Soundstream Technologies SPL 170 Building the Enclosure, Selecting AN Enclosure, Infinite Baffle

BUILDING THE ENCLOSURE

∙Determine the dimensions of your enclosure.

∙Be certain the box you have designed will fit into the location you have chosen. Sometimes making a cardboard box with the same outside dimensions is helpful.

∙Use 3/4 inch thick Medium Density Fiberboard (MDF) or High Density Particleboard. It is preferable to cut the wood with a table saw to ensure straight, even joints. If a table saw is not available, a circular saw is acceptable.

∙Use a “T” square to verify precise right angle gluing.

∙Use a high quality wood glue and air nails or wood screws to assemble the enclosure. Elmer’sâ woodworker’s glue and Weldwoodâ work well. To guarantee an airtight box, seal each inside joint with silicone sealant.

∙For Sealed Enclosures, stuff the chamber with 50-75% filling (approximately 1.5 pounds per cubic foot) of fiberglass insulation or Dacronâ.

∙For Vented Enclosures, staple 1 inch thick fiberglass insulation or Dacron to all walls of the enclosure except the baffle to which the woofer is mounted.

∙Use the supplied gasket to seal the woofer in the enclosure and eight(8) wood screws or T-nuts and bolts. Progressively tighten each of the bolts or screws to prevent warping the woofer frame.

∙Use slide-on connectors to attach speaker wires. Do not solder wires to the

SUGGESTED ENCLOSURES

The following designs include a variety of enclosure sizes and types. Each design has two frequency response curves; one showing predicted

“In-Car” response, and the other showing “Half-Space Anechoic” (out-of-car) frequency response. The performance difference between the two curves is a result of the natural acoustics of an “average” automotive environment. This “average” transfer functionis only an approximation of what you may expect to see in your car. Every car is different. Each curve was generated using 2.83

SELECTING AN ENCLOSURE

There are several different enclosure designs for different applications. The SPL subwoofers work very well in all the following enclosure designs. It is up to you to select the specific enclosure that will work the best for your particular application.

Infinite Baffle

Infinite baffle is the simplest type of subwoofer installation. In this type of installation, the woofer(s) is mounted to a baffle which is then mounted to either the rear deck or back seat of the vehicle. The best results are achieved when the trunk area is virtually airtight and isolated from the passenger compartment.

	Pros		Cons
∙	Excellent low frequency extension	∙	Lower power handling
∙	Excellent transient response	∙	Low to medium efficiency

∙Uses almost no trunk space

Sealed Enclosure

Sealed enclosures are relatively simple to build and install, as all that is required is an airtight box. The larger the sealed enclosure, the more the performance resembles that of an infinite baffle installation.

Pros	Cons
∙ Very good low frequency	∙ Medium efficiency
extension
∙ Very good transient re-
sponse
∙ High power handling

Sealed

Vented Enclosure

Vented enclosures use a sealed enclosure with a vent or port in the box which is tuned to resonate at a specific frequency.

Volts across both voice coils in parallel and measured at 1 meter. Also, each frequency response curve includes a 12 dB/octave low pass at 100 Hz for sealed and vented enclosures and 200 Hz for bandpass enclosures. The response curves can help you visualize relative performance differences between designs. Read through the descriptions given for each enclosure and select the one that suits your needs.

Remember: all suggested enclosure volumes are Net, and DO NOT include woofer, port, and bracing displacement!

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Pros

∙Good low frequency exten- sion down to the tuning fre- quency

∙High power handling down to the tuning frequency

∙Higher output than sealed enclosures

Cons

∙ Low power handling below the tuning fre- quency

∙ Almost no output below the tuning fre- quency

Vented (V)

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