Speakers are an essential part of our auditory experience, converting electrical signals into vibrant sounds that we perceive. Widely used in various sound-producing electronic devices, speakers are common yet indispensable components. However, despite their seemingly simple design, understanding how speakers operate and how they influence sound production requires a deeper look into their underlying mechanisms and key components. This article provides a comprehensive overview of the use of speakers in audio design, covering their basic operation, key specifications, design considerations, cone and magnet types, and the features of speaker products offered by Same Sky.
The working principles and technical specifications of speakers
The production of sound in a speaker involves a precise interplay between electromagnetism and mechanical motion. It begins with an electrical signal, which represents the audio we want to hear. This signal can originate from various sources, such as a smartphone, laptop, or any other audio device capable of generating sound.
Inside the speaker, key components start to function. The core components are the voice coil and the permanent magnet. The voice coil is made of wire and is connected to a flexible cone or diaphragm. This voice coil surrounds a sturdy permanent magnet, forming the foundation for sound generation. When the electrical signal flows through the speaker’s wires, it energizes the voice coil, initiating a series of electromagnetically controlled actions. This electrical energy generates a magnetic field around the coil, with polarity mirroring the change in the electrical signal.
The essence of speaker operation lies in the interaction between these magnetic fields. As the fields fluctuate, they alternately repel and attract, causing the voice coil and its attached cone to oscillate rapidly. This oscillating motion interacts with surrounding air molecules, causing them to vibrate in sync with the movement of the cone. These vibrating air molecules generate pressure waves that propagate through the air and ultimately reach our ears as sound.
Before introducing the fundamental principles of speaker operation and structure, we first need to understand the various key specifications and performance standards to consider when designing and selecting speakers.
First, the Sound Pressure Level (SPL) is measured in decibels (dB) and is used to measure the intensity of sound waves in the air, determining loudness. SPL is influenced by factors such as the distance from the sound source and environmental conditions. It is also an important parameter for assessing noise levels in various settings, from industrial environments to residential areas, providing valuable information for noise control and regulation.
The maximum input power, measured in watts (W), represents the highest power a speaker can handle in an extremely short duration without sustaining permanent damage. The nominal input power, also measured in watts, refers to the power a speaker can safely handle over an extended period.
Impedance, measured in ohms (Ω), represents the resistance to the flow of electrical current from an amplifier. Lower impedance ratings mean the speaker consumes more power. It is crucial to match the speaker's impedance with a compatible amplifier impedance to ensure optimal performance and prevent potential damage to the equipment. Matching impedance also helps achieve efficient power transfer and maintain the fidelity of audio reproduction.
The resonant frequency refers to the frequency at which a speaker vibrates most efficiently and is measured in hertz (Hz). The resonant frequency specification provides an approximate comparison of the low-frequency response among different speakers. Additionally, the frequency range of a speaker is determined by its sizes; smaller speakers operate best at higher frequencies, while larger speakers perform better in lower frequency ranges. Low frequencies are used for deep bass sounds, while mid-range frequencies are crucial for voice reproduction.
The total Q factor refers to the Thiele-Small parameters, which serves as a broad reference for determining the ideal enclosure type. A total Q value of 0.4 or lower indicates that the speaker is best suited for a vented enclosure. If the total Q is between 0.4 and 0.7, a sealed enclosure is recommended. A total Q of 0.7 or higher suggests that the speaker is suitable for free-air, semi-open, or infinite baffle setups. However, there are exceptions to these guidelines, making it important to evaluate all relevant parameters comprehensively.
Speaker size, shape, installation, and testing considerations
Generally, speakers with a larger surface area produce higher sound levels under the same drive signal and offer a better low-frequency response. The use of DSP pre-distortion can significantly enhance the performance of small speakers, a technique commonly employed in cell phone and laptop computer designs. A slight performance boost can also be achieved by designing the enclosure surrounding the back of the speaker.
The shape of the speaker cone is typically determined by the available installation space. An oval-shaped speaker cones allow for a larger cone surface area to fit into non-square spaces. The speaker’s frequency response graph should be examined to determine whether the size or shape negatively impacts the speaker’s expected performance.
Regarding connection configurations, speakers offer various options depending on the application requirements, including wire leads, through-hole, and solder pads. Additionally, some speakers are equipped with Ingress Protection (IP) ratings to handle moisture and contaminants in harsh environments. On the other hand, speakers do not have a specific lifespan rating since they can provide years of reliable performance when operated within their rated specifications.
After selecting a speaker using the key specifications mentioned above, additional measurements and tests can be conducted to ensure the speaker is properly integrated into the design and meets the required specifications.
One fundamental test is the frequency response measurement, which visually represents how an audio component reproduces the audible sound range. The stepped frequency sweep is similar to frequency response testing but is specifically designed to detect alias frequencies for a more comprehensive response analysis.
Additionally, testing level and gain is crucial. Level determines how much energy the device can output, while gain is the ratio of the output level to the input level of the device. Furthermore, Total Harmonic Distortion plus Noise (THD+N) should be measured. Harmonic distortion refers to the addition of unwanted new tones in an audio signal. THD+N serves as a widely understood and accepted single number mark of performance.
Phase measurement describes the positive or negative time offset in a cycle of a periodic waveform relative to a reference waveform. The two most common measurements are device input/output phase and inter-channel phase (for systems with multiple speakers). Rub and buzz tests detect the presence of high-frequency harmonic products produced in response to low-frequency stimulus.
The Thiele-Small parameters capture the complex impedance of the tested speaker and provide calculated electromechanical parameters, which define the speaker driver’s low-frequency performance. These parameters—including the total Q factor—accurately describe the interaction between the speaker and its enclosure, making them essential for speaker system design and production testing.
