Short answer: the Polk Reserve R100 for better sound quality, the Emotiva Airmotiv B2+ for the lower price. The Polk Reserve R100 ranks #65 of 84 bookshelf speakers at $649. The Emotiva Airmotiv B2+ ranks #66 at $449, $200 cheaper.
What the Polk Reserve R100 offers: Compact cabinet, unusually useful bass for its size and well-controlled woofer breakup. Watch for: Erin measured only about 85dB sensitivity and the impedance reaches 3.6 ohms, so it is neither efficient nor an entirely benign AVR load.
What the Emotiva Airmotiv B2+ offers: Erin measured a useful 86dB average sensitivity and strong midbass punch around 120Hz. Watch for: The replacement B2+ did not deliver the neutral upgrade Erin expected.
Buy the Polk Reserve R100 if sound quality matters more than the price. Buy the Emotiva Airmotiv B2+ if the price matters more than sound quality.
If sound quality matters at all to you, skip both of these and look higher up the 84 bookshelf speakers instead.
Specifications Side By Side
| Polk Reserve R100 | Emotiva Airmotiv B2+ | |
|---|---|---|
| Price | $649/pair | $449.00 |
| Ranked | #65 of 84 in Large Size Bookshelf Speakers | #66 of 84 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | 68Hz (measured, Erin’s Audio Corner) | 66Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 49Hz (measured, Erin’s Audio Corner) | 43Hz (measured, Erin’s Audio Corner) |
| Sensitivity | 85dB/2.83V/1m (measured, Erin’s Audio Corner) | 86dB (measured average, Erin’s Audio Corner) |
| Impedance | 3.6 ohms minimum (measured, Erin’s Audio Corner) | 4 ohms nominal (manufacturer specified) |
| Drivers | 1" Pinnacle ring-radiator tweeter; 5.25" Turbine Cone midwoofer | 6.5" woven-fiber woofer, 32 x 25mm folded-ribbon tweeter |
| Dimensions | 12.8"H x 6.5"W x 10.2"D | - |
| Weight | 12.2 lb each | - |
| Woofer Cabinet | ported, rear X-Port | ported, rear |
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More useful head-to-heads from the same speaker class:
- ELAC DB63 vs Polk R200
- KEF Q Concerto Meta vs Polk R200
- Wharfedale Linton 85 vs Polk R200
- SVS Prime Bookshelf vs Emotiva Airmotiv B2+
- Revel Performa M22 vs Polk Reserve R100
The Two Speakers In Full
Polk Reserve R100: $649/pair Amazon Polk Audio
Pros: Compact cabinet, unusually useful bass for its size and well-controlled woofer breakup. Erin measured F3/F10 points of 68Hz/49Hz, and the X-Port vent avoids much of the chuffing and pipe resonance common to budget rear ports. The 5.25-inch Turbine Cone woofer and 1-inch Pinnacle ring-radiator tweeter produce good detail at moderate levels, while listening roughly 20° off-axis reduces part of the elevated top octave.
Cons: Erin measured only about 85dB sensitivity and the impedance reaches 3.6 ohms, so it is neither efficient nor an entirely benign AVR load. The treble runs roughly 3dB above the midrange and becomes aggressive above about 85dB SPL. A directivity discontinuity through the woofer/tweeter crossover means EQ cannot fully repair the power response, and a 400Hz impedance feature plus 500Hz-1kHz response irregularity suggests a cabinet or system resonance. Substantial low-frequency compression at higher playback levels limits clean dynamics.
Full Polk Reserve R100 review and specifications →
| Bass Extension (-10dB) | 49Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 68Hz (measured, Erin's Audio Corner) |
| Dimensions | 12.8"H x 6.5"W x 10.2"D |
| Drivers | 1" Pinnacle ring-radiator tweeter; 5.25" Turbine Cone midwoofer |
| Impedance | 3.6 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 85dB/2.83V/1m (measured, Erin's Audio Corner) |
| Weight | 12.2 lb each |
| Woofer Cabinet | ported, rear X-Port |
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Emotiva Airmotiv B2+: $449.00
Pros: Erin measured a useful 86dB average sensitivity and strong midbass punch around 120Hz. The folded-ribbon tweeter provides very broad upper-treble radiation, and the speaker can create a spacious presentation when positioned carefully. Response and directivity remain reasonably orderly below the roughly 2kHz crossover region. The 6.5-inch woofer offers more output capability than compact 5-inch competitors, while F3/F10 of 66/43Hz leave adequate overlap for a conventional 80Hz subwoofer crossover. Horizontal directivity data makes the broad baffle-step trend amenable to partial EQ below the crossover.
Cons: The replacement B2+ did not deliver the neutral upgrade Erin expected. A baffle-step loss around 500Hz depresses the lower midrange while the AMT’s much wider radiation above crossover injects excess room energy, yielding a bright, forward balance and false impression of cymbal detail. The directivity discontinuity near 2kHz cannot be completely equalized. Erin measured F3 at 66Hz and F10 at 43Hz, so meaningful kick-drum fundamentals and low bass still need a subwoofer. Vertical listening tolerance is roughly +/-10 degrees, with best results between the top of the woofer and tweeter axes. Broad lateral treble energy may require careful toe-out and sidewall absorption. Despite a large cabinet, it offers limited deep-bass advantage and was not Erin’s hoped-for successor to the more linear B1+.
Full Emotiva Airmotiv B2+ review and specifications →
| Bass Extension (-10dB) | 43Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 66Hz (measured, Erin's Audio Corner) |
| Drivers | 6.5" woven-fiber woofer, 32 x 25mm folded-ribbon tweeter |
| Impedance | 4 ohms nominal (manufacturer specified) |
| Sensitivity | 86dB (measured average, Erin's Audio Corner) |
| Woofer Cabinet | ported, rear |
As an eBay Partner, we may be compensated if you make a purchase.
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