Sealed enclosures exert the most control over the motion of a sub- woofer because the air acts like a spring against the motion of the woofer cone. Larger boxes allow for more excursion (cone movement), thus more low- frequency output for the amount of power used. When placed in a sealed box larger than the com- pliance (Vas) of the subwoofer, it will perform as if it were in an infinite baffle installation.

Vented and bandpass enclosures have the lowest amount of excur- sion for the amount of sound out- put. This is a result of port tuning reinforcing the sound output.

Vented boxes will not provide

adequate woofer control when dri- ven below the port tuning range, so proper design is important. A fourth-order bandpass box will have the lowest overall cone excursion at the expense of limited bandwidth.

In addition, there are a number of points you’ll want to keep in mind as you construct an enclosure:

1.Use 3/4" (19mm) MDF (medium- density fiberboard) or marine birch plywood to build an enclosure. Enclosures for 12" and larger subwoofers, or small subwoofers driven by high-power amplifiers, should be constructed using 1" (25mm) material.

2.Seal all joints with glue and screws; do not use nails. We recommend “deck” or “zip” screws since they have coarse threads for better grip and don’t require pre-drilling holes. Once the box has been tested, seal all interior joints with silicone caulk.

3.Depending on the application, fill the enclosure according to the design you have chosen from the enclosed data sheet in one of three ways: zero-percent fill (i.e., no fill), or 50-percent fill (i.e., 1"- thick polyfill sheets on all inside walls except where subwoofer is mounted), or 100-percent fill

(i.e., entire box is stuffed with loosely-packed polyester fiberfill).

4.Use PVC or ABS pipe for ports. Keep in mind that the openings at either end of the port must be at least one port diameter away from any obstructions, including filling material inside or outside the box. Rectangular vents can be used as long as the cross- section area matches the recommended port-area values in the enclosed data sheet.

01

Page 3 Page 5
Page 4
Image 4
JBL GT800d, GT1000d, GT1500d, GT1200d owner manual
Page 3 Page 5

GT1000d, GT800d, GT800, GT1200, GT1200d specifications

JBL is a renowned name in the audio industry, well known for its high-quality speakers and subwoofers. Among their impressive lineup, the JBL GT series, including the GT1000, GT1500D, GT1200D, GT1200, and GT800, stands out for their powerful performance and innovative features catering to car audio enthusiasts.

The JBL GT1000 is designed to provide robust bass response and clarity. It employs a polypropylene cone that ensures durability while delivering crisp sound quality. With its high power handling, the GT1000 can produce deep bass without distortion, making it a popular choice among car audio lovers. Its compact design allows for flexible installation options in various vehicle types.

Moving on to the JBL GT1500D, this model stands out with its dual voice coil design, which enhances its versatility in wiring configurations. Capable of generating a significant amount of power, the GT1500D employs advanced technology to ensure efficient energy conversion, resulting in powerful, clear bass that can elevate any car audio experience. The incorporation of a built-in low-pass filter allows users to customize their sound profile easily.

The JBL GT1200D is another powerful option in this series, featuring a lightweight yet sturdy construction that aids in its performance. This model is engineered with a vented pole piece to enhance airflow and reduce overheating during prolonged use, ensuring longevity and reliability. The GT1200D's optimized frequency response allows for truly immersive sound quality.

Next in the lineup is the JBL GT1200, which is tailored for users seeking good bass without sacrificing space in their vehicle. It combines a sleek design with an efficient motor structure, delivering impressive low-frequency response while maintaining clarity in the higher frequencies. This makes it ideal for a balanced sound output, whether it be pop, rock, or hip-hop.

Lastly, the JBL GT800 is an entry-level subwoofer that provides exceptional value for those looking to upgrade their car audio system without breaking the bank. Despite its smaller size, the GT800 still packs a punch, delivering solid bass response. Its robust build quality ensures it can withstand the rigors of vehicle use while still performing at a high level.

Overall, the JBL GT series offers a variety of options, delivering powerful sound performance suited for any listener's needs, thanks to their innovative technology and high-quality materials used in construction. Whether seeking deep bass or balanced sound, these models are designed to enhance any car audio experience.
Top Page Image Contents