Boasting a custom Rupert Neve‑designed transformer, one of the best‑sounding DI circuits out there just got more affordable.
It’s almost a decade since I reviewed Rupert Neve Designs’ (RND’s) first active DI, the RNDI. Including the newer two‑ and eight‑channel variants that followed, RND have now sold some 35,000 channels (and counting!) of that circuit. But it’s always been priced for professionals...
Now, the company’s RNDI‑M Active Transformer Direct Interface puts the same Class‑A, FET‑based input stage and custom transformer in a more pedalboard‑friendly box for a significantly lower price, something made possible by the decision not to cater for power‑amp outputs (if that’s important to you, the RNDI remains available).
Outside & In
The RNDI‑M is an active design, that takes its power from a preamp’s 48v phantom supply.The RNDI‑M’s rectangular metal enclosure has a classy black and light grey aesthetic. Paralleled In and Thru quarter‑inch isolated jacks and a 48V phantom power indicator LED are located on the front. On the rear are a balanced output XLR and a switch to lift the pin 1 chassis ground. Inside, the phantom‑powered circuitry sits on a single PCB carrying the connectors, LED and switch, along with the input stage and the transformer, which isolates the unbalanced input and balances the output.
The input stage accepts levels up to +20.5dBu, so the RNDI‑M can handle any electric guitar or acoustic preamp, modeller, effects pedal, modular synth, keyboard, drum machine or (if you gain stage correctly) other line‑level source I can think of.
The 2.2MΩ input impedance also ensures that passive guitar/bass pickups see a suitably high load, even if connected in parallel to a typical amp or pedal. The voltage loss inherent in such a configuration is negligible, and is in any case due almost entirely to what you connect to the thru output. In other words, not only does the RNDI‑M correctly load passive guitar/bass pickups, but also, all but the tiniest percentage of the voltage produced by the pickup reaches both the RNDI‑M and any connected amp or pedal.
The noise floor (‑110dBu) and frequency response (28Hz‑60kHz ±0.25dB) are also impressive, and ensure that the RNDI‑M sounds quiet and transparent. Importantly, that allows the subtle sense of body and warmth that’s created by the transformer to really shine. With an output impedance of only 40Ω, this transformer is also capable of driving long cables with minimal signal loss, at output levels up to a maximum of +11.5dBu.
Inside the RNDI‑M, everything sits on a single PCB, including the Rupert Neve‑designed R‑5052 transformer that’s responsible for much of the unit’s subtle but pleasing musical character.
Boxing Clever?
As I’d expected it would, the RNDI‑M performed impressively, conveying the sound of connected instruments with clarity, depth and precise detail. In fact, I couldn’t fault it: as well as accurately reflecting the characters of various electric guitars and basses and delivering detailed results from my growing collection of synths — all of which I’d expected — it underlined the individuality of my acoustic guitars and the various piezo pickup/preamp combinations I use.
The subtle but distinctive sense of warmth, definition and depth is extremely attractive, both sonically and musically.
Much as I love the sonic character of Rupert Neve’s vintage transformer‑based designs, I believe that much of his best work was done later in the USA, and the R‑5052 transformer is a case in point. As with the original RNDI, the subtle but distinctive sense of warmth, definition and depth is extremely attractive, both sonically and musically, and it becomes more pronounced at increased signal levels as the input stage and transformer increase their contribution.
The RNDI‑M’s sonic performance places it amongst the best active DIs that are currently available. My own go‑to DI is a similarly priced phantom‑powered, FET‑based, device, but it’s transformerless and, wonderful though it is, it can sound somewhat ‘clinical’ compared with the RNDI‑M. The one DI that I have which can keep up with the RNDI is a valve‑plus‑transformer 500‑series module costing over three times what the RNDI‑M does — so the RNDI‑M is priced competitively too. If you want a high‑quality, transformer‑based active DI box that also offers ‘a certain something’ sonically, the new RNDI‑M should definitely be on your shortlist.
Summary
Equally at home in the studio or on stage, the RNDI‑M delivers a superb sonic performance, conveying detail, clarity and precision, while also lending a sense of warmth and weight.
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