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 microcontroller running proprietary firmware that not only controls all the parameters of the SPE’s passive filter network, but also handles two‑way communication with the front panel and, via USB, with the SPE plug‑in.
As its full name implies, the circuitry that performs the actual equalisation is entirely passive. Four separate filters, Lo Cut, Lo Boost, Hi Boost and Hi Cut, make up the network, the design of which follows that of the EQP‑1A (a design which, incidentally, was originally licensed by Pultec from Western Electric). The Lo Boost and Lo Cut filters can deliver 15dB of boost and 16dB of cut, and possess the same shelving responses and the approximate half‑octave frequency offset that, when the two filters are used simultaneously, produce the famously characteristic ‘boost and cut’ curve. In the Hi filters, the SPE delivers up to 18dB of boost and 16dB of cut. The overall audio performance is impressive, delivering an overall frequency response within ±0.2dB of 20Hz‑20kHz, a dynamic range of 101dB and THD+N ratio of 0.009% (+4dBu, 1kHz). Maximum input and output levels are +24dBu and +27dBu, respectively, with an output gain adjustment range of ±8dB.
Plug‑ins are an integral part of the Bettermaker approach and the SPE plug‑in, available in AAX Native, AU and VST3 formats and compatible with Mac OS 10.11‑12 and Windows 8‑11, enables remote control, adjustment, automation and snapshot storage of all SPE parameters. The plug‑in appears as a virtual replica of the SPE’s physical front panel, and adds an extra encoder and button to control the operation of its variable, 20Hz‑250Hz 24dB/octave digital high‑pass filter (DHPF). This filter sits in the signal path after the A‑D conversion of the analogue return from the hardware SPE, giving you the useful ability to insert an instance of the plug‑in on any track in order to access the DHPF.
In addition to the DHPF, the plug‑in makes available a 32‑slot snapshot memory and an FFT spectrum analyser that displays both the pre‑EQ and post‑EQ signals, allowing you to see the effects of any EQ changes that you may make. The spectrum analyser has its own dedicated control panel that allows you to switch the display on/off, select the source (stereo or either channel), change resolution, set window size, and set the speed, slope and zoom of the display.
I spent a bit of time with the SPE patched in straight after my Tegeler Audio Manufaktur Crème mastering compressor/EQ, which is a permanent fixture in my stereo bus chain. If you read my review of the Crème in SOS October 2017, you may recall that it has a boost‑only, multi‑frequency, two‑band Pultec‑style EQ, and comparing its EQ with that of the SPE was an interesting experience.
Unsurprisingly, due to the differences between their respective peak and shelving responses, although the SPE couldn’t quite do what the Crème does in boosting the high frequencies overall, the greater precision offered by its variable Hi Boost bandwidth more than justified its presence. Low‑frequency boosts were much closer in effect, but the SPE’s Pultec‑style ability to simultaneously cut and boost in the bass band produced results on certain old mixes that left me wishing (somewhat wistfully!) that I’d owned an SPE back in the day.
Overall, the SPE’s audio performance was exemplary, and whilst it does more or less exactly what a Pultec EQP‑1A does in the equalisation department, its sonic signature is entirely its own. You’re not going to run your signal through an SPE to get some of that three‑transformer and tube‑amp goodness that the Pultec is prized for as those particular items don’t exist in it, but what you do get is a transparent, crisp, precisely defined, modern sound that still somehow manages to convey a subtle sense of the warmth and weight of its spiritual ancestor.
However, all gods have feet of clay, and operating the SPE manually was, at times, a little frustrating because there seems to be no consistent correlation between the number of encoder detents that it takes to move an LED one place around its indicator ring, and this makes it well‑nigh impossible to recall a setting manually. Mitigating that are the facts that this does force you to use your ears, and, of course, the plug‑in remote control...
Once you’ve installed the SPE plug‑in (a painless process), connected the SPE to your computer via USB, and inserted the plug‑in into a stereo track or mix, connection between the software and hardware is very fast — the plug‑in GUI takes control of the SPE almost immediately. Assuming that you’ve already set up an analogue send/return loop between your audio interface and the SPE, you’re all set.
