JBL C40

The JBL C40 is a compact 2-way bass reflex loudspeaker from JBL's "Century" series, sold as a bookshelf system for small to medium rooms. The record on this one is thin. No production years or original pricing have surfaced, but the documented specs are enough to work with.

The C40 uses a 10" JBL 123A-1 woofer and a 3/4" JBL LE20-1 tweeter, crossing over at 3000 Hz. According to Hifi-Wiki, these are the same high-performance components used in the JBL 4311 Control Monitor. The cabinet is 3/4-inch walnut veneer, measuring 22-7/8" x 13" x 11-5/8" and weighing 35 lbs. Rated sensitivity is 98 dB (1W/1m) with 8-ohm nominal impedance and a frequency response of 55-20,000 Hz (±3dB). Recommended amplifier power is 10 to 60 watts. An Audio (March 1957, p.2) advertisement from the period described the C40 as a lowboy console model with a backloaded folded horn, and said the enclosure with legs stood 23-3/4" high. That is a different configuration from the bookshelf version documented elsewhere, so the C40 name may have covered more than one cabinet style.

Hifi-Wikia and Hifi-Wiki both describe the C40 as often considered the predecessor to the L40, listed directly below it in JBL's catalog and essentially a smaller, less expensive version. That lineage claim comes from those secondary sources alone, so treat it as collector consensus and not confirmed JBL history.

Collector commentary calls the C40 a classic example of JBL's "West Coast sound" - forward, dynamic and punchy - with surprisingly deep and tight bass for its size. It's also described as revealing rather than warm, and it can sound harsh on poor recordings. These are owner impressions, not measured reviews, but they're consistent across sources.

Two practical problems for anyone buying today. Foam surround rot on the 123A-1 woofer is common and means reconing or replacement. The LE20-1 tweeter is fragile, and its diaphragms are difficult to source. If the original crossover capacitors are still in place, replace them.

- **Type:** 2-way bass reflex, bookshelf

- **Drivers:** 10" 123A-1 woofer, 3/4" LE20-1 tweeter

- **Crossover:** 3000 Hz

- **Impedance:** 8 ohms

- **Sensitivity:** 98 dB (1W/1m)

- **Frequency response:** 55–20,000 Hz (±3dB)

- **Recommended amplifier:** 10–60 watts

- **Dimensions:** 22-7/8" x 13" x 11-5/8"

- **Weight:** 35 lbs.

- **Cabinet:** 3/4" walnut veneer