MartinLogan Motion Foundation B1 Bookshelf Speaker

What You Need to Know

Detail and Scale Unexpected in Its Class

The Foundation B2 is the largest bookshelf speaker in MartinLogan's Motion Foundation Series—and the one that sounds least like a bookshelf speaker. Its 6.5-inch aluminum mid-bass driver reaches down to 42Hz, delivering a fullness and scale that make a stand or shelf-mounted system feel far bigger than it looks.

MartinLogan's Signature Thin-Film Sound

At the heart of the B2 is the Gen2 Obsidian Folded Motion Tweeter S, trickle-down technology from MartinLogan's famous electrostatic designs. Its folded thin-film diaphragm packs 3.5 square inches of surface area into a tiny space—fast, light, and low-excursion for stunning detail and clarity. The Folded Motion Waveguide controls dispersion, minimizing room reflections while blanketing a wide seating area with consistent, precise sound.

A Finish for Every Room, Sold by Each

Choose Walnut with bronze trim, Gloss Black with gunmetal trim, or Satin White with silver trim. The B2 is sold individually—buy two for stereo, or mix with other Motion Foundation models for a matched surround system. Pairs perfectly with the MartinLogan STAND25 for a solid stand-mount setup.

Features & Specifications

Gen2 Obsidian Folded Motion Tweeter S — Thin-film speed and detail derived from MartinLogan electrostatic technology.

Folded Motion Waveguide — Controlled 90° x 90° dispersion for precise imaging across a wide seating area.

6.5" Aluminum Mid-Bass Driver — Unibody aluminum cone with non-resonant asymmetrical chamber; bass to 42Hz.

Easy to Drive — 90dB sensitivity—sings with amplifiers from 15 to 100 watts.

Flexible Placement — Rear-ported cabinet; shelf, stand (STAND25 compatible), or surround duty.

Specifications

• Type: 2-Way Rear-Ported Bookshelf Speaker
• Frequency Response: 42Hz - 23kHz ± 3dB
• Sensitivity: 90dB
• Impedance: 5 Ohms
• Recommended Amplifier Power: 15 - 100 Watts
• Crossover Frequency: 3,800Hz
• Tweeter: 0.94" x 1" Gen2 Folded Motion Tweeter S (3.5 sq. in. diaphragm)
• Mid-Bass Driver: 6.5" Aluminum Cone, Stamped Steel Basket
• Tweeter Dispersion: 90° x 90°
• Inputs: 5-Way Binding Posts (Non Bi-Wire)
• Dimensions: 15"H x 7.75"W x 11.5"D
• Weight: 15 lbs
• Finish: Walnut, Gloss Black, or Satin White
• Sold By: Each

Frequently Asked Questions

Is this the price for one speaker or a pair?

The Foundation B2 is sold by each. Order two for a stereo pair, or add singles as surround channels in a Motion Foundation home theater system.

What amplifier do I need?

With 90dB sensitivity and a recommended range of just 15 to 100 watts, the B2 is easy to drive—most receivers and integrated amps will do nicely. Its 5-ohm impedance is compatible with virtually all modern amplifiers. Ask us if you're unsure about your electronics.

What makes the Folded Motion tweeter different?

Instead of pushing air with a dome, it squeezes air between the folds of a pleated thin-film diaphragm—like an accordion. The result is far more surface area, faster response, and the airy, detailed high end MartinLogan is famous for, at a fraction of electrostatic prices.

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