Heritage Audio 73 DI ACTIVE ONE CHANNEL DI

The Heritage Audio 73 DI ONE is a single-channel active DI box with a Class A JFET input stage, a custom low-impedance output transformer, and full phantom power operation.

Classic 73 Topology for Modern Instruments

Heritage Audio has adapted its renowned 3-transistor Class A topology into a DI format, retaining the iconic 2N3055-driven transformer-coupled output stage. The first transistor is replaced with a J109 JFET, delivering a 2.2 MΩ input impedance, ideal for extracting the full tonal character of passive instruments while ensuring compatibility with active sources. Powered by +48V phantom power, the 73 DI ONE preserves headroom while delivering the harmonic saturation associated with vintage 73 preamps.

Transformer-Driven Output

A custom-designed silicon steel, grain-oriented output transformer — a phantom-safe version of the classic LO1166 — drives the signal with remarkable integrity. The transformer enhances the natural body of the instrument while maintaining clarity, dynamics, and noise rejection. A ground lift switch eliminates unwanted hum, while the isolated output ensures interference-free performance.

Enhanced Functionality

The 73 DI ONE features a 15dB pad, allowing direct connection of hotter instruments or even speaker outputs. Gold-plated input, thru, and XLR connectors guarantee maximum conductivity and reliability. A red LED indicator confirms phantom power status, while durable metal switches rated for over 25,000 cycles ensure road-ready operation. The frequency response fully captures the harmonic complexity of instruments, adding warmth and definition where needed.

Built for Professional Environments

The 73 DI ONE employs a rugged extruded aluminium case with recessed connections, making it virtually indestructible on stage or in the studio. A MIL-spec PCB with a full ground plane ensures ultra-quiet operation, while the 14-gauge steel housing protects against physical stress and potential component failure.

Why Choose the 73 DI ONE?

• Class A JFET discrete input stage for maximum fidelity

• Custom-designed 73-DI output transformer for vintage tone and noise rejection

• Wide headroom to handle guitars, basses, keyboards, and even speaker outputs

• Rugged 14-gauge steel enclosure with extruded aluminium housing

• MIL-spec PCB with full ground plane for ultra-low noise operation

• Durable switches tested to 25,000 cycles

• Gold-plated jacks and XLR for superior connectivity

• 15dB pad for hotter signals

• Ground lift switch to eliminate hum

• Phantom powered via +48V with red LED indicator

• Single channel active DI
• Class A JFET discrete input stage for high input impedance
• Heritage Audio custom 73-DI transformers with vintage LO1166 design
• 2N3055-driven transformer output for harmonic saturation
• Operates on +48V phantom power with red LED indicator
• Wide input headroom for guitars, basses, keyboards, synths, and samplers
• 15dB pad for hot signals or speaker-level inputs
• Ground lift switch for hum elimination
• Gold-plated input, thru, and XLR connectors
• Rugged extruded aluminium housing with recessed connections
• 14-gauge steel chassis for durability
• MIL-spec circuit board with full ground plane for ultra-quiet performance
• Durable switches tested for 25,000 cycles

This item, like everything we supply, comes with the complete support of our expert team. Our excellent technicians have been specifying, building and supporting studios for over twenty years. If you have any problems with installation, setup or everyday use, they’re never more than a click away, and always happy to help.

You can contact them here.