RNDI-S: Active Transformer DI Box
The RNDI-S is designed to deliver uncompromising audio integrity for direct input from instruments (electric guitar, bass, keyboards, piezo pickups, etc.). Its Class A discrete circuit topology, built around a proprietary transformer designed by Mr. Rupert Neve, ensures exceptional sonic performance and superior noise rejection.
The RNDI-S accepts extremely high input levels without clipping (up to +20.5dBu), while its transformer-coupled output features a very low 40-ohm output impedance, guaranteeing minimal signal loss over long cable runs. Housed in a rugged, milled aluminum enclosure, the RNDI-S is built to withstand demanding live environments as well as studio applications.
User Guide
The RNDI-S is powered independently via standard 48V phantom power applied to both XLR output connectors, with status indicated by two front-panel LEDs. To minimize potential noise interference, avoid placing the unit near strong electromagnetic sources such as power amplifiers.
To reduce ground loop hum, maintain a single ground point throughout the signal chain. If hum is encountered at the RNDI-S output or connected amplifier, engage the ground lift switch on the RNDI or check corresponding switches on other components in the signal path. If issues persist, systematically isolate each device in the chain to identify the source.
The RNDI-S provides two input options: a 1/4" unbalanced instrument input and a 3.5mm stereo unbalanced input. In Instrument mode, the DI matches impedance, balances the signal (if sourced from unbalanced output), provides buffered output to the console, and offers a parallel THRU output via the 1/4" jack for amplifier connection. For optimal RNDI-S performance, we recommend using high-quality cables and microphone preamps while driving maximum level from your instrument. The 3.5mm stereo input accepts stereo sources, with CH1 corresponding to left channel (Tip) and CH2 to right channel (Ring). The 3.5mm audio source can be converted to balanced output through the RNDI-S.
RNDI-S Specifications
Noise
(Output measurement, unweighted, 22Hz-22kHz, source impedance 150Ω) | Better than -110 dBV |
| Input Impedance |
|
| Instrument Input | 2.2 MΩ |
| 3.5mm Input | 95 kΩ |
| Output Impedance | Less than 40 Ω |
| Frequency Response |
|
| ±0.25 dB | 30 Hz - 63 kHz |
| ±1 dB | 12.5 Hz - 120 kHz |
| -3 dB | 5 Hz |
| Maximum Input Level |
|
| Instrument Input | +20.5 dBu typical |
| Maximum Output Level | +11.5 dBu typical |
| THD+N |
|
| @ 1 kHz, +20 dBu input level, no load | 0.35% typical (2nd & 3rd harmonic) |
| @ 1 kHz, -20 dBu input level, no load | 0.09% typical (2nd & 3rd harmonic) |
| @ 20 Hz, -20 dBu input level, no load | 0.9% typical (2nd & 3rd harmonic) |
| Crosstalk @10kHz |
|
| Instrument Input | -115 dB |
| 3.5mm Input | -108 dB |
| Power Requirements |
|
| Phantom Power | 4.5 mA per channel @ 48 VDC |
| Weight | 1.3 kg |
| Dimensions | 178 × 134 × 41 mm |
