Short answer: the Polk Reserve R500 for better sound quality, the Infinity Primus 360 for the lower price. The Polk Reserve R500 ranks #28 of 56 floorstanding speakers at $699. The Infinity Primus 360 ranks #32 at $650, $49 cheaper.
What the Polk Reserve R500 offers: Dual 5.25” midwoofers paired with a ring radiator tweeter in a floorstanding tower design. Watch for: A bump around 4-6kHz gives a “shouty,” mildly sibilant quality in the lower treble.
What the Infinity Primus 360 gets right: A three-way tower from 2005 (two 6.5” mid-woofers, a 4” mid-range, and a 0.75” dome tweeter, 8 ohms nominal) that holds up remarkably well by modern measurement standards: on-axis linearity is within about ±2dB. The catch: Manufacturer-spec sensitivity of 93dB runs about 3-4dB optimistic versus the measured 89.4dB average.
Buy the Polk Reserve R500 if sound quality matters more than the price. Buy the Infinity Primus 360 if the price matters more than sound quality.
Specifications Side By Side
| Polk Reserve R500 | Infinity Primus 360 | |
|---|---|---|
| Price | $699.00 | $650.00 Discontinued |
| Ranked | #28 of 56 in Large Size Floorstanding Speakers | #32 of 56 in Large Size Floorstanding Speakers |
| Bass Extension (-10dB) | 33Hz (measured, Erin’s Audio Corner) | 37Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) | 53Hz (measured, Erin’s Audio Corner) |
| Dimensions | 40.3"H x 6.8"W x 12.4"D (1023.6 x 172.7 x 315 mm) | 39"H x 8-1/8"W x 13-7/8"D (990 x 208 x 330mm) |
| Impedance | 4.1 ohms minimum above 80Hz (measured, Erin’s Audio Corner; 8 ohms nominal per manufacturer) | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 86.2dB (measured, Erin’s Audio Corner) | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) |
| Drivers | Two 5.25" Turbine Cone woofer, 1" Pinnacle Ring Radiator tweeter | Two 6.5" mid-woofers, 4" mid-range, 0.75" dome tweeter |
| Weight | 39.2 lbs / 17.8 kg each | 48.5 lbs (48.5 lbs / 22 kg) each |
| Woofer Cabinet | ported, rear | - |
| Discontinued | - | Yes |
| Frequency Response | - | 38Hz - 20kHz (±3dB, Manufacturer specified) |
| Crossovers | - | 350Hz & 3.3kHz, 24dB/octave |
| Recommended Power | - | 10-200W |
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The Two Speakers In Full
Polk Reserve R500: $699.00 Amazon
Pros: Dual 5.25” midwoofers paired with a ring radiator tweeter in a floorstanding tower design. Surprisingly neutral overall compared to Polk’s smaller bookshelf models - notably more even-handed than the brighter-sounding R200 the reviewer tested previously. Good linearity on-axis, within about -3/+2dB. Sensitivity close to 86dB, easily driven to adequate levels in a small-to-medium room with a 100W-capable amplifier. Takes very well to EQ - a single band of correction (about a 2dB cut around 4-5kHz) resolves the main tonal issue and transforms the sound. Dynamic range and compression performance is solidly “medium,” holding up fine through about 20dB of level increase before higher-frequency and bass output start to taper at extreme volumes.
Cons: A bump around 4-6kHz gives a “shouty,” mildly sibilant quality in the lower treble. Counterintuitively, toeing the speaker out to reduce brightness makes this worse rather than better, since the ring-radiator tweeter’s directivity narrows rapidly above about 6-7kHz - pointed on-axis retains enough top-end air to balance the bump, but toed away that air drops off and the shoutiness stands out more. Bass is adequate for its 5.25” woofers but lacks real weight below about 40-50Hz; a subwoofer is still needed for movies and bass-heavy music. A cabinet resonance around 160-170Hz subtracts from rather than adds boom to the mid-bass region. Vertical listening window is fairly narrow - sitting more than about 10-20° above or below the tweeter axis causes a suckout in the 2-5kHz range, reducing clarity and attack. Multitone distortion ramps up noticeably around 1kHz, and crossing over to a subwoofer at 80Hz doesn’t meaningfully reduce it - likely a surround-related effect rather than excursion-related. Without applying corrective EQ, the reviewer says the 4-6kHz brightness would make it harder to live with day to day.
