Many music lovers have been listening to audio from music and video without understanding how. The whole listening experience, however, relies on the making of a good speaker. If you are wondering how speakers are made, read this article to find out more information.
Speakers are made from iron, aluminum, fabric and paper. The frame is made from iron and aluminum. The magnet is made from a ceramic ferrite material consisting of iron oxide, strontium, and a ceramic binder. The cone, spider and surround are made from treated paper coated with an adhesive glue. The voice coil is a thin copper wire usually wound around a plastic bobbin
What Are Speakers?
Speakers are electroacoustic transducers that convert electromagnetic waves into sound waves.
The frequency and amplitude of the sound waves determine the significant characteristics of the sound produced by the speaker. The sound frequency determines whether it will be how or high pitched, while amplitude determines the loudness.
A good speaker should reproduce a wide range of sound frequencies. However, the amplitude is regulated by the variation of air pressure occurring due to the sound waves.
What Are Speakers Made From?
The most commonly used speakers are dynamic speakers. They are found in the most widely used speakers systems such as radios, TVs, professional speaker monitors, and many other home speaker systems.
Therefore, the design is the same, and similar speaker components are used across the many different speakers.
The most common components that speakers are made of include:
- Basket: Also called “frame,” the basket is made of metal and the framework that supports the other components of the speaker.
- Voice Coil: This is a thin copper wire usually wound around a plastic bobbin and placed on top of a soft iron core. The coil sits inside the opening of the basket.
- Top Plate
- Dust cap
Speakers have had a long history, but over time, most of the raw materials have remained the same.
Speaker Raw Materials
The process of creating a dynamic speaker has not changed a bit for several decades since its earlier design.
The speaker frame is designed from stamped aluminum or iron. The spider, cone, and surround are created using a treated paper coated with adhesive glue. The speaker voice coil comprises a plastic bobbin using fine gauge shielded copper wire curled around it.
These are the main components that make speakers.
- Voice coil
- Top plat
How Are Speakers Made?
The process of making speakers involves a long manufacturing process. This involves manufacturing the magnet, frame, cone, coil, and general assembly. Let’s look at the step-by-step process.
Step 1: Constructing The Permanent Magnet
When constructing the permanent magnet, iron oxide is mixed with strontium. The mixture is then milled into a fine powder. Once ground into a very fine powder, it is combined with a ceramic binder and closed in a metal die which is then placed in a furnace. This is done to bind the mixture together.
Step 2: Building The Frame
The speaker frame is built from aluminum or steel sheet. Once the sheet is made, it is placed on a conveyor and transported to a cutting machine. The machine uses a hydraulic press to cut holes in the sheet at their proper locations. This is mainly done to allow the air to flow freely from the cone.
Step 3: Assembling The Cone, Surround, And Spider
At this stage, the spider, cone, and surround are formed individually out of composite paper. They are then glued together as an assembly.
Step 4: Building The Voice Coil
A voice coil is a thin copper wire that is wound around a plastic bobbin. The voice coil is constructed by winding several fine insulated copper wire turns on a plastic spindle. The assembly of bobbin and voice coil is placed on top of a soft iron core then glued to the dust cap of the cone. It sits inside the opening of the basket.
Step 5: Bolting The Frame, Magnet, And Core
Once the voice coil is constructed correctly, the soft iron core, the permanent magnet, and the frame are assembled and bolted together.
Step 6: Attaching The Cone Assembly To The Frame Assembly
Once the frame assembly is ready, it is attached to the cone assembly. This is done by first gluing the spider to the base of the frame. The surround is then glued to the top of the frame.
Usually, the rubber surround is attached to the front of the cone, while the spider is attached to the backside.
Step 7: Speaker Housing
Once the speaker is made, housing materials help focus the sound signals reproduced during operation. The speaker is therefore placed in a box enclosure. Speaker enclosures can be made in different shapes and from different materials. Typically, speaker enclosures are made from medium-density fiberboards (MDF), which helps by dampening unwanted sounds as well as providing a stable frame to minimize vibrations from the speaker.
However, for devices with built-in speakers such as portable radios, plastic or aluminum are occasionally used. Plastic is more affordable and is majorly used. Although also affordable, aluminum is less likely to shield speakers from vibrations and is less commonly used.
Once the speaker is made, the manufacturing process is monitored by inspectors. During this process, the permanent magnet is checked for cracks or chips. Also, the paper cones are inspected for holes or any flaws in the material and adequately glued.
The whole speaker assembly is therefore inspected for quality and conformity with specifications. The final assembly is then connected to an audio generator to test its frequency response and power. This is done as a final step to ensure the speaker reproduces sound within the required specifications.
How Does A Speaker Reproduce Sound?
Speakers that have been appropriately made and passed all the quality checks will be ready to reproduce sound signals.
Audio is sent to the speaker in the form of an electrical signal from an audio device or amplifier. The signal is transmitted through the speaker wires to the voice coil of the speaker.
When the signal reaches the speaker, an electromagnetic field is formed around the coil. As a result, the voice coil begins to move forth and back aided by the permanent magnet. This movement causes the speaker cone to vibrate and reproduce the sound carried in the electromagnetic field.
What Are Speaker Cones Made Of?
