Car speakers glossary
Essential words and phrases when you're shopping for car speakers
Alexander Hrabe is a member of Crutchfield's car audio A/V writing team. It was only a matter of time. He's been writing professionally for a decade, and his first car stereo was purchased from Crutchfield. Worlds have officially collided.
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The basket, or frame, is the structural support of a speaker.
In bi-amping, separate amplifiers (or amp channels) drive the woofer and tweeter of a speaker. This way, both low-frequency drivers (woofers) and high-frequency drivers (tweeters) receive dedicated amplification.
Coaxial speakers contain two elements: a woofer, to reproduce the low notes, and a tweeter, mounted inside the woofer, for the highs. See also "Two-Way Speakers", below.
Any change in the character of a sound that reduces its accuracy, such as an over- or under-emphasis of certain frequencies.
Component systems, or separates, use a superior speaker design to give you the best possible sound. A typical separates system includes 2 woofers, 2 tweeters, and 2 external crossovers — all of which are designed to work smoothly with one another.
Generally, components are made of better materials than their two- or three-way counterparts. You can position the separate tweeters for optimal imaging. Given adequate power, separates deliver exceptional dynamics and detail.
Found in some speakers, a high-frequency (or midrange) driver fires into a horn-shaped enclosure for powerful, highly efficient output. Adapted from concert systems, compression horn tweeters and midranges move with less excursion, so they produce less distortion and have higher power-handling levels than other designs.
A network of filters, made up of coils and capacitors, that directs specific frequency ranges to the appropriate speaker components (woofer, midrange, and tweeter, for instance). That way, the drivers do not strain to reproduce notes out of their intended range.
Component systems and full-range speakers include passive crossovers, which are designed for the specific components and mounted between the amplifier and speakers. Active crossovers divide the frequency range before amplification, and can be adjusted to adapt to any speaker setup.
The standard unit of measure for expressing relative power or amplitude differences. A decibel describes the ratio between the value of a measurement and a reference point. With audio, it often represents loudness, or sound pressure level (SPL). 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 volume will sound roughly twice as loud.
Another dB fact: For any given set of speakers, each 3 dB increase in volume level requires a doubling of the amplifier power.
A speaker diaphragm is the surface that radiates sound. For a woofer, this is the speaker cone. In a tweeter, it's usually dome-shaped.
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.
A dust cap covers the center of a speaker's cone and keeps dirt out of the voice coil gap.
Although a speaker's efficiency rating is almost always correlated to its sensitivity rating, it's actually a different measurement. The efficiency rating for a speaker measures how well a speaker converts watts of electrical power into watts of acoustical power. Most speakers have a very low efficiency rating — between 1% and 10% — so manufacturers rarely provide this information, choosing instead to list sensitivity ratings.
The range of frequencies the speaker will reproduce (lowest frequency to the highest). The optimal range is 20-20,000 Hz, the range of human hearing. Many high-quality tweeters, however, are able to reproduce frequencies well above 20,000 Hz. While the human ear can't detect these ultra-high frequencies, they do contain harmonics that affect the way listeners perceive sound and its nuances.
Full-range speakers 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.).
Imaging describes the extent to which a stereo system reproduces the location of instruments and vocalists as they were positioned during recording and mixing. (See also soundstage below).
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 is a measure of the resistance of a speaker's voice coil to the audio current supplied by the amplifier.
The magnet provides a stationary magnetic field against which the voice coil reacts to create sound.
Maximum RMS Power Handling
Maximum RMS Power-Handling refers to the maximum amount of power a speaker can handle on a continuous basis.
A midrange speaker ranges in size from 3-1/2" to 6-3/4" and reproduces the middle frequencies. Component systems sometimes 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.
Peak Power Handling
Peak power handling refers to the maximum amount of power a speaker can handle during a brief musical burst.
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. Since a round woofer is more accurate than an oval one and is not encumbered with a cone-mounted tweeter, 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.
In order to get the polarity right, you must wire the positive speaker terminal to the positive amplifier terminal, and the negative speaker terminal to the negative amplifier terminal. Proper wiring ensures that all the cones in a multiple speaker setup will move in the same direction at the same time. If you wire your speakers improperly, one speaker cone will move backward while another is moving forward, canceling out much of the sound both speakers are trying to make.
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.
All car speakers require a power source (receiver or amp). The lower number of a power-handling rating tells the absolute bare minimum wattage required to get 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).
The vibration of a speaker's cone. All speaker cones vibrate at a certain frequency. Too much resonance can interfere with a speaker's accuracy.
A sensitivity rating tells you how effectively a speaker converts power (watts) into volume (decibels). The higher the rating, the louder your speakers will play with a given amount of amplifier power. Sensitivity is often measured by driving a speaker with one watt and measuring the loudness in decibels at one meter.
The chart below illustrates that a few dB in sensitivity can make a big difference:
to produce a given volume
|Speaker A||85 dB||100 watts|
|Speaker B||88 dB||50 watts|
|Speaker C||91 dB||25 watts|
The soundstage refers to your sense of width, depth and height 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 stereo system's soundstage. See also "imaging" above.
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.
A small driver dedicated to ultra-high-frequency reproduction. You can usually find supertweeters alongside tweeters in 4- or 5-way full-range speakers.
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, 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.
This three-way 6x9 features a separate woofer, midrange, and tweeter for improved clarity and detail in the bass, midrange, and high frequencies.
This audio tuning method allows you to delay the sound arriving from the speakers closest to your ears so that it reaches your ears at the same time as the output from more distant speakers. Proper time alignment helps your speakers produce a sharper sonic image. In car audio, time alignment is used to place the driver directly in the "center" of the stereo image, rather than off to one side. You can also use this technique to tune your speakers to work more effectively with the bass from your system's subwoofer.
Tinsel leads are flexible, stranded wires that connect the voice coil to the speaker's terminals.
A small driver dedicated to high-frequency reproduction. Cone tweeters are efficient and they're also 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, 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.
The voice coil (a small coil of wire) creates a magnetic field that varies according to the amplified signal sent to the speaker. In conjunction with the permanent magnet and the speaker's other parts, the voice coil converts electrical signals into mechanical energy to produce sound. Many of the speakers on this site offer a heat-resistant voice coil to prolong speaker life. Dual voice coil design allows a stereo mix to be played from a single speaker.
Voice coil former
The voice coil former is the part of the speaker around which the voice coil is wound, usually made from a heat-resistant material like aluminum or Kapton.
Voice coil gap
The voice coil gap is the space between the magnet and the pole piece where the voice coil can freely move in and out. This creates vibrations in the speaker cone, resulting in sound.
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.