An enhancer, an exciter and a tube amplifier – what is common?
Exciter (from the English Exciter), also called harmonic exciter (harmonic exciter), psychoacoustic processor (psychoacoustic processor), enhancer (enhancer) and acoustic exciter (aural exciter) – a processing device used for the harmonious synthesis of high-frequency signals using thin harmonic distortion.
This harmonic synthesis is to create higher harmonics based on lower signal frequencies. Typically, noise is not present in different frequency bands in equal amounts, and harmonics obtained from a clean frequency band will be clearer. Less commonly, exciters (enhancers) are used to synthesize low-frequency harmonics in order to simulate deep bass.
Sound processed by an exciter becomes more “pure”, “transparent”, “voluminous”, “warmer” than the original, and also spatially more localized. All these properties are enclosed in quotation marks, since they are perceived by a person subjectively. Also, subjectively, this is similar to adding high frequencies, although an increase in level is barely measurable. Too much “improvement” in signal quality using an exciter significantly degrades the sound, gives unnaturalness, distortion and irritates the human hearing.
A special case of excitation is “saturation” (saturation), which is the effect of saturation of the signal with even harmonics.
The effect of excitation by the American company Aphex is discovered. She developed a device called Aural Exciter. The name “exciter” is protected by copyright, so other manufacturers usually call their similar devices “enhancer” or “psychoacoustic processor”).
Initially, exciters were made on the basis of tube amplifiers, but now they exist in the form of digital processors.
The difference between exciters and equalizers
Exciters and enhancers are used to change the tonal qualities of sound. But, unlike the equalizer, which simply enhances or attenuates the frequency found in the signal, enhancers can create new harmonics.
Equalizer does not add additional harmonics to the sound. It is used to amplify or attenuate an existing frequency. An equalizer is used to emphasize the characteristic overtones of musical instruments and amplifies a specific frequency domain. In the case when the required frequencies are initially small, the equalization will not give the desired effect, or together with a weak signal it will remove all unwanted noises.
Unlike the equalizer, the exciter itself completes the higher harmonics, starting from the envelopes of the fundamental tones. That is, there is no amplification of the required frequencies, but a logical addition of new overtones (harmonics).
Exciters, as a rule, create even harmonics that are multiples of 2, (2, 4, 8 …), which, according to auditory sensations, gives clarity and greater expressiveness to the sound, “volume” and “warmth”. While the overall volume remains the same. Unlike harmonizers, which, as a rule, create harmonics in the entire band of the audio signal, exciters make it possible to choose the frequency of enrichment.
But exciters also have an inverse negative property: when listening for a long time, the listener wants to constantly increase the saturation of sound with harmonics, so after some time when listening to sound without an exciter, a recording made with his participation may seem like an oversaturated “mess”.
Now we turn our attention to tube amplifiers, which are so often presented to us almost as the only devices capable of amplifying sound vibrations “qualitatively” and transmitting all the bulk, warmth and many other attributed properties.
At present, tube amplifiers are an object of commerce and speculation precisely because the nature of amplification of sound vibrations is based on the excitation mechanism (but usually sellers don’t like to focus on this, because it’s because of this effect, the “heat” of which given as genuine “quality” manages to attract buyers of expensive equipment). Audiophiles, who are often sellers of tube amplifiers concurrently, claim that transistor sound amplifiers distort the signal, although the harmonic distortion detected by the instruments in almost any modern transistor sound amplifier is many times smaller than that of tube amplifiers.
The coefficient of nonlinear distortion of the signal (SOI, KH, THD, THDf) is a value that expresses the degree of nonlinear distortion of the signal, equal to the ratio of the rms value of all the higher harmonics of the signal to the voltage of the first harmonic:
It can be generalized that harmonic distortions are distortions that are multiples of the fundamental tone of the signal. Spurious harmonics in the spectrum give the sound a new timbre and lead to irreparable loss in sound. Often, harmonic distortion is measured by supplying a sinusoidal signal to the input of the sound path with a frequency of 1000 Hz, using a special filter in the sound signal, excess harmonics are found and their power is determined.