A digital music CD developed by Sony and Philips, available in 12cm diameter and 8cm diameter. The former is the most common, providing 74 minutes of high-quality music.


A read-only CD for storing computer data.


An audio-visual disc using MPEG-1 compression coding technology has image resolution similar to that of a VHS video tape.

Super VCD

VCD's improved product, using MPEG-2 encoding, has improved image clarity.


A new generation of ultra-large-capacity optical discs with a CD-like appearance, which will be widely used in high-quality audio and video program recording and as a mass storage device for computers.


Sony's mini-recordable music CD, which looks like a 3.5-inch floppy disk for computers, but uses an optical signal pickup system, similar to a CD. MD uses efficient compression technology to achieve the same recording time as CD, and the sound quality is close to CD.

D/A converter

A device for converting digital audio signals into analog audio signals in digital audio products such as CDs and DVDs. The D/A converter can be made as a stand-alone machine for use with the CD turntable, often referred to as a decoder.

CD turntable

A machine that separates the mechanical transmission of the CD player.


The sampling frequency is several times the standard sampling frequency of the CD system of 44.1 kHz. The purpose is to facilitate the filtering of digital noise after D/A conversion and improve the high frequency phase distortion of the CD player. Early CD players used 2x or 4x sampling, and recent machines have reached 8x or higher.


Abbreviation for High Definition Compact Disc - an encoding system that improves CD sound quality and is compatible with traditional CDs, but needs to be played back on an HDCD-decoded CD player or an external HDCD decoder can be improved. effect.


The smallest constituent unit of a binary digital signal, which always takes one of two states, 0 or 1.

Bit stream

A Philips technology that converts CD digital signals into analog music signals.

Dolby B, C, S

A series of tape noise reduction systems developed by Dolby in the United States to reduce the "click" produced by tape recording and extend the dynamic range. The B-type noise reduction system can reduce noise by 10dB, the C type increases to 20dB, and the S type can reach 24dB.

Dolby HX Pro

It is not a noise reduction system, but a technique to improve the distortion of high-frequency recording of tapes, which is also commonly referred to as "upper headroom expansion."

Dolby Surround

A sound that encodes a rear effect channel into a stereo channel. A decoder is required to separate the surround sound signal from the encoded sound during playback.

Dolby Pro-Logic

A front center channel is added to Dolby Surround to lock the dialogue in the movie to the screen.

Dolby Digital, also known as AC-3, is a new generation of home theater surround sound systems from Dolby Laboratories. The digitized accompanying sound includes signals for the left front, center, right front, left surround, and right surround 5 channels, all of which are independent full-band signals. There is also a separate subwoofer channel, commonly known as 0.1 channel. All of these channels are combined into a so-called 5.1 channel.

V amplifier

Amplifiers designed specifically for home theater use typically have more than 4 channels and surround sound decoding.

Directional logic surround sound amplifier

AV amplifier with Dolby Pro Logic decoding.

Dolby Digital Amplifier

Also known as the AC-3 amplifier, an AV amplifier with Dolby Digital decoding.


An amplifier with a radio function.


A surround sound standard developed by Lucas Pictures of the United States, which improves the Dolby Pro Logic surround system and further enhances the surround sound effect. The THX standard has a strict and specific set of requirements for playback equipment such as audio and video sources, amplifiers, speakers and even connecting wires. The THX logo is awarded to products that meet this standard and passed Lucas certification.

THX 5.1

THX based on Dolby Digital.


Discrete-channel home cinema digital sound system, which also uses a separate 5.1 channel, which is even better than the Dolby Digital Surround system. It is a strong competitor to Dolby Digital Surround. .


A system of American SRS that produces surround sound with two speakers.

Frequency divider

A circuit device in a speaker for separating an input music signal into different parts such as a treble, a midrange, a bass, and the like, and then respectively feeding them into a corresponding high, medium, and low woofer unit for playback.

Dual amplifier crossover (Biamping)

A connection method in which each speaker unit of the speaker is driven by a separate amplifier channel. A pair of two-way speakers requires two stereo amplifiers and two pairs of speaker cables. See "Double Line Split".


