BOSS US-20 GK Unit Selector Footswitch

The BOSS US-20 is a floor-based unit selector for a guitar equipped with a 13-pin GK-compatible pickup system. It lets one compatible guitar connect to two GK IN-equipped processors, such as guitar synthesizers, V-Guitar systems, or Guitar-to-MIDI interfaces. The US-20 provides practical control when a player wants to move between two connected GK devices without reconnecting cables.

Two onboard footswitches support direct performance control. The A/B pedal selects either the device connected to Unit A or the device connected to Unit B, while the BOTH pedal enables both connected devices to be played at the same time. Status indication identifies the selected output or combined-operation mode.

The US-20 is a routing and control accessory rather than an audio effect or amplifier. It does not add an EQ, distortion, or modeled sound of its own; its purpose is to manage GK-system signal routing between compatible equipment. This makes it useful for players building a multi-device guitar-synth or processing rig.

A durable metal enclosure supports pedalboard and stage use while keeping the controls accessible underfoot. The unit uses dedicated 13-pin GK connections for its GK In, Unit A, and Unit B ports. Power is supplied through the 13-pin connection from the device connected to the Unit A connector.

For system expansion, connect the GK-equipped guitar to GK In and connect compatible processing devices to Unit A and Unit B. Unit A must be connected for the US-20 and the GK pickup system to operate. Two 1.2-meter C-13D GK connecting cables are included for linking the selector to compatible units.

Key Features

• One GK Input: Connects one guitar with a 13-pin GK-compatible pickup.
• Dual GK Outputs: Routes the guitar system to two compatible devices.
• A/B Footswitch: Selects the Unit A or Unit B device.
• BOTH Footswitch: Enables simultaneous operation of both connected units.
• 13-Pin GK Connections: Uses dedicated GK In, Unit A, and Unit B ports.
• Metal Construction: Provides a durable enclosure for floor-based operation.

Design & Installation

The US-20 is housed in a durable metal floor unit with two foot-operated switches and status LEDs. Its compact chassis measures 160 mm wide, 134 mm deep, and 38 mm high, with a weight of 0.6 kg. The design is intended for use alongside GK-compatible guitar processing equipment.

Connect the guitar's GK pickup system to the GK In connector, then connect compatible GK IN devices to Unit A and Unit B using proper 13-pin GK cables. The device connected to Unit A supplies power through the GK cable, so it must be connected even when using only one device. Keep the total cable run from the pickup through the US-20 to either connected unit at 10 meters or less.