The Muramasa JFET Boost is a modified version of the Keeley Katana Boost pedal. It is a two-stage JFET boost pedal that can provide clean tones or add a touch of grit. This pedal was notably used by John Mayer.

The circuit of the Muramasa JFET Boost is based on the original Keeley Katana Boost, which was released in 2005. However, the circuit itself dates back to 2000 when Robert Keeley collaborated with Legendary Tones to create the Time Machine Boost pedal.

The Muramasa JFET Boost features two cascaded JFETs powered by an 18V charge pump. The first JFET can push the second into clipping, especially when the Boost mode is engaged. The pedal is fairly simple in design and does not have a Boost switch like the Katana.

There have been two major versions of the Katana Boost. Version 1 used the 2N5484 or 2N5458 JFETs, while version 2 uses J201s. The component values in version 2 are different from version 1. The provided parts list in the build documentation shows the values for version 1, while the values for version 2 are mentioned in the “Notes” column.

The original JFETs used in the Katana Boost are not currently manufactured in through-hole format. However, extra pads have been provided in the Muramasa JFET Boost if you want to use surface-mount JFETs like the MMBFJ201 or MMBF5484. Aion FX also offers pre-soldered MMBFJ201s on adapter boards for those who find surface-mount parts intimidating.

Overall, the Muramasa JFET Boost is a modified version of the Keeley Katana Boost that allows for boost configuration in either stage. It is a versatile pedal that can provide clean or gritty tones, and it is a popular choice among guitarists, including John Mayer.

Summary created by AI from the original source.