Напольная акустика — JBL S3900

The S3900 is a three-way floor-standing loudspeaker in JBL's Synthesis range that pairs two 10-inch woofers with a pair of horn-loaded compression drivers. Introduced in 2016 at USD 7,999, it uses professional-grade components and takes design cues from the Project K2 S9900, and it sits below the bigger S4700 in the same family. In the UK the pair was priced at GBP 10,000 in 2017, and cabinets were offered in black or natural cherry.

Key specs that matter

Two 250 mm pure-pulp cone woofers with ferrite motor assemblies cover the bass. Above 850 Hz a 1.75-inch compression driver with an Aquaplas-treated pure titanium diaphragm takes over, and from 12 kHz a 19 mm titanium ultrahigh-frequency driver with a neodymium motor covers the top octaves. JBL quotes 33 Hz to 40 kHz at the -6 dB points, 92 dB sensitivity for 2.83 V at 1 m and a 6 ohm nominal load. Each enclosure stands 100.1 cm high, 37 cm wide and 36.8 cm deep, and weighs 39 kg.

Engineering and use context

Both compression drivers load into a patented Bi-Radial horn moulded in SonoGlass, the same horn family JBL uses on its Project systems. The cabinet is a three-way hybrid of horn loading and bass reflex. Handing the top octaves to a separate small titanium diaphragm lets the larger driver stay within its comfortable range instead of stretching to the upper limit of the response. The cabinet is built from 25 mm thick MDF and vented through a large rear-facing port. The crossover is described by JBL as an advanced network, and the rear panel carries separate gold-plated low-frequency and high-frequency inputs for bi-wiring. Grilles are supplied for the woofers, while the horn stays exposed. Because the mid driver hands over to the woofers this low, the twin cones work only in the bass and lower midrange, and the titanium diaphragm carries the whole vocal band without a crossover point inside it.

Pairing

Recommended amplifier power runs from 25 to 250 W per channel, so the high sensitivity allows modest amplifiers to be used, while the nominal impedance and twin woofers still call for an amplifier that stays stable into loads below 8 ohm. The split terminals permit two runs of cable per speaker, or passive bi-amping with two identical stereo amplifiers, one on the woofers and one on the horn section.

Alternatives

JBL's S4700 is the larger floor-standing model above the S3900 within the same Synthesis series.