Total Harmonic Distortion (THD)
Total harmonic distortion measures unwanted harmonics relative to the fundamental signal, usually expressed as a percentage.
Ordinary THD excludes broadband noise; THD+N includes it. Preserve the actual metric and test conditions with each figure. A lower percentage under equivalent conditions means less measured distortion.
Total Harmonic Distortion (THD) — Tuner
Here harmonic distortion describes unwanted harmonics in recovered tuner audio. Its value depends on how hard the signal path is driven.
Compare the same reception band, mono/stereo mode, signal strength and modulation. A single low-level figure does not describe distortion at every operating level, and a stated upper limit remains a limit rather than an exact measured value.
Total Harmonic Distortion (THD) — Power Regenerator
For a regenerator, distortion describes the AC supply waveform rather than an audio output. Harmonics measure departures from the fundamental mains waveform.
Keep the measurement point, incoming supply conditions and connected load with the result. Input and output distortion are different observations; a percentage alone does not establish the effect on an audio component.
Total Harmonic Distortion (THD) — Reel-to-Reel
Here harmonic distortion describes unwanted harmonics in the tape signal path. Its value depends on how hard the signal path is driven.
Compare the same tape speed, formulation, recording level and test frequency. A single low-level figure does not describe distortion at every operating level, and a stated upper limit remains a limit rather than an exact measured value.
Total Harmonic Distortion (THD) — Preamp
For a preamplifier, distortion refers to the analogue line stage at a stated output level and frequency. Connector path and load can also matter.
Retain whether the stated metric is THD or THD+N; the latter includes noise. Do not substitute a phono-stage or DAC measurement for the line-stage result.
Total Harmonic Distortion (THD) — Optical Equalizer
For an optical-cartridge equalizer, distortion belongs to the optical-cartridge processing path. Signal level and test frequency describe the operating point.
Keep THD and THD+N labels distinct and preserve any stated bound. An MM or MC input measurement in the same component does not establish optical-path performance.
Total Harmonic Distortion (THD) — Headphone Amp
Here harmonic distortion describes unwanted harmonics in the headphone amplifier output. Its value depends on how hard the signal path is driven.
Compare the same load impedance, output level, gain and test frequency. A single low-level figure does not describe distortion at every operating level, and a stated upper limit remains a limit rather than an exact measured value.
Total Harmonic Distortion (THD) — Tape Deck
Here harmonic distortion describes unwanted harmonics in the cassette signal path. Its value depends on how hard the signal path is driven.
Compare the same tape type, recording level, noise-reduction setting and test frequency. A single low-level figure does not describe distortion at every operating level, and a stated upper limit remains a limit rather than an exact measured value.
Total Harmonic Distortion (THD) — Equalizer
Here harmonic distortion describes unwanted harmonics in the processed audio output. Its value depends on how hard the signal path is driven.
Compare the same control settings, signal level, load and test frequency. A single low-level figure does not describe distortion at every operating level, and a stated upper limit remains a limit rather than an exact measured value.
Total Harmonic Distortion (THD) — Power Filter
For a power filter, distortion describes the AC supply waveform rather than an audio output. Harmonics measure departures from the fundamental mains waveform.
Keep the measurement point, incoming supply conditions and connected load with the result. Input and output distortion are different observations; a percentage alone does not establish the effect on an audio component.
Total Harmonic Distortion (THD) — MC Head Amp
For a phono head amp, distortion describes the cartridge-level gain stage at a stated signal level, frequency and gain. Larger signals can approach the stage’s limits.
Preserve the exact metric, including whether noise is included. A figure labelled only distortion should not silently become THD+N, and comparisons need equivalent gain and signal conditions.
Total Harmonic Distortion (THD) — Headphone
For headphones, harmonic distortion describes unwanted acoustic harmonics produced at the measured sound level and frequency. The fixture and fit are part of the result.
Compare the same acoustic level, frequency range and measurement method. An electrical amplifier distortion figure does not describe the headphone’s acoustic distortion, and a single frequency does not represent the entire band.
Total Harmonic Distortion (THD) — Power Amp
Here harmonic distortion describes unwanted harmonics in the power amplifier output. Its value depends on how hard the signal path is driven.
Compare the same output power, load impedance, test frequency and channels driven. A single low-level figure does not describe distortion at every operating level, and a stated upper limit remains a limit rather than an exact measured value.