A wiring method for transmitting the high and low parts of a music signal by two sets of speaker wires. Two-wire crossover requires a specially designed speaker with two pairs of terminals.


A general term for preamplifiers and power amplifiers.

Power amplifier

Referred to as a power amplifier, an electronic device used to enhance the signal power to drive the sound of the speaker. A power amplifier without an accessory function such as source selection and volume control is called a post stage.


The pre-amplification and control section before the amplifier is used to enhance the voltage amplitude of the signal, providing input signal selection, tone adjustment and volume control. The preamplifier is also called the preamplifier.


See "Power Amplifier".


See "Preamplifier".

Combined amplifier

Amplify the preamplifier and power amplifier in one chassis.


Another term for tube amplifiers.

Rated power For power amplifiers, the rated power generally refers to the RMS power that can be continuously output. For the speaker, the rated power refers to the power that the speaker can withstand this value for a long time without damage, which does not mean that it is necessary. Such a high-power amplifier can only be pushed, and the difficulty of driving the speaker is mainly determined by its sensitivity and impedance characteristics. It does not mean that it cannot be equipped with a power amplifier whose output power is greater than the rated power of the speaker. Just like driving a car, driving a sports car with a speed of 300 kilometers is not the same as a car accident. You can't drive it so fast. Similarly, as long as the volume is not blindly increased, high-power amplifiers can be equipped with low-power speakers.

Peak music output power (PMPO)

The output power calculated from the peak voltage that can be reached instantaneously by the music signal is more commercial than the actual effect. PMPO power can be three to four times higher than the internationally recognized rms rated output power (RMS). For example, the early portable recorder had an RMS power of only 4 or 5 watts per channel, but with PMPO, the value can be increased. Up to 20W or so.

Single-ended amplification

The output stage of the amplifier is amplified by two a half cycles of positive and negative signals by an amplifying component (or multiple components but in parallel). Single-ended amplification machines can only take Class A work status.

Push-pull amplification

The output stage of the amplifier has two "arms" (two sets of amplifying elements). When the current of one "arm" increases, the current of the other "arm" decreases, and the states of the two are alternately switched. For the load, it seems that an "arm" is pushing, and an "arm" is pulling to jointly complete the current output task. Although Class A amplifiers can be push-pull amplifiers, it is more common to use a push-pull amplifier to form a Class B or Class A amplifier.


The conduction mode of the power amplifier tube in the power amplifier is divided into Class A (Class A), Class B (Class B) and Class A (Class AB).

Class A

Also known as Class A, a class of amplifiers that do not have a current cutoff (ie, stop output) for any power output component of the amplifier over the entire period of the signal (both positive and negative sine waves). Class A amplifiers generate high heat during operation and are inefficient, but the inherent advantage is that there is no crossover distortion. Single-ended amplifiers are Class A working methods, and push-pull amplifiers can be Class A or Class B or Class A.

Class B

Also known as Class B, the positive and negative sinusoidal signals are amplified by the two "arms" of the push-pull output stage. The conduction time of each "arm" is half a cycle of the signal. Class B amplifiers have the advantage of high efficiency and the disadvantage of crossover distortion.

Class A and B

Also known as class AB, between Class A and Class B, each "arm" conduction time of push-pull amplification is greater than half a cycle of the signal and less than one cycle. Class A and Class B amplification effectively solve the crossover distortion problem of Class B amplifiers, and the efficiency is higher than that of Class A amplifiers, so it has been widely used.

The output of the distortion device does not fully reproduce its input, resulting in distortion of the waveform or an increase or decrease in signal components.

In addition to the amplified input components, some frequency components (harmonics) of 2 times, 3 times, 4 times ... or even higher times of the original signal are added, which causes the output waveform to be out of shape. This distortion caused by harmonics is called harmonic distortion.

Crossover distortion

A type of distortion unique to Class B amplifiers. The mechanism of this distortion is that the positive and negative half cycles of the signal are amplified by different sets of devices, and the waveforms on both sides of the signal cannot be smoothly connected.

