Speakers Glossary
November 24, 2007
Basket
Basket or frame is the structure holding the cone, voice coil and magnet rigidly to preserve the proper alignment. It is important, since the voice coil gaps are very narrow. Two types of baskets are popular: Stamped & Cast brackets. Cast brackets are very rigid but expensive.
Bi-amping
In Bi-amping, the woofer and tweeter of a loudspeaker are driven by separate amplifiers. This provides dedicated and flexible amplification of low-frequency (woofer) & high-frequency (tweeter) signals. With such arrangement you can adjust different amp. gains for woofer & tweeter.
Coaxial speaker
Co-axial speakers are usually 2-way speakers. I contain two driver elements: a woofer, for low notes reproduction and a tweeter mounted inside the woofer, for high frequency sound reproduction.
Component System
Component system, also called as “Seperates”, includes 2 woofers, 2 tweeters and 2 crossovers. All these drivers and crossovers are designed to work optimally with one another. The separate drivers design provides the manufacturer with very less or almost no compromise in design. And hence, generally they are made of better materials. You can position the separate tweeters for optimal imaging. Given adequate power, separates deliver exceptional dynamics and detail.
Compression horn
Compression horns are generally used in super tweeters. “Compression” name comes from the type of drivers it is made of. These drivers produce high pressure but little displacement. The diaphragm therefore moves very little, which results in less distortion than a conventional radiating driver.
Crossover
Crossovers are also called as frequency dividing network. They are made of filters, coils & capacitors, and direct specific frequency ranges to appropriate speaker components (woofers, midrange and tweeter). The acoustic behavior of low and high frequency drivers outside their recommended frequency ranges may not add up well, thus resulting in poor frequency response. Crossovers avoid this problem and thus provide proper sound staging. Two generic types of crossovers are available:
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High level passive: Fits between the power amplifier and speakers. This type is widely used in car audio.
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Low level active: Fits before the power amplifier. Expensive and used only in profession concert sound systems.
Decibel (dB)
Decibel is a standard unit of measure for expressing relative power or amplitude differences. With audio, it represents loudness. One dB is the smallest change in loudness most people can detect. A 1 dB difference is barely noticeable, but a 10 dB difference is big — a speaker playing at 10 dB higher volumes will sound roughly twice as loud.For any given set of speakers, each 3 dB increase in volume level requires a doubling of the amplifier power.
Diaphragm
Diaphragm (also known as the cone) is the thin, semi-rigid membrane attached to the central magnet. The magnet induces the diaphragm to vibrate, producing sound. This diaphragm is also found in headphones. In woofer, this is the speaker cone. In a tweeter, it is usually dome shaped.
Dual Cone
A dual cone speaker uses an inexpensive design in which a small “whizzer” cone attached to the center of the woofer reproduces the high frequencies.
Dust cap
The dust cap is a gently curved dome mounted over the central hole of most loudspeaker diaphragms. It prevents the inner mechanics (such as the pole piece and the spider) from getting soiled. Dust caps also contribute to structural integrity to the voice coil assembly.In some speakers, dust cap serves as high frequency radiator.
Efficiency
The efficiency rating for a speaker measures how well a speaker converts watts of electrical power into watts of acoustical power. Efficiency is related to the “Sensitivity” rating, but it is a different measure. Most manufacturers choose to provide sensitivity rather than efficiency. Most speakers have a very low efficiency rating — between 1% and 10%.
Frequency Response
Frequency Response of a device describes its correctness in terms of passing the signal from its input to its output with regard to the signal amplitude & frequency. This tells us the usable range of signal frequencies with this speaker.
Usually, frequency response of woofers will be above 100Hz up to 2 kHz.
Frequency response of Tweeters will be above 2,500 Hz and below 21,000 Hz (or sometimes up to 25 kHz).
Component systems specify the combined frequency response of its tweeter and woofer elements. Usually it will be above 50Hz and up to 25 kHz.Subwoofers have frequency response below, 100 Hz.
