This classy EQ marries vintage tone with the convenience of software control.
Bettermaker, the highly regarded Polish pro‑audio manufacturing company founded by Marek Walaszek, first caught my attention back in 2012 with the appearance of their EQ230P stereo analogue equaliser, which could be controlled and automated digitally by a dedicated DAW plug‑in. The company continued to develop this approach, introducing its premium‑priced Mastering Equaliser in 2018, and elements of that device form the nucleus of their latest product release — the more affordable and considerably less complex Stereo Passive Equalizer (I’ll abbreviate that to SPE from here on).
As with both its hardware ancestors, the SPE is based around the passive EQ filter network of the legendary Pultec EQP‑1A equaliser. However, unlike the monophonic behemoths from a time when thermionic valves ruled the audio universe, the SPE is a solid‑state, digitally‑controlled stereo equaliser, and it can be operated both from its front panel and, via USB, from a DAW plug‑in. This plug‑in not only offers parameter automation, snapshot recall and remote control of the unit’s functions but it also features a digital high‑pass filter that runs inside the DAW.
The SPE’s surprisingly weighty, black 2U all‑metal chassis and fascia feature silver‑coloured switches and detented rotary encoders, accompanied by a constellation of red indicator LEDs. As is common in EQP‑1A‑derived/inspired passive equalisers, the SPE’s front panel is split into three operational areas: shelving low‑frequency cut and boost; peak‑response mid‑high frequency boost; and shelving high‑frequency cut.
As in the EQP‑1A, the SPE’s shelving +15dB Lo Boost and ‑16dB Lo Cut bands operate at four corner frequencies (20, 30, 60 and 100 Hz). The variable‑bandwidth, peak‑response, mid‑high Hi Boost adds 6kHz and two ‘air’ centre frequencies (20 and 28 kHz) to the Pultec’s 3, 4, 5, 8, 10, 12 and 16 kHz options, while the High Cut shelf sticks with the original’s choice of 5, 10 and 20 kHz. Frequency selection is handled by a pair of up/down momentary buttons in the Lo Boost, Lo Cut and Hi Boost sections, and a single ‘step through’ button in the Hi Cut. A second momentary button linked to the Hi Cut knob, when pressed and released, switches that control to act as an overall +8dB gain, and when held for a couple of seconds resets all the SPE’s EQ parameters to their minimum positions. Lastly, but by no means least, non‑latching buttons labelled Standby and Engage activate switching relays that handle those functions.
The back panel is a rather spartan affair, with two pairs of XLR sockets to carry the electronically balanced left and right audio input and output signals, a USB socket for connection to a computer, and a non‑locking connector for the unit’s 12V DC external power supply.
All the electronics sit on two large rectangular printed circuit boards, the first of which sits vertically behind the front panel, whilst the second occupies most of the enclosure’s bottom panel. The vertical board carries all the front‑panel encoders, buttons and LEDs, with the horizontal board housing the components that make up the digital control circuitry, the identical left and right channel analogue audio paths and the internal power supply for the ±15V rails. As with other Bettermaker products I’ve used, the boards and their components are of very high quality, and the board layout, to my eye, looks impeccable.
All user interactions with the SPE’s analogue electronics, whether manually from the front panel or from a DAW via the SPE plug‑in, are carried out in the digital domain, and are handled by a 32‑bit...