I built an 18″ 1000 watt subwoofer for my home theater system. The cabinet was my design and build, while the driver and amplifier were purchased items.
This is the front view of the cabinet. It’s made from 3/4″ double-wall MDF (1-1/2″ total thickness) covered in oak veneer. The completed assembly weighs about 120 lbs.
This is the rear view of the cabinet. The square opening is for the 1000W plate amplifier:
This picture shows a close-up of the heavy gauge wire feed that leads from the 18″ driver into the amplifier compartment. The feedthrough bulkhead provides an airtight seal for the driver enclosure.
The subwoofer driver. It’s a 15″ A JBL SUB1500 featuring a 4″ voice coil, 800W RMS / 1500W peak power handling, 94 dB SPL @ 1W and an X-Max of 18mm. This means that It can displace about 3 liters of air at its full displacement.
This is a rear view of the 1000W plate amplifier:
Here is the business side of the plate amplifier. Large toroidal transformer supplies high current for the transistor output stage. This amplifier is a class H type, meaning that the supply rail voltage varies with amplifier output, which helps reduce the thermal power dissipation of the amplifier.
This shot shows the amplifier filter Caps and output stage MOSFETs that are thermally coupled to the front plate to dissipate the heat generated.
This shows the signal Input board and parametric equalizer circuitry.
The moment of truth. Here’s the rear view of the final assembled cabinet, ready for testing.
Front view of the subwoofer without the grill.
Moved into position next to one of the Klipsch KLF-20 main speakers.
Subwoofer fitted with grill designed to match the main speakers.
Project Logs of Mike Helbig 