Highland Dynamics Dual Delta 4-7 Mk2

Much more than ‘just’ a preamp, the Dual Delta from Highland Dynamics is also a versatile and creative tone‑shaping tool.

The Highland Dynamics Dual Delta 4‑7 Mk2 is a boutique, vintage‑inspired dual‑channel valve preamp, whose price makes it clear that it’s aimed at discerning users who know what they want and are prepared to pay for it. Over the weeks I’ve had the review unit, I’ve been impressed, by its sound and flexibility. It’s proven to be considerably more versatile than I’d expected — and a lot more fun!

Highland say it’s based on “designs from the early ’60s in England,” and the product’s name strongly hints at that inspiration lying in the EMI REDD.47. But the Dual Delta (as I’ll call it from here) feels very much its own thing, very much a modern interpretation rather than a clone.

Overview

Worth noting up front is that describing this device simply as a ‘mic preamp’ really undersells it. It most definitely has character, it doubles as a well‑specified DI box and line‑level processor — one that’s capable of anything from subtle harmonic enhancement to aggressive distortion. It can be used for parallel processing too, so it’s equally attractive as a colour box or saturation tool.

This all comes in a solidly constructed 2U rack unit that features white legending on an all‑black faceplate, which is clear and easy to read. The two identical channels arrange suitably vintage‑looking chicken‑head and knurled knobs, metal toggle switches and the instrument in/thru jack sockets in a layout that’s both distinctive and practical. Around the back, the Dual Delta keeps things simple, with just two pairs of XLR connectors, an IEC mains inlet, and a bright blue externally‑mounted transformer that protrudes a few inches from the panel.

Nothing to see here on the rear... well, apart from that mahoosive blue mains transformer!

The input gain stage features EF86 pentode valves, while output amplification is handled by a 6DJ8 dual triode. The microphone and instrument input levels are set using continuously variable pads and, when fully padded, the mic preamp functions as the line input. The balanced microphone input’s impedance is switchable between 600Ω and 150Ω, while the DI presents a fixed 1MΩ input impedance, making it suitable for passive instruments. There’s also a four‑position high‑pass filter for each channel.

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