KEF R3 vs MartinLogan Motion XT B100

Short answer: the KEF R3. It ranks #15 of 131 bookshelf speakers by sound quality, rated 4.5/5, at $2,200. The MartinLogan Motion XT B100 ranks #81, rated 3.6/5, at $1,699.98, $500.02 cheaper, not enough of a saving to outweigh the sound-quality gap.

What the KEF R3 does well: True three-way stand-mount with a 6.5-inch woofer below KEF’s 5-inch Uni-Q midrange/1-inch tweeter. Watch for: The low-frequency alignment rolls gradually rather than delivering high-output sub-bass; KEF specifies 58Hz +/-3dB and Erin’s high-level data supports using an 80Hz subwoofer crossover.

The case for the MartinLogan Motion XT B100: A premium 6.5-inch standmount with MartinLogan’s large folded-motion tweeter and high rated sensitivity. The tradeoff: The measured response rises strongly at +0.84dB per octave and directivity-index consistency is a poor 4.34, so tonal balance and off-axis behavior are less neutral than the price implies.

Buy the KEF R3. It is rated higher for sound quality, and saving $500.02 with the MartinLogan Motion XT B100 does not make up for the sound-quality gap.

Still deciding? The full Passive Home rankings cover every ranked option.

Specifications Side By Side

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Prices on this page were last checked September 30, 2026 at 2:57 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.

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The Two Speakers In Full

KEF R3: $2,200 per pair Amazon eBay

Pros: True three-way stand-mount with a 6.5-inch woofer below KEF’s 5-inch Uni-Q midrange/1-inch tweeter. Erin measured approximately 86-87dB/2.83V/1m sensitivity, exceptionally low sub-1% distortion at 86dB and orderly directivity in both planes. The coaxial geometry maintains image stability across seats, while Flexible Port Technology avoids the strong midrange port resonance common to rear-vented competitors. A 110W Parasound drove it successfully in Erin’s listening. Measured bass extension of 35.2Hz (-10dB), with a measured sensitivity of 87dB.

Cons: The low-frequency alignment rolls gradually rather than delivering high-output sub-bass; KEF specifies 58Hz +/-3dB and Erin’s high-level data supports using an 80Hz subwoofer crossover. Narrow high-frequency features and natural Uni-Q narrowing toward the top octave make toe angle audible, although off-axis tracking remains smooth. Sensitivity is moderate, the cabinet weighs almost 30 lb, and this original R3 lacks the Meta successor’s MAT absorber.

Full KEF R3 review and specifications →

Bass Extension (-10dB)	35.2Hz (measured, Audio Science Review)
Bass Extension (-3dB)	Approximately 58Hz (manufacturer specified; consistent with Erin’s measured roll-off)
DIY Kit	No
Dimensions	16.6”H x 7.9”W x 13.2”D
Drivers	1” tweeter coaxial with 5” midrange; 6.5” woofer
Impedance	8 ohms nominal; suitable for Erin’s 4/8-ohm-rated amplifier
Sensitivity	Approximately 86-87dB/2.83V/1m (measured, Erin’s Audio Corner)
Spinorama Preference Score	6.2 (spinorama.org)
Spinorama Preference Score with Perfect Sub	7.97 (spinorama.org)
Weight	29.9 lbs (13.55 kg) each
Woofer Cabinet	ported, rear Flexible Port

• Links
  • Official KEF R3 Page
• Reviews, Comparisons and Sound Samples
  • Erin’s Audio Corner: KEF R3 Review More from Erin’s Audio Corner →
  • Erin’s Audio Corner Website: KEF R3
  • Audio Science Review Measurements More from Audio Science Review →
  • Audio Science Review Measurements (spinorama.org)
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MartinLogan Motion XT B100: $1,699.98 per pair MartinLogan Dealer Network eBay

Pros: A premium 6.5-inch standmount with MartinLogan’s large folded-motion tweeter and high rated sensitivity. Erin’s data predicts 55Hz in-room extension, a 6.35 subwoofer-assisted preference score and good 0.153 sound-power smoothness. Measured bass extension of 71.8Hz (-3dB).

Cons: The measured response rises strongly at +0.84dB per octave and directivity-index consistency is a poor 4.34, so tonal balance and off-axis behavior are less neutral than the price implies. The cabinet is large, heavy and $850 per pair before stands.

Full MartinLogan Motion XT B100 review and specifications →

Bass Extension (-10dB)	50.7Hz (derived, log-interpolated between spinorama.org -9dB/-12dB points)
Bass Extension (-3dB)	71.8Hz (measured, Erin’s Audio Corner via spinorama.org)
Country	United States (design)
DIY Kit	No
Dimensions	14.5H x 8W x 12.5D in
Drivers	1.25 x 2.4” folded-motion XT tweeter, 6.5” Kevlar woofer
Enclosure	2-way, rear-ported
Impedance	4 ohms
Sensitivity	93dB
Spinorama Preference Score	3.83
Spinorama Preference Score with Perfect Sub	6.35
Weight	20.5 lbs (9.3 kg) each

• Links
  • MartinLogan Motion XT B100 Official Page
• Reviews, Comparisons and Sound Samples
  • Erin’s Audio Corner Measurements (spinorama.org) More from Erin’s Audio Corner →
• Head-to-Head Comparisons
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