Short answer: both are discontinued, so this only matters if you are buying used. Used, the JBL HDI-3800 is the better pick: it ranks #25 of 188 floorstanding speakers by sound quality (rated 4.5/5), against #77 (rated 4.2/5) for the Infinity Primus 360. If you want one new, the MoFi SourcePoint 888 ranks #8 at $5,495.
The JBL HDI-3800 is the more accurate, deeper-bass choice. 2410H-2 1” Teonex compression driver matched to a custom High-Definition Imaging (HDI) horn geometry achieves exceptional horizontal directivity control, high output capability, and effortless transient response. Its measured preference score, a predictor of how neutral it sounds, is 5.62 against 4.97 for the Infinity Primus 360. Its bass reaches about 37Hz before falling 3dB, against 53Hz for the Infinity Primus 360. Watch for: On-axis frequency response features a narrow upper-frequency elevation around 8-10kHz, performing noticeably smoother when toed out 10-20° off-axis.
What the Infinity Primus 360 does well: 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. Watch for: Manufacturer-spec sensitivity of 93dB runs about 3-4dB optimistic versus the measured 89.4dB average.
Buy the JBL HDI-3800 only if you find one used in good condition; both are discontinued, and it is the better rated of the two. For a new speaker, start with the MoFi SourcePoint 888 instead.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| JBL HDI-3800 | Infinity Primus 360 | |
|---|---|---|
| Price | $5,000 per pair Discontinued | $650 per pair Discontinued |
| Ranked | #25 of 188 in Large Size Floorstanding Speakers | #77 of 188 in Large Size Floorstanding Speakers |
| Bass Extension (-10dB) | 28Hz (measured, Erin’s Audio Corner) | 37Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 37Hz (measured, Erin’s Audio Corner) | 53Hz (measured, Erin’s Audio Corner) |
| Dimensions | 43.3”H x 11.8”W x 16.4”D (1100.5 x 300.0 x 417.8 mm) | 39” x 8.2” x 13” (990 x 208 x 330 mm) |
| Impedance | 4 ohms nominal (3.8 ohms minimum, measured by Erin’s Audio Corner) | 8 ohms nominal, 3.5 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 92dB (measured average, Erin’s Audio Corner) | 89.4dB (measured, Erin’s Audio Corner; 93dB manufacturer specified) |
| Drivers | 1 in. 2410H-2 Teonex compression driver with HDI horn, triple 8 in. Advanced Aluminum Matrix cone woofers | Two 6.5” mid-woofers, 4” mid-range, 0.75” dome tweeter |
| Weight | 83.8 lbs (38.0 kg) each | 48.5 lbs (22 kg) each |
| Woofer Cabinet | ported, rear | - |
| Spinorama Preference Score | 5.62 | 4.97 |
| Spinorama Preference Score with Perfect Sub | 7.03 | 7.10 |
| DIY Kit | No | No |
| Frequency Response | - | 38Hz - 20kHz (±3dB, Manufacturer specified) |
| Crossover Frequency | - | 350Hz & 3.3kHz, 24dB/octave |
| Recommended Power | - | 10-200W |
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Prices on this page were last checked October 9, 2026 at 8:01 AM 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
JBL HDI-3800: $5,000 per pair Discontinued eBay
Same family: the JBL HDI-1600 (bookshelf, rated 4.2/5), the JBL HDI-3600 (smaller floorstanding, ranked lower, rated 4.3/5) and the JBL HDI-4500 (center, rated 3.7/5).
Pros: 2410H-2 1” Teonex compression driver matched to a custom High-Definition Imaging (HDI) horn geometry achieves exceptional horizontal directivity control, high output capability, and effortless transient response. Triple 8” Advanced Aluminum Matrix woofers deliver deep, authoritative bass extension down to an F3 of 37Hz and F10 of 28Hz with minimal low-frequency compression. Outstanding sensitivity (92dB SPL at 2.83V/1m) and ultra-low THD/multitone distortion allow extremely high undistorted SPL output in large home theater spaces. Measured bass extension of 37Hz (-3dB), with a measured sensitivity of 92dB.
Cons: On-axis frequency response features a narrow upper-frequency elevation around 8-10kHz, performing noticeably smoother when toed out 10-20° off-axis. Vertical directivity handoff across the triple woofer layout creates vertical soundstage height tilt depending on listening distance and ear height. Minimum impedance dips to 3.8 ohms, requiring high-current amplifier stability. Substantial cabinet dimensions and 38kg weight require significant room real estate. Discontinued.
Full JBL HDI-3800 review and specifications →
| Bass Extension (-10dB) | 28Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 37Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 43.3”H x 11.8”W x 16.4”D (1100.5 x 300.0 x 417.8 mm) |
| Drivers | 1 in. 2410H-2 Teonex compression driver with HDI horn, triple 8 in. Advanced Aluminum Matrix cone woofers |
| Impedance | 4 ohms nominal (3.8 ohms minimum, measured by Erin’s Audio Corner) |
| Sensitivity | 92dB (measured average, Erin’s Audio Corner) |
| Spinorama Preference Score | 5.62 |
| Spinorama Preference Score with Perfect Sub | 7.03 |
| Weight | 83.8 lbs (38.0 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Infinity Primus 360: $650 per pair Discontinued eBay
Same family: the Infinity Primus 150 (bookshelf, rated 3.4/5).
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. Measured bass extension of 53Hz (-3dB), with a measured sensitivity of 89.4dB.
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.
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) |
| Crossover Frequency | 350Hz & 3.3kHz, 24dB/octave |
| DIY Kit | No |
| Dimensions | 39” x 8.2” x 13” (990 x 208 x 330 mm) |
| 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) |
| Spinorama Preference Score | 4.97 |
| Spinorama Preference Score with Perfect Sub | 7.10 |
| Weight | 48.5 lbs (22 kg) each |
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