Sound dyeing

The opposite of the natural neutrality of music, that is, the sound is dyed with some features that the program itself does not have. For example, the sound that is spoken in a jar is a typical sound. The sound dye indicates that some of the components are added (or reduced) in the reproduced signal, which is obviously a distortion.

Sound pressure

A physical quantity indicating the strength of sound.

Sound pressure level

Sound pressure expressed in decibels.


For the amplifier, the sensitivity generally refers to the voltage of the signal applied to the input terminal when the rated output power or voltage is reached, so it is also called the input sensitivity. For the speaker, the sensitivity refers to applying 1W of input power to the speaker. How many decibels of sound pressure can be produced at a distance of 1 meter ahead.


A general term for the physical quantity of voltage, current, power, etc. in an electronic system. Levels are generally expressed in decibels (dB). That is, a voltage or current number is taken as a reference value (0dB) in advance, and the ratio of the amount to be represented to the reference value is taken as a logarithm, and multiplied by 20 as the decibel level of the level (the power level value is multiplied by 10) .

Decibel (dB)

The unit of level and sound pressure level.

Damping coefficient

The ratio of the load impedance to the output impedance of the amplifier. Transistor amplifiers that use negative feedback have very low output impedances, only a few ohms or less, so the damping factor can range from tens to hundreds.


Also known as feedback, a technique that returns a portion or all of the output signal back to the input of the amplifier to change the circuit magnification.

Negative feedback

Feedback that results in reduced magnification. Although the negative feedback suffers from loss of magnification, it can effectively widen the frequency response and reduce distortion, so it is widely used.

Positive feedback feedback that increases the magnification. The effect of positive feedback is just the opposite of negative feedback, so care should be taken when using it.

Dynamic Range

The level difference between the strongest part of the signal and the weakest part. For equipment, the dynamic range indicates the ability of this equipment to handle both strong and weak signals.

Frequency response

Referred to as the frequency response, it measures the ability of a piece of equipment to uniformly reproduce signals in high, medium and low frequency bands. There are two requirements for the frequency response of the equipment. First, the range is as wide as possible, that is, the lower limit of the frequency that can be replayed is as low as possible, and the upper limit is as high as possible; second, the response of each point in the frequency range is as flat as possible to avoid excessive fluctuations.

Transient response

The ability of the equipment to follow the burst signal in music. The equipment with good transient response should respond immediately when the signal comes, and the signal will stop when it stops, and it will never drag the water.

Signal to noise ratio (S/N)

Also known as the signal-to-noise ratio, the useful components of the signal are compared to the strength of the noise, often expressed in decibels. The higher the signal-to-noise ratio of the device, the less noise it produces.

Sine wave

A signal with the most single frequency component is named because the waveform of this signal is a mathematical sinusoid. Any complex signal, such as a music signal, can be thought of as a composite of many sine waves of different frequencies and sizes.


The travel of sound waves in one cycle. The wavelength is numerically equal to the speed of sound (344 m/s) divided by the frequency.

Air-bearing tonearm

Refers to the vocal arm of the LP turntable that is supported by an air cushion.

Air-bearing turntable

The turntable is a kind of turntable that is held up by an air cushion.


Also called the sense of envelopment. Refers to the sense of envelopment of a certain scale and space produced by the sound of a movie. It is usually created by surround speakers.


The unit of measurement of the current, denoted by A.


It means that the audio equipment can reproduce every detail in the sound recordings, but it uses the wrong way. This kind of analysis is very lack of music.


Refers to the voltage change of the analog signal is a simulation of the sound wave, that is, the voltage will continuously change with the original acoustic waveform. Opposite to the digital signal of the audio or video signal represented by 0 and 1 in the binary.

Image deformation (anamorphic)

A wide-screen image of a film or video is "narrowed" in the horizontal direction by lens or digital processing to accommodate a standard 4:3 aspect ratio. During playback, the original aspect ratio of the image is restored by "back pressure narrowing". The format of the image distortion provides the correct aspect ratio without sacrificing resolution.

Acoustic (anechoic)

Literally speaking, it means "no echo".

