JBL Charge Coupled Crossover DIY Timelapse Build for 4343 Studio Monitors

Follow along as I complete the board assembly for my new charge coupled crossovers. The JBL 4343s sound amazing, but further improvement could be made by replacing the aging internal crossover network with a charge coupled version, made popular by Greg Timbers, former Chief Engineer at JBL. The good folks at the Lansing Heritage website provided the schematic that I used to build my new crossovers. I still have to do the wiring and testing (as well as rewire the JBL 4343s to accept an external crossover network), but they should sound better than the day they were made once it's all done.

The simplest way to explain the electrical principle behind a charge coupled crossover vs a standard crossover is this: If you could take a standard crossover and redesign it to add a DC bias to each capacitor in the crossover (while making sure no DC is passed along to the drivers), then you would effectively reduce or eliminate one of the biggest issues with capacitors in an audio circuit - dielectric absorption, which has a harmful effect on the audio signal as it crosses the zero point (positive-to-negative, and vice versa). A simple and safe way to implement this DC bias to a design is to replace each capacitor with two capacitors in series, with each having twice the C value , then adding the DC bias (in this case, a 9V battery) to a point between them. The capacitor pair blocks the DC from going anywhere, and the bias keeps the capacitors operating in a region that avoids dielectric absorption. Credit goes to Greg Timbers and Ed Meitner for the concept and Giskard of Lansing Heritage for the schematic.

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