As we mentioned already, you can make speaker cones from several different types of materials such as paper, plastic, fiber, and aluminum. Each material has unique properties making them reproduce sound differently from the others.
Paper is, however, the most preferred material and can be produced from a combination of wood, resins, fibers, and waxes. The mixture is compressed to increase the flexibility and sensitivity of the speaker.
On the other hand, plastic cones are affordable and offer improved sound dampening. This can, however, muddle the sound and limit the frequency range of the speaker.
Aluminum and other metals can be used. However, due to the limited flexibility, they are primarily used in toys and small gadgets. Fiber is, however, a premium material, offering optimal rigidity for quicker response to vibrations. The material can effectively reproduce a wide range of sound frequencies, including high tones and bass tones.
What Are The Parts of a Speaker
In the middle of every loudspeaker, you will find an electromagnet, also known as the voice coil. It normally uses an electric current to produce a magnetic field.
The process of making a voice coil happens through the winding. Nomex, paper, fiberglass (former material), or Kapton material is used to wrap around a steel mandrel, which maintains its round shape in the process.
After that, copper aluminum wire is curled to precise lengths agreeing to the design. After that, the coil is baked to help cure the used adhesive for covering the wire. A bead of glue is later placed on the top and the bottom part of the winding. And for quality purposes, the coil is double baked.
The speaker coil is added its strength through the use of copper or beryllium. After that, the paper collar is used to wrap around the coil to keep the wire connected from the winding to tensile leads protected. Then on each winding end, the leads are spliced. The final process is to check the DC resistance and quality of the coil.
The construction of loudspeakers requires few metal parts for support. And they are the backplate, the basket, core, and top plate. Usually, the top plates and back plates are stamped from the steel rolls. The top plate is staked or welded to the basket, and then the backplate will be staked to the center part. The two plates are instrumental in sandwiching the permanent magnet.
After metal parts assembling, they are later taken through an in-house e-coat painting process. A uniform coating is applied over the whole surface of the metallic parts to a balanced thickness of less than 0.0001”.
Voice coils obtain an electronic current and produce a magnetic field; the permanent magnet fixed to the loudspeaker basket repels it. The magnets come in different forms, materials, and sizes, but they are not magnets until the loudspeaker’s assembly arrives at the end of the production line. Some speaker production companies use alnico magnets, ferrite, and lightweight neodymium.
Soft Parts – Spider, Cone, Surround and Dust Cap
The loudspeaker’s soft parts are spider, cone, surround, and dust cap. Speakers cones are designed in various sizes, and you’ll find the bodies created using typical paper. But the surround can be made of rubber, cloth, Santoprene, foam, or paper. Both surround and spider make up the mechanical suspension, which gets the cone back to its original resting place.
Now that everything is set, the last part is to assemble the pieces into a whole speaker. The terminal board should be attached to the top plate/ basket assembly using rivets or glue. The next step is to apply a gasket to the basket to help create a seal using the enclosure if the speaker is to be front-mounted.
After that, you glue the painted backplate/ core assembly and magnet to the top plate with a centering gauge to make sure there’s a uniform magnetic gap, the metal core that holds the voice coil, and the narrow space amid the permanent magnet.
You then apply a bead of glue to the flange of the speaker’s basket to help attach the cone surround. Then you remove any debris in the magnetic gap using a vacuum.
And the final assembly goes through various processes before settling to a functional speaker. After a series of connections here and there, the gasket front part is added to the basket to create a seal using the enclosure if the speaker is to be rear-mounted.
The tensile leads require them to be crimped, especially the terminals, and any excess wire is cut. After that, every terminal is applied with a bead of glue to stick wires in the place.
After all that process, the speaker is finally assembled. At this stage, a conveyer belt is used to move the speakers through another process to cure the glue via the oven while a technician makes sure the speakers undergo sweeping using an audio signal at the end of the line. And this allows the end product is working properly without a single visible or audible defect.
Why are speakers mounted in boxes?
The movement of the speaker’s driver’s cone brings about pressure waves from the front and backside. When it moves towards you, it pushes the air, creates positive pressure, and then simultaneously pulls the air back, creating negative pressure.
So, in short, the speaker enclosure idea prevents sound waves generated through the diaphragm rearward facing surface of an open speaker driver working together with sound waves generated at the front part of the speaker driver.
Why do some speakers have holes in them?
For audiophiles who love woofers, the front wave cannot be canceled by the back wave. But some wonder why do some speakers have holes in them that let out the threatening back wave?
The holes in these types of speakers are called ports and are specific dimensions engineered to bring out exactly what is required to allow speakers to produce the right sound. The removal of some pressure via port adds quality bass and permits the woofer to breathe with ease.
Why it’s worth knowing how speakers work
Learning how speakers are made and work can avoid many problems for your gadgets at home. You don’t need to get in-depth science behind their functionality to enjoy music, but some understanding may guide you to choose the right equipment to purchase.
Choosing to learn how speakers function can give you knowledge of why some designs sound differently from others. Also, you can easily diagnose any problem that may arise without asking for technician intervention.
There you have it! All the information about step by step process of how speakers are made. So, if you are an audiophile, you are now armed with the correct information about speakers and their sound.