The MB58R Mini CMD 121 Pure is a self-contained bass combo built around a custom 12-inch neodymium speaker and a hi-fi tweeter. Its enclosure uses a lightweight construction that keeps the weight at 21.7 lbs / 10.3 kg, and the cabinet is made in Italy.

The amplifier section provides 500 W RMS into 4 ohm or 300 W RMS into 8 ohm. Controls include gain, a 4-band EQ, an old school filter, master volume, mute switch, line out level control, pre/post EQ and ground switches, and a 3-way switch with flat, scooped-mid and footswitch positions. A bi-band limiter is included, and an optional footswitch handles mute and scooped-mid functions.

The combo can be extended into a 2x12" rig of about 500 W by adding an MB58R 121 Pure cabinet. The rear-ported cabinet is rated at 400 W RMS (AES) and 99 dB sensitivity, with a 3.5 kHz crossover and a 45 Hz to 20 kHz response.