Full-range Speakers
These are capable of reproducing both low and high level ranges of frequencies. They accurately reproduce your music’s frequency range by mounting a tweeter inside the woofer cone. This is also known as a coaxial or 2-way speaker. Some versions may add midranges or supertweeters to better reproduce other parts of the frequency spectrum. These are also referred to by the number of drivers (3-way, 4-way, etc.). Due to size limitations, Full-range speakers used in car generally don’t reproduce very low frequency ranges. For very low frequency range, subwoofers are used.
Imaging
Imaging is a qualitative term used to explain the live sound reinforcement capability of the audio system. Optimal imaging creates a listening experience that seems natural and lifelike. The key to attaining the best possible imaging is to have equal (or as close to equal as possible), unobstructed path lengths between your tweeters and your ears. The ability to mount your tweeter separately, as with components, or in an angled mount, as with some full-range speakers, can improve imaging.
Impedance
Impedance is a measure of the resistance of a speaker’s voice coil to the audio current supplied by the amplifier.Strictly speaking, actual impedance of speaker varies considerably with frequency of input audio signal. So, few manufacturers mention impedance ratings at specific frequencies.
Nominal impedance is more dependable rating that tells the minimum impedance the speaker offers to the input load. Most speakers use 4 ohm coils. This rating should be matched with amplifier’s output impedance rating.
Magnet
The magnet provides a stationary magnetic field against which the voice coil reacts to create sound. The magnets used in speakers are permanent magnets usually made of ceramic, ferrite, Alnico, or, more recently, rare earth (Neodymium magnet).
Maximum RMS Power Handling
“RMS” is an abbreviation for Root Mean Square. Maximum RMS Power-Handling refers to the maximum amount of power a speaker can handle on a continuous basis. This is the most dependable power rating in speakers.
Midrange Speaker
A midrange speaker reproduces the middle frequencies. Component systems often use separate midranges, as do systems that amplify the low, midrange, and high frequencies separately. Some full-range speakers include a midrange element for better detail. Usually midrange speaker sizes range from 3-1/2″ to 6-3/4″.
Most component systems are made of: 2 midrange woofers + 2 tweeters+2 crossovers.
Peak Power Handling
Peak power handling refers to the maximum amount of power a speaker can handle during a brief musical burst.
Plate Speaker
Since a round woofer is more accurate than an oval one, Plate speakers feature a separate round woofer and tweeter, mounted side by side on a plate that’s designed to replace oval-shaped 4″x6″ and 5″x7″/6″x8″ speakers. A plate speaker reproduces music more accurately than an oval speaker. However, the woofer cone on a plate speaker is smaller than a similarly-sized oval speaker, so its bass output will usually be slightly lower.
Polarity
The positive and negative terminal connections decide the direction in which the speaker diaphragm moves. Polarity should be checked before connecting the input signals to ensure, proper terminal points. Polarity should be maintained in all the speakers and other elements such as amplifiers & crossovers for the proper working of overall setup. If you wire your speakers improperly, one speaker cone will move backward while another is moving forward, cancelling out much of the sound both speakers are trying to make.
Pole piece
A pole piece concerns the metal piece in a speaker that concentrates and focuses energy from the speaker magnet into creating a magnetic circuit. Because heat can accumulate during this process, many manufacturers vent pole pieces for cooler, more efficient operation.
Power handling
All car speakers require a power source (receiver or amplifier). Power handling rating is usually specified in range. The lower number of a power-handling rating tells the absolute bare minimum wattage required in getting acceptable sound from the speaker, and the higher number tells the maximum amount the speaker can handle for an extended time. For best results, match your power source level (RMS, or continuous watts) to the upper part of the speaker’s recommended range (RMS rating).
Resonance
It is vibration of a speaker’s cone. All speaker cones vibrate at a certain frequency. Too much resonance can interfere with a speaker’s accuracy.
Sensitivity
Sensitivity is the sound level produced by a given input power at a specified distance directly in front of the speaker. A sensitivity rating tells you how effectively a speaker converts power (watts) into volume (decibels). It is specified in dB SPL at one meter in front of the speaker with 1 Watt input signal.Note: An increase of 3dB in sensitivity creates an increase in sound pressure level in front of the speaker that is same as doubling the amplifier power!As many receivers provide usually 22watts (RMS) power per channel, amplifier is recommended for most speakers for better sound.In case, you are not using power amplifier and directly powering the speakers from receiver, speakers with high sensitivity ratings may be chosen for better sound.
Soundstage
The soundstage refers to the sense of width, depth and height your ears’ perceive, when you listen to music — just as you would sense the placement of different instruments in a live concert setting. Individual vocal and instrumental “images” make up your system’s soundstage. Note that, tweeters are more directional, and are thus provides more sound localization. Hence, the tweeters must be position properly for better soundstage. Subwoofers are least directional.
Spider
The spider is a flexible ring that keeps the voice coil aligned in its gap and secures the rear of the speaker cone to the frame while still allowing the voice coil and the cone to vibrate freely.
Subwoofer
Subwoofer refers to either a woofer, or a complete loudspeaker dedicated to the reproduction of bass audio frequencies, typically from 150 Hz down to 20 Hz. Subwoofer sizes typically measure from 10″ to 12″. As subwoofers require more power, a power amplifier is always recommended.
Supertweeter
A small driver dedicated to ultra-high-frequency reproduction, usually above 10 kHz. You can usually find supertweeters alongside tweeters in 4- or 5-way full-range speakers. Typically these are either compression drivers or piezoelectric drivers.
Surround
The surround refers to the flexible ring encircling the edge of the woofer cone — it connects the cone to the speaker basket. It must be pliable enough to let the woofer travel freely, yet strong enough to guide and control cone movement. (The further the cone can travel, the stronger the bass.) Surrounds are usually made of cloth, foam, or rubber. Rubber tends to last the longest.
Three-way speaker
Three-way, or triaxial, speakers take the separate woofer and tweeter from a two-way design and add a midrange driver for enhanced warmth and texture. Select three-ways use a supertweeter, instead of a midrange, for extended high-frequency response. Four-ways combine a woofer, a midrange, a tweeter, and a supertweeter for even more detail. In theory, n-way speaker will have ‘n’ number of drivers.
Tinsel leads
Tinsel leads are flexible, stranded wires that connect the voice coil to the speaker’s terminals.
Tweeter
A small driver dedicated to high-frequency reproduction. Cone tweeters are efficient and the most economical. Most home speakers use dome or “edge-driven” tweeters — they disperse sound over a wider area for smoother, more accurate reproduction. Semi-dome (or balanced-dome) tweeters use a combination cone and dome construction for excellent sound clarity and dispersion.
Tweeters are made from a variety of materials — paper, aluminum, titanium, or synthetic films such as polyetherimide (PEI) or Kaladex (polyethylene naphthalate). It’s best to listen to a variety of tweeters to determine which one you prefer.
Two-way speaker
Two-way, or coaxial, designs reproduce your music’s frequency range accurately. These speakers use a separate tweeter — mounted inside the woofer — to deliver the high-frequencies.
Voice coil
A voice coil (consisting of a bobbin, collar and winding) is the coil of wire attached to the apex of the cone of a loudspeaker. It provides the motive force to the cone by the reaction of a magnetic field to the current passing through it. Many of the speakers on this site offer a heat-resistant voice coil to prolong speaker life.
Woofer
The woofer, a speaker’s largest cone, reproduces bass and lower midrange notes. To operate efficiently, a cone should be made of material that is stiff, yet lightweight. Cones made of aluminum, synthetic film (like polypropylene), poly mixed with other materials (like mica), or treated paper provide excellent sound, and stand up to the heat, cold, and moisture that car speakers face on a daily basis.
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