United Studio Technologies • Vintage Direct • Vintage-Style Large-Transformer Direct Box

An old-school DI box done right.

It’s a labor of love.

United’s Vintage Direct bridges the gap between old-school tape operators and modern recordists. When the most demanding recording engineer needs the very best, the Vintage Direct delivers massive sound from its massive transformer. Its circuit design is based around eliminating any of the potential tone-robbing components in the signal path that you’re likely to find in a lesser DI Box. You get all the gain you could ever want, with no need for a boost pedal or preamp — neatly tucked into a sturdy, tour-worthy chassis.

When you need the very best, the Vintage Direct delivers.

Featuring Custom Large-Core United Transformers.

We did the research.

While typical DI circuits are simple, the very best depend on great transformers — and this is where the Vintage Direct excels.. The design of Vintage Direct was inspired by the earliest hand-wired DI boxes, such as the Wolfbox and Bruce Swedien’s Bass Box, both of which used massive early transformers made by Triad, UTC, and others.

Our research began with the UTC A12 transformer, first manufactured in the early ‘60s. Several original transformers were measured to accurately reproduce their winding ratios, bobbin and magnet wire type, and lamination style.

We spent years exploring many versions of this design, experimenting with different winding ratios and alloys; we ultimately settled on a high-nickel lamination and a winding ratio very close to the classics that inspired us. The result: United’s US-made 5078 — one of the largest transformers you’ll find in a DI. It delivers a pristine low-noise signal, wide frequency response, extraordinary headroom, and outstanding noise rejection.

Flexible options with audiophile-grade components.

We decided that nothing would come between the transformer and source that could rob tone or add noise. Most passive DI boxes use smaller, unshielded transformers reliant on resistor pads, volume pots, and RC network filters before the signal hits the transformer. Vintage Direct has none of it.

Instead, level tailoring in the Vintage Direct is built into the transformer taps of its output, which is far more tolerant of adjustment without affecting tone. Vintage Direct uses three different secondary winding configurations in conjunction with a precision resistor T-pad output attenuator for six evenly-spaced output level settings. True ground isolation mitigates ground-loop hum while tracking.

We built a large, well-shielded transformer that can take any line- or instrument-level signal without risking overload. It wasn’t cheap, but it ensures pinnacle performance and the highest preservation of tone. Custom audio-grade resistors are made (in the USA) for United by PRP — a component provider for NASA.

It’s not just another DI box — it’s a United.

The most exceptional passive DI box built in decades, The Vintage Direct sports an aluminum, road-worthy chassis that will survive a tour and still impress studio clientele when it gets back home. Its recessed front-panel design protects from both studio accidents and on-stage flying kicks. Removable feet add options for creative mounting.

With over 50 years of combined industry experience, we at United have spent years on research and development of this box. We can’t wait to hear what you make with it.

Specs:

Input impedance: 80 kΩ (unbalanced)

Output impedance 50-250 Ω , depending on setting (balanced)

Maximum recommended input levels: +10 dB or lower

Frequency response: 20 hZ-20 KhZ, +/-0.5 dB