Short answer: the ELAC DF63. It ranks #25 of 54 floorstanding speakers by sound quality at $649; the Infinity Primus 360 ranks #30 and costs $650, so there is not much of a tradeoff to weigh.
What the ELAC DF63 offers: Three-driver floorstanding layout: two 6” dedicated midbase drivers plus a separate 6” mid-range driver (confirmed by measuring different driver impedance/inductance) and a 1” dome tweeter, each woofer given its own stuffed… Watch for: A genuine measured resonance around 200-300Hz (visible in frequency response, impedance, and group delay) causes an audible “droning” coloration on female vocals.
What the Infinity Primus 360 offers: 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… Watch for: Manufacturer-spec sensitivity of 93dB runs about 3-4dB optimistic versus the measured 89.4dB average.
Buy the ELAC DF63. It ranks higher for sound quality than the Infinity Primus 360 and costs less, so there is no real case for the other one.
Specifications Side By Side
| ELAC DF63 | Infinity Primus 360 | |
|---|---|---|
| Price | $649.00 | $650.00 Discontinued |
| Ranked | #25 of 54 in Large Size Floorstanding Speakers | #30 of 54 in Large Size Floorstanding Speakers |
| Bass Extension (-10dB) | 29Hz (measured, Erin’s Audio Corner) | 37Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 71Hz (measured, Erin’s Audio Corner) | 53Hz (measured, Erin’s Audio Corner) |
| Dimensions | 43.1"H x 7.7"W x 10.6"D (1094.7 x 195.6 x 269.2 mm) | 39"H x 8-1/8"W x 13-7/8"D (990 x 208 x 330mm) |
| Impedance | 6 ohms nominal (3.4 ohms minimum, measured, Erin’s Audio Corner) | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) |
| Drivers | Two 6.5" Aramid Fiber woofer, 6.5" Aramid Fiber midrange, 1" Aluminum Dome tweeter | Two 6.5" mid-woofers, 4" mid-range, 0.75" dome tweeter |
| Sensitivity | 86.6dB (measured, Erin’s Audio Corner) | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) |
| Weight | 58.2 lbs / 26.4 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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- Definitive Technology BP-9020 vs Bose 901 Series V
- ELAC DF63 vs Polk Reserve R500
- Infinity Primus 360 vs Monolith Encore T6
The Two Speakers In Full
ELAC DF63: $649.00 Amazon
Pros: Three-driver floorstanding layout: two 6” dedicated midbase drivers plus a separate 6” mid-range driver (confirmed by measuring different driver impedance/inductance) and a 1” dome tweeter, each woofer given its own stuffed chamber inside the cabinet. The dedicated midrange driver keeps distortion low even at higher output, avoiding the intermodulation grain typical of two-way bookshelf designs. The waveguide keeps high-frequency directivity well controlled, and overall horizontal directivity is good up to about 2kHz. Harmonic distortion looks good at both 86dB and 96dB, and multitone distortion stays below the reviewer’s 3% threshold. A shallow bass rolloff (F3 71Hz, F10 29Hz) lets it extend fairly low without a hard cutoff. Preferred by the reviewer over the similarly-priced Polk R500 (too much high-frequency narrowing, less neutral) and considered ahead of the Polk R700 as well.
Cons: A genuine measured resonance around 200-300Hz (visible in frequency response, impedance, and group delay) causes an audible “droning” coloration on female vocals. A mild peak around 10kHz makes shakers and similar high-frequency percussion jump too far forward in the mix; needed about 2dB of EQ to tame in testing. A dip in the 1-3kHz range gives the speaker a warm, slightly veiled character - the reviewer suspects the tweeter crossover point (around 2-3kHz) is set a bit high and could be lowered to fill this in. Directivity shows a noticeable handoff mismatch around 2.5kHz where the midrange driver hands off to the tweeter, though it’s minor at the -6dB point. Vertical directivity is narrower than horizontal, so listeners need to stay close to the tweeter axis. Low EPDR (about 1.5 ohms minimum) means a Class AB amplifier should be well-ventilated. Best positioned pointed directly at the listener and closer to the front wall - toeing it out into the room causes too much high-frequency rolloff.
Full ELAC DF63 review and specifications →
| Bass Extension (-10dB) | 29Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 71Hz (measured, Erin's Audio Corner) |
| Dimensions | 43.1"H x 7.7"W x 10.6"D (1094.7 x 195.6 x 269.2 mm) |
| Drivers | Two 6.5" Aramid Fiber woofer, 6.5" Aramid Fiber midrange, 1" Aluminum Dome tweeter |
| Impedance | 6 ohms nominal (3.4 ohms minimum, measured, Erin's Audio Corner) |
| Sensitivity | 86.6dB (measured, Erin's Audio Corner) |
| Weight | 58.2 lbs / 26.4 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 |
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