RNDI: Active Transformer DI Box
The RNDI is designed to provide unparalleled musical integrity for instruments (electric guitar, bass, keyboards, piezo acoustic pickups, etc.) and speaker-level direct inputs. Its Class A discrete circuitry, built around a proprietary transformer designed by Mr. Rupert Neve himself, delivers exceptional sonic performance and outstanding noise rejection.
The RNDI can handle extremely high input levels without clipping (+21dBu on Instrument input, +41.5dBu on Speaker input). The transformer-coupled output features a very low 40-ohm output impedance, ensuring minimal signal loss over long cable runs. Housed in a rugged, milled aluminum enclosure, the RNDI is built to perform reliably in both live sound and studio environments.
User Guide
The RNDI is powered by standard 48V phantom power supplied via the XLR output connector, with status indicated by a front-panel LED. Avoid placing the RNDI near strong electromagnetic sources (such as power amplifiers), as interference could potentially couple into the transformer despite its shielding. To minimize ground loop hum, ensure the entire signal chain uses a single ground point. If hum is encountered at the RNDI output or connected amplifier, engage the RNDI's ground lift switch or check for ground lift options on other equipment in the signal path.
In Instrument mode, the DI box matches the instrument's impedance, balances the signal (if sourced from an unbalanced output), provides a buffered output to the console, and optionally routes a parallel signal via the THRU output to an amplifier. For optimal performance, we recommend using high-quality cables and microphone preamps, and driving the output of your instrument as high as possible without clipping.
In Speaker mode, the DI is used after a power amplifier to capture the combined tonal character of the preamp and power amp stages. Always set the RNDI input level switch to the Speaker position and ensure the amplifier and speaker are properly connected before powering on the amplifier. For tube power amplifiers, a speaker must be connected to the THRU output to provide a proper load. Solid-state amplifiers can typically operate safely without a speaker load connected.
RNDI Specifications
Noise
(Output noise, unweighted, 22Hz-22kHz, source impedance 150Ω to 10kΩ) | Better than -110 dBV |
| Input Impedance |
|
| Instrument Setting | 2.2 MΩ |
| Speaker Setting | 200 kΩ |
| Output Impedance | Less than 40 Ω |
| Frequency Response |
|
| ±0.25 dB | 25 Hz – 44 kHz |
| ±1 dB | 12.5 Hz – 63 kHz |
| -3 dB | 92 kHz |
| Maximum Input Level |
|
| Instrument Input | +21 dBu typical |
| Speaker Input | +41.5 dBu, 92V RMS (266V Peak-to-Peak) |
| Maximum Output Level | +11.5 dBu output at maximum input level |
| THD+N |
|
| @ 1 kHz, +20 dBu input level, no load | 0.25% typical (2nd & 3rd harmonic) |
| @ 1 kHz, -20 dBu input level, no load | 0.15% typical (2nd & 3rd harmonic) |
| @ 20 Hz, -20 dBu input level, no load | 0.75% typical (2nd & 3rd harmonic) |
| Power Requirements | Phantom Power, 4.5 mA @ +48 V DC |
| Weight | 1.1 kg |
| Dimensions | 101 × 164 × 41 mm |
