Catalinbread Epoch Bias

The Catalinbread Epoch Bias is a preamp pedal that emulates the preamp circuit from the vintage Maestro Echoplex EP-3 tape delay, the section of that machine that many players ran their signal through just for its tone, delay engaged or not¹. Catalinbread describes it as part of a family of EP-3-inspired pedals that also includes the Belle Epoch Deluxe, the Belle Epoch Tape Echo and the Epoch Boost¹. Delicious Audio called it a circuit derived from the Belle Epoch, which it described as arguably the company's most successful and consequential pedal to date².

Where the earlier Epoch Boost reproduced the EP-3 preamp with a fixed character, the Epoch Bias adds two controls, Bias and Filter, that let a player adjust the circuit's gain and voicing. MusicRadar's Jonathan Horsley framed the appeal: the new controls give players "the chance to dial in the sort of unit-by-unit variances that can be found across the vintage Echoplex units," such as the brighter-voiced first-run Echoplex units¹.

What the EP-3 preamp is

The Echoplex EP-3 was a tape delay, but the part many players cared about was its preamp, a solid-state stage the signal passed through on the way to the tape. Aion FX, whose project pages document vintage circuits, describes the EP-3 preamp as "a pretty simple JFET gain stage, but it does something special with the phase response of the signal"³. That phase behavior is a large part of why running a guitar through an EP-3 preamp was heard as adding gloss rather than just level.

Catalinbread's EP-3-derived line goes back years. The Epoch Pre, an earlier pedal in the line, is now discontinued⁴. Delicious Audio describes the Epoch Bias Preamp as "yet another circuit derived from what's arguably the company's most successful and consequential pedal to date, the Belle Epoch"², and the Belle Epoch and Belle Epoch + carry the Echoplex preamp inside full tape-echo emulations.

Controls and what they do

The Epoch Bias has four knobs: Preamp, Bias, Boost and Filter⁴. Two come from the Epoch Boost and two are new.

The Preamp knob is the heart of the pedal. Catalinbread notes it essentially acts as the "Volume" knob from the EP-3, and that at its core it is a wet-dry mix control⁵. The Boost knob is the one that pushes beyond stock: with it all the way down you get the EP-3 circuit as it was, and turning it up adds gain and volume on top⁵.

The Bias knob addresses something a vintage EP-3 owner could not change. Delicious Audio's Paolo De Gregorio explained that "the Bias control functions like a gain knob, addressing the fixed gain structure of vintage EP-3 units"². On the original units the preamp's gain was fixed; here you can set it yourself. The Filter control, according to gearnews.com, "offers a mixture of the sound characteristics of the first 100 and late EP 3 models"⁶, which is another way of saying it moves the voicing between different vintages of the original machine.

Delicious Audio also flagged a practical use for the Filter beyond tone shaping: the high-cut filter is "particularly useful for guitarists managing multiple guitars or long signal chains," since rolling off some top end can keep brighter guitars or long cable runs from sounding harsh².

How it differs from the Epoch Boost

The Epoch Boost is a preamp/buffer pedal reproducing the early-model EP-3 preamp, with Preamp and Boost controls: one for the level of EP-3 preamp in your signal, plus boost⁷⁸⁴. The Epoch Bias keeps those two controls and adds Bias and Filter¹². MusicRadar called the result "a neat twist on the original Epoch Boost"¹.

In use, the difference is adjustability. The Epoch Boost gives you the EP-3 preamp as Catalinbread voiced it; the Epoch Bias lets you run that circuit hotter or colder and darken it. MusicRadar positioned the Epoch Bias as "something always-on at the end of your signal chain, adding that final bit of gloss, just as many players did with the [Echoplex] head," and as more versatile than the Epoch Boost¹.

Power and setup

This is the same polarity convention as most modern pedals, so a typical center-negative 9V power brick works. For comparison, Catalinbread's Belle Epoch + asks for 9V DC center-negative with at least 200mA available, and warns that center-positive or AC supplies will cause malfunction or damage⁹; the Epoch Bias page does not state a current draw.

Where it came from

The Epoch Bias Preamp sits at the end of a long line of Catalinbread pedals built around the Echoplex EP-3 preamp. Delicious Audio describes it as "yet another circuit derived from what's arguably the company's most successful and consequential pedal to date, the Belle Epoch"². It is available now, priced £179 / $179¹.

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