Speaker impedance measures the resistance to an alternating current (AC) signal such as audio from an amplifier. It is expressed in ohms (Ω) and represents the speaker’s resistance to electrical signals.
Lastly, the frequency response curve is crucial for evaluating a speaker. The term "response" refers to the speaker's ability to reproduce input frequencies accurately. When plotted, the data forms a frequency response graph, visually depicting the relationship between amplitude and frequency. The vertical axis represents sound level in decibels (dB), while the horizontal axis represents frequency in hertz (Hz).
Selecting the ideal speaker cone and magnet material
The type of material used for the speaker cone and other factors will affect the sound quality. Evaluating this through listening and experimentation is more accurate than relying solely on numbers and data. The durability of common cone materials is also an important factor to consider. Generally, plastic is the most durable, followed by paper and cloth, and then foam materials. However, the actual lifespan of a speaker depends on factors such as humidity, environment, and application specifics.
Speaker cones made from plastic are popular due to their durability and resistance to environmental factors like dust and water. They are also easy to manufacture and have precise tolerances, leading to better performance in reducing distortion and improving sound quality. Plastic diaphragms can quickly absorb and dissipate mechanical energy, exhibiting good damping characteristics similar to traditional paper cones. Although commonly referred to as plastic, these materials include various composites, with costs varying based on thickness, pressing technology, size, and temperature resistance.
Paper and cloth cones are known for their excellent sound quality and self-damping properties but may be affected by humidity. They are made from various wood fibers, and additives like cotton and wool are mixed in to achieve specific sound characteristics. This mixture enhances strength and compensates for weaknesses, resulting in diverse sounds. Due to their light weight, they are mainly used in large speakers.
Foam materials are rarely used as the sole diaphragm material and are usually combined with other materials like metal, plastic, or paper. In composite diaphragms, foam materials are added to the interlayers. Their main function is to enhance internal losses, which is a key physical characteristic of speakers.
High internal loss helps to minimize the inherent sound characteristics of raw materials. For example, metal diaphragms have lower internal loss, which easily leads to a metallic sound. In contrast, paper cones have higher internal loss, resulting in a more natural sound with minimal influence from the raw materials’ timbre.
Another key component of the overall speaker construction and performance is the type of magnet used. First, ferrite magnets, also known as ceramic magnets, are a low-cost option that maintains its magnetic strength well. They are heavy and are typically not used in applications that require portability. Speakers with ferrite magnets tend to sound better when approaching their maximum handling capacity. Ferrite magnets are also highly suitable for applications in humid environments, as they have natural corrosion resistance.
AlNiCo (aluminum-nickel-cobalt) magnets were the first magnets used in speakers and help to produce a smooth, classic tone. Speakers using AlNiCo magnets are more expensive than those based on ferrite, but they are less likely to break. These magnets are certainly not as common as neodymium (NdFeB) magnets today, but they are still used in high-end applications where precise tuning is required.
Neodymium (NdFeB) magnets, also known as rare-earth magnets, offer the highest magnetic field strength of any known permanent magnet. Speakers made with NdFeB magnets have excellent frequency response, are lightweight, and are much smaller than speakers with ferrite or AlNiCo magnets. This makes them ideal magnets for small speakers that require high sound pressure levels. The main disadvantage of neodymium magnets is that they are more prone to shattering.
Samarium-cobalt (SmCo) magnets are used less frequently than other types of magnets due to their higher cost. Their main advantage is corrosion resistance, and they maintain stable output under extreme temperature changes, making them ideal for harsh environments. They are prone to shattering and their strength is not as high as neodymium magnets. However, cost remains their biggest downside.
A complete series of speakers in various specifications
Same Sky’s speakers product offering features frame sizes ranging from 10mm to 205mm and sound pressure levels from 72 to 135 decibels, providing quality and convenience to meet customer sound requirements. Same Sky's speaker selection includes various frame shapes, magnet types, and mounting styles, allowing for quick adaptation to customer designs. Same Sky can also customize speakers to suit customer needs through various mechanical and electrical modifications.
The types of speakers offered by Same Sky include miniature speakers and standard speakers. In response to the trend of miniaturization, Same Sky provides a range of miniature speakers with compact package sizes as small as 10mm and depths as low as 2mm. The sound pressure levels of Same Sky's miniature speakers range from 72 to 135 dB, with impedance ratings of 4, 6, 8, 16, 20, 25, 32, or 50 ohms, and resonant frequencies of up to 1700 Hz.
As a key player in the industry, Same Sky's standard speakers are designed for high power output and reliable performance, with package sizes ranging from 41 to 205 mm. Same Sky's standard speakers have a sound pressure level of 78 to 107 dB, a resonant frequency of 50 to 3000 Hz, and rated impedances of 4, 6, 8, 16, or 32 ohms.
Same Sky offers a variety of cone types, magnet types, frame shapes, and mounting styles, making it easy for customers to find speakers that meet their design requirements. They also provide various models of tweeters, as well as medical speakers designed to meet IEC 60601-1-8 regulatory standards, tailored to comply with medical alarm signal requirements. Same Sky also offers audio design services to assist engineers with critical speaker measurements and testing. You are welcome to visit the following website to search for speakers that suit your needs: https://www.arrow.com/en/manufacturers/cui-devices/audio-components/speakers.
Conclusion
Understanding the mechanism of speakers allows engineers to create immersive auditory experiences. This article introduces various components and specifications that can assist customers in selecting the appropriate speaker. However, even with a deeper understanding of key speaker parameters, it is essential to conduct proper testing and measurements of the chosen speaker in the final design. Same Sky's full range of miniature speakers and standard speakers can meet the diverse needs of customers, while Same Sky's audio design services can also provide additional assistance!