JBL 660GTI, 560GTI manual LOW-DISTORTION Woofer

1.	Spider-Landing Vents: Minimize distortion from mechanical noise.
2.	Nomex® Spider: Provides linear force in both movement directions.

GTi COMPETITION SPEAKER SYSTEM TECHNOLOGY:

LOW-DISTORTION WOOFER

Distortion – sound produced erroneously – is the enemy of great speaker performance. At its worst, distortion makes speakers sound broken. At more moderate levels, distortion clouds the midrange, making vocals sound muddy and obscuring the music’s detail. At JBL, we’ve had more practice than any other speaker company at eliminating distortion, and it shows. GTi competition speaker systems include the lowest-distortion woofers we’ve ever built.

In a loudspeaker, distortion can be produced by the cone, the motor, the suspen- sion and even the movement of air through the speaker’s assembly. In designing the 560GTi and 660GTi woofers, JBL engineers have left no stone unturned. The basket, polepiece and voice coil former all include vents to eliminate any potential distortion caused by the movement of air trapped within these parts. The ultra- rigid Kevlar® cone eliminates unwanted cone flexing (also called modal distortion), which can cause big peaks and dips in the midrange response. The spider and surround are designed to ensure linear forward and rearward motion, minimizing distortion caused by the speaker’s suspension. The motor includes a copper pole- piece cap and a flux stabilization ring that work together to produce a linear voice coil inductance that minimizes intermodulation distortion. Finally, an extralong voice coil ensures that the coil remains in the magnetic gap to minimize distortion at low frequencies and their harmonics, and during high-output transients. The result is crystal-clear midrange, snappy mid-bass without any audible ringing or hang-over, and a smooth frequency response that needs no compensation circuitry in the crossover (see Figure 1).

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3.	Nitrile-Butylene Surround: Ensures superior longevity.
4.	Copper Polepiece Cap: Provides linear inductance over the full
	range of forward voice-coil travel for reduced intermodulation
	distortion. Provides crystal-clear vocals and midrange, even
	during heavy bass signals.
5.	Polished and Flared Polepiece Vent: Provides a low-velocity inlet
	and outlet for the movement of air in and out of the motor structure.
	Minimizes distortion from mechanical noise.
6.	Neodymium Magnet: Provides high flux density. Also allows more
	room for larger steel motor components to provide critical heatsink
	mass for the voice coil.
7.	Vented Gap Cooling™ Ports: Provide movement of air over the voice
	coil for superior power handling.
8.	Flux Stabilization Ring: Provides global stabilization of the static
	magnetic field and works with the copper cap to minimize
	coil inductance during inward movement of the voice coil.
9.	Voice Coil: Long, over-hung 2" diameter, aluminum edge-wound
	voice coil provides high excursion for improved low-frequency
	capability. Reduces distortion at low frequencies and high input
	power.

10.Vented Voice Coil Former: Minimizes distortion from mechanical noise.

11.Screw-Down Terminals: Ensures reliable high-quality connections.

12.Kevlar® Dustcap and Cone Body: Ultrarigid Kevlar dustcap and cone body minimize unwanted cone flexing for smooth frequency response.

13.Cast-Aluminum Basket: Provides a rigid support for motor and moving assembly.

Figure 1

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