MartinLogan Motion Foundation B2 Bookshelf Speaker - Walnut - Each

The Largest Foundation Bookshelf, With the Folded Motion Tweeter

The Motion Foundation B2 is the bigger of two bookshelf speakers in MartinLogan's entry Foundation series. It pairs the Gen2 Folded Motion Tweeter S with a 6.5-inch aluminum-cone woofer in a rear-ported cabinet 15 inches tall. It is sold by the each, so order two for stereo.

Foundation is where MartinLogan's thin-film tweeter reaches its lowest price. The Tweeter S is a smaller version of the Folded Motion design: a pleated film diaphragm that squeezes air between its folds. It has 3.5 square inches of surface, still more than a 1-inch dome.

Why It Sounds Like a MartinLogan

The folded film barely moves for a given output, which keeps the treble clean and quick. A waveguide controls dispersion to 90 degrees both ways. Below the 3,800 Hz crossover, the aluminum cone borrows its construction from the more expensive Motion series.

The Numbers, and What They Ask of You

MartinLogan quotes 42 Hz to 23 kHz within 3 dB and 90 dB sensitivity. Impedance is 5 ohms. Recommended power is 15 to 100 watts. That 42 Hz figure is the deepest bass in the Foundation series, and deeper than many bookshelf speakers at twice the size of this budget.

How Much Room It Takes

Each cabinet is 7.75 inches wide, 15 tall and 11.5 deep, and weighs 15 pounds. Finishes are black with gunmetal trim, walnut with bronze trim and satin white with silver trim. A single pair of 5-way binding posts sits on the back. A removable grille covers the woofer.

What Reviewers Are Saying

A full written review of the B2 had not been published when we wrote this page. AV-Obsessed reviewed it on video in October 2024, embedded below.

Audioholics previewed the Foundation series in August 2023 and noted that the B2 "promises bass response down to 42Hz" from a cabinet standing 15 inches tall.

Who Is This Bookshelf Speaker Best For?

• You want a MartinLogan on a tight budget — the Folded Motion tweeter at the lowest price the company offers it
• You want real bass from a bookshelf — 42 Hz from a 6.5-inch woofer covers nearly all music without a subwoofer
• You are building a Foundation home theater — the matching Foundation C1 center and the smaller Foundation B1 as surrounds share the tweeter
• You run a receiver or small amplifier — 90 dB sensitivity and 15 to 100 watts recommended means almost anything will drive it
• You want the bigger tweeter and a step up in finish — the Motion B10 moves to the full-size Gen2 Obsidian tweeter and a woven fiberglass woofer in a smaller cabinet

How Do They Connect to Your System?

Speaker cable runs from your amplifier to the binding posts on each cabinet, red to red and black to black. The posts take banana plugs, spades or bare wire. There is one pair, so no bi-wiring. These are passive speakers, so there is nothing else to power.

Put them on stands with the tweeter at seated ear height, with several inches behind the rear port. Toe them in slightly toward the seat. The B2 also bolts to the STAND25 stand.

Pairs Well With

What finishes the setup. These are the categories most Foundation B2 owners shop next.

• MartinLogan STAND25 — puts the tweeter at ear height and bolts to the base
• Foundation C1 center channel — the matching center
• Dynamo Foundation 10 subwoofer — the series subwoofer, for film and the last octave
• AV receivers — the natural partner for a Foundation system

Frequently Asked Questions

Is the price for one speaker or a pair?

One speaker. MartinLogan sells the Foundation range by the each. Order two for stereo, or add singles as surround channels.

How much amplifier does it need?

MartinLogan recommends 15 to 100 watts. At 90 dB sensitivity and 5 ohms, a receiver or a small integrated amplifier is plenty.

How is the B2 different from the Foundation B1?

The B2 has a 6.5-inch woofer, a larger cabinet and bass to 42 Hz. The B1 has a 5.5-inch woofer, reaches 48 Hz and is about an inch shorter. Both use the same tweeter.

Do I need a subwoofer?

Not for music. The B2 reaches 42 Hz, lower than almost anything on a record. For film, a subwoofer adds the last octave.

Can I bi-wire?

The Foundation B2 has a single pair of 5-way binding posts, so a single run of cable is the only option.

What finishes are available?

Black with gunmetal trim, walnut with bronze trim, or satin white with silver trim. Check the title of this listing for the finish you are ordering.

See It in Action

AV-Obsessed reviews the Motion Foundation B2:

MartinLogan introduces the Motion Foundation series:

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Learn More

Want to learn more about speaker placement, amplifier matching, or when to add a subwoofer? Visit our Learning Center for guides, tips, and expert advice.