MartinLogan Motion Foundation B1 Bookshelf Speaker - Black - Each

MartinLogan's Most Affordable Folded Motion Speaker

The Motion Foundation B1 is the smallest and least expensive speaker MartinLogan makes with its Folded Motion tweeter. It pairs the Gen2 Folded Motion Tweeter S with a 5.5-inch aluminum-cone woofer in a rear-ported cabinet under 14 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 3,400 Hz crossover, the aluminum cone borrows its construction from the more expensive Motion series.

The Numbers, and What They Ask of You

MartinLogan quotes 48 Hz to 23 kHz within 3 dB and 89 dB sensitivity. Impedance is 5 ohms. Recommended power is 15 to 100 watts. Those numbers make the B1 one of the easiest speakers to drive in our store, and a natural partner for a receiver or a small streaming amplifier.

How Much Room It Takes

Each cabinet is 7.25 inches wide, 13.7 tall and 9.5 deep, and weighs 11.5 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

Chris Boylan reviewed the Foundation B1 for ecoustics on August 30, 2025: "What struck me most about the B1 is their airy transparency in the upper mids and treble regions."

His verdict: "With excellent transparency and refined upper midrange and treble response, the B1s perform extremely well with acoustic, jazz and singer-songwriter fare and can easily keep up with the complexity of movie and TV soundtracks."

The caveat: "While the low bass leaves something to be desired, an affordable powered subwoofer can bring these little gems to the next level of performance." He heard little below about 60 Hz in his room.

Who Is This Bookshelf Speaker Best For?

• You want a MartinLogan on the smallest budget — the Folded Motion tweeter in the least expensive cabinet the company makes
• You listen to voices and acoustic music — ecoustics heard the B1 at its best on singer-songwriter, jazz and acoustic material
• You are building a Foundation home theater — the B1 works as a front pair in a small room or as surrounds behind the larger Foundation B2, with the matching Foundation C1 center channel
• You run a receiver or a streaming amplifier — 89 dB sensitivity and 15 to 100 watts recommended means almost anything will drive it
• You want bass without a subwoofer — step up to the Foundation B2, which reaches 42 Hz with a 6.5-inch woofer

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. If you add a subwoofer, cross over around 80 Hz and let the B1 do what it does best.

Pairs Well With

What finishes the setup. These are the categories most Foundation B1 owners shop next.

• Dynamo Foundation 10 subwoofer — the series subwoofer, and the upgrade ecoustics recommended first
• MartinLogan STAND25 — puts the tweeter at ear height and bolts to the base
• Foundation C1 center channel — the matching center
• 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 89 dB sensitivity and 5 ohms, a receiver or a small integrated or streaming amplifier is plenty.

Do I need a subwoofer?

For casual listening, no. For full bass, yes. MartinLogan rates the B1 to 48 Hz, but ecoustics heard little below about 60 Hz and found a modest subwoofer transformed the system.

How is the B1 different from the Foundation B2?

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 and 3.5 pounds lighter. Both use the same tweeter.

Can it go on a bookshelf?

Yes. At 9.5 inches deep it fits a normal shelf. Leave a few inches behind the rear port.

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

MartinLogan introduces the Motion Foundation series:

Audible Elegance's first look at the Foundation B1 and B2:

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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.