JBL 2231H

The 2231H is hard to pin down, because the record disagrees with itself. JBL's own 2100/2200-series transducer listing calls it the predecessor of the 2235H - a 15-inch low-bass driver, now obsolete. The company's Professional Systems Reference Chart shows it as the low-frequency unit in the 4331B, 4333B, 4343B, and 4350B studio monitors. A substitution table lists it as a drop-in acoustic equivalent of the 2235H, with no baffle modification required. All of that comes from JBL's own service literature, and it agrees.

What isn't consistent is the basic spec sheet. One widely-circulated set of figures describes an 18-inch, 460 mm transducer with a 100 mm aluminium voice coil, 300 W continuous program / 150 W continuous sine wave, 95 dB sensitivity, and a 30 Hz–2.5 kHz range. Another source gives a 38 cm cone, 8 ohms, 200 W continuous program, 94 dB/W/m, 25 Hz–2 kHz, Fs of 16 Hz, 12,000 gauss flux density, and 85–170 L recommended enclosure volume. Even the diameter is disputed — JBL's own monitor chart assigns the 2231H to the 4343B in a 380 mm (15") position, and parts listings and recone kits consistently call it a 15-inch driver. We're not going to pretend to adjudicate that here; the honest answer is that the 2231H was a 15-inch-class low-bass woofer with a nominal 8-ohm impedance, built for bass-reflex monitor duty, and the rest of the numbers depend on which sheet you're reading.

One source describes the voice coil as an edge-wound copper ribbon, which is an unusual construction. A repair video circulating among hobbyists covers rewinding the flat-wire coil specifically. The 2231H can be reconed with a 2235H cone, and that is how a lot of surviving examples have been kept alive. Foam surround rot and cone-edge damage are the usual failure points, and cone-only parts are reportedly hard to source. No source on hand records the original production years. A Japanese catalogue listing places a single unit at ¥62,000 around 1981, and Modern Recording (February 1982, p.82) lists it among professional audio hardware in that era's dealer listings.