JL Audio C3-570: 5 x 7 / 6 x 8-inch (125 x 180 mm) Convertible Component/Coaxial Speaker System

Convertible Drivers: Coaxial or Component

Summary:
Sometimes a coaxial is the best solution... and sometimes you need to mount the tweeter separately. It's great to have complete flexibility.

Detailed Information:
Coaxial or Component: Both approaches can yield excellent results.

Coaxial mounting has the benefit of placing the tweeter in close proximity to the acoustic center of the woofer, resulting in more coherent output and predictable crossover behavior. From a purely practical perspective, it also avoids having to cut a separate hole for the tweeter.

Separate mounting has the benefit of placing the tweeter where it is less likely to be blocked by legs or other obstructions. As long as you don't separate the tweeter too far from the woofer, this approach will still yield good coherence and predictable crossover behavior.

JL Audio's Convertible Components give you the option of installing the speakers as separate components or as coaxial systems (tweeters mounted onto the center of each woofer). In coaxial mode, the tweeter installs onto a post that attaches to the top of the pole piece with a bayonet-mount mechanism. Short leads are used to connect the tweeter to dedicated terminals on the pole piece (see figures A-D). In separate component mode, a phase plug installs onto the pole piece via the bayonet-mount mechanism (see figures A & F), and the tweeter can be installed with the supplied flush-mount or surface-mount fixtures.

Dynamic Motor Analysis - DMA Optimized Motor

Summary:
JL Audio's proprietary Dynamic Motor Analysis system is a powerful suite of FEA-based modeling systems, first developed by JL Audio in 1997 and refined over the years to scientifically address the issue of speaker motor linearity. This leads to vastly reduced distortion and faithfully reproduced transients... or put simply: tight, clean, articulate bass.

Detailed Information:
Since 1997, JL Audio has been at the forefront of Finite Element Analysis-based modeling of loudspeaker motors and suspensions. This research is aimed at decoding what we refer to as the "Loudspeaker Genome"... a project aimed at understanding the true behavior of loudspeakers under power and in motion. A major component of this integrated system is DMA (Dynamic Motor Analysis). Starting with the 15W3 and the W7 Subwoofers in the late 1990's and early 2000's, DMA has played an important role in the design of all JL Audio woofers sold today, including our component woofers.

DMA is a Finite Element Analysis (FEA)-based system, meaning that it takes a large, complex problem, breaks it down into small solution elements for analysis and then assembles the data to form an accurate, "big-picture" solution. DMA's breakthrough is that it actually considers the effects of power through the coil as well as coil/cone position within the framework of a time-domain analysis. This gives us a highly accurate model of a speaker's actual behavior under real power, something that the traditional Thiele-Small models or other low power measurements cannot do. Because DMA does not rely on a steady-state model, it is able to consider shifts in the circuit elements being analyzed. These modeling routines are intense, requiring hours to run for a whole speaker.

DMA is able to analyze the real effects of fluctuating power and excursion upon the magnetic circuit of the motor, specifically the dynamic variations of the "fixed" magnetic field. This delivers intensely valuable information compared to traditional modeling, which assumes that the "fixed" field produced in the air gap by the magnet and the motor plates is unchanging. DMA not only shows that this "fixed" field changes in reaction to the magnetic field created by current flowing through the voice coil, but it helps our engineers arrive at motor solutions that minimize this instability. Analyzing this behavior is critical to understanding the distortion mechanisms of a speaker motor and sheds light on the aspects of motor design that determine truly linear behavior:

1. Linear motor force over the speaker's operational excursion range
2. Consistent motor force with both positive and negative current through the coil
3. Consistent motor force at varying applied power levels
    

Our ability to fully analyze these aspects of motor behavior allows our transducer engineers to make critical adjustments to motor designs that result in extremely linear, highly stable dynamic loudspeaker motor systems.

The payoff is reduced distortion, improved transient performance and stellar sound quality.

Elevated Frame Cooling (U.S. Patent #6,219,431 & #6,229,902)

Summary:
JL Audio's patented Elevated Frame Cooling design delivers cool air through slots directly above the top-plate to the voice coil of the speaker. This not only enhances power handling, but also sound quality by minimizing dynamic parameter shifts and power compression.

Detailed Information:
Many speakers employ venting techniques to enhance voice coil cooling. This is typically accomplished by having big holes in the sides of the frame just below the spider attachment shelf. While it provides a modest cooling benefit, this low-velocity air-flow does not blow directly or strongly on the voice coil.

Our patented design improves upon this cooling technique in a number of ways. By elevating the frame above the top-plate of the motor (via stand-offs integrated into the bottom of the frame) a narrow, high-velocity air-path is created between the bottom surface of the frame and the top surface of the top-plate. This air path leads directly to the voice coil and then turns upward into the spider air cavity. By utilizing the pumping action of the spider through this focused air path, a large volume of cool air hits the coil windings directly.

Another important benefit is that the upper surface of the top-plate (one of the speaker's hottest parts) is directly exposed to cooling air flow, whereas on a conventional design it is isolated from the air flow by the lower flange of the frame. The elevated frame technology greatly increases thermal power handling, reduces compression effects and does so without any additional parts.

Silk Dome Tweeter

Summary:
Light, fast moving silk dome material promotes high-frequency accuracy. 

Detailed Information:
Silk is a natural material with inherently good characteristics as a tweeter diaphragm. In addition to being very light in weight, silk exhibits excellent damping properties, which reduces ringing and resonances in the tweeter’s passband, leading to a smooth, pleasing high-frequency character free from unnatural sibilance or exaggerated brightness. Compared to a harder material dome, a silk tweeter does not exhibit as much ultra-high frequency extension, but is preferred by many audiophiles for its overall balance.