JBL L300A (1977–1980)

The JBL L300A is the big one. It topped JBL's "Summit" series in the late 1970s. It's a three-way, bass-reflex floor-stander built around a 15-inch LE15H woofer, an LE5-12 cone midrange, and the 077 slot-loaded dome tweeter. It was produced from 1977 to 1980 and sold for $1,149 per speaker, which was a serious investment at the time. It was essentially a scaled-down version of the JBL 4350 studio monitor, the flagship of JBL's professional line, and it was aimed at both studio monitoring and serious home use.

The numbers are solid and consistent across sources: 91 dB sensitivity (1 watt/1 meter), 8-ohm impedance, 300-watt power capacity, and a frequency response of 38 Hz to 25 kHz. The crossover points sit at 850 Hz and 6 kHz. The cabinet is large at 33-1/2"H x 20-7/8"W x 15-1/8"D, and heavy at 98 pounds. The bass-reflex enclosure is ported, which helps explain the low-end extension.

What separates the L300A from the consumer L300 is murky in the record. One source calls the L300A the professional studio monitor version of the L300. Another implies it was essentially the same design with a tweeter waveguide change. The two models overlap in production years and share the same driver complement, so the exact distinction is unclear. The L300A is widely regarded as one of JBL's finest loudspeakers of the 1970s, praised for powerful, dynamic sound and excellent imaging.

Audio-Express (September 2001, p.37) ran a piece by George Brooke about tracking down and renovating a pair of L300s a quarter-century after first hearing them, which gives you a sense of the staying power these speakers have had with their owners.

As with most JBLs of this era, there are known maintenance issues. The foam surrounds on the LE15H woofer degrade with age and need refoaming. The 077 tweeter diaphragms can be damaged by overdriving. Recapping the crossovers is recommended to keep performance up. The internal insulation can also decompose over time and leave dust inside the cabinet. These are all well-understood repairs.