RJM Music RJM Mastermind PBC/6X

The RJM Mastermind PBC/6X is a pedalboard switcher from RJM Music, suited to pedalboards both large and small¹. It combines analog audio loop switching with a MIDI controller, a built-in tuner and amp control in one floor unit, with a 100% analog signal path¹. Premier Guitar described it at launch as a unit that "combines the best features of the original Mastermind PBC in a smaller footprint"².

The core idea is matrix switching: the six audio loops can be reordered digitally, per preset, without rewiring the board¹. Each of its seven buttons is user configurable, with any button assignable to any function and LED color through the Mastermind Editor app¹.

What the Mastermind PBC/6X does

The PBC/6X sits at the center of a pedalboard and does three jobs at once. As an audio switcher, it puts each pedal in a true-bypass-style loop and turns loops on and off, so effects not in use are out of the chain. As a MIDI controller, it sends program changes and other messages to MIDI gear. And as an amp controller, it can switch amplifier channels and functions²⁴¹.

The Mastermind PBC series grew out of RJM's Mastermind line of MIDI foot controllers. RJM describes the PBC series as similar to the Mastermind LT, "but also has audio switching capability to switch analog effe"cts⁵. The original Mastermind PBC, announced in December 2014, "combines a 10 loop true-bypass audio switcher, a line mixer, an A/B/Y switch, an amplifier controller, a tuner and a MIDI controller in one unit"⁴. The PBC/6X, announced in April 2019, carries that feature set into a smaller box².

Its front panel features:

• 7 user configurable buttons, each with a multi-color LED indicator¹
• An easy to read backlit LCD display that can show preset and song names, plus other status¹
• A built-in tuner¹
• 768 preset locations¹

Buttons can be set to any function and LED color using the Mastermind Editor software, which connects over USB¹.

Loops, matrix switching and stereo

The PBC/6X has 6 audio loops plus an insert loop¹. Matrix switching is the headline feature: the order of the loops can be changed from preset to preset¹. In practice that means a drive pedal that normally sits before a delay can be placed after it in one preset and before it in another, all stored digitally rather than by moving cables.

The last three loops and the insert loop are stereo capable¹. The output is flexible: it can be mono, stereo, or used as an A/B/Y switch¹, which covers running two amps or a stereo effects rig from one unit. Premier Guitar's reviewer noted of the PBC line that it "can also be configured for a stereo setup or for A/B routing to different amps"⁶.

The larger PBC/10 also offers features the 6X trims away: each of its last four loops can be switched between series and parallel routing using an internal line mixer⁷, it has three audio buffers that can be enabled or disabled by button or preset⁷, and its B output has a switchable isolation transformer and a programmable phase switch⁷. MusicPlayers.com's review of the original PBC noted the same series/parallel routing on its last four loops, courtesy of the internal line mixer⁹.

Power and connections

The PBC/6X runs on 9VDC or 12VDC at 220mA, using a Boss-type center negative 5.5/2.1mm barrel connector¹. That draw is low enough for most isolated pedalboard power supplies, but there is no battery option.

Connections on the unit cover audio, control and computer use:

• Two inputs, one with a switchable buffer¹
• Flexible output: mono, stereo, or A/B/Y switch¹
• A 1/4-inch TRS jack providing two function switches, for amp channel switching or externally switchable pedal features¹
• An external switch input allowing two more switches, programmable to perform any function the internal buttons can¹
• A MIDI connection powered by the MIDI "brain" of the Mastermind GT controller; the port can be split into MIDI input and output using a special Y cable¹
• A USB device port for PC or Mac, for sending MIDI commands to a computer or communicating with the Mastermind Editor software¹
• An expression pedal input, programmable to generate MIDI messages based on pedal position¹

The function switch jack is the amp control path: two switches over one TRS cable handle channel switching and other amp features¹. Where a rig needs more, the external switch input adds two more programmable switches¹. On the original PBC, MusicPlayers.com found two TRS jacks providing four external switch controls for multi-channel amplifiers⁹.

The Mastermind PBC family

RJM Music's Mastermind line spans MIDI foot controllers and pedalboard switchers. The Mastermind PBC came first, announced by RJM Music Technology Inc.⁴, and the PBC/6X followed, combining what RJM calls "the best features of the original Mastermind PBC in a smaller footprint"². The PBC/6X is a pedalboard switcher "suited for pedalboards both large and small"¹, and it began shipping mid-April 2019². The company's MIDI expertise also reached beyond its own line: Fender's Switchboard Effects Operator, announced in January 2024, was developed in collaboration with Ron Menelli of RJM Music³.

When the original Mastermind PBC was evaluated, it was placed against the Boss ES-8 Effects Switching System, the TheGigRig Pro-8 and MIDI-8, the Guitar Laboratory GSC-3, and the Rocktron PatchMate Loop 8 Floor⁹. That comparison set shows the category the PBC competes in: full-featured loop switchers with MIDI control, rather than simple true-bypass loopers. The PBC/6X carries the line's core features into the smaller format, with 7 user-configurable buttons, a built-in tuner, and an expression pedal input that can be programmed to generate MIDI messages based on the position of the pedal¹.

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