DIY SYSTEMS
JX92S MLTL
This enclosure is designed by Greg Monfort and originally appeared on the fullrange driver forum. It is a quarter wave, mass-loaded TL designed with the aid of Martin King's MathCad software.
Two versions are shown below. The original MLTL-31 has been widely built and has a bass extension to around 45Hz. The more recent MLTL-48 extends the JX92S to below 35Hz. Both designs may benefit from frequency compensation if used well away from the wall or corner.
The dimensions shown come directly from the computer simulations and can be rounded off.
MLTL-31All dimensions are internal Height - 31.04" (78.8cm) Width - 6.97" (17.7cm) Depth - 4.31" (11cm) Driver - JX92S centred 11.14" (28.3cm) from top Port - 2" diameter x 5" long (5 x 12.7cm) Stuffing - 0.54lb The stuffing suggested (shown in grey on the drawing) is based on computer simulations - as always adjust to suit. Stuffing fills the top section of the cabinet, stopping just below the driver. Recommended material is 18-25mm birch ply. The backside of the driver cutout should be bevelled at 45 degrees to reduce reflections. To raise the driver to ear height, a stand can be incorporated by extending the back and sides downwards (shown in blue). The front is left open. The port exits through the base and can be augmented by a reflector panel (shown in red), angled towards the open front of the stand. The back of the stand can be filled with dry, sterile sand to add mass to the enclosure.
|
 |
MLTL-48All dimensions are internal Height - 48" (122cm) Width - 6.97" (17.7cm) Depth - 4.31" (11cm) Driver - JX92S centred 15.46" (39.3cm) from top Port - 2" diameter x 2.75" long (5 x 7cm) Stuffing - 0.54lb The stuffing suggested (shown in grey on the drawing) is based on computer simulations - as always adjust to suit. Stuffing fills the top section of the cabinet, stopping just below the driver. Recommended material is 18-25mm birch ply. The backside of the driver cutout should be bevelled at 45 degrees to reduce reflections. No stand is required for this design. The port exits through the front panel and should be placed as close to the bottom of the enclosure as practical.
As long as the cross-sectional area is kept the same, alternative cabinet shapes can be used. A trapezoid MLTL-31 has been built and is reported to have a tighter bass than the rectangular cross-section enclosure. An alternative for the MLTL-48, is the triangular enclosure below.
|
 |
TRIANGULAR CROSS-SECTION CABINETSTo reduce internal reflections, the MLTL cabinets can be made with an equilateral triangular cross-section. The example shown has interior sides 8.33 inches (21.2 cm) wide and has the same cross-sectional area as the rectangular design. This would allow room for a front-firing port in the MLTL-31 cabinet. This shape has the additional advantage of placing the JX92S at the recommended toe-in angle, when side (A) is parallel to the back wall. |
 |