- Written by Jim Clements
- Published on 19 May 2014
Design of the JL Audio E-Sub E112 Powered Subwoofer
JL Audio's E-Sub powered subwoofers incorporate numerous technologies that have been developed and refined over the years. These proprietary and patented design elements carry some pretty beguiling names – "DMA" (Dynamic Motor Analysis), "VRC" (Vented Reinforcement Collar), "FCAM" (Floating Cone Attach Method) and the "Engineered Lead-Wire System" (no acronym). These features are important keys to a well designed sub, but there is even more than this packed into the E-Sub cabinets.
Let's start by talking about the driver. This E-Sub e112 sub is a sealed design with a custom-built long-throw 12" driver. The most obvious peculiarity is in the driver's depth. This massive driver nearly fills up the cabinet due to its deep motor structure. There are several reasons for this depth: First, the motor structure is designed to support the driver's substantial 2-1/2" peak-to-peak excursion with excellent linearity. Another reason is that the depth allows for the dual spiders which are spaced 6" apart. The additional spider prevents twisting of the voice coil under the demanding acceleration-induced forces that come into play at higher SPL's or during quick transients.
JL Audio's DMA system is a mature Finite Element Analysis package they use to design woofers with a precise and reliable pistonic motion. Unlike similar systems, the JL Audio system not only analyzes driver forces and movements but it also takes into account the system behavior under varying power inputs as well. To this point, their research has indicated that the magnetic field of the magnet is not static as assumed in most other FEA models. Instead, the magnetic field fluctuates considerably in reaction to the flux generated by the voice coil. So JL Audio claims that their DMA system accounts for this additional variable. Their designs subsequently benefit in greater linearity at high excursions.
JL Audio also uses their FEA system when designing the surrounds and this leads to optimal surround geometry for each custom driver.
The e112 sub is powered by a 1,500 watt RMS (peak) switching amp with a regulated power supply. This architecture is claimed to hold the rail voltage steady even under heavy current demands. The amp module is protected by an isolated case which can be seen in the cutaway view.
JL Audio wanted this subwoofer to have much the same installation flexibility you get with their larger subs so they included some high value features. There is a ground lift switch that is handy for quickly isolating a ground loop. The sub has a 24 dB/octave high-pass filter on the line outs. There is also a high-level input on a removable plug for those whose setups lack a line level hookup option.
They didn't skimp on the cabinet, either: It features ¾" MDF sidewalls and donut bracing. Finishes are either gloss black or black ash.
Every E-Sub is precision-built in JL Audio's U.S. factory and individually performance-verified and tested.