Dangerous Music BAX

Dangerous Music’s BAX EQ earned an enviable reputation. Now there’s both a 500‑series version and, in a partnership with dynamic‑convolution pioneers Acustica, a new, official plug‑in emulation.

I have real respect for Dangerous Music’s hardware. Whether it be performing analogue summing, D‑A conversion or processing, everything of theirs I’ve owned or had in for review has not only sounded superb, but has measured well too. Very well, in fact. Chief designer Chris Muth has achieved some extraordinary technical specs — for instance, the class‑leading crosstalk discussed in my SOS March 2023 review of their 2‑BUS‑XT summing mixer (https://sosm.ag/dangerous-2-bus-xt-crosstalk).

What Dangerous aren’t so well known for is software. Until now they’ve only dipped their toes in those waters, but their new BAX EQ plug‑in suggests that might be about to change. For reasons unknown, it seems SOS never reviewed the BAX EQ hardware it emulates; that stereo analogue mastering EQ was released in 2011 and would soon enjoy a stellar reputation. Neither have we yet looked at the 500‑series version that was launched at NAMM in January 2026.

So rather than assess the new plug‑in in isolation, I figured it would make good sense to assess it alongside both of the hardware equivalents — and to make that possible, the company kindly sent over a 19‑inch rackmount BAX EQ and a pair of BAX 500 modules.

Dangerous & Acustica

The new BAX EQ plug‑in has been developed from the ground up, using a very different approach from the 2014 plug‑in, which was developed under licence by Brainworx and later made its way into the Universal Audio plug‑in ecosystem. To my knowledge, that was the only official Dangerous Music plug‑in out there until November last year, when I was surprised to see, in a partnership with Acustica Audio and Studio DMI, the CONVERT‑AD+ plug‑in appear. This emulates Dangerous’s A‑D converter of the same name (a converter might not be an obvious target for a plug‑in emulation, but there’s more to that unit than the conversion!). I sensed that the project might, for Dangerous, have been a low‑key way to start exploring software options. Either way, it was clearly a positive experience, because Dangerous looked to the same partnership to develop their BAX EQ plug‑in.

SOS readers may know something of Acustica’s Volterra‑kernel‑based ‘dynamic convolution’ approach, but to simplify, they capture many thousands of impulse responses from analogue hardware at a range of control settings and signal levels, and then create a plug‑in around a sophisticated playback engine that rapidly switches between these IRs. Sonically, it can be incredibly convincing, particularly for ‘static’ effects like EQ and preamps. It hasn’t always been the most CPU‑efficient technology, and users once complained about laggy GUIs and other inconveniences seemingly being the trade‑off. But that’s in the past: Acustica have built on that technology, and the latest engines combine dynamic convolution and an algorithmic approach to deliver sonically convincing plug‑in emulations of analogue hardware that feel much more responsive. It seems to me a very good fit for Dangerous...

BAX Back Story

But before I dive into the plug‑in, it makes sense to explore the hardware. At the heart of Dangerous’ stereo rackmount BAX EQ lies a variation on the famous tone‑control circuit developed by British electrical and audio engineer Peter J Baxandall in the early 1950s. The classic Baxandall EQ comprises a pair of first‑order (6dB/oct) shelves, one for the low frequencies and another for the highs. It’s based on an active, negative‑feedback, RC (resistor‑capacitor) bridge network wrapped around a single inverting amplifier stage, but from a user point of view its attractiveness lay in the simplicity of operation (the circuit meant a single knob could be used for both boosting and cutting) and that the gentle, broad boosts and cuts made it pretty hard to do significant damage. It’s hardly surprising, then, that the Baxandall EQ found a home in many a hi‑fi amp...

Those same features, plus the very low phase‑shift, had strong potential in music production too, but in Baxandall’s original circuit the turnover frequencies were fixed (100Hz low shelf, 10kHz high shelf, I believe), which limited its utility. Several console designers adapted it, not least by offering multiple, switchable turnover frequencies, and pairing it with high‑/ low‑pass filters or peaking/bell bands.

Such variations can be found, for example, in the EQ stages of the Trident A‑Range, and various Neve and Electrodyne desks. But it was Chris Muth at Dangerous Music who first developed a dedicated stereo rackmount version: the BAX EQ. Released in 2011, this treads a broadly similar path to those console EQs of yesteryear, in that its Baxandall shelves have multiple user‑selectable turnover frequencies, and are joined by second‑order Butterworth high‑ and low‑pass filters (a design that creates a smooth roll off, with no ripple or resonant bump). As with the shelves, these filters have a range of user‑selectable frequencies. The bands are arranged in series, with the signal flow following the left‑right front‑panel control sequence: the high‑pass filter feeds the low and high shelf, which in turn pass the signal on to the low‑pass filter.

For the original rackmount hardware and the new plug‑in, the ±5dB gain controls are stepped, in 0.5dB increments, while the 500‑series version’s gain is set using a pot.

It differs significantly from those old console EQs, though. It was conceived primarily with mastering and stereo mix‑bus applications in mind and, as such, the ±5dB gain range for the shelves is controlled in stepped 0.5dB increments, using separate knobs for each channel. The incredibly fine control over the levels makes A/B comparison of settings a breeze and manual recall similarly quick and easy, and the high‑/low‑pass filters combine with the shelves to create sometimes surprising scope to rebalance the energy in complex programme material. But...