Anechoic chamber

Refers to a room without reflection. Sound absorbing materials with good sound absorption properties are laid on the walls of the anechoic chamber. Therefore, there is no reflection of sound waves in the room. The anechoic chamber is designed to test speakers, speaker units, and more.

Clear (articulate)

Refers to acoustic terms that indicate that audio equipment can clearly distinguish tones.

Anti-state adjustment

It is attached to the vocal arm to adjust the force applied to the vocal arm, thereby offsetting the tendency of the vocal arm to slide naturally inside.

Aspect ratio

Also called the aspect ratio, which is the ratio of the width to the height of the screen on the screen. The standard TV has a 4:3 (1.33:1) aspect ratio, while the widescreen TV and HDTV HDTV have a 16:9 (1.78:1) aspect ratio.


Refers to adaptive transform acoustic coding, a low bit rate data compression coding technique adopted by Sony Corporation of Japan in its MD magneto-optical disk drive.

Audiophile (audiophile)

Commonly known as "audio fans" or "fans", it refers to some people who are very concerned about the sound quality of the replayed music.

Audiophile (audiophile nervosa)

Refers to those who are always slamming the sound equipment and not being able to enjoy the music and only obsessed with the sound.


It is an abbreviation for Audio and Video, and refers to those audio and video products that have both audiovisual characteristics.

A/V input (A/V input)

Refers to the input of an A/V amplifier receiver or A/V preamplifier that has both audio and video jacks.

A/V loop (A/V loop)

Refers to the A/V input and A/V output pairs installed on the A/V power amplifier receiver and A/V preamplifier. It is used to connect with A/V equipment that can record and play audio and video signals. of. For example, a VCR can be connected to the A/V loop of an A/V amplifier receiver or A/V preamplifier.

A/V preamplifier (A/V preamplifier)

Also known as "A/V Controller", it is an audio equipment used to control the volume, select the source of the program and complete the surround decoding amplifier.

A/V preamplifier/tuner (A/V preamplifier/turner)

Refers to an A/V preamplifier with an AM (amplitude modulation) or FM (frequency modulation) receive tuner in the same chassis.

A/V amplifier receiver (A/V receiver)

For the heart part of the home theater system. Responsible for receiving signals sent from the program source, selecting signals to be watched and listened to, controlling the volume of playback, decoding surround sound, listening to radio programs, and amplifying selected signals to facilitate the home theater's complete set of speakers . Also known as a "surround receiver."

Azimuth (azimuth)

The angle between the recording head and the direction of travel of the tape in the tape recorder should ideally be 90°; in the LP turntable, the angle between the pointer arm and the surface of the record.

Baffle refers to the front panel of a speaker with some pronunciation units on it.


Refers to the objective relationship between the high and low segments of the audio spectrum in relative loudness; also refers to the same (balance) of the signals between the two-channel stereo left and right channels.

Balanced connection

Refers to a connection between audio equipment, there are 3 wires in a single cable, one for transmitting audio signals, the other for transmitting audio signals of opposite polarity, and the other is ground.

Banana jack (banana jack)

A small round socket that is attached to the speaker and power amplifier for connection to the banana plug of the speaker cable.

Banana plug

A plug that is commonly installed at the ends of a speaker cable for insertion into a banana jack.

Band width

Refers to a range of frequencies that the audio device can handle or pass. For example, the bandwidth of the surround channels of Dolby Surround is 100Hz-7kHz. The surround channel only passes frequencies between 100 Hz (bass) and 7 kHz (lower treble). The frequency that the human ear can hear is in the range of 20 Hz to 20 kHz. When it comes to the bandwidth of electrical or acoustic equipment, it often refers to a frequency range between -3dB.


Refers to the sound in the lower part of the audio, usually below 500Hz (the other means below 160Hz).

Bass extension

Refers to the lowest frequency that audio equipment can reproduce. It is used to determine the extent to which the sound system or speaker can dive when replaying the bass. For example, a small subwoofer can have a low frequency extension of 40 Hz, while a large subwoofer dive to 16 Hz.

