How is a Subwoofer paper cone made?

Cones are one of the moving parts of subwoofers and speakers, hence are essential components when it comes to creating sound.

A voice coil in motion is responsible for moving the cone in a back-and-forth motion which allows the cone to displace the surrounding air and produce sound.

There are different recipes and methods used by manufacturers to design subwoofer and speaker cones.

Cones for subwoofers and speakers can be made from tree pulp to produce a paper cone, and other materials include plastic (propylene) and other additives.

The most common types are made using special paper pulps also known as treated paper cones.

Let us look into the useful information below to understand the recipes and various methods in the making of paper cones for subwoofers and speakers.

What are the factors involved in making subwoofer paper cones?

There are many factors considered by the designers and manufacturers in the making of subwoofer paper cones.

Let us look into the major and important factors considered in their making.

Raw Materials

The properties of the subwoofer or loudspeaker cone are typically influenced by the pulp formulae or recipes and other additives used in their making.

Machinery

The beating procedure for the pulp slurry in a large beating machine followed by different construction techniques.

Technical and mechanical factors

Technical and mechanical characteristics such as speed and quality of sound, burst and tear strength, etc., are also considered when choosing raw materials. Hence specific categories of pulps are used to make subwoofer paper cones.

Environmental Factors

Environmental factors such as humid and damp conditions are also considered in the making of paper cones.

In simple words, the pulp and additives used to make paper cones are specifically based on environmental factors.

Other factors

Vulnerability to UV, fungus, and ozone resistance are other major factors that cannot be ignored in the making of subwoofer paper cones.

Surface Treatments & Finished Product (Techniques)

Techniques such as press, semi-press, and non-press are the most common types of methods used to make finished paper cones out of the pulp slurry.

Finally, several surface treatments are offered to enhance the appearance and achieve the appropriate paper cone characteristics.

Above are the major factors that make perfect paper cones for subwoofers, speakers, and other audiophiles or pro-sound diaphragms.

How is a subwoofer paper cone made?

The process might look simple in layman’s terms, but technically it is a bit complicated on practical grounds.

Let us look into the step-by-step process of making paper cones.

Step 1: Considering Additives and Raw Materials

At first, sheets of assorted pulps and additives are put together in a beating machine.

So let us look at the raw materials or pulps and additives considered to make paper cones.

Pulps and additives

The special pulps can be found in different parts of the world such as from the most popular Douglas fir or other exotic blends.

Moreover, these special types of pulps include eucalyptus and are typically made available from Brazil, Australia, New Zealand, and other nations.

Apart from the above types, kapok seed fibers, Dai-Ichi (similar to banana leaves), and other synthetic fibers are also used to prepare the pulp slurry.

Finally, salt is added as an additive to the blend along with the pulps and to hold the dyes (usually black color dyes are added).

As an additive carbon fibers such as Kevlar, Conex, and other aramid fibers are also included to retain the cone’s strength and also reduce the weight to some extent.

Let us move to the next step to understand the treatment process of the raw material followed by the preparation of slurry and the final product.

Step 2: Pre-treatment of raw materials

The raw pulp and additives are pretreated for fine-sorting by extracting the unwanted pulp fibers or layers.

  • The selected pulp and additives are set to soak in hot water for a specific or required period of time.
  • The shredding pieces are then torn off the wet pulp either by hand or using machines.
  • It helps separate the waste from the raw pulp and additives and ensures that a quality blend is used further.

Now, it’s time to prepare the pulp slurry which is done using a machine typically a beating machine.

Step 3: Making paper pulp slurry (Fibrillation)

The most common method used in the making of pulp slurry is to use a beating machine followed by agitation.

Some manufacturers also use hydropulpers which is again a type of machinery used in the beating process.

Additionally, Hydropulpers use advanced technologies and are capable of boosting the process by preparing the slurry in less time.

However, most manufacturers prefer using the old beating machines as they offer better fibrillation compared to hydropulpers.

Let us look into the process of making pulp slurry below:

Beating or Pressing

The technique of beating helps distribute the strands while also fluffing them up so they will tangle and become firm enough to hold the cone together.

  • The treated pulps and additives are transferred into the beating machine filled with water.
  • Salt is also added as an additive to the beater to hold the dye color (black).
  • The machine presses and beats the raw materials (pulps and additives) in batches.
  • The beating is done by a beating wheel that comes closer to the beating bedplate (the base) to mash and press the mixture.
  • Finally, the blend is worked into a slurry of fibrillated fibers.

Agitation

  • The blend of pressed pulp in the form of a thick fluid is poured or transferred to a holding tank.
  • This particular tank includes an agitator that keeps the slurry spread and normalized inside the tank.
  • The pulp slurry is ready to be shaped in the form of subwoofer cones of different sizes and shapes.

Step 4: Techniques used in the making of subwoofer cone

Now that the paper pulp slurry is ready there are typically three techniques used to make the finished product such as press and semi-press or non-press cones.

Methods to make subwoofer cones

  • For the Press method, the pulp slurry fibers are transferred into a large basket or a bin that includes a filter mesh screen.
  • It helps to drain fine liquid from the mixture and separate the slurry (referred to as “carcass”) from the mesh.
  • Next, the usable material is then transferred to the cone-pressing machines.
  • It is then pressed firmly with a set amount of heat and pressure to gain the finished shape of a paper cone (The cone pressing involves heating which helps discharge excess moisture.).
  • The making of Non-pressed cones includes chemical treatment, where the slurry is treated with several chemicals for the production of stiffer and highly sensitive cones.

Process of Making Subwoofer Paper Cone (Diagram)

Process of making subwoofer paper cone

Final Thoughts

The creation of paper cones for subwoofers and speakers is a nuanced process that involves careful selection of raw materials, specialized machinery, and precise techniques.

Factors like sound quality, environmental conditions, and material properties are meticulously considered.

From the initial pulp slurry preparation to the final pressing or chemical treatment, each step is crucial for achieving the desired acoustic performance and durability.

Armed with a Diploma in electrical engineering and a remarkable 12 years of expertise, he excels in rejuvenating music systems, washing machines, dryers, and laundry-related appliances. Manish's profound insights and practical know-how establish him as a credible authority in appliance and music system repairs. Contact: manish.singh (at) subwooferblog.com. He's always ready to lend a helping hand!