Keeley Electronics Boss DS-1 Distortion Ultra Mod

The Keeley Electronics Boss DS-1 Distortion Ultra Mod is a Boss DS-1 distortion pedal that has been modified by Keeley Electronics rather than a pedal built from the ground up¹. The DS-1 itself is a distortion pedal and was the first distortion pedal made by Boss²³. The Ultra Mod keeps the familiar orange box but adds a Mode switch with two settings, Ultra and Seeing Eye, which the reviewer at Pedal of the Day found "just add more sonic possibilities"⁴.

The mod sits in a tradition of boutique builders reworking the DS-1 circuit. MusicRadar notes that "boutique builders such as Keeley and Analog Man have put their own stamp on the circuit"⁵, and JHS Pedals has offered its own DS-1 Lexi Drive Mod, conditioning the pedal "for optimum performance with high quality components"⁶.

What the Ultra Mod changes

The Ultra Mod is a rework of the DS-1's distortion circuit rather than a cosmetic change. Pedal of the Day's reviewer, Mike B., described the modified pedal as having a wide gain range, "giving your signal anything from a slightly overdriven boost to an all-out fuzzy distorted mess"⁴. The same review described the pedal as "Marshall-Amp Tone-In-A-Box"⁴.

A later comparison on Guitar Pedal X gives a sense of how the modded pedal behaves against a stock DS-1 in a real rig. Reviewer Stefan Karlsson wrote⁷⁸:

In other words, where the unmodified DS-1 needed help to sit right in his rig, the Keeley-modded version worked by default. Karlsson also noted on a separate occasion that "for the longest time the Keeley Ultra / Seeing Eye Modded version was my favourite - but I have other preferred varietie[s] now"⁸.

Ultra and Seeing Eye modes

The Mode switch is the mod's main control addition. It selects between two settings, Ultra and Seeing Eye mode, and Pedal of the Day highlighted how quickly you can move between them, "to go from Ultra to Seeing Eye mode with just a flick"⁴. The review credits the switch with adding more sonic possibilities on top of the pedal's gain range⁴.

How it compares to the Boss DS-1W

Boss itself later addressed the DS-1's legacy with the DS-1W, a Waza Craft version announced in October 2022 and based on the original DS-1 Distortion⁹. Where the Keeley Ultra Mod is a third-party modification of an existing pedal, the DS-1W is a Boss-made product with two distortion modes of its own, Standard and Custom¹⁰. Delicious Audio describes the Custom mode as a new mode "next to the Standard one replicating the sound of the original circuit"¹⁰.

So the two take different routes to the same goal of extending the DS-1: Boss redesigned its own circuit with a switchable second voice, while Keeley reworked the original circuit and added the Ultra and Seeing Eye switch. A player weighing the two would be choosing between a factory Waza Craft pedal and a modded original¹⁰¹¹⁴.

Modding a DS-1 yourself

The Keeley Ultra Mod is a service performed on a Boss pedal, but players who want to do the work themselves have kit options¹¹².

• Fromel Electronics DS-1 Mod Kit: a modification kit for the Boss DS-1 that lets you voice the pedal in five different styles. Fromel describes it as "an easy project with basic soldering skills" and says the modded pedal gains "thick, rich distortion with gain to spare - surprisingly warm, with great bass response and a wide range of usable tones, from roaring distortion to gnarly, splatty fuzz." It comes as a Supreme Kit with all parts plus detailed photo instructions, or you can send your pedal to Fromel to install it¹².
• Griffin Effects DS-1 The One Kit: a modification kit for the Boss DS-1 Distortion pedal¹³.
• Griffin Effects DS-1 Rock Hard Kit: another DS-1 modification from Griffin Effects, a company that says it has "been tweaking with the DS-1 for many years trying to make is sound better"¹⁴.

The Fromel kit requires the DS-1 pedal itself plus a soldering iron, desoldering braid and/or a solder sucker, a Phillips screwdriver, and wire clippers¹².

For more on the effect type itself, see distortion pedals.

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