JBL S3100MKII (c. 1999)
The JBL S3100MKII is a floor-standing, 2-way bass reflex speaker system from the late 1990s. JBL was pushing its horn design work into new territory then. The centerpiece is the "Differentiated Directivity Horn," an original 3-D curved horn (driver unit 275nd mated to horn H2600-1). JBL claimed it concentrates mid and high frequencies within the horn's directional angle, which keeps the sound pressure level uniform across a wide listening area. The 275nd is a one-inch throat compression driver with a titanium diaphragm and a neodymium magnet. The woofer is the ME150HS, a 38 cm (15") cone type with a fiber composite cone and Aqua Plus coating.
The enclosure is a wedge-shaped bass reflex cabinet made of MDF. It narrows toward the rear along the horn angle to suppress internal standing waves, and bracing keeps the low end tight. The top panel is black high-gloss lacquer. The rest is a wood-grain decorative panel. Inside, the low- and high-frequency networks are installed independently. The high-frequency network uses a charge-coupled method that applies a DC bias to run the capacitors in class A, which JBL said eliminates zero-cross distortion and improves transient response. Two sets of gold-plated input terminals allow bi-wiring or bi-amplifying once the bus bar is removed.
Specs as documented: frequency response 30 Hz to 20 kHz, output sound pressure level 95 dB, impedance 8 Ω, allowable input (IEC) 200W, crossover at 750 Hz. Dimensions are 561 x 1102 x 406 mm (W x H x D), weight 63.5 kg. The original price was ¥450,000 per unit around 1999. A technical manual (dated 12/00, listing JBL's Woodbury, NY address) covers specifications, parts lists, wiring diagrams, and schematics.
Documentation on this model is thin beyond the spec sheet. No period reviews have surfaced in the archive. One owner on an audio forum measured an S3100MKII and noted the response looked very similar across the couch in the horizontal plane, which fits the horn's claimed wide, even coverage. The same commenter compared the non-MKII S3100 to the JBL L300 and called the S3100 "BY FAR the best sounding" of the two, but also predicted the L300 would remain the icon. A used listing in Malaysia asked RM9,990. A Yahoo! Auctions Japan listing noted the foam surrounds needed replacement, a common failure point for woofers of this era.
- Type: 2-way, 2-speaker, bass reflex, floor type
- Low band: 38 cm cone woofer (ME150HS)
- High range: horn type — 275nd compression driver + H2600-1 horn
- Frequency response: 30 Hz – 20 kHz
- Output SPL: 95 dB · Impedance: 8 Ω · IEC input: 200W
- Crossover: 750 Hz
- Dimensions: 561 x 1102 x 406 mm · Weight: 63.5 kg
- Original price: ¥450,000 per unit (c. 1999)
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