Rupert Neve Designs RNDI-S Stereo Active Transformer DI

Rupert Neve Designs’ RNDI-S Overview:

The RNDI’s distinct sound is due to new custom Rupert Neve-designed transformers and class-A one-sided, discrete FET speakers. The meticulously coordinated combination of these two components is critical to the RNDI’s unique reaction, which produces a powerful and energetic direct sound suitable for recreating the full consonant depth of basses, guitars, acoustic instruments, and professional line-level sources. With its compact, powerful, great tone for your instrument and enhancer flags, the RNDI is indeed the first independent DI worthy of the Rupert Neve brand.

The Development
After being created during an experiment with new transformer designs, the RNDI was fine-tuned through a series of listening tests against the most popular high-end DIs available. During these tests, the RNDI consistently added a new dimension to the sound and brought the instruments to life. The lows felt richer, deeper, and fuller, while the highs were exceptionally clear with no extra harshness. Most significantly, the design team stated: “As musicians, the RNDI consistently stood out as the DI we wanted to play through.”

Elements of Direct Tone.
The RNDI’s distinctive sound is the result of both new custom Rupert Neve-designed transformers and class-A-biased, discrete FET amplifiers. The proper integration of these two components is critical to the RNDI’s distinct response.

The transformers provide excellent passive isolation while also adding beautiful harmonics and depth to the sound. The low impedance, transformer-balanced output is ideal for driving lengthy wire runs, and performance is extremely consistent, independent of the attached equipment. This is critical in both live and studio contexts, as an unamplified signal may travel nearly 100 feet before reaching an amplifier. In other systems, these high capacitance lines result in significant reductions in high frequencies; nevertheless, the RNDI’s output stage is unequaled for handling long runs with low losses.

The RNDI’s class-A and discrete FET amplifier is fed by industry-standard 48V phantom power via the XLR connection, resulting in a very high impedance input of 2 mOhms, ensuring consistent performance with a wide range of instruments. The RNDI’s class-A architecture is significant because it eliminates crossover distortion, which can introduce upper-order odd harmonics to the sound that are musically discordant. The RNDI’s harmonic content is predominantly second-order (octave), with some third-order (fifth above octave) present. These musically important harmonics, which appear in small amounts, really add to the richness of the original signal. The RNDI design is discrete, which means there are no ICs or digital components that can affect the tone.

These efforts to match the performance of the transformer and the FET amplifier resulted in the RNDI’s extraordinarily balanced response. The low-end tone is rich and strong, with a frequency response many octaves below audibility. The high end is clear, present, and smooth, with a frequency response that exceeds 100 kHz. The phase coherence is unequaled at all frequencies, ensuring that the sound is as genuine as possible, especially when merging the direct signal with a microphone recording from the same source. Simply put, the RNDI outperforms any DI ever produced.

Game-Changing Headroom
In instrument mode, the RNDI’s large input headroom of +21.5 dBU allows it to handle not only instruments but also professional line-level sources such as interfaces, CD players, and drum machines without a pad. This enables the RNDI to “re-preamp” any previously recorded track with your interface and a preferred pre-amp. Simply connect one of the interface’s channel outputs to the RNDI’s input, then connect the RNDI’s output to the preamp and engage 48V. “Re-Preamping” allows you to adapt the tone of another preamp to the source and more accurately automate or adjust the preamp’s drive level.

In speaker mode, the RNDI can handle the screaming output of a 1000-watt power amplifier (92 Vrms or 266 Vp-p) to record the complete tone of the instrument, preamplifier, EQ, inserts, and amplifier output stages before it reaches the speakers. This technique allows the engineer to avoid bleed in a live scenario, as well as any undesirable tone added by the speaker cabinets or microphone. When used with contemporary speaker emulation plug-ins, this technique enables the engineer to benefit from both the flexibility of digital modeling and the improved non-linear response of a real analogue amplifier.

Features include groundbreaking direct tones.
When class-A discrete amplifiers meet Rupert’s handmade transformers, your tone improves significantly. The RNDI is loaded with unique components and design knowledge that make it worthy of the Rupert Neve brand.

Huge headroom.
The RNDI’s large input headroom of +21.5 dBU allows it to handle professional, line-level sources without a pad, and in speaker mode, it can withstand the full output of a 1000-watt power amplifier (92 Vrms or 266 Vp-p).

Rugged Solid Steel Frame
The sturdy steel chassis includes an industrial-grade powder finish and is engineered to endure the harsh strains of life on the road.

Takes All Kinds
The RNDI’s 2 mOhm discrete FET input and large headroom ensure extremely consistent performance across a wide range of sources. The RNDI works well with basses, guitars, acoustic instruments, keyboards, and even professional line-level devices. In instrument mode, you can also connect a professional line-level interface output to “re-preamp” a previously recorded source.

