JBL 4312BMKII
The 4312BMKII is a Japanese-market variant of JBL's long-running 4312 Control Monitor series, a line that traces back to the original 4310 of 1968. According to the period documentation, the only difference from the standard 4312 MKII is the high-frequency unit. The rest of the driver complement is shared.
The speaker is a three-way, three-driver bass reflex design in a bookshelf format. The low end comes from a 30 cm white-cone 2213H woofer with a 75 mm copper ribbon edge-wound voice coil. It uses JBL's SFG (symmetrical field geometry) magnetic circuit and an aluminum die-cast frame. The midrange is a 12.5 cm 104H-3 driver derived from the LE5 series. The tweeter is the 035ti, a 25 mm pure titanium dome formed to 25 μm thickness. Crossover points are 1100 Hz and 4200 Hz, with independent attenuators for the mid and high ranges.
The enclosure is finished in black with anti-slip embossing, and the driver layout was designed to concentrate the sound sources. It's a fairly compact speaker for the era at 362 × 597 × 298 mm and 20 kg. Rated impedance is 6 Ω, sensitivity is 93 dB/2.83V/m, frequency response is 45 Hz to 20 kHz (−6 dB), and power handling is 100 W RMS. The original Japanese price was ¥78,000 per unit, around 1999.
Production years aren't clearly documented, and reception is thin in the English-language record. What does surface is mostly Japanese auction and resale activity. Restored pairs have changed hands at meaningful premiums, and one fully serviced pair was listed at ¥210,000. The 4312BMKII's reputation among Japanese collectors appears solid, with the titanium-dome tweeter the main talking point versus the earlier MKII.
**Known specifications:**
- 3-way, 3-speaker bass reflex, bookshelf type
- 30 cm 2213H woofer / 12.5 cm 104H-3 midrange / 25 mm 035ti titanium dome tweeter
- Frequency response: 45 Hz - 20 kHz (−6 dB)
- Sensitivity: 93 dB / 2.83V/m
- Impedance: 6 Ω
- Power handling: 100 W (RMS)
- Crossover: 1100 Hz, 4200 Hz
- Dimensions: 362 × 597 × 298 mm (W×H×D); 20 kg
- Price: ¥78,000 per unit (circa 1999)
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