MartinLogan Motion XT B100 Bookshelf Speaker - Each

MartinLogan's Biggest Folded Motion Tweeter, in a Box You Can Shelve

The Motion XT B100 is the top bookshelf speaker in MartinLogan's Motion range. It pairs the Gen2 Obsidian Folded Motion XT tweeter with a 6.5-inch Nomex-reinforced Kevlar woofer in a rear-ported cabinet. It is 14.5 inches tall and sold by the each, so order two for stereo.

MartinLogan is best known for electrostatic panels. The Folded Motion tweeter brings some of that character to a conventional box. A pleated film diaphragm squeezes air between its folds, so it barely has to move. The XT version has 12.4 square inches of surface, 40 percent more than the standard tweeter.

Why a Folded Diaphragm Sounds Different

A dome tweeter pushes air with a small cup. The folded film moves far less for the same output, which lowers distortion and keeps the treble clean at high volume. A molded waveguide, chosen from nearly 50 profiles, matches its dispersion to the woofer at the 2,600 Hz crossover.

The Numbers, and What They Ask of You

MartinLogan quotes 45 Hz to 25 kHz within 3 dB and 93 dB sensitivity. Impedance is 4 ohms. Recommended power is 20 to 250 watts. Dispersion is 90 degrees horizontal and 45 degrees vertical, so tweeter height matters more than with most speakers.

How Much Room It Takes

Each cabinet is 8 inches wide, 14.5 tall and 12.5 deep with feet, and weighs 20.5 pounds. Finishes are gloss black, walnut and satin white. The 5-way binding posts are doubled for bi-wiring or bi-amping. A threaded insert in the base bolts to the STAND25 stand.

What Reviewers Are Saying

Mark Gusew reviewed the XT B100 for StereoNET on July 19, 2023: "From the moment I started my listening sessions, I was impressed by how balanced a musical communicator this little loudspeaker is."

Nasim Abbu-Daggar reviewed it for Future Audiophile on October 9, 2024: "The Folded Motion tweeter excelled in bringing an incredible amount of detail and sparkle to the upper registers." Bass was "tight and controlled."

His caution: a "relatively narrow horizontal sweet spot." Off to the side the sound thins, so the XT B100 rewards a well-placed seat more than a scattered crowd.

Who Is This Bookshelf Speaker Best For?

• You want the MartinLogan sound without panels — the largest Folded Motion tweeter MartinLogan makes, in a cabinet that sits on a stand
• You listen to detail — strings, cymbals and voices are where both reviewers heard the XT B100 pull ahead
• You are building a Motion home theater — the Motion XT C100 center channel and Motion MP10 surrounds share the tweeter, so the system speaks with one voice
• Your amplifier can drive 4 ohms — 93 dB sensitivity means little power is needed, but the load is 4 ohms, so check your amplifier's rating
• You need a wide sweet spot for a crowd — the 45 degree vertical dispersion and focused imaging favor a seated listener; for wide seating, consider the Motion B10 with its 90 by 90 degree pattern

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. For a single run, leave the jumpers between the two pairs of posts in place. Remove them to bi-wire or bi-amp. These are passive speakers, so there is nothing else to power.

Put them on stands with the tweeter at seated ear height, a foot or more from the wall behind the rear port. Toe them in toward the seat. Future Audiophile placed them about two and a half feet from the back wall and toed in.

Pairs Well With

What finishes the setup. These are the categories most XT B100 owners shop next.

• MartinLogan STAND25 — bolts to the base and puts the tweeter at ear height, with color-matched trim
• Motion XT C100 center channel — the matching center for a Motion XT home theater
• MartinLogan Dynamo 10 subwoofer — for the octave below 45 Hz on film and bass-heavy music
• integrated amplifiers — a 4 ohm rated amplifier of 50 watts or more is plenty

Frequently Asked Questions

Is the price for one speaker or a pair?

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

How much amplifier does it need?

MartinLogan recommends 20 to 250 watts. At 93 dB sensitivity it plays loud on modest power, but the 4 ohm impedance means the amplifier should be rated for 4 ohm loads.

Can I bi-wire or bi-amp?

Yes. The XT B100 has two pairs of 5-way binding posts with jumpers. It is the only Motion bookshelf model with this option.

What is the difference between the XT B100 and the Motion B10?

The XT B100 has the larger XT tweeter, a 6.5-inch Kevlar woofer and deeper bass, 45 Hz against 56 Hz. It is also two inches taller and 6 pounds heavier. The B10 has a wider vertical dispersion.

Do I need a subwoofer?

Not for most music. The XT B100 reaches 45 Hz. For film, or if you want the lowest octave with real weight, add a subwoofer and cross over around 60 to 80 Hz.

Does it come with a grille?

A clip-on cover for the woofer is supplied. The tweeter sits in its waveguide and stays exposed.

See It in Action

Andrew Robinson reviews the Motion XT B100:

Erin's Audio Corner measures and discusses the XT B100 and B10:

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