Colorsound Overdriver

The Colorsound Overdriver is a British boost-and-overdrive pedal built by Sola Sound around 1971. It grew out of the earlier Colorsound Power Boost, an 18-volt pedal from 1969-70, and it kept the same basic circuit while dropping the power requirement to a single 9V battery¹²³. Tru-Fi's history of the pedal describes it as a design by Gary Stewart, who later founded Colorsound, and says vintage units are now sought after by guitar enthusiasts and collectors¹.

For a player, the Overdriver matters because it sits between two categories. GuitarPCB, whose ColorTone board is a copy of the circuit, describes the original this way⁴⁵⁶:

At low drive settings it works as a clean-ish boost with bass and treble shaping; pushing the overdrive control drives the transistors into breakup. Users named in the sources include David Gilmour of Pink Floyd, Jeff Beck, Marc Bolan of T. Rex, and Jan Akkerman of Focus²⁴.

Where the Overdriver came from

The Overdriver was created by Sola Sound, a British company, around 1971, and was designed by Gary Stewart, who later founded Colorsound¹. Tru-Fi's account dates the change precisely: "In 1971 Colorsound changed the Power Boost to the 9V Overdriver"²³. The pedal gained popularity in the 1970s and was used by various guitarists of that era¹.

Colorsound itself, the company Stewart founded, produced a variety of effects pedals beyond the Overdriver, with its own designs and tonal characteristics¹. Analog Man's page on the pedal describes one American-market version as a "1974 era fuzz box made for the American market" in a "thin stamped grey metal case (narrow)," listed at $259 in 2015¹⁰. That price is Analog Man's own list price for a unit it sold, not the original 1970s retail price.

The circuit's reach extends beyond straight reissues. Premier Guitar, reviewing the BAE Hot Fuzz, noted that "BAE says the Hot Fuzz's design has Colorsound Overdriver origins"¹¹, and the pedal's circuit family is one of the most copied British designs among boutique builders and DIY PCB makers.

How it works: three transistors with bass and treble boost

The Overdriver is a three-transistor circuit, not an op-amp or clipping-diode design like the Tube Screamer. Its original units came with BC169C transistors in the Q1 and Q2 positions and a BC184C in Q3¹².

The original transistors were BC169C in the first two positions (Q1 and Q2) with a BC184C in the third (Q3)³¹². Tru-Fi, building its 18V Colordriver as "a true Power Boost replica," says it is "done to the correct BC184 Transistors"³. The circuit is a three-stage silicon design, and the original transistors are now the hard-to-source part of any faithful build.

The tone shaping is the other half of the character. The pedal carries separate bass and treble controls, which allow a wide range of tonal options, including a full-on treble boost, rather than a single rolled-off treble cut like a classic treble booster such as the Rangemaster. This distinctive bass and treble boost is part of what marks it as an overdrive pedal rather than purely a boost⁸.

The Power Boost connection: same circuit at 18V

The Overdriver is really the second act of one circuit. The Colorsound Power Boost, an 18-volt pedal from 1969-70, came first³. Aion FX describes the lineage: "The Power Booster ran at 18V using two batteries in series," and "The Colorsound Overdriver was an updated version of this circuit, a third revision from 1972"⁹. PastFx calls the Power Booster "one of the first overdrive effects pedals made available to the masses"¹³, and its own 18V Power Booster is "inspired by the legendary Colorsound Power Booster circuit"¹⁴.

The reason for the change, according to Tru-Fi, was volume:

So the story of the two pedals runs in two steps. First, the master volume was added to the 18V Power Boost circuit to make its overdrive usable at reasonable levels. Then the power supply was dropped to a single 9V battery, which tamed the pedal further and became the Overdriver²⁹. Aion FX's summary of the Overdriver is that it "dropped the power requirement down to a single battery"⁹.

