The Anatomy of a Subwoofer


Before we discuss why subwoofers blow, let’s go over the anatomy of a subwoofer.

Knowing the anatomy of a subwoofer and the role each component plays in creating sound will help us understand why those parts may perform in an undesirable fashion and help avoid those subwoofer snafus.

In previous articles, we broke the subwoofer in and wired the subwoofer. Now we’ll dissect an 18-Inch HDX4 to get to the core of what we’re breaking in and what we’re wiring.

Dust Cap

Close up image of a subwoofer dustcap showing detail.

The small curved piece mounted over the large hole in your subwoofer is a dust cap. It serves to keep the parts below it safe while also reinforcing the structure of the cone. Dust caps are typically made of the same material as the cone it rests on.


Side view of Subwoofer Cone, from surround to surround.
Rear view of Subwoofer Cone showing texture.

The cone is one of two parts of the subwoofer that move. The cone is stimulated by the oscillations of the voice coil. This oscillation pushes and pulls the cone, which creates sound waves.


View of Subwoofer Surround

The surround, which surrounds the cone, is part of the subwoofer’s suspension. The surround assists in the excursion and in keeping the cone linear through the path of excursion.

Tinsel Leads

Photo of Tinsel Leads coming off the side of a Spider.

The tinsel leads are electrical wire that carries current from the terminals to the voice coil. Tinsel leads are attached to the voice coil from the spider.


Face up view of subwoofer spider with tinsel leads attached.
Image of Tinsel Leads underneath Cone and above Voice Coil.

This spider doesn’t weave a web but is a layered series of wavy, corrugated pieces.

The spider suspends the cone and coil, centered within the motor gap to sustain the linear movement of the voice coil.

Voice Coil

Side view of Subwoofer Voice Coil.
Close up image of Subwoofer Voice Coil, focused on the black winding.
Image looking down inside Subwoofer Voice Coil.

The voice coil is one of the most fundamental elements of a speaker or subwoofer. The voice coil consists of two parts: The coil, and the former.

The former gives the voice coil its form and its shape and keeps it in place. The coil is copper or aluminum wire tightly wound around the former and is the element that creates an alternating field within the motor. Glue is used to keep the winding on the former. 

The Basket

Perspective view of Subwoofer Basket.
Side view of Subwoofer Basket.

The basket is the frame that holds all of the above together. Its stiffness and non-resonance contribute to overall sound quality.

Top Plate

Close up view of Top Plate with Voice Coil partially in view.
View of Top Plate between Motor and Voice Coil.

The top plate is found just underneath the basket. It rests above the magnet directs flux into the voice coil gap. The top plate works with the t-yoke to create and maintain a magnetic field.


Close up view of Subwoofer Motor.

See also: Muscle. This is the driving force of the subwoofer. The magnet is held in place by the force of the top and bottom plates. SoundQubed subwoofers use ferrite magnets. Ferrite is heavy and retains its magnetism well over time, so you can enjoy bass for years to come.

Bottom Plate

Perspective view of Subwoofer Bottom Plate.

The bottom plate is also known as the T-Yoke. It creates an oppositional force in the magnetic field along with the top plate. The bottom plate acts as a heatsink, pulling and dispersing heat.

Pole Piece

Pole Piece with adhesive removed.

The pole piece attaches to and extends the pole of a magnet. The voice coil slips over the pole piece, which is connected to the bottom plate of the motor.

Ready for your own HDX4 Series Subwoofer?