RJM Music Mastermind PBC

The RJM Music Mastermind PBC is a pedalboard controller and audio loop switcher: a floor unit that combines a ten loop true bypass audio switcher, a line mixer, an A/B/Y switch, an amplifier controller, a tuner and a MIDI controller in one box¹. Premier Guitar described it at launch as "an all-in-one MIDI controller and loop switching system for guitar pedalboards"¹. Where a basic loop switcher just brings pedals in and out of the signal path, the PBC is fully programmable, so a single button press can activate audio loops, control amps and send multiple MIDI commands at once¹.

What the Mastermind PBC is

Premier Guitar's loop switcher roundup called the PBC "ostensibly a control station for your pedals," and that is the clearest way to think about it: every pedal on your board sits in a loop, and the PBC decides which ones are in the signal path, in what order, on every preset³. The unit features 10 loops with insert points in between groups, and there is room to store up to 768 presets³.

The ten audio loops are arranged in a group of 4 loops, a group of 2 loops and another group of 4 loops, with insert points in between². MusicPlayers.com's review spells out the arrangement: a group of four loops in series, an insert point, a group of two loops in series, another insert point, and another group of four loops in series, with the series routing selectable⁴. The last four loops are stereo capable using TRS jacks, and can be switched between series and parallel routing on a per preset basis¹.

The PBC is one of a family of RJM MIDI controllers. RJM describes the Mastermind PBC series as similar to the Mastermind LT, but with audio switching capability to switch analog effects as well⁵. Its MIDI engine comes from the larger Mastermind GT foot controllers: the launch announcement noted the PBC's MIDI input and output connections are powered by the MIDI "brain" of the Mastermind GT¹.

Loops, buffers and bypass

All loops are true bypass and relay switched, which RJM describes as giving maximum transparency². MusicPlayers.com's reviewer, Derek Davodowich, confirmed the technical approach: "The Mastermind PBC uses relays to perform its switching."⁴

Because true bypass alone can make long cable runs sound dull, the unit carries three audio buffers: one in front of loop 1, one before loop 7, and one after loop 10⁴. Each buffer can be enabled or disabled by an IA (instant access) button or as part of a preset⁶, and Premier Guitar noted the three switchable buffers can be saved as part of any given preset³. By default the buffers are on, but they can be turned off⁴. A Click Stopper noise reduction circuit, which can be switched between two positions, before loop 7 or after loop 10, addresses switching clicks².

Outputs, amps and stereo routing

The two outputs can be used as left and right outputs for a stereo signal, or as A and B outputs to A/B switch a mono signal between two amps². The B output has a switchable isolation transformer and a programmable phase switch, both useful when running two amplifiers². Premier Guitar noted the PBC can also be configured for a stereo setup or for A/B routing to different amps³.

For amp control, the PBC provides two 1/4" TRS jacks giving four external switch controls for operating a multi channel guitar amplifier⁴. The launch announcement also listed a built in A/B/Y switch and amplifier controller among the unit's functions¹.

Strymon's rig rundown with Ross Chapman, who uses the PBC as the switcher at the center of his board, shows how this works in practice⁷:

Chapman called the PBC "the brain of the board," praising it as "incredibly customisable and easy to use," and relying on its built in tuner⁷.

MIDI and USB

The PBC can control up to 16 MIDI devices², and up to 20 MIDI messages can be assigned per button, including PC, CC, Note and Sysex messages². A USB device port connects to a PC or Mac, letting the PBC send MIDI commands to a computer or communicate with the editor software². The launch announcement also listed USB ports for connecting a USB flash drive for settings backup¹.

An easy to read LCD display shows preset and song names plus other status⁶, and the PBC stores 1000 songs and 64 setlists², which is how it organizes presets into a setlist for live use.

Editor software

Mac and PC editor software allows for faster and more comprehensive editing than the front panel alone¹. MusicPlayers.com found the editing software, available for Macintosh and Windows PCs, "provides an easier interface to configure the device"⁴. On the PBC/6X, any button can be set to any function and LED color using the Mastermind Editor app⁸.

Where it came from

The Mastermind PBC launched with a US street price of $999 and was expected to start shipping in January 2015¹. It arrived as a floor based switching system from RJM Music Technology, a maker already known for its rack based switching systems, bringing that approach to the pedalboard.

The smaller PBC/6X, announced April 22, 2019, combines what Premier Guitar called "the best features of the original Mastermind PBC in a smaller footprint"⁹. It has 6 audio loops plus an insert loop, with the last three loops and the insert loop stereo capable⁸. Its matrix switching allows reordering loops digitally per preset without rewiring, and the order of the loops can be changed from preset to preset⁸.

What reviewers said

The Mastermind PBC launched at a US street price of $999, with shipping expected to start in January 2015⁴¹. Published coverage of the unit appeared in the guitar press, where reviewers took it up as a floor based control system rather than a simple loop switcher³.

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