Rupert Neve Designs RNDI-M
Compact Active Transformer Direct Interface
Product Overview
The RNDI-M is designed to provide instrument (electric guitar, bass, keyboard, piezo pickup, etc.) direct injection. The discrete Class-A circuit topology found in the RNDI-M is based around Mr. Rupert Neve's custom transformers, allowing for outstanding sonic performance and excellent noise rejection. The RNDI-M can handle extremely high input levels without clipping (up to +20.5 dBu), and the transformer-coupled output has a low impedance of less than 40 Ohms, thereby allowing the RNDI-M to drive long lines with minimal loss. The RNDI-M chassis is a compact, rugged steel design that will stand up to the rigors of stage and studio use.
Specifications
| Noise (22Hz - 22kHz, Un-weighted) | Better than -110dBV |
| Input Impedance (ZIN) | 2.2 Megohm |
| Output Impedance (ZOUT) | Less than 40 Ohm |
| Frequency Response | +/- 0.25 dB (28 Hz - 60 kHz) |
| +/- 1dB (14 Hz - 90 kHz) | |
| -3dB (Below 5 Hz) | |
| Maximum Input Level | +20.5 dBu (8.2 Volts RMS) Typical |
| Maximum Output Level | +11.5 dBu Typical |
| Total Harmonic Distortion + Noise | 0.25% Typical (2nd and 3rd Harmonic) @ 1 kHz, +20 dBu Input Level |
| 0.015% Typical (2nd and 3rd Harmonic) @ 1 kHz, -20 dBu Input Level | |
| 0.75% Typical (2nd and 3rd Harmonic) @ 20 Hz, -20 dBu Input Level | |
| Power Requirements | 4.5mA @ +48VDC |
| Weights & Dimensions | Product Dimensions (D x W x H): 3.25" (8.25 cm) x 4.75” (12.1 cm) x 1.75” (4.45 cm) |
| Shipping Dimensions (L x W x H): 4.125" (10.5 cm) x 5.125” (13 cm) x 2" (5.1 cm) | |
| Shipping Weight: 1.25 lbs (0.57 kg) |
Front & Rear Panel Description
The RNDI-M features a robust steel chassis with clearly labeled connectors and indicators.
Front Panel:
- IN: A 1/4" input jack for HI-Z unbalanced instrument signals (Input Impedance ZIN = 2.2 MΩ).
- THRU: A parallel 1/4" jack that sends the input signal directly to an amplifier or speaker, allowing for signal splitting.
- 48V POWER: A blue LED indicator that illuminates when +48VDC Phantom Power is present and active on the unit.
Rear Panel:
- GND LIFT: A switch designed to lift XLR Pin 1 from circuit ground, which can help eliminate ground loop hum.
- OUTPUT: A transformer-balanced XLR output utilizing a custom RND transformer, providing a low output impedance (ZOUT < 40 Ω) suitable for driving long cable runs.
Usage Notes
Power for the RNDI-M is supplied via standard 48V Phantom Power through its XLR output connectors. The 48V Power Status is confirmed by the blue LED on the front panel.
To ensure optimal performance and minimize potential noise, it is recommended to avoid placing the direct box near strong electromagnetic fields, such as those generated by power amplifiers.
If audible hum is detected on the RNDI-M output, users can try engaging the RNDI-M's ground lift switch. If the hum persists, users should also check ground lift settings on other devices within the signal chain. If the issue remains unresolved, isolating the source by removing individual devices from the same power circuit may be necessary.
The RNDI-M is equipped with one 1/4" input, one 1/4" THRU output, and one custom RND transformer-balanced XLR output. It effectively converts the impedance of the input signal, balances it, and buffers the output for connection to a separate microphone preamp. Simultaneously, it splits the input signal to the THRU jack for routing to an amplifier or speaker.
For the best overall sonic performance, Rupert Neve Designs recommends using high-quality audio cables and microphone preamplifiers, and ensuring the instrument source provides its maximum output level to the RNDI-M.
