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Bereich03 Audio BAX-EQ

500‑series EQ By Bob Thomas
Published August 2023

Bereich03 Audio BAX-EQ

Each band of this mastering‑grade module can process the Mid, Sides or Stereo signal.

The two‑band Baxandall tone control that crops up in millions of hi‑fi units must rank as the greatest gift ever given to the audio industry! Until relatively recently, Baxandall’s signature achievement appears to have been virtually ignored by the professional recording industry but, fortunately, over the last decade or so, a few boutique pro‑audio manufacturers have sought to rectify that situation. Among these is Michael Heilrach’s Munich‑based Bereich03 Audio. Focused entirely on 500‑series‑format mastering equipment, the company have earned a considerable reputation for the functionality, quality and cost‑effectiveness of their products — as evidenced by their reviews in this very magazine. Bereich03’s most recent release, the BAX‑EQ, is a 500‑series, Baxandall‑based mastering EQ, each of whose three bands can be switched individually between Mid‑only, Sides‑only and stereo operation.

The audio performance is impressive, including a frequency response that’s flat from 5Hz until it drops by ‑1dB at 199kHz.


Featuring Bereich03’s signature cosmetics and engraved model designation, the BAX‑EQ is a superbly built double‑width module. The audio performance is impressive, including a frequency response that’s flat from 5Hz until it drops by ‑1dB at 199kHz, a noise level of ‑113dBA, and a maximum input/output level of +24dBu. All the rotary controls are selector switches, and a solitary LED illuminates when the BAX‑EQ has been activated, and taken out of hard bypass.

Controls for each band are identical. A dial on the left sets the band’s corner frequency, and between it the gain control on the right sit two toggle switches, the upper selecting between Mid, Sides and full stereo operation, and the lower setting the gain function to boost or cut mode. Two gain configurations are available: ±5db in 1dB steps, and ±3dB in 0.5dB steps. As you’d expect, the high and low bands have a shelving response that appears to be classic Baxandall, whilst the mid band has a bell‑shaped response with a wide Q and relatively gentle frequency response curve that gives you the ability to finesse the midrange.

The corner frequency choices for each band are decidedly individual and, I would imagine, drawn from Michael Heilrach’s long experience as a mastering engineer. The high‑shelf frequencies are 1.2, 2.5, 4.7, 8, 11 and 18 kHz; the midrange’s are 190, 340, 540, 770 and 1100 Hz; and the low shelf offers 35, 47, 62, 82, 120 and 210 Hz.

Bereich03 Audio BAX-EQ

In Use

I inserted the BAX‑EQ into my master bus after my Tegeler Audio Crème mastering compressor, which features a passive, boost‑only, two‑band Pultec‑style EQ with shelving treble and bass. The first thing I noticed is that operating the BAX‑EQ’s switches produces low‑level transients, some of which can be audible — not a big deal for me, as I don’t change master bus compression and EQ within a track, but your workflow may differ. Other than that, when set flat and whether in or out of circuit, the BAX‑EQ is completely transparent: it adds and subtracts nothing.

As a stereo two‑band equaliser, the BAX‑EQ has a much wider high‑frequency coverage than the Tegeler and, although I preferred the BAX‑EQ overall, there were tracks where the Pultec’s more granular approach worked better. Add in the BAX‑EQ’s additional mid band and Mid‑Sides capabilities, and the contest is over... though combining the two EQs can create serendipitous results! The BAX‑EQ is intuitive to use, and after working on a few masters, stem projects and complete mixes it didn’t take me long to develop what now serves as my starting point: a 3dB, 82Hz low‑frequency Mid boost; a 1dB, 1.1kHz midrange Sides cut; and a 2dB, 8.0kHz high‑frequency Stereo boost.

The ability to switch each of its bands into either Mid, Sides or stereo mode offers significant sonic benefits that can’t be found elsewhere and, given its audio performance, feature set and price, the Bereich03 BAX‑EQ offers great value for money. Purchasing one is, to me, a no‑brainer: this review example is not going anywhere!


A three‑band, mastering‑grade equaliser for the 500 series, the BAX‑EQ is based on the Baxandall design and boasts an audio performance of the highest quality. It also has the unique ability to run each band in Mid, Sides or Stereo modes.


€700 plus shipping, duty and VAT.

€700 (about $765) plus tax and shipping.