The essentials to know about Heritage Audio P DI Series passive direct boxes
- Custom HA-DI transformer with nickel core and MU METAL shielding for ultra-transparent transmission and excellent immunity to interference.
- Passive DI without power: high-to-low impedance conversion, balanced output, and noise reduction for clean recording both in the studio and on stage.
- Effective hum elimination: removal of hum and buzz caused by ground loops via ground lift and transformer isolation.
- Professional construction, built to last: 14-gauge steel chassis, MIL-spec PCB with full ground plane, and metal switches rated for over 25,000 cycles.
A Heritage Audio DI born from 15 years of development
The P DI Series (P DI ONE and P DI 2) follows Heritage Audio's philosophy: add nothing, remove nothing. The brand developed these passive direct boxes as an "invisible link," leveraging over 15 years of research, measurements, and prototypes, as well as experience with transparent passive processing from its R.A.M. monitoring control range. The goal is simple: to offer a high-end transformer DI capable of remaining neutral, stable, and silent, even in electrically noisy environments.
For whom and for what uses: studio, stage, keyboards, synths, basses
The Heritage Audio P DI ONE and P DI 2 are ideal for connecting sources with active electronics or high output levels (keyboards, synthesizers, drum machines, samplers, modules, active pedalboards, and certain guitars and basses) to a console, mic preamp, stagebox, or audio interface. By adapting level and impedance while converting the signal to balanced, they enable retrieval of a strong, clean signal with excellent noise rejection over long cable runs.
The choice between the two models mainly depends on configuration: the
P DI ONE is perfect for a mono source (bass, mono synth, machine), while the
P DI 2 is naturally suited for stereo setups (stereo keyboards and synths, players, racks) or for two independent sources on stage.
Transparency, isolation, and control: the "forget it's there" approach
The heart of the sound: HA-DI transformer, nickel core and MU METAL shielding
At the core of the P DI Series is the custom-designed
HA-DI transformer. Its nickel core aims for very transparent signal transfer with minimal coloration, while the MU METAL shielding helps limit disturbances caused by electromagnetic interference (EMI) and stray sources around the stage or studio (power supplies, lighting, power strips, computers).
Passive DI: impedance conversion, balancing, and ground problem reduction
The passive operation, without power, relies on a magnetic transformer to transfer audio while blocking unwanted DC voltages and limiting the impact of RFI-type interference. This architecture is particularly useful for reducing hum and buzz from ground loops while preserving the natural character of the instrument. Heritage Audio also claims clean reproduction with
virtually zero phase shift and
virtually no harmonic distortion, for clear and easy-to-mix direct recordings.
15 dB pad and ground lift: essential everyday tools
On stage and in the studio, some sources can saturate a console or preamp's mic input: the
15 dB pad allows clean attenuation of the signal. The
ground lift remains indispensable for breaking ground loops without jury-rigging and quickly restoring a stable signal during soundchecks.
Technical specifications
Models
- Heritage Audio P DI ONE: passive direct box 1 channel
- Heritage Audio P DI 2: passive direct box 2 channels
Audio and performance
- Frequency response: 20 Hz - 18 kHz
- Delivers virtually zero phase shift or harmonic distortion
- Signal integrity and noise rejection claimed as superior
- Effective elimination of hum and buzz caused by ground loops
- Passive architecture, no power required
- High-to-low impedance conversion and balancing via transformer
- Audio transfer with blocking of unwanted DC voltages and limitation of RFI-type interference
Transformers
- P DI ONE: 1 custom HA-DI transformer
- P DI 2: 2 custom HA-DI transformers
- Nickel core for optimized signal transfer
- MU METAL shielding against EMI interference
Controls
- 15 dB pad
- Ground lift
- Metal switches rated for over 25,000 cycles
Connectivity
- Input / Thru jacks with gold-plated contacts
- XLR output with gold plating
Construction and reliability
- 14-gauge steel chassis reducing stress on the PCB and risk of component failure
- MIL-spec PCB with full ground plane for very quiet operation
- Robust and durable design, suitable for studio and touring
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