In 1973 JBL reworked the L100 Century and kept selling it under the same name, which is why listings mix the two up. JBL's brochure for the new, improved Century lists a better tweeter, a 1.4-inch direct radiator with a smaller cone for wider dispersion, new crossover points at 1,500 and 6,000 Hz, and midrange and treble controls on the front behind the grille. Studios then asked for a monitor version of the new speaker, and that became the 4311. JBL said engineers from Warner Bros. and Elektra Records compared the new L100 with their 4310s and called it a significant advance. The 12-inch Alnico V woofer, the LE5-2 midrange and the ported walnut cabinet carried over, and the foam grille came in Ultra Blue, Chocolate Brown or Burnt Orange. JBL listed it through 1977, and the L112 took over after that.
With the grille off
Ask for a photo of every driver with the grilles off, on both speakers. They should match each other and this list.
The front level controls can crackle after decades, and the painted foam grilles age like any foam. Tweeters and woofers get swapped between pairs, so check that both speakers carry the same drivers.
New to old speakers? How to check a used pair walks through every driver, the crossover and the cabinet.
We haven’t been through this model’s listings yet. Search eBay and run every listing through the checklist above. Ask for photos of both speakers with the grilles off and the serial labels on the back, and pass on any seller who won’t send them.
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BookshelfSpecs and what to check →
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BookshelfSpecs and what to check →
JBL · 3-way
BookshelfSpecs and what to check →
JBL · 3-way
FloorstanderSpecs and what to check →