Anchor Drive Dual Voice MOSFET Overdrive Hand Wired Tagboard Circuit

Description

Description of Product

The Anchor Drive Dual Voice is built around the way real amplifiers generate distortion.

Most overdrive pedals rely on op amp clipping stages. The Anchor Drive takes a different approach. Inside are two cascaded MOSFET gain stages designed to behave more like the front end of a guitar amplifier. Instead of a single clipping circuit, the pedal allows one stage to drive the next, which produces the layered saturation guitarists normally associate with loud valve amplifiers.

The circuit uses BS170 or 2N7000 MOSFET devices and is assembled on traditional tagboard using through hole components selected during the build. The layout remains visible and serviceable in the same way many vintage amplifiers were constructed.

Two gain controls shape the interaction between the stages.

Preamp sets how hard the first MOSFET stage drives the second.

Power Amp determines how strongly the second stage saturates.

A Master Volume sits after both stages so the pedal can run as either a gain stage or a level boost into an amplifier.

The Dual Voice switch changes the way the first gain stage feeds the rest of the circuit. Rather than simply adding more distortion, it shifts the feel and response of the entire pedal.

Vintage voice introduces a small amount of germanium clipping after the first stage. This keeps the overall gain lower and preserves the open character of the circuit. The sound stays bright, dynamic and responsive, closer to the behaviour of a cranked vintage amplifier where the front end remains relatively clean but the output stage is working hard.

Fat voice replaces that clipping structure with LEDs that allow the MOSFET stages to swing harder before limiting. The circuit becomes thicker and more saturated with stronger sustain. The feel moves toward the type of dense, modded amplifier tones associated with later high gain boutique amplifiers.

Power is supplied by a standard 9V centre negative supply and current draw is low enough to sit comfortably on most pedalboards.

Description of Sound

In Vintage voice the Anchor Drive behaves like a loud amplifier that is just beginning to work hard. The response is open and articulate with plenty of upper detail. With the Preamp control set lower the pedal adds presence and edge without excessive compression. Turning up the Power Amp control introduces the type of breakup associated with classic British stacks pushed to stage volume, where the front end stays relatively clean but the amplifier itself begins to strain.

Fat voice changes the behaviour of the circuit in a different direction. The LED clipping allows the MOSFET stages to drive harder before flattening out, which produces thicker saturation and longer sustain. The tone becomes denser and more aggressive, similar to the character of hot rodded boutique amplifiers that extend the gain structure of classic British designs.

Because the two MOSFET stages can be driven independently, the Anchor Drive covers a wide range of ground. It can sit on a pedalboard as a clean tone shaper, move into classic rock overdrive, or push into saturated stack style distortion when both stages are driven harder.

The circuit also responds well to the guitar volume control, making it easy to move from driven rhythm tones to cleaner sounds without touching the pedal itself.

This is a hand built pedal assembled individually on tagboard using traditional construction methods. Component selection and finish may vary slightly from build to build as part of the workshop process.

If a two stage amplifier style drive with switchable gain character appeals to you, this one is available.