Enclosure Construction, Your subwoofer, Patent pending

The Official Brand of Live Music

Enclosure Construction

5. Use PVC or ABS plastic pipe for ports.

Dual Coil Versus Differential Drive®

Figure 2. Conventional dual-voice-coil design

Please observe the following suggestions when building an enclosure for GTi Series subwoofers.

1.	Choose an enclosure design from the
	Enclosure Design Sheet included with
	your subwoofer.
2.	Use at least 3/4" (19mm) MDF (medium
	density fiberboard) or marine birch
	plywood to build the enclosure.
	Enclosures for 12" and larger
	subwoofers and smaller woofers driven
	by high-power amplifiers should be
	constructed using 1" (25mm) material.
3.	Join pieces of wood with glue and

Keep in mind that the openings at either

end of the port must be at least one port

diameter away from any obstruction.

6. Use the 10/24" machine screws and

T-nuts provided to mount the woofer to

the baffle. See Figure 1.

(patent pending)

Conventional dual-voice-coil woofers use a pair of voice coils “interwound” on the former and centered in the magnetic gap. The two coils may be connected in series or parallel in order to maximize an amplifier’s output power. Both coils drive the cone forward and rearward. Xmax (one-way-linear) is determined by the amount of voice coil exposed above and below the top plate. A conventional voice coil is made up of several layers of windings, each transferring heat to the winding next to it until the heat is finally

BOTH COILS DRIVE CONE FORWARD AND REARWARD

CONE

SPIDER

OVERHANG DETERMINES

Xmax

TOP PLATE

MAGNET

screws; do not use nails. Once the box

has been tested, seal all joints inside

the box with silicone caulk.

4. Fill the enclosure with damping material

(dacron, fiberglass insulation or

long-fiber wool) according to the design

you have chosen from the Enclosure

Design Sheet. “0% fill” indicates

that no damping material

Figure 1. Mounting the GTi woofer

in its enclosure

dissipated by the outside layer through the top plate, magnet and backplate. This arrangement is inefficient, and results in low thermal power handling. See Figure 2.

POLE PIECE / BACKPLATE

JBL GTi Series subwoofers employ Differential Drive, a technology developed by JBL Professional. Differential Drive employs two voice coils positioned at opposite ends of the former, each suspended in a separate magnetic gap. These two coils may be connected in series or parallel, like a conventional DVC woofer,

should be used; “50% fill” indicates that all interior walls except the baffle should be lined with 1" thick damping material, and “100% fill” indicates that the box should be loosely stuffed with damping material.

10/24"

SCREWS

(PROVIDED)

to maximize an amplifier’s output power. Both coils MUST be connected to the amplifier in correct polarity! At low power, both voice coils drive the woofer’s cone, and any motor nonlinearities are cancelled by the out-of-phase coils and gaps. As power input increases so that one coil rides completely out of its gap, force is still applied to the cone by the other coil. At extremely high power, each coil will enter

		T-NUTS
	04	T-NUTS
		(PROVIDED)

W12GTi, W10GTi, W15GTi specifications

JBL has long been a name synonymous with high-quality audio equipment, and their GTi series of subwoofers—specifically the W15GTi, W10GTi, and W12GTi—are standout examples of their commitment to performance and innovation. Each model in this lineup is designed to deliver deep, accurate bass, making them ideal for serious audiophiles and car audio enthusiasts.

The JBL W15GTi is the largest subwoofer in the series, featuring a massive 15-inch cone. This model is engineered to handle substantial power, boasting RMS ratings up to 2,500 watts, with peak power capabilities reaching 10,000 watts. The W15GTi utilizes a fiberglass reinforced cone for enhanced rigidity and reduced distortion, combined with a large, vented pole piece that allows for better heat dissipation. This innovative design not only increases the subwoofer's longevity but also ensures that it performs optimally even during extended use.

Moving to the W12GTi, the 12-inch variant, we see a balance of size and power. It supports an RMS power handling of 1,500 watts and can peak at up to 6,000 watts. The W12GTi incorporates an advanced suspension system that includes a progressive-roll surround for improved excursion and a cast-aluminum basket that reduces unwanted resonance. This model is ideal for those who want impactful bass without excessive weight, making it easier to install in a variety of vehicles.

Finally, the W10GTi rounds out the series with its compact 10-inch size. Despite being the smallest of the trio, the W10GTi does not compromise on performance. It has an RMS rating of 1,200 watts and peak power handling up to 4,800 watts. Its lightweight design, paired with JBL’s signature low-frequency extension technology, produces a rich and dynamic bass response that enhances any audio experience. The W10GTi is particularly suited for smaller cars or for those looking to maximize space without sacrificing sound quality.

All three models feature advanced technologies such as JBL's patented Vented Spider, which provides linear movement and allows for greater excursion, and a dual voice coil configuration that enhances their versatility in different setups. Constructed with high-quality materials and precise engineering, the W15GTi, W12GTi, and W10GTi subwoofers offer unmatched audio fidelity, deep bass, and reliability, making them a popular choice for those seeking high-performance audio solutions. Whether you’re aiming for a thumping low-end experience or precise sound reproduction, JBL’s GTi series has a model tailored for your needs.

JBL W10GTi, W15GTi Enclosure Construction, Dual Coil Versus Differential Drive, Your subwoofer

Models: W12GTi W10GTi W15GTi