Class A passive tube equalizer

“Sounds fabulous” (Resolution)

The MCAudioLab EQ1 is designed to deliver the soft and musical tone of vintage passive tube EQ designs. We pay our tribute to a classic sweet-sounding EQ topology, but we don’t revere the noise floor and limited headroom of the collectibles: the EQ1 meets the high performance standards required by modern professional studios. Great vintage tone, and it’s about as silent as it gets.

The EQ1 shines on vocals, bass, drums, guitars and pretty much anything you throw at it. You can use it for its sweet and musical tone shaping, or simply run your tracks through the EQ in flat mode to add some vintage tube warmth. And it’s a great master insert too: we’ve had more than one engineer come back and pick up a second unit for buss duties.

On top of it all, the budget-aware price tag makes the EQ1 a great choice for smaller project studios ready to step up to some out-of-the-box analog magic, and for seasoned pros who are looking for a sweet high-performance classic passive EQ.

Front panel design

The LF shelving section of the EQ1 features the classic boost/cut ergonomy. Use the stepped frequency selector to move your low shelf between 20, 30, 60, 90 and 150 Hz. While the Boost shelf starts from the selected frequency, the Cut knob acts on ten times (10x) that frequency to produce a soft low-mid scoop: great for rounding out the tone while carving out some boxiness or mud.
The HMF Boost section operates in the 600 Hz - 16 kHz range and is parametric, so you have and additional bandwidth control. This is especially useful to tailor the interaction with the HF shelf, which produces a sweet and natural but effective high cut in the 4 kHz - 20 kHz range.
The EQ1 features a tube make-up gain to compensate level changes due to the equalization. Use the Output control to set the final level while checking the 3-LED meter for visual reference. Finally the true Bypass switch lets you completely disengage the EQ circuitry from the signal path.

Classic tone without the quirks

When engineers put their hands on the EQ1, the feedback we receive usually goes “sounds fabulous even at insane settings, and it’s incredibly silent!” That’s more or less our mantra: we put a huge amount of effort in nailing a great tone while keeping our gear up to the performance standards of state-of-the-art modern recording studios. From a design point of view, this means class A operation, hand-picked tubes, Lundahl transformer in the output and an audio path kept as short and clean as possible. And for design purists: yes, you do get your Sowter inductor.

If the EQ1 is your first shot at a passive equalizer, here’s our tip: use your ears, and don’t believe what the front panel is telling you. That’s because it’s somehow a lot more of a musical tone shaper than a surgical EQ tool. You can dial in ridiculous amounts of boost and cut - and in frequency ranges you’d normally be very careful with.

Try boosting 20 Hz and hear for yourself: the sound becomes rounder, softer and richer without losing definition or becoming muddy. You can be equally generous with high-mid and high frequencies without that piercing glass effect. You’ll never feel you’ve gone too far, and even at extreme filter settings you won’t hear frequencies jumping out at you or typical weird EQ artifacts.

A true beauty in passive EQs is the extremely musical interaction between frequency bands: use overlapping filter settings to create resonant shelves. Once you’re done tweaking your HF, start tweaking the high mids and lows to see how this affects the overall tone shaping of your source.

And when you don’t really need to EQ, you can still run your tracks through the EQ1 with flat settings to benefit from the subtle warmth and sweetening provided by the tube output stage and Lundahl transformer.

Tube vs. solid state power supply: pure vintage or modern tone

The standard version of the EQ1 is fitted with our custom tube power supply (EQ1tp), which provides a subtle harmonic enhancement and a typically vintage soft peak limiting for a fat, rich and warm sound. If you’re after a 100% classic tone, this kind of behaviour can save you a lot of hassle in the mixing stage. You can find out more about our tube power supply in this tech article.

If you prefer a different dynamic response, we offer the option of a solid state power supply (EQ1ch) similar to the technology typically used in modern gear: you still get the great tone provided by the tube EQ circuitry and output stage, but the overall tone is more transparent and transients remain unaffected by the power supply.


In the box:  SKNote MCAudioLab EQ1 plug-in

The great guys at SKNote coded a software emulation of our EQ1. Sounds more than right, and with the software version you get quite a number of additional goodies: dual channel operation (L-R or M-S) with linked or independent controls, switchable tube/solid state power supply and master output level controls. Available in VST/AU formats for Windows and Mac OS, and free with every hardware EQ1 purchase. Head over to www.sknote.it for pricing and purchase info.


- Single channel class A 3-band passive tube equalizer
- LF: shelving, typical Boost/Cut controls, stepped frequency selector (Boost 1x, Cut 10x)
- HMF Boost: parametric, stepped frequency selector, Q control
- HF Cut: shelving, stepped frequency selector
- Extremely low distortion and noise floor, high headroom
- Tube make-up gain stage with Lundahl transformer in output
- 3-LED output level meter
- True bypass switch
- Separate Ground and Earth lift switches to avoid ground loops
- Optional solid state power supply (EQ1ch)

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MCAudioLab EQ1 video tutorial (c) MCAudioLab
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