A measure of all the harmonic distortion components (i.e.,second harmonic, third harmonic,etc.) produced by an audio device, expressed as a percentage of the fundamental signal. Called "total" because it is the sum of all the individual harmonic-distortion components created by the component.
A number representing the total amount of distortion or misrepresentation of a sound passing through an amplifier or speaker; how much unwanted coloration the system adds to the original sound.
(THD) - the percentage, in relation to a pure input signal, of harmonically derived frequencies introduced in the sound reproducing circuitry and hi-fi equipment (including speakers).
this term has come into common usage to define either voltage or current "distortion factor."
A measure of the distortion of the sine wave on alternating current (ac) systems caused by higher order waves superimposed on the fundamental (usually 60hz) frequency of the system. Thd is expressed in percent and may refer to individual electrical loads (such as a ballast) or a total electrical circuit or system in a building. The ansi recommendation is for thd to be no greater than 32% although some electrical utilities may require lower thd's on some systems. Excessive thd's on electrical systems can cause efficiency losses as well as overheating and deterioration of system components.
the sum of all amplifier distortion components, plus system noise. THD measurements are sometimes quoted as THD+noise. Usually measured at specified frequencies and power levels
The ratio of the rms sum of the first six harmonic components to the rms value of the measured fundamental. It is expressed as a percentage or in decibels (dB).
A measure of the distortion caused by ballasts and other inductive loads of the input current on alternating current (AC) power systems caused by higher order harmonics of the fundamental frequency (60Hz in North America). THD is expressed in percent and may refer to individual electrical loads (such as ballast) or a total electrical circuit or system in a building. ANSI C82.77 recommends THD not exceed 32% for individual commercial electronic ballasts, although some electrical utilities may require lower THDs on some systems. Excessive THDs on electrical systems can cause efficiency losses as well as overheating and deterioration of system components.
(THD): A specification used as a single number representation of the distortion present in the output of an active circuit. It is the RMS sum of the individual harmonic distortions (i.e. 2nd, 3rd, --- etc.) that are created by the non-linearity of the active and passive components in the circuit when it is driven by a pure sinusoidal input at a given amplitude and frequency.
The remaining signal appearing at the output of the oscillator after the signal at the operating frequency is subtracted. It is expressed in percent of the rms value signal at the operating frequency. This term only applies to sine wave output wave forms (MIL-PRF-55310D, 4.8.24).
A measure of the degree to which a sinusoidal wave shape is distorted by harmonic wave forms, with higher values of THD indicating greater distortion. Electrical devices, such as computers and fluorescent lighting systems, can send harmonic wave forms at many frequencies back onto the power supply line, thereby distorting the current wave shape. For 4-foot lamps, the American National Standards Institute (ANSI) recommends a THD limit of 32 percent, but some electric utilities only provide financial incentives for ballasts that produce less than 20 percent THD. Ballasts that produce less than 10 percent THD are available for installations with critical power requirements.
The percentage of the total sound that is unintentionally created harmonics from the original signal. . When comparing audio components, the lower the number, the better.
Excessive THD (defined by ANSI as greater than 32%) may cause adverse effects to the electrical system. THD levels below 20% provide optimal system compatibility, but levels below 10% may not add any practical benefit. 10% THD types may also introduce excessive in-rush current unless circuitry is added that limits in-rush levels.
THD measures the distortion content of a signal, and is specified in decibels relative to the carrier (dBc). For ADCs, THD is the ratio of the RMS sum of the selected harmonics of the input signal to the fundamental itself. Only harmonics within the Nyquist limit are included in the measurement.
The ratio of the root-mean- square of the harmonic content to the root-mean-square value of the fundamental quantity, expressed as a percent of the fundamental. Typically a supply sine wave is considered acceptable when THD levels are 5% or less. See harmonics, harmonic distortion and distortion.
Describes how much the circuit voltage deviates from a perfect sine wave. A poor voltage THD is most often manifested in a “flat topped †waveform that comes from the inability of a power source to respond to the demands of highly non-linear loads.
Refers to a device adding harmonics that were not in the original signal. For example: a device that is fed a 20Hz sine wave that is also putting out 40Hz, 80Hz etc. Not usually a factor in most modern electronics, but still a significant design problem in loudspeakers.
The percentage of harmonic distortion present in an output signal over a specified frequency range.
THD is a measure of the degree to which a sinusoidal wave shape is distorted by harmonics. Fluorescent lamps operated with either magnetic or electronic ballasts reflect harmonics back into the electrical supply system and may range from 12-20% for magnetic ballasts and 5-30% for electronic ballasts. ANSI has recommended a limit of 32%.
The amount of undesirable harmonics present in an output audio signal expressed as a precentage. The lower the percentage the better.
The square root of the sum of the squares of the RMS harmonic voltages or currents divided by the RMS fundamental voltage or current. Typically a supply sine wave is considered acceptable when THD levels are 5% or less. See harmonics, harmonic distortion and distortion. Can also be calculated in the same way for only even harmonics or odd harmonics.
The measure of closeness in shape between a waveform and it's fundamental component.
The noise referenced to signal in decibels (dB) as a percentage.
(THD+N) - THD (or THD+N) is an acronym that means "total harmonic distortion (plus noise)". THD+N is a measure of the amount of audio distortion from an audio system, as a result of imperfections in the reproduction of the audio signal (and also as a result of the amount of noise in the system). THD+N is typically measured in units of percentage (%), with respect to a specified reference frequency at a specified level. Weighting filters are not used with this measurement, though band limiting filters such as AES17 may be specified.
The total harmonic distortion, or THD, of a signal is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental.