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

In previous articles, we broke the subwoofer in and wired the subwoofer. In this article, we’ll identify the parts of a subwoofer and their function. Knowing the parts of a subwoofer and what they do helps prevent damage.

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.
Close up image of a subwoofer dustcap showing detail.

The domed piece glued in the center of the cone is the dust cap. The dust cap prevents dust and other small objects from entering the gap where the voice coil moves back and forth. It also helps the cone maintain its shape. Dust caps are often made of the same material as the cone, or can be made from a material such as carbon fiber to further strengthen the cone.

Cone

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

The cone is one of two parts of the subwoofer that move. The cone is glued to the voice coil. When the coil moves, the cone moves with it. This rapid back and forth movement of the cone and voice coil is what creates the sound of the subwoofer.

Surround

View of a Subwoofer Surround
View of a Subwoofer Surround

The surround is part of the subwoofer’s suspension. It consists of a flexible rubber profile that connects the rim of the frame to the outer edge of the cone. The surround’s consistent profile and flexibility allow the cone to stay aligned with the coil as it moves up and down.

Tinsel Leads

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

The tinsel leads are the electrical connection between the voice coil and the terminals. They attach to the spider, following its profile to connect to the terminals. Electricity flows through the tinsel leads to the voice coil to create the movement that generates sound.

Spider

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

The spider consists of layered corrugated pieces of cloth that have been stiffened with resin into a wavy profile. The spider plays an important part in the efficiency of a speaker depending on its stiffness and number of layers.

The spider attaches to the frame, and suspends the voice coil in the center of the motor gap. This keeps the coil moving in a straight line so it doesn’t touch the motor or pole piece.

Voice Coil

Side view of Subwoofer Voice Coil.
Side view of Subwoofer Voice Coil.
Close up image of Subwoofer Voice Coil, focused on the black winding.
Close up view of a Subwoofer Voice Coil, focused on the winding.
Image looking down inside Subwoofer Voice Coil.
View looking down inside a 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 a Subwoofer Basket.
Perspective view of a Subwoofer Basket.
Side view of a Subwoofer Basket.
Side view of a 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.
Close up view of Top Plate with Voice Coil partially in view.
View of Top Plate between Motor and Voice Coil.
View of Top Plate between Motor and Voice Coil.

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

Magnet

Close up view of Subwoofer Motor.
Close up view of a 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.
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.
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?