The only deviation from the physical front panel appearance in the GUI is the variable 20Hz‑250Hz, 24dB/octave, digital HPF. Since this sits in the return path post the audio interface’s A‑D converter I found myself starting with it off whilst equalising a mix, and only turned it on to remove anything that turned up in the extreme low end which I didn’t want to hear. In my home studio, a 20/30 Hz shelving boost will throw up something every time, so this HPF was an extremely useful addition. It also has its uses when tracking, should you need to remove any sub‑bass artefacts from microphones in the same space, be they separate sources or a stereo pair.
The plug‑in’s 32‑slot snapshot facility is another useful feature, especially since its undo/redo function allows you not only to instantly check the effect of an EQ change against its previous setting, but also, seemingly, to step backwards and forwards through everything that you’ve done. The supplied manual is somewhat sketchy on operational details but, from my experience, snapshot 1 is loaded by default at startup and if this is empty, all functions on the SPE will be reset to their minimum positions. Any changes will then be automatically saved to that snapshot. To create or recall another snapshot, you select another location (either by using the arrows in the Snapshot bar or by opening the Snapshot window), which will instantly load its settings if already programmed, or reset the SPE’s controls if empty. A copy and paste function allows you to load a previously‑stored snapshot into a different slot for further editing. As you’d expect, snapshot recall can be automated within your DAW, as can changes to individual parameters.
The FFT spectrum analyser is a useful tool should you wish to visualise the effect of the SPE’s filters and the plug‑in’s DHPF on the original signal as it displays both the signal going to the SPE and the return signal post the DHPF. Although being able to adjust the analyser’s resolution, response and window size is useful, the Freeze function is somewhat impractical as the display does not stop moving immediately.
Finally, the front panel’s ‘foot of clay’ is still in evidence in the GUI: despite the fact that adjusting an encoder using a mouse brings up a pop‑up window that runs from 1‑10 (1‑8 on the Gain encoder) in 0.1 steps — so giving you precise control — the inconsistent correlation with the movement of the indicator LEDs remains.
Whilst it does more or less exactly what a Pultec EQP‑1A does in the equalisation department, its sonic signature is entirely its own.
Despite that irritation with the indicator LEDs, which I am sure will be addressed going forward, I was very impressed by Bettermaker’s Stereo Passive Equalizer. Its overall audio performance is superb, delivering sonic clarity and precision whilst carrying a subtle hint of weight and warmth. Most importantly, you can exploit a simultaneous Lo Boost and Lo Cut to deliver the famous ‘boost and cut’ EQ curve on which the reputation of the Pultec EQP‑1A was built. Good though the SPE is on its own, it absolutely blossoms when it’s paired with the companion plug‑in and your DAW, giving you full remote control and recall, plus the ability to add automated analogue EQ to a mix.
A device such as this inevitably has a professional price tag, but given that this is a stereo processor with a very high level of audio performance, and one that’s capable of being automated inside a DAW, I believe the SPE still represents good value for money. There’s still something about the sound of good analogue hardware that inspires me more than even the best of software emulations, and if you feel the same, the Bettermaker Stereo Passive Equalizer deserves a place near the top of your audition list.
If the idea of plug‑in‑controlled analogue processing appeal to you, also check out the offerings of Wes Audio and Tegeler Audio Manufaktur. A slightly different approach is offered by McDSP through their APB range.
- Passive analogue equalisation.
- Superb sonic performance.
- Parameter automation and instant snapshot recall via companion DAW plug‑in.
- Does that Pultec low‑end magic trick.
- Inconsistent correlation between digital controller values and indicator LEDs.
A great‑sounding, digitally‑controlled, Pultec‑derived stereo passive equaliser that can be integrated into a DAW studio workflow through its dedicated companion plug‑in.
£2049 including VAT.
KMR Audio +44 (0)20 8445 2446