The Keeley Super Bass Overdrive and Distortion is an amp-in-a-box overdrive pedal from Keeley, built to put the character of a specific amp on a pedalboard. Guitar World describes it as "a Marshall-amp-in-a-box JFET overdrive pedal", replicating the Marshall Super Bass, a 100-watt amp the magazine notes was "adored by Jimmy Page"12. It sits in Keeley's collaboration with Sweetwater, where "the Sweetwater/Keeley tag team has built an amp-in-a-box based on a legendary, and tactfully unspecified, amp"2.
What it does to your sound
As an amp-in-a-box design, the pedal aims to deliver the drive character of the amp it models without needing that amp behind it. Keeley champions how its "amp-like sensitivity responds to your pick attack", meaning the pedal tracks how hard you dig in rather than flattening everything to one level2. Guitar World's news piece adds that "there's plenty of dirt to be drawn from its Level, Tone, and Drive knobs"2.
The Open/Closed switch changes the speaker-cabinet emulation behind the drive. It toggles between Open Back and Closed Back amp emulations, a two-way switch Guitar World calls "a nifty toggle"2. In the reviewer's testing, "the Open setting was more versatile, but with a bit of EQ tweaking, the Closed mode was heavier and more resonant for chunky riffing"1.
The JFET circuit
The pedal uses a JFET-driven circuit working beneath its all-black housing2. JFETs (junction field-effect transistors) are a common choice in amp-in-a-box designs because their response can resemble the way tube stages clip and compress. Guitar World's reviewer summed the approach up: "this JFET amp-in-a-box is a wonderful-sounding, affordable and fun alternative"1.
What reviewers said
Guitar World's reviewer, Alex Lynham, came away impressed. His verdict on the pedal:
"The Super Bass is excellent. Even as a fuzz lover, I have to admit that it was this pedal of the three that caught my imagination."
He found it worked well into every amp with whatever guitar he paired it with, and that it "comes alive pushing a tube amp with level past 1 o'clock"1. In other words, like the amp it models, it rewards being driven hard rather than run quietly into a clean channel.
How it fits Keeley's range
The Super Bass is one of several drive pedals in the Keeley line, alongside the Keeley Noble Screamer, the Keeley Manis, the Keeley Blues Disorder and the Keeley Tube Drive. Where those cover Tube Screamer-style, Klon-inspired and tube-powered approaches, the Super Bass takes the amp-in-a-box route, aiming at one specific amp's voice. For more on the wider category, see Overdrive Pedals and Distortion Pedals12.
Videos
A77.STUDIO
The Bad Guitarist
The Distortion Principle
Questions
Is the Keeley Super Bass Overdrive and Distortion true bypass?
Yes. Guitar World's reviewer listed the Super Bass as true bypass, meaning the pedal takes itself out of the signal path entirely when switched off, leaving your guitar's signal untouched until you engage the effect.
What amp is the Keeley Super Bass Overdrive based on?
It is an amp-in-a-box pedal built to replicate the Marshall Super Bass, a 100-watt amp that Guitar World notes was adored by Jimmy Page. Keeley packaged that amp's character into a pedal with Level, Tone and Drive controls and an Open/Closed switch.
What does the Open/Closed switch do?
The two-way toggle switches between Open Back and Closed Back amp emulations. Guitar World's reviewer found the Open setting more versatile, while with some EQ tweaking the Closed mode was heavier and more resonant, better suited to chunky riffing.
Does the Keeley Super Bass Overdrive use a JFET?
Yes. Guitar World describes it as a JFET amp-in-a-box overdrive, with a JFET-driven circuit working beneath its all-black housing. JFETs are transistors often used to mimic the feel and clipping behavior of tube preamp stages.
Sources (2)
- Keeley x Sweetwater Soft Reverb, Super Bass Overdrive and Distortion and Suns Ultravoid Fuzz review, Guitar World, 2025-03-10
- Keeley launches $99 Sweetwater-exclusive pedal series, Guitar World, 2025-01-06
