JBL C51 Apollo (1967–1969)
The JBL C51 Apollo was the company's first bookshelf loudspeaker. JBL introduced it in 1967 as the top model in its compact speaker line. It was built to compete with the popular compact speakers of the mid-1960s, with the AR-2ax and KLH models the obvious targets. JBL also marketed it as a companion to the SE408 "Energizer" amplifier. The name came from the NASA Apollo space program, which was very much in the public eye at the time.
It's a three-way system built around an 8-inch LE8T woofer, a 5-inch LE5-2 midrange and an LE20A tweeter, with crossover points at 1,500 Hz and 5,000 Hz. The cabinet has two compartments and an internal volume of 1.4 cubic feet. The woofer fires through the front, while the midrange and tweeter radiate through the top of the enclosure. The speaker was intended to be used horizontally. JBL's own catalog copy listed the frequency response at 45 to 15,000 cps, though other sources cite figures ranging from 40 Hz to 20 kHz. The record is inconsistent here. Impedance is 8 ohms across all sources, and power handling was rated at 25 watts continuous, 50 watts peak. The cabinet came in walnut, teak or rosewood veneer and weighed 38 lbs. Original price was $189.00 each, per JBL's advertising, while a 1968 catalog shows $176.
Reception at the time was generally warm. The Apollo was praised for smooth, detailed sound and solid bass. Critics noted a somewhat forward upper midrange and a relatively high 5 kHz crossover that could cause occasional harshness. The midrange itself is described as smooth and natural, the tweeter as sweet, and the bass as tight if not extremely deep. The weak point, by most accounts, is the dated crossover design, which can cause a slight lack of cohesion between drivers.
Today the Apollo is regarded as one of the finer compact loudspeakers of its era. Some things to watch for: the foam surrounds on the 8-inch woofer are notorious for deteriorating after several decades, and the crossover capacitors may need replacement due to age. The tweeter's ferrofluid can also dry out over time. Restored pairs have sold for up to $800, with typical market prices ranging from $300 to $750 depending on condition.
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