Catalinbread Dirty Little Secret Deluxe

The Catalinbread Dirty Little Secret Deluxe is a Marshall Plexi emulation pedal, an amp-in-a-box built by Catalinbread that models a full Plexi signal path: an all-discrete analog circuit with a preamp, phase inverter, power amp sim and output transformer¹. What started internally as a fourth version of the flagship Dirty Little Secret grew into the Deluxe, adding an external Super Lead/Super Bass toggle, a rebuilt tone section, a built-in boost, and a +10dB line out for direct recording¹.

The boost side is a single preamp tube simulator taken from the Dirty Little Secret circuit, and it works on its own or with the main overdrive². Catalinbread describes the result as a six-amp experience: boost alone gives chime-y Marshall cleans, the DLS side alone gives a cranked Plexi, and both together give the sound of a roaring JCM, in both Super Lead and Super Bass voicings¹.

A Plexi preamp in a pedal, with a boost

The Deluxe goes further than earlier Dirty Little Secret pedals by modeling more of the amp than the preamp alone. Inside there is a MOSFET-driven phase inverter and power amp sim, along with an output transformer that Catalinbread says injects "a little iron" into the signal¹. The Master control sits before the phase inverter and output transformer rather than at the end of the circuit, just as on a real amp, so cranking it does not noticeably change the tone; at full volume it adds subtle sag and gentle compression, which Catalinbread suggests suits always-on use¹.

The boost is a piece of the Dirty Little Secret itself, a single preamp tube simulator that can run independently of the main circuit². The two sides can be ordered either way: boost before the DLS for a high-powered saturated tone, or boost after it to pummel the front end of your amp². Catalinbread ships the pedal with the boost first, and an internal switch reverses the order¹.

The controls

The Deluxe carries two footswitches, Boost and Bypass, and its controls sit in a horizontal 1590-BB enclosure⁵.

Because the tone stack is passive, the Bass control in particular is not flat at noon, and the knobs interact the way a Marshall front panel does¹.

Super Lead and Super Bass modes

The external toggle selects between the two voicings: Super Lead mode is a cutting, upper-midrange-heavy tone, and Super Bass mode is smoother and smokier with a lower midrange emphasis¹. On earlier Dirty Little Secret pedals this choice was an internal slider switch⁶⁷⁸, so moving it to the outside of the enclosure is one of the Deluxe's practical changes. The Super Bass voicing follows the tone and gain structure of a Marshall Super Bass, which is very similar to a JTM45 or JTM50/100⁹.

Power, outputs and direct recording

The pedal runs on a 9-volt center-negative DC supply delivering at least 7mA¹.

The rear panel adds a Line Out, a dedicated +10dB output for direct recording or mixing into a DAW¹. The dry signal is boosted to +10dB on that jack, and the standard output and Line Out can be plugged in at the same time, so you can feed an amp and a mixer at once¹. Because of this output split, the pedal uses a buffered bypass with an output buffer to preserve signal integrity¹.

History and versions

The Dirty Little Secret line goes back over a decade. The Mk. II arrived in 2011 and was replaced in 2013 by the Mk. III, a full redesign that Catalinbread has kept in production¹⁰. The Mk. III launched on February 12, 2013 with a redesigned three-knob treble-middle-bass tone control that reconfigures for each mode setting¹¹. Its gain range runs from classic plexi to modified JCM800 levels in Super Lead mode⁹.

The Deluxe began as a fourth version of the circuit and ended up as its own pedal, released in September 2023¹⁴. It followed a run of limited editions, including the DLS Red Mod, a hot-rodded version of the Mk. III in a red enclosure with more gain and a more hi-fi EQ section¹²¹³. Compared with the standard Mk. III, the Deluxe externalizes the Super Lead/Super Bass switch and adds Presence and Boost controls⁵.

What reviewers said

Guitar Pedal X's reviewer could not fault the control topology or feature set, and considered the $299 price about right⁵. The same writer noted that Andy Martin has long cited the Dirty Little Secret as his favorite Marshall-in-a-box pedal⁵.

MusicRadar's Trevor Curwen reviewed the standard Dirty Little Secret as "a versatile tone-building dirt box with two distinct M-style flavours"¹⁴, and on That Pedal Show the hosts called it "very vibby" with a real classic character¹⁴¹⁵. Dave Depper, in a Strymon pedalboard feature, called it "the best Marshall-in-a-box pedal I've come across"⁷.

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