For players comparing the two today, the practical difference is headroom. The 18V versions have more clean boost range before the transistors break up; the 9V version distorts earlier. Builders offer both: Tru-Fi makes a 9V Colordriver based on the 9V Overdriver and an 18V Colordriver based on the Power Boost²³, and PastFx builds its 18V Power Booster on the original circuit¹⁴¹³.

The controls and the master volume

Analog Man lists the control set as four knobs: Treble, Bass, overdrive, and Master Volume, with the "Master Volume added to allow overdrive at useable volumes"¹⁰.

The master volume is the control that defines the pedal's place in history. Before it, the Power Boost at 18V was simply too loud to use its overdrive at band volumes². After it, the same circuit became a practical overdrive pedal. GuitarPCB's ColorTone v3 board adds the same idea to its copy: "We have added some modifications to the original by adding a Master volume control"⁵.

One thing the master volume does not do is turn the pedal all the way down to silence. Its job is trimming a loud circuit to a usable level, not acting as a full attenuator, which is why reissues and clones built the same way cannot be dialed down to zero output¹⁵.

Versions and reissues

Tru-Fi's history notes that "Over the years, there have been different variations and reissues of the Colorsound Overdriver. Some versions featured slight modifications to the circuit or enclosure design"¹. Aion FX identifies the Overdriver itself as "a third revision from 1972" of the Power Boost circuit⁹, so even within the original run the circuit was revised.

Current production options include:

• Tru-Fi Colordriver 9V: a hand-made recreation of the 9V Overdriver²
• Tru-Fi Colordriver 18V: a Power Boost replica built with BC184 transistors³
• Tru-Fi ColorDriver '71 Mini: the 1971 Sola Sound circuit in a smaller, modern enclosure¹⁶
• PastFx 18V Power Booster: the earlier 18V circuit, built by PastFx¹⁴¹³
• IdiotBox Power Drive: based around the old Colorsound Power Boost¹⁷
• Dr. No Effects PowerDriver & Booster: a two-in-one take, with the overdrive side giving "raw but clear overdrive" for rhythm and a booster side for lead¹⁸

RockBoard's PedalPedia describes the Tru-Fi Colordriver as "a handmade recreation of the vintage Colorsound Power Booster / Overdriver circuit"¹⁹, which captures the point that modern builders treat the two pedals as one circuit family.

Pedals and DIY layouts based on it

The Overdriver is a favorite among DIY builders because the circuit is simple, documented, and built from ordinary parts. The main options:

• GuitarPCB ColorTone Overdrive v3: a DIY PCB for building a similar circuit, with a master volume added to the original design⁴⁵. The v2 build document, written by Bruce R, describes the same circuit and the same boost-to-overdrive character⁶.
• Aion FX Plasma: Aion FX offers the Overdriver circuit as one of its own projects, called the Plasma⁹.
• PedalPCB Powersound Overdrive: a DIY PCB listed for comparison to the Colorsound Overdriver.

GuitarPCB's pitch for its board is straightforward:

That is the practical appeal of the circuit today. Vintage units are collector pieces¹, but the design uses a handful of transistors and passive parts, so a builder can reproduce the boost-and-overdrive character for the cost of a PCB and components. The one challenge is the original transistors: the BC169 family is described as difficult to obtain and expensive, so most builds substitute modern silicon parts¹².

For a player who wants the sound without a soldering iron, the reissues above cover both voltages: 9V versions voiced like the Overdriver and 18V versions voiced like the Power Boost²³¹⁴.

Pedals on this page

Colorsound Overdriver

Colorsound · Fuzz

$259 list price

BAE Hot Fuzz

BAE · Fuzz

$225 list price

Tru-Fi Colordriver 18V

Tru-Fi · Overdrive

PastFx 18V Power Booster

PastFx · Boost

Tru-Fi Colordriver 9V version

Tru-Fi · Overdrive

$209.95 list price

Tru-Fi Mini '71 Colordriver

Tru-Fi · Overdrive

$199 list price

IdiotBox Power Drive

IdiotBox Effects · Overdrive

$139 list price

Tru-Fi Colordriver

Tru-Fi · Boost

$209.95 list price

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