Full Polk Reserve R500 review and specifications →
| Bass Extension (-10dB) | 33Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 51Hz (measured, Erin's Audio Corner) |
| Dimensions | 40.3"H x 6.8"W x 12.4"D (1023.6 x 172.7 x 315 mm) |
| Drivers | Two 5.25" Turbine Cone woofer, 1" Pinnacle Ring Radiator tweeter |
| Impedance | 4.1 ohms minimum above 80Hz (measured, Erin's Audio Corner; 8 ohms nominal per manufacturer) |
| Sensitivity | 86.2dB (measured, Erin's Audio Corner) |
| Weight | 39.2 lbs / 17.8 kg each |
| Woofer Cabinet | ported, rear |
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Infinity Primus 360: $650.00 Discontinued
Pros: A three-way tower from 2005 (two 6.5” mid-woofers, a 4” mid-range, and a 0.75” dome tweeter, 8 ohms nominal) that holds up remarkably well by modern measurement standards: on-axis linearity is within about ±2dB, and the listening window stays consistent out to roughly ±30° horizontal and ±10° vertical off the mid-range axis. Horizontal directivity is well controlled out to about ±75° before tonality starts to drift, meaning the reflected sound in a room stays close in character to the direct sound - a speaker that takes EQ well without fighting itself. Harmonic distortion measures low at both 86dB and 96dB, and multitone distortion stays under the reviewer’s 3% threshold. Silky, smooth midrange with a rich lower-midrange/upper-bass character. No mechanical issues or surround degradation found in a 20-year-old pair, and a second unit measured within about 1-1.5dB of the first, suggesting good long-term consistency for the design.
Cons: Manufacturer-spec sensitivity of 93dB runs about 3-4dB optimistic versus the measured 89.4dB average. Bass output drops off fairly quickly below about 50Hz in-room (F3 53Hz, F10 37Hz), so a subwoofer is needed for real low-end extension. Resonances show up around 170Hz, 220Hz, and 350Hz. On-axis, the lower treble can sound a bit bright or sibilant when the speaker is aimed directly at the listener; toeing out about 10-15° (rather than the more extreme 30°) gave the best balance, and some sidewall acoustic absorption further tamed a 4-5kHz peak. Placed close to the rear wall, bass gets boomy - pulling the speakers out about a foot resolves most of it, with roughly 1.5 feet from the wall as a good compromise between bass character and typical room aesthetics. Straying beyond about 25° above or below the mid-range axis introduces audible suckout. No longer in production, so it’s a used/secondhand purchase only. Discontinued.
Full Infinity Primus 360 review and specifications →
| Bass Extension (-10dB) | 37Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 53Hz (measured, Erin's Audio Corner) |
| Crossovers | 350Hz & 3.3kHz, 24dB/octave |
| Dimensions | 39"H x 8-1/8"W x 13-7/8"D (990 x 208 x 330mm) |
| Discontinued | Yes |
| Drivers | Two 6.5" mid-woofers, 4" mid-range, 0.75" dome tweeter |
| Frequency Response | 38Hz - 20kHz (±3dB, Manufacturer specified) |
| Impedance | 8 ohms nominal, 3.5 ohms minimum (measured, Erin's Audio Corner) |
| Recommended Power | 10-200W |
| Sensitivity | 89.4dB (measured, Erin's Audio Corner; 93dB manufacturer specified) |
| Weight | 48.5 lbs (48.5 lbs / 22 kg) each |
As an eBay Partner, we may be compensated if you make a purchase.
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