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Phobos (Legacy)

Based On
Tone Bender Mk III
Effect Type
Build Difficulty

Legacy PCB

Designed for the 1590B enclosure with side-mounted jacks, which some builders prefer. Bypass PCB (optional) sold separately.


In stock

Updated Version

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Project description

Aion Phobos - Tonebender Mk III Clone PCBThe Phobos Fuzz is a clone of the Colorsound / Sola Sound Tone Bender Mk. III. Using this PCB, you can also build a Baldwin-Burns Buzzaround. Just make sure to read the documentation because there

The Tonebender was sold under a number of different brand names, including Vox and Park Sound. While the official Sola Sound version was just called the “Tone Bender” officially, the Vox version included the “Mark III”, and it was the direct successor of the “Mark II” (my Deimos project) so the Mk III designation has come to represent this version. It’s also commonly called the 3-Knob Tonebender to distinguish it from versions 1 and 2 that only had two knobs.

Tone Bender Mk III circuit history

David Main from D*A*M has written up a history of the Tone Bender up until Mk II, so you would do well to check out his page on the history for the full background story. His history stops at the release of the Mk III so this is where we’re picking up.

In 1968, the Mk II circuit was “updated”, which is another way of saying “completely revised and bearing no resemblance to the previous version”. The new version had three transistors, with the first two transistors being arranged in a Darlington configuration. This has the advantage of coaxing higher gains (HFe) than germanium transistors are normally capable of, while also being much easier to bias and being tolerant of poor-quality transistors.

The gain control on a Fuzz Face or Tone Bender I / II is a pot off the emitter of one of the transistors, directly controlling the gain of that stage. In contrast, the TB Mk III cranks up the gain to a fixed amount in the first stage and then lets you bleed off the signal before it hits the second stage. In other words, it’s a gain cut control wired in reverse, so it has the illusion of increasing it in the same way as other fuzzes or overdrives.

The Mk III also had a tone control, which is something sorely missing from any of its predecessors. It essentially has two fixed passive tone paths at the tail end of the circuit, one that cuts the treble & enhances bass and one that leaves most of the treble intact, and then a potentiometer that pans between them.

The Mk III circuit was also released in a smaller enclosure and called the “Mk IV”, although it’s the same circuit. The two were sold alongside each other for a period of time before they transitioned completely over to the Mk IV.

Later Tone Benders such as the Supa Tone Bender from 1973 and the Jumbo Tone Bender from 1976 were silicon Big Muff clones and again bore no resemblance to any prior versions. (They’re fantastic and worth a look—just not the same circuits.)

Baldwin-Burns Buzzaround

The Buzzaround was released sometime between 1965 and 1968 by Baldwin-Burns, the new name of Burns Guitars London after they were bought by the Baldwin Piano Company. They had no affiliation with Sola Sound / Colorsound.The most likely release date was 1967, but so few of these units still exist that there’s no way of really knowing. It’s an extremely rare effect, having sold for as much as $3,000 on eBay.

Most people think the Buzzaround to be a tweaked clone of the TB Mk III, but actually it’s more likely that the reverse is true since the Mk III came a year later in 1968. The Buzzaround was rumored to have been designed by Gary Hurst, the designer of the first four Tone Bender versions (1, 1.5, 2 and 3), but Gary has denied this.[1] The TB Mk III is a little more ‘refined’, having a true output volume control instead of a bias control that can never get down to zero and only sounds good at certain settings. It’s unlikely that a person experimenting with the Tone Bender circuit would try out the Burns method and think of it as an improvement.

So, at the end of the day, the origins of the Buzzaround aren’t really known for sure—“probably” is the best we can do. What matters is that they’re really easy to build with the Phobos PCB, so you can try one out for significantly less than $3,000.

Notes & references

  1. Kit Rae’s Fuzz/Big Muff Timeline. “Gary Hurst claims he did not design this, but he did make the Buzzaround reissue prototypes for Burns in 2009.”


Project Documents