“A fully customizable amp-in-a-box experience”: Has Catalinbread’s Dirty Little Secret Deluxe just redefined amp-like overdrive pedals?

Catalinbread has supersized its venerable Plexi-in-a-box drive pedal and launched a Deluxe version of its Dirty Little Secret – “The ultimate Marshall Plexi emulation and fully customizable amp-in-a-box experience”, according to the company.

You think you know an overdrive pedal and then you check back in on it and the thing has grown, acquired new features, and then makes an even more persuasive case that it should be added to the pedalboard, stat. This looks to be one of those occasions.

The Dirty Little Secret has always been a top-tier option for players whose tastes in electric guitar tone were shaped by the Marshall amps of the late ‘60s and early ‘70s, but sadly, like the rest of us, don’t really have the space nor the opportunity to grab one of these vintage amplifiers, turn it up and push air around the room.

This Deluxe version has even more tone-shaping capabilities. And, okay, the enclosure is bigger, but Catalinbread has positioned the outputs on the top of the unit, and is banking on all these new capabilities persuading you that it’s worth the extra real estate on the ‘board.

As per previous versions of this hardy perennial, the control setup is reassuringly amp-like, with, left to right, knobs running Master, Preamp, Presence, Treble, Middle and Bass. 

There is a Boost Volume mini-dial and a SB/SL mini-toggle for switching between the upper-midrange bite of the Super Lead and the smoother, lower-mid warmth of the Super Bass modes, a new feature that Catalinbread describes as the most-requested in its history.

As ever with Catalinbread, there’s more than meets the eye. There’s a Tightness control under the hood that applies a subtle high-pass filter to attenuate some of the bass – and mids – when at maximum. 

Catalinbread Dirty Little Secret Deluxe | Plexi-In-A-Box & Boost Pedal - YouTube

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The Master control is designed to be more “impervious to input saturation than most power sections”, meaning you can crank it without it noticeably affecting the tone. But Catalinbread says there is still some sag and a little compression at all positions of the volume.

The Preamp has been given a wider gain range, more cleans, and more dirt than before. Presence? Well, Presence is new. That used to be an internal trimmer and now it’s up front as on the amps that inspired this whole enterprise, applying a low-pass filter taking 3dB off frequencies above 1.59KHz when fully counterclockwise, and opening right up when turned fully clockwise.

The Boost will behave a little differently depending on whether it is run in front of or after the drive. If before, it behaves like an extra preamp tube and gives you a bit more saturation on the front end – Catalinbread’s tasting notes suggest a whiff of “JCM900”. Run it post-drive and it just makes it all louder.

Catalinbread Dirty Little Secret Deluxe - YouTube

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Finally, the three-band EQ behaves similarly to the tone stack on a Marshall, and the controls are highly interactive. They are passive too, so setting it at noon is not flat. You might find yourself running this with the Bass at 10 o’clock. 

And there is more – they don’t call it the Deluxe for nothing. There’s a line out offering a +10dB output for sending the signal direct to desk or DAW, and you can use the direct and regular outputs simultaneously.

The Dirty Little Secret Deluxe is available now, priced $/£299. See Catalinbread for more details.