Drive longer lines.
The low-impedance transformer-coupled output (less than 50 ohms) can drive lengthy lines with unequal high-frequency performance.1/4″ THRU Output.
In instrument mode, the THRU output can be routed to the amplifier input for reinforcement. In speaker mode, the THRU is used to feed the amplified signal into the speaker.

Best-in-Class Phase Coherence
Phase coherence is excellent at all frequencies, keeping the sound well-balanced and natural. This is especially important when blending the direct signal with a microphone recording of the same source.

Ground Lift
A ground lift switch is provided on the back to assist with any grounding issues.

Phantom Powered.
The RNDI uses normal 48V phantom power. Power is shown by a blue LED on the front panel.

Features:

• Mono Active Direct Box with Custom Transformers.
• Transformers and active circuits offer total circuit isolation.
• The device features gold-plated XLR output, 1/4″ input, and Thru jacks. It is powered by a 48V Phantom.
• The extremely low output impedance and phase shift produce excellent, consistent performance.
• Rugged steel chassis designed to endure life on the road

Specifications:

Noise was measured at unweighted output frequencies of 22Hz-22kHz with source impedances ranging from 150 Ohms to 10,000 Ohms.
Higher than -110dBV input impedance.
Instrument setting: 2.2 megaohm.
Speaker setting: 200k Ohm
Output Impedance
Less than 40 Ohms.
Frequency Response: +/- 0.25dB from 25Hz to 44kHz, +/- 1dB from 12.5Hz to 63kHz, and -3dBu at 92kHz.
Maximum Input Level: +21dBu. Typical speaker = +41.5 dBu, 92 Vrms (266 Vp-p)
Maximum output level: +11.5 dBu at maximum input level.
Total Harmonic Distortion plus Noise at 1kHz and +20dBu input level: 0.25%. Typical (2nd and 3rd harmonic) at 1kHz, -20dBu input level: 0.015%. At 20Hz and -20dBu input level, the typical second and third harmonic is 0.75%.
Power Requirements: Phantom power (4.5mA @ +48VDC)
Weight – 1.5 lbs
Dimensions: 6.25″ long x 4″ broad x 1.5″ high

For musicians, audio engineers, and producers who demand pristine sound quality and versatile connectivity in their signal chain, the Rupert Neve Designs RNDI-S Stereo Active Transformer DI offers a professional-grade solution. Whether you’re recording instruments, routing signals on stage, or integrating studio gear, this active DI box ensures your audio remains clear, balanced, and free from unwanted noise. It addresses common issues such as impedance mismatches, signal degradation, and ground loop hum, providing a reliable interface that preserves the integrity of your sound.

At the heart of the RNDI-S is its active circuitry combined with proprietary transformer technology. Unlike passive DIs, this active design ensures a high input impedance and a transparent, low-noise signal path. This means your instrument or line-level sources can be connected without losing tonal detail or dynamics, resulting in a sound that’s true to your original performance. The built-in transformers further enhance the audio by delivering warmth and depth that elevate the sonic character, making it ideal for capturing the nuances of acoustic guitars, keyboards, or other stereo sources.

One of the standout features of the RNDI-S is its stereo and dual mono channel capability. It accommodates two 1/4″ TRS inputs, typically used for instruments or line-level devices, as well as a 1/8″ TRS input for stereo sources like laptops or mobile devices. This flexible input configuration allows seamless integration of multiple sound sources without requiring additional gear. The outputs include two 1/4″ thru connections to maintain your original signal path and two balanced XLR outputs that feed clean, balanced signals to mixers, consoles, or audio interfaces. The inclusion of a ground lift switch helps eliminate hum caused by grounding issues, ensuring a quiet, professional setup.

Powered by standard 48-volt phantom power, the RNDI-S does not require batteries or external power supplies, simplifying your setup and reducing cable clutter. Its compact footprint, measuring just 7 inches wide, 5 inches deep, and 1.75 inches tall, makes it easy to fit on pedalboards, in racks, or on studio desks without taking up unnecessary space. Despite its small size, the build quality is rugged and dependable, designed to withstand the rigors of live performance and frequent transport.

In practical terms, the RNDI-S is an essential tool for anyone needing to convert unbalanced instrument or line-level signals into balanced outputs for professional audio systems. It excels in live sound environments where noise reduction and signal integrity are paramount, as well as in studio recordings where capturing the authentic tone of instruments is critical. Its stereo functionality is especially valuable for keyboard players and multi-mic setups, providing a clean and balanced stereo image without compromising headroom or clarity.

Choosing the Rupert Neve Designs RNDI-S Stereo Active Transformer DI means investing in a premium accessory that elevates your audio quality and workflow. Offered at a competitive price of ₹66,490, down from the regular ₹73,900, it delivers outstanding value given its superior components and reputation for sonic excellence. With this DI box, you gain confidence that your sound will be delivered with fidelity, warmth, and professional-grade performance every time you play or record.