Bass management

Refers to the integrated control circuit in the A/V amplifier receiver or A/V preamplifier, which is used to determine how much low frequency signal should be sent to the corresponding speaker.

Inverted speaker (bass reflex)

Also known as the inverted phase opening box, it is a type of speaker with an inverted phase hole (slot) on the speaker panel. Thanks to the opening, the sound inside the box can be radiated outside. Inverted speakers are better than low-frequency extensions of closed-type speakers, but the bass is often not as strong and compact. Compare "infinite baffle".

Two-way power amplifier (bi-amping)

A special connection that uses two power amplifiers to push the same speaker, using a power amplifier to push the woofer; another power amplifier to push the midrange and tweeter.

Big screen

Refers to the large screen in an intuitive color TV or rear projection projection TV. Typically, the diagonal dimensions of the screen are mostly above 40 inches.

Special stereo recording (binaural recording)

Refers to a special recording method that intentionally mounts the recording microphone in the ear channel of the artificial head. Due to the physical structure of the human head, some special spatial information will be included in the recording. When listening to such sound recordings with headphones, there is a three-dimensional sense of space that is different from the real situation but is wonderful.

Binding post

It is a terminal block for power amplifiers and speakers that is connected to the speaker cable.

Bipolar speaker

A type of speaker that radiates sound waves while pointing forward and backward. Unlike dipole speakers, the sound waves radiated forward and backward by the bipolar speakers are in phase.

Bipolar transistor

Refers to a transistor that is very popular in audio circuits. Bipolar is derived from the relationship in which current flows through two semiconductor materials. The bipolar transistor can be classified into an NPN type or a PNP type depending on the polarity of the operating voltage.

Special (bit)

The basic unit of binary digits. Usually take one of two states, 0 or 1. The more bits, the more accurate the expression of the analog signal and the better the restoration of the audio signal.

Bit rate

Refers to the number of bits stored or transmitted per second by digital audio or digital video signals. For example, the bit rate of each channel of a CD disc is 705600 kbs, while the bit rate of 5.1 channel of Dolby Digital (DD) is 384 kbs. A higher bit rate often means better sound quality.


Refers to a type of wiring that connects two sets of speaker cables to each speaker. Use one (a pair) of speaker cables to connect to the woofer input in the speaker; the other speaker cable is connected to the speaker's tweeter. Only those speakers with two pairs of input terminals can be connected by a two-line split.


It means that the high-pitched sound is not enough, especially when a sound-absorbing material such as a blanket is hung on the front of the speaker to absorb the sound.

Black level (baack level)

Refers to the level of the video signal that does not have a bright output on a calibrated display device.

Weak (bleached)

An acoustic term used to denote the vocal characteristics of audio equipment of the type that is particularly focused on instrumental harmonics without paying attention to low harmonics and fundamental frequencies. The pale voice sounds too bright, thin and lacks warmth.

Air sensation (bloom)

An acoustic term used to mean that there is air around the sound image of the instrument.

Booming (bloomy)

Refers to bass overweight at around 125 Hz, especially over a fairly wide range of frequencies. It is caused by insufficient damping of low frequency or low frequency resonance.

冒牌(boutique brand)

It refers to those sounds that seem to be high-end on the surface, but in fact they are fake products with inferior components in the chassis.


It means that the middle of the bass in the 250Hz zone is too strong. Resonant damping for low and low frequencies is not sufficient. See "tubby".


It means that the transient response is poor, the stereo image is blurred, and the condensation is poor.

Muffled (boxy)

It means that the music that is heard is like a resonance from a closed box. Sometimes it is a bit too strong at 250-500Hz.


It means that the newly purchased audio equipment will be powered on for a period of time before the sound quality of the playback will be better.


Refers to a special connection between the power amplifier and the speaker to increase the output power. Bridging is the conversion of a two-channel stereo amplifier to a single-channel power amplifier. One of the amplifiers is responsible for amplifying the positive half of the waveform, and the other is for amplifying the negative half of the waveform. The speaker acts like a "bridge" between the two amplifier channels. Two identical two-channel stereo amplifiers are required for bridging.


