High-end audio is not merely about playing music and movies.  Any audio system can play music so you can easily recognise the songs and singers you love. You can follow the dialogue and action in your movies with any TV, soundbar or home theatre system. That’s not what high-end audio is about. There are also lots of ways to play music and movies really loud, but high-end audio isn’t about loudness for its own sake either.

High-end audio aims to present to the listener the full scope of the performers’ and producers’ sonic craft. It’s about delivering an immersive sound experience, connecting you fully to the emotion of your music and movies. That emotion is communicated as much by nuance, subtle shadings, textures and inflexions, as by intensity and power. It’s not just the roar thundering through fierce fangs, but also the almost silent slither in the grass behind you. It’s in the authority of a stentorian shout of a command, as well as the chilling menace hinted at, almost hidden, in the tone of that command. It not only conveys the power of the kick-drum driving the beat forward, but also the subtle timing and syncopation of the drummer, and the gentle swish of the brushes on the snare. It doesn’t just convey the beauty of the singer’s voice, but also the sly, knowing smile she wears.

It’s the little things which elevate merely hearing into an almost incarnate acