Напольная акустика — JBL PROJECT K2 S9900

The Project K2 S9900 is a three-way floor-standing system from JBL built around a 15-inch woofer and two horn-loaded compression drivers. JBL places it in the lineage of its Project loudspeakers, a sequence that began with the Hartsfield in 1954 and continued through the Paragon, Project Everest DD55000, K2 S9500, K2 S5500, K2 S9800, K2 S5800 and Project Everest DD66000. The S9900 carries forward the K2 S9800 layout and borrows several design elements from the DD66000, and it dates from 2009.

Key specs that matter

Bass is handled by the 380 mm 1500AL-1 pulp-cone driver, the midrange and treble come from the 476Mg compression driver with a 100 mm magnesium-alloy diaphragm, and the 045Be-1 ultrahigh-frequency unit uses a 25 mm pure beryllium dome. Crossover points sit at 900 Hz and 15 kHz, both at 24 dB per octave. JBL rates response at 48 Hz to 50 kHz within -6 dB, with the -10 dB point at 33 Hz, and sensitivity at 93 dB for 2.83 V at 1 m. Nominal impedance is 8 ohm, falling to 7 ohm at 100 Hz and 4 ohm at 40 kHz. The main horn covers 100 by 60 degrees and the ultrasonic horn 60 by 30 degrees. The cabinet measures 560 x 1200 x 350 mm plus 20 mm of feet and weighs 82.7 kg.

Engineering and use context

In JBL terms this is an augmented two-way - one crossover in the middle of the band, with the beryllium unit only adding the top two octaves. The 1500AL-1 has a large voice coil in an alnico 5DG motor, copper and steel laminations in the top plate, dual inverted Nomex spiders and Vented Gap Cooling, and it takes about 25 percent more power than the older 1500AL. The magnesium diaphragm of the 476Mg is 130 microns thick at roughly 3.4 g of moving mass. Its Bi-Radial horn gets side walls from the curved baffle and SonoGlass lips top and bottom. The enclosure is 25 mm MDF, with a 45 mm total woofer baffle and a 100 mm flared rear port tuned to 35 Hz. Two rear switches shift the upper band and the 1.5 to 3 kHz region by about 0.5 dB, and a 9 V battery biases the network capacitors.

Pairing

JBL says 70 to 100 W is enough to run the system, but advises at least 100 W for full-range use and names 100 to 500 W high-current amplifiers as the ideal. A bi-amp switch exists, yet active bi-amplification is not advised because an ordinary external crossover cannot supply the voltage curve required.

Alternatives

JBL's Project Everest DD66000 is the other floor-standing model in the same Project family whose design the S9900 draws on.