It refers to the high frequency band of 4kHz-8kHz, and the harmonics are relatively stronger than the fundamental wave. There is nothing wrong with the brightness itself. The live concerts have bright sounds. The problem is that the brightness is well controlled, and the brightness is too bright (or even whistling).


For video, it refers to the amount of light produced on the video display screen.

Brightness signal

The "Y" indicates that the highlight signal of the video signal contains all the display information, and the color video signal is a combination of the luminance and chrominance signals.

Sharp (brittle)

An acoustic term used to denote the acoustic characteristics of an intermediate or high frequency that makes the instrument's tone sound harsh.


Refers to the circuit used to separate the audio or circuit level. The preamplifier is the buffer between the source and the power amplifier because the preamplifier reduces the burden on the power amplifier.

Bypass test

A method of auditioning audio equipment. At this time, the audio equipment to be tested is either in the process of accessing or not accessing the signal, so that the acoustic characteristics can be judged.


Refers to the precise adjustments made to make the sound or A/V film and television equipment work properly. In audio systems, correction involves setting the level of each channel; in video devices, the correction is to adjust color, brightness, chrominance, contrast, and other parameters.

Needle arm

Refers to a thin tube that protrudes from the cartridge end of the LP turntable and has a stylus on it.

Capacitive reactance refers to a characteristic exhibited by a capacitor that blocks low-frequency passage but allows high-frequency to pass. The capacitive reactance makes the capacitor an impedance that is dependent on frequency. It is the capacitive reactance of the capacitor that connects the capacitor to the tweeter and allows the treble to pass without letting the bass pass.


An electronic component that stores charge. The storage capacitor in the power amplifier is used to store energy; the filter capacitor in the DC power supply is used to filter out the AC component; the coupling capacitor in the amplifier circuit is used to communicate through the audio. Signal and block DC.

Capture ratio

To receive the technical specifications of the tuner. Refers to the decibel value of the difference between the signal strengths of the two stations required before the tuner locks a station with a stronger signal and suppresses a station with a weaker signal. The lower the capture ratio, the better the performance of the tuner.

Cartridge demagnetizer

Refers to a device that is specifically designed to eliminate the stray magnetic field of the metal portion of the cartridge.

CAV LD Laser Disc (CAV laserdisc)

Refers to LD discs recorded at constant angular velocity (CAV). Regardless of where the laser pickup reads the signal, the disc will always rotate at a constant speed. Also known as the "standard format" LD video disc. It can record up to 30 minutes on each side. See "Constant Line Speed" (CLV).

CD disc (compact disc)

It refers to a disc with a diameter of 12cm (individually 8cm) that can record 74 minutes of music jointly developed by Sony Corporation of Japan and Philips of the Netherlands.

DR Recordable CD

Refers to a disc that can record digital audio. CD-R is a disc that is entered once. It cannot be erased after entering.

CD-ROM read-only disc

A read-only disc used to store computer data.

CD-RW recordable rewritable disc (CD-Rewritable)

A CD that can be erased and repeatedly re-recorded. However, most of the existing CD players are not available for playing CD-RW discs.

Center channel

In a multi-channel sound system, the center speaker placed in the middle of the viewing room and located in the left and right front speakers is used to reproduce the information in the center channel. Almost all of the dialogues in the film in the center channel.

Center-channel mode

Refers to the working mode of the center channel of the A/V amplifier receiver and A/V preamplifier.

Center-channel speaker

Refers to a speaker in the home theater system that is mounted on the top, bottom or back of the video monitor. It is used to replay information such as vocal dialogues sent from the center channel and other sounds related to actions on the screen.

Consumer Electronics Show (CES)

Refers to the International Consumer Electronics Show held in Las Vegas, USA at the beginning of each year.

Channel balance

Refers to the relative level or volume of the left and right channels in the audio system or in individual audio equipment. Also used to represent the relative difference between the left and right signals in a Dolby encoded signal. For the best Dolby decoding, some A/V amplifier receivers and A/V preamps can also adjust the channel balance.

Channel separation

A measure of the degree of isolation between one channel and the other. In a home theater system, when channel isolation is not sufficient, the sound in one channel “snoops in” into the other channel. A typical example is Dolby Surround, where the sound in the front main channel "snap" into the surround channel. When the channel is isolated, the pan position is more accurate.

Chest (chesty)

Refers to a kind of sound staining of a speaker, just like the voice of a singer who releases a loud volume due to a large chest. It is caused by a bump in the low frequency response of a period of 125 to 250 Hz.

Chroma (chrominance or chroma)

Refers to the colored portion of the video signal. The chrominance signal contains color and hue information but no luminance information.


Refers to the kind of click that the inverted speaker makes when it plays back the bass at a high level. The reason is that a large amount of air passes through the opening of the speaker at this time.

Class A amplification (class-A)

Also known as Class A amplification. A working state for the amplifier. At this point the transistor or tube amplifier will amplify the entire audio signal.

Class B amplification (class-B)

Also known as Class B amplification. A working state for the amplifier. At this point one transistor or tube amplifier will amplify the positive half of the audio signal, while the other transistor or tube amplifier amplifies the negative half of the signal.

Class AB amplification (class AB)

Also known as class AB amplification. A working state of the amplifier. At this time, the output stage of the amplifier is in the Class A amplification state when the output power is low, and is converted to the Class B amplification when the output power is high.

D-class amplification (class D)

Also known as Class D amplification or digital amplifiers. A very high frequency transfer switch circuit is used to amplify the audio signal. It has the advantages of high efficiency and small volume. Many of these digital amplifiers, which have a power of up to 1000W, are just as large as a VHS video cassette. These amplifiers are not suitable for use as broadband amplifiers, but they are used in active subwoofers.


When the amplifier output is required to exceed its allowed output power, the top and bottom of the output audio waveform are flattened. It's like flattening the peaks. Limiting introduces a lot of distortion. Let people hear a squeaking noise at the peak of the music.


It means that the sound is not wide enough, not soft and lacking in air and detail. More due to the attenuation at frequencies above 10kHz.

CLV LD laser disc (CLV laserdisc)

Refers to an LD laser disc recorded at a constant line speed. Depending on where the laser pickup is read on the disc, the rotational speed of the LD disc will change. When the laser pickup is read on the outer edge of the disc, the rotational speed of the LD disc is relatively slow; when the pickup is read along the inner diameter of the disc, the rotational speed is increased. Therefore, from the perspective of the laser pickup, the linear velocity remains unchanged. Also known as the "Extended Play" disc, because one-sided video can be stored on one side of the disc.

Coaxial cable

A cable in which an inner conductor is surrounded by a braid of a barrier layer.

Coaxial digital output

Refers to an RCA socket for outputting digital audio installed on a digital recording source device such as a CD player or a DVD player. A coaxial digital signal cable can be used to connect to other audio equipment.

Coaxial driver

Refers to a type of speaker that houses a sounding unit (usually a tweeter) inside another sounding unit (usually a midrange unit).

Coded Orthogonal Frequency Division Multiplexing (COFDM)

The original text is coded orthogonal frequency division multiplex, which is a method of channel coding and modulation. In Europe, it is mainly used for DTV digital TV and DAB digital audio broadcasting. It is used to separate each adjacent signal as much as possible and transmit on up to 1536 discrete frequencies, respectively, thus reducing interference such as transmission errors and multipath transmission.


Refers to the feeling that music can have an overall feeling rather than being composed of many separate parts.

Sound coloring

Refers to the change in sound caused by an audio device in an audio system. A sound-stained speaker cannot accurately reproduce the sound signal applied to the speaker. For example, a sound-stained speaker may reproduce too much bass, but it is lacking in high-pitched sound.

Comb filtering

Refers to a series of deep peaks and valleys that appear in the frequency response. Typically, such comb filtering occurs when the direct sound and the reflected sounds reflected by the side walls on either side of the listening room are slightly delayed.

Common-mode rejection When a balanced signal is applied to a differential amplifier, only the phase difference between the balanced signals is amplified. Any two phase common noise (common mode noise) is suppressed by the differential amplifier.

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