JBL Project K2 S5800
The JBL Project K2 S5800 is a floor-standing, three-way, four-speaker bass-reflex system. It was JBL's flagship consumer design at the turn of the millennium. It was priced at ¥980,000 per unit around 2002 - roughly $8,000 at the time - which is firmly high-end money. Two 30 cm cone woofers (model 1200 FE) flank a horn-loaded midrange and tweeter mounted between them. The midrange is a 7.5 cm compression driver (435 AL). The highs come from a 2.5 cm titanium-diaphragm compression driver (045 Ti). The arrangement is sometimes called a symmetrical vertical array, and it aims for coherent time alignment across the drivers.
The woofers use Kevlar-composite cones with an Aqua-Plus coating on the rear to suppress breakup. They have double dampers for linearity and JBL's symmetrical field geometry (SFG) magnetic circuit, with an aluminum ribbon voice coil and a bent pole piece that helps dissipate heat. The midrange and tweeter both use lightweight aluminum ribbon voice coils and high-flux neodymium magnets. The midrange diaphragm is aluminum. The tweeter diaphragm is pure titanium with an integrally molded edge. Both horns are cast as a single integrated unit from high-density SonoGlass, with three-dimensional curved ribs to control acoustic diffraction from the woofers above and below.
The crossover is split into separate networks for the low band and mid/high band, using JBL's charge-coupled linear definition method — a DC bias applied to the capacitors to reduce nonlinear distortion. Two sets of terminals allow bi-wiring, and a mode switch permits active bi-amplification. An HF trim switch fine-tunes midrange level. The enclosure is high-rigidity MDF in a slim tower design, finished in high-gloss mahogany. It comes with large spike feet. Each speaker weighs 83.9 kg and measures 432 × 1245 × 413 mm (W×H×D) per one source, though another source lists 75.8 kg and 435 × 1245 × 385 mm. Frequency response is rated at 50 Hz–40 kHz (−6 dB), with low-frequency extension to 28 Hz (−10 dB). Output sensitivity is 96 dB/m (2.83 V), impedance is 8 ohms, and RMS power handling is 300 W. Crossover points are 800 Hz and 10 kHz.
Documentation on the S5800's market history is thin. The manual includes a chapter on the historical development of JBL's Project loudspeakers, and it describes the S5800 as preceding the K2 S9500 and K2 S5500 in that lineage. It also calls the S5800 "the first consumer-available listening system" to achieve something, but the sentence is cut off in the record, so what that was is unclear. The used market is healthy. Listings have appeared on Yahoo Auctions Japan (a pair closing around ¥390,000 in June 2026), on Russian classifieds, on HifiShark, and on hi-fi.org.uk, where a pair was tagged "Rare" and "Working." A restored pair was also offered on jbl43.com.
- Type: 3-way, 4-speaker, bass-reflex floor-standing system
- Drivers: 30 cm cone woofer (1200 FE) ×2; 7.5 cm horn compression driver (435 AL); 2.5 cm horn compression driver (045 Ti)
- Frequency response: 50 Hz–40 kHz (−6 dB); 28 Hz (−10 dB)
- Sensitivity: 96 dB/m (2.83 V)
- Impedance: 8 Ω
- Power handling: 300 W RMS
- Crossover: 800 Hz, 10 kHz
- Dimensions: 432 × 1245 × 413 mm (W×H×D)
- Weight: 83.9 kg
- Original price: ¥980,000 (1 unit, circa 2002)
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