Introduction
Speaker drivers are the heart of any Bluetooth speaker, responsible for converting electrical signals into sound. They play a critical role in determining the overall audio quality, volume, and fidelity of the speaker. This article discuss exploring their types, functions, and impact on sound quality.
What are Speaker Drivers?
Speaker drivers, commonly known as loudspeakers, are components that produce sound in Bluetooth speakers. They consist of various parts including the diaphragm, voice coil, magnet, and frame, working together to convert electrical signals into mechanical vibrations, which then create sound waves.
Types of Speaker Drivers
Dynamic Drivers
Dynamic drivers, also known as moving coil drivers, are the most common type found in Bluetooth speakers. They operate on electromagnetic principles, using a voice coil attached to a diaphragm that moves within a magnetic field to produce sound.
Advantages:
- Efficient and can produce high sound levels
- Cost-effective and widely available
- Good bass response
Disadvantages:
- Can be larger, affecting speaker design
- May have distortion at higher volumes
Balanced Armature Drivers
Balanced armature drivers are more commonly found in in-ear monitors and hearing aids but are sometimes used in high-end Bluetooth speakers for enhanced sound detail. They use an armature balanced between two magnets that vibrates to produce sound.
Planar Magnetic Drivers
Planar magnetic drivers are less common but are known for their precise and high-fidelity sound. They use a thin diaphragm with embedded conductive elements that is suspended between two magnetic fields.
Electrostatic Drivers
Electrostatic drivers are used in high-end audio equipment and some Bluetooth speakers for audiophiles. They employ a thin, electrically charged diaphragm placed between two conductive plates.
What are the speakers commonly used in Chinese speaker factories?
Dynamic speakers are also the most commonly used type by Chinese speaker manufacturers, among which external magnetic speakers and internal magnetic speakers are commonly used in portable speaker products. Let’s learn about the working principles and differences of these two types of speakers.
What is an external magnetic speaker?
An external magnetic speaker is a speaker with a magnet designed outside the speaker. It uses an external magnetic system. When current flows through the wire, the wire interacts with the external magnet, generating vibrations and making sounds. This design exposes the magnet directly to the outside, so you can visually see a circle of black magnets on the speaker.
What is an internal magnetic speaker?
An internal magnetic speaker is a speaker that uses a built-in magnetic system. In this design, the magnet is wrapped inside the speaker’s shell, so the magnet cannot be seen on the outside of the speaker. When current flows through the wire, the built-in magnetic field exerts force on the diaphragm, which in turn produces sound.
What is the difference between external magnetic speakers and internal magnetic speakers?
Magnetic field design: The magnet of the external magnetic speaker is designed outside the speaker, while the magnet of the internal magnetic speaker is wrapped inside the speaker. This is the most intuitive difference between the two.
Appearance: Due to the different magnetic field designs, a circle of black magnets can be seen on the appearance of the external magnetic speaker, while the magnet cannot be seen on the internal magnetic speaker, and the magnet is completely wrapped inside the shell.
Sound quality effect: The external magnetic speaker has a wide frequency response characteristic and can efficiently transmit the low frequency band, but it may not be as good as the internal magnetic speaker in the processing of the high frequency band. The internal magnetic speaker has better processing of the details of the sound quality, less distortion, and accurate sound quality, which is more suitable for small-scale sound effects such as offices and families.
Volume and weight: Under the condition of the same size, the internal magnetic speaker is relatively small and flat, and the bottom will not attract the magnet, so the volume and weight are relatively small. The external magnetic speaker is usually larger and higher in height because the magnet is exposed outside, and it is easy to attract ironware, so the weight is also relatively large.
Sensitivity: The external magnetic speaker has a higher sensitivity because the magnet uses more material and forms a stronger magnetic field. Although the internal magnetic speaker has a short magnetic circuit and less ferromagnetic material, it is difficult to form a strong magnetic field, so the sensitivity is relatively low.
Anti-interference ability: The internal magnetic speaker is less affected by the external magnetic field and is not easy to leak magnetic flux. The external magnetic speaker is easily affected by the external magnetic field (but can be shielded to eliminate interference), and the leakage magnetic flux is larger.
What are the advantages and disadvantages of external magnetic speakers and internal magnetic speakers and their application scenarios?
Advantages of external magnetic speakers:
Wide frequency response characteristics and efficient low-frequency transmission capabilities. It is suitable for occasions that require large volume output and low-frequency sound effects, such as recording studios and concerts in professional audio needs. In addition, the price of external magnetic speakers is relatively low and the cost performance is high.
Disadvantages:
Its disadvantages are large size, heavy weight, and easy to be disturbed by external magnetic fields.
Advantages of internal magnetic speakers:
Its sound quality details are well processed, distortion is small, and sound quality is accurate, which is suitable for small-scale sound effect needs. At the same time, it is less disturbed by external magnetic fields, not easy to leak magnetic field, and small size and light weight, suitable for use in places susceptible to magnetic fields, such as built-in speakers of cars, TVs, tablets, mobile phones, etc.
Disadvantages:
The sensitivity of internal magnetic speakers is relatively low, and the price is usually higher.
Summary
External magnetic speakers and internal magnetic speakers have their own advantages and disadvantages, and the choice should be made according to actual needs. For small-scale sound effect needs such as home entertainment needs or offices, internal magnetic speakers are a better choice because they have better sound quality details and less distortion. For professional audio needs or occasions that require high volume output and low-frequency sound effects, external magnetic speakers are more suitable. When purchasing, consumers can choose the appropriate speaker type based on their budget, sound quality requirements and usage scenarios.
Key Components of Speaker Drivers
Diaphragm
The diaphragm is the driver’s part that vibrates to create sound waves. It can be made from various materials, including paper, plastic, and metal. The material and design of the diaphragm significantly affect the sound quality.
Chinese Speaker manufacturers often use rubber diaphragms, which are cheap and can improve sound quality, and have a relatively high cost-effectiveness. When the product is designed with LED lights, if the light transmittance is relatively high, silicone diaphragms are used, but their cost is relatively high. Paper diaphragms and metal diaphragms are rarely used and are only used when customers require them.
However, the diaphragm is only part of the many design links. It can provide basic sound characteristics, but these characteristics may change with changes in acoustic structure, electrical performance and other factors. The final sound performance of the speaker or headphones depends on the overall design.
Voice Coil
The voice coil is a coil of wire attached to the diaphragm. It interacts with the magnetic field to create movement in the diaphragm. The number of turns in the coil and the wire gauge impact the driver’s performance.
Magnet
The magnet creates a static magnetic field within which the voice coil moves. Stronger magnets generally result in better control of the diaphragm and improved sound quality.
Suspension
The suspension system, including the surround and spider, keeps the diaphragm centered and allows it to move freely. It must be flexible enough to allow movement but rigid enough to return the diaphragm to its rest position.
Performance Metrics of Speaker Drivers
Evaluating the performance of speaker drivers involves examining several key metrics:
Frequency Response
Frequency response indicates the range of frequencies a speaker can reproduce. A broader frequency response range generally means better sound quality, covering lows (bass), mids, and highs (treble).
Sensitivity
Sensitivity measures how effectively a speaker converts electrical power into sound. Higher sensitivity means the speaker can produce louder sound at lower power levels, which is crucial for battery-operated Bluetooth speakers.
Impedance
Impedance is the resistance a speaker offers to the electrical signal. It affects the compatibility with amplifiers and the overall sound output. Most Bluetooth speakers have an impedance of 4 to 8 ohms.
Total Harmonic Distortion (THD)
THD measures the distortion a speaker introduces to the audio signal. Lower THD values indicate cleaner sound reproduction, which is especially important at higher volumes.
Impact of Speaker Drivers on Sound Quality
The choice and quality of speaker drivers directly impact the overall sound quality of a Bluetooth speaker. Here are some ways they influence the audio experience:
Bass Response
The size and type of the driver largely determine the bass response. Larger dynamic drivers typically produce deeper and more powerful bass, while smaller drivers might struggle with low frequencies.
Clarity and Detail
Balanced armature and planar magnetic drivers excel in delivering detailed and clear audio, making them ideal for genres that require high fidelity, such as classical or jazz.
Volume and Loudness
Dynamic drivers are known for their ability to produce high sound levels, making them suitable for larger rooms or outdoor use. Sensitivity plays a crucial role in determining how loud a speaker can get without distortion.
Soundstage and Imaging
Drivers like planar magnetic and electrostatic can create a wide and precise soundstage, offering an immersive listening experience where the placement of instruments and vocals is clearly discernible.
How to choose the correct Bluetooth speaker based on the drivers ?
- Choose a bigger one instead of smaller one.
When the structural dimensions are met, try to choose a speaker unit with a larger diameter, because this can achieve higher sound efficiency and lower low-frequency extension. For example, if a well-designed 3-inch speaker is changed to a 4-inch speaker, the price will not be expensive, and the parameters can easily exceed the 3-inch speaker. That is to say, we must first consider the sound area. Physical principles determine that no matter how a small-diameter speaker is designed, it will not produce good low frequencies. - If a speaker cannot complete a task, design two. Because no matter how well a speaker is designed, it is difficult to take into account all the low, medium and high frequency bands, and the cost is quite high. At this time, you can add a cheap small-sized tweeter. The total cost will not be higher than a speaker that reaches the physical limit in all aspects.
- When the speaker opening can be facing forward, do not face it downward. It will cause strong mid-frequency sound coloration. It is like the sound of speaking with your hand covering your mouth. When facing downward, you can only make a groove at the back to use the reflected sound of the wall behind to reduce this distortion. Or add a tweeter on the side or top of the back of the TV to improve the high-frequency response.
- If the duct in front of the speaker can be made into a trumpet-shaped shape, do not make it into a rectangular shape. That is to say, it is better to be wide outside and narrow inside than to be the same width inside and outside. It is not good to be wide inside and narrow outside.
- The speaker should be installed as far forward as possible. This will minimize the sound coloration (horn effect).
Conclusion
Speaker drivers are pivotal in Bluetooth speakers, significantly influencing their sound quality and overall performance. By understanding the different types of drivers, their components, and performance metrics, consumers and businesses can make informed decisions when selecting or manufacturing Bluetooth speakers. Whether prioritizing bass, clarity, volume, or portability, the right choice of speaker driver can enhance the listening experience and meet diverse audio preferences.