A variety of speaker systems have been used for various audio systems. For example, a speaker system having a large sound output is used in a concert hall, while a compact speaker system is used in a television receiver. A bass reflection type speaker system is popular as a speaker system which is small but is able to radiate powerful low tones. Speaker systems are often provided with speaker components specifically adapted for operating at different frequency ranges, including low range, mid range and high range. Most speaker systems include a woofer which is actuated in response to the low frequency segment of the audio frequency spectrum; a midrange speaker which is actuated in response to the midrange frequency segment of the audio frequency spectrum; and a tweeter which is actuated in response to the high frequency segment of the audio frequency spectrum. Low range components often include special sub woofer speaker systems operable solely in the lowest frequency ranges. Subwoofer speaker systems are designed to reproduce the lowest bass frequencies in music and sound, such as audio frequencies below 35 Hz. These low frequencies cannot be reproduced by conventional smaller woofers so larger audio drivers or speakers cones having a diameter of ten inches or more are typically used in sub-woofer speaker systems. Subwoofers are typically used with stereo amplifiers or home entertainment systems to give an enhanced, realistic listening experience in which these lower frequencies can be heard and felt by the listener. Regular speaker systems include two types, namely, the enclosed type and the lower frequency transmission type. In an enclosed type speaker system, the drive unit of each speaker is enclosed, and sound is driven out of each speaker from its front side. In a regular audio system, the speaker systems and the tuner are separately disposed. When the speaker systems are driven to produce sound, the cabinets of the speaker systems may be forced to vibrate. The vibration must be properly controlled so as not to interfere with the quality of the sound. Directivity is one of the characteristics used to evaluate the performance of a speaker. Directivity is a property that the magnitude of a sound pressure differs depending on direction. In some speaker systems having a speaker mounted in a speaker box, a bass reflex duct is located at a rear of the speaker inside of the speaker box. The bass reflex duct leads to a bass reflex port opened in the speaker box. In this speaker system, the resonance frequency is determined by the interior volume of the speaker box, and by the diameter and the length of the bass reflex duct according to the Helmholtz resonance phenomenon. In order to reproduce music or announcement in a large space such as concert halls, outside theaters and stadiums, a large-size professional-use loudspeaker system for reproducing a large volume of sound is generally used.

In the audio reproduction technology, particularly the hi-fi reproduction technology, one of the objects is to reproduce an original sound field with a high fidelity. In the past, numerous monophonic and stereophonic sound systems have been developed in an attempt to achieve high fidelity sound reproduction. With the advent of home theater systems and with high definition television rapidly becoming a commercially viable technology, speaker systems must be available for the home audiophiles that are suitable for such high-fidelity use. Various multi-speaker systems have been developed with the advent of high fidelity and stereophonic sound systems. While some such systems incorporate several speakers in a single cabinet, many such systems mount speakers of discrete frequency range in separate cabinets. This permits the user to position the speakers in various relative positions within a room. A speaker system having superior acoustic characteristics can emit into free space sound waves having frequencies extending over a wide range, from the treble range to the bass range. Consequently, speaker systems currently in use possess a plurality of lowest resonant frequencies according to a plurality of speakers being provided therein, these speakers having a similar structure but of different sizes. Wireless speaker systems provide a particularly attractive solution since installation does not require extensive and possibly expensive wiring. In order to prevent interference between sound waves of different frequencies, equalizers may be installed in a speaker to treat acoustic signals of different frequencies. Speakers of different ranges may be used and installed in a cabinet to increase the sound of different frequencies. In a low frequency transmission type speaker system, the phase of the sound from the back side of the woofer is reversed and then directed out of the cabinet through a transmission tube which defines an acoustic path. Wireless speaker systems may be moved about within a room to obtain optimum performance or, alternatively, may be moved from room-to-room or even from house to house with minimal inconvenience. In recent years, digital storage of audio programs has become increasingly popular. Digital audio disks have become well established in the marketplace. Digital audio storage has a number of advantages over traditional analog storage methods. With the use of error correcting codes, digital storage of audio programs and their subsequent retrieval is substantially distortion free. In addition, some media, such as CDs, do not suffer wear with use as do traditional analog media such as LP records. With the increased video and audio applications in multimedia personal computers, a user can potentially use the computer to control the television, telephone and home stereo as well as connect signals from cable television links, satellite TV and various other video/audio sources such as compact disc (CD) players, VCRs and digital versatile disc (DVD) players to the home entertainment system.

Current progress of technology in the field of audio-visual systems has given rise to a demand for a system which would enable one to enjoy images projected on a large screen with powerful sound. Typically, speakers utilized in home stereo systems include several individual speakers extending into a housing and arranged on a speaker mounting panel for projecting audio through openings in the mounting panel. Such speaker systems generally operate by dividing the audio frequency spectrum into several segments and then providing a different speaker to transform the electrical signal components in each spectrum segment into an audio sound. Some high-end home entertainment systems have multichannel audio systems, such as surround sound systems with three or more channels to provide theater sound effects. The surround sound channels are often presented at a lower volume level than front channels since movies contain most of the audio information in the front channels and use the surround channels sparingly as effects channels. A surround multichannel system may include six channels. These channels typically consist of a left, right and center front channel, a left and right surround channel and a subwoofer channel. Differing prerecorded equalization settings among surround channel recording or among the various formats can sound different on the same speakers. As computers are used more frequently for multimedia applications, there has been an increased demand for high-quality speakers for use with computers. Speaker systems with integral amplification electronics provide simple, compact audio transducers for multimedia personal computers. These speaker systems, referred to herein as multimedia computer speaker systems, typically include pairs of wide-band speaker drivers mounted in separate housings with amplification electronics incorporated into one or both housings. A two-channel computer audio system includes a two-channel audio system control circuit, which is commonly configured as a separate computer expansion board called a sound card, and two wide-band audio transducers or speakers. A sub-woofer audio transducer or speaker is also included in many implementations. Some multimedia computers now include four-channel multimedia computer audio sub-systems, sometimes called surround sound systems, environmental audio systems, or multi-channel audio systems. A four-channel multimedia computer audio sub-system includes a multimedia computer speaker system with four wide-band audio transducers or speakers, and typically a sub-woofer audio transducer or speaker. The four wide-band speakers receive four different audio signals or channels.