz +/-0.2 dB

THD+N: < 0.3% (20 Hz - 20 kHz)

Intermodulation distortion: < 0.01% SMPTE

Noise: -90 dB below output (22 Hz - 22 kHz bandwidth)

Max output level: -12 dBm nominal

Front Panel Features

4 locking 1/4 in instrument inputs

LED indicators per channel (signal and ground lift status)

4 ground lift switches (locking toggle style)

Power switch with integrated red pilot light

Fully regulated power supplies for filament and plate voltages

Rear Panel Features

4 gold-plated XLR mic-level outputs

4 input/pass-through pairs (1/4 in TS jacks)

GND terminal for external grounding schemes

IEC power inlet with voltage selector (115V / 220V)

Fuse: 1A (115V) / 0.5A (220V)

Mechanical and Power

Rackmount: 2U height (3.5 in), all-steel construction

Dimensions: 6.25 in W - 2.25 in H - 9.5 in D (15.9 - 5.7 - 24.2 cm)

Weight: 14 lbs (6.35 kg)

Power: 120/220 VAC 50/60 Hz, 25 W

Suggested warm-up: 5 minutes for optimal performance

Maintenance

Tubes: 4 - 6072 / 12AY7 (user replaceable, matched for low noise and microphonics)

Tube life: multiple years, tested for noise and microphonics

Filter capacitors rated for >20 years

User-replaceable with manufacturer-recommended parts

Applications

Electric and acoustic guitars/basses with pickups

Electric pianos, synthesizers, samplers

Suited for studio recording, live sound reinforcement, and broadcast scenarios

Compatible with any professional mic preamp; optimized for VT-1, VT-2, and VLC