JBL 1500AL (2002)
The JBL 1500AL is a 15-inch cone woofer unit released in 2002, priced at ¥200,000 per unit in Japan. It uses an Alnico 5 magnet, which was an odd choice by then. Most manufacturers had long since moved to ferrite or ceramic magnets for cost and power-handling reasons. The 1500AL was built for JBL's flagship loudspeakers. It powered the K2 S9800 and the Everest DD66000, and a revised variant, the 1500AL-2, later appeared in the Project Everest DD6700.
The cone is pure pulp, made from carefully selected natural long-fiber pulp and naturally dried to strengthen fiber bonds. It has a corrugation rib coating on the front and JBL's original Aqua Plus coating on the back. JBL claimed this gives high rigidity without breakup even at high output. The edge is lightweight, low-loss EPDM foam rubber, chosen for durability and weather resistance. A NOMEX double damper with a symmetric structure cancels even-order harmonic distortion, promoting linear cone movement from minute to large outputs.
The magnetic circuit is where the 1500AL gets interesting. Around the Alnico 5 dg magnet, JBL placed a large-capacity aluminum short ring and a copper-steel laminated inner gap ring under the voice coil gap. This stabilizes the local magnetic field and suppresses magnetic modulation — addressing the classic Alnico problem of demagnetization under high-power drive. The frame uses a bent-frame structure to rectify unit back pressure, and a bent-gap cooling mechanism with three air tunnels from the pole piece to the bucket cover dissipates voice coil heat.
Enclosure recommendations from period sources: the original 1500AL works very well in a 4.6 cubic foot box tuned to 28 Hz. The JBL factory box for the 1500AL-1 variant is 3.4 cubic feet tuned to 36 Hz. One forum user noted that in that smaller box you "give up the bottom octave," but "the rest of the bandwidth is top shelf."
The 1500AL was not sold as a standalone driver in the US domestic market. Obtaining one reportedly required negotiations with people close to JBL executives. The units are scarce and sought-after. A pair sold through the Japanese vintage dealer MUSiCA, and a pair of new-in-box units appeared on diyAudio with the seller unsure what to ask. One diyAudio member called them "one of the absolute best 15 inch woofers JBL has ever produced." The Alnico magnet's fragility under abuse is real, but as one pinkfishmedia.net poster noted, the 1500AL is one of the few exceptions that can take serious power without weakening.
Specifications as documented:
- Type: 15" cone woofer unit
- Impedance: 8 Ω
- Allowable input: 400W (RMS)
- Output sound pressure level: 94dB/2.83V/m
- Frequency characteristic: 20 Hz – 2 kHz
- fo: 26 Hz
- Recommended crossover: 800 Hz
- Recommended enclosure: 99–127 liters, bass-reflex
- Dimensions: 387 mm diameter × 235 mm depth
- Weight: 18.1 kg
- Magnet: Alnico 5
Little is documented about the 1500AL's service history, spare parts availability, or common failure modes. These are scarce flagship drivers, and most surviving examples live inside complete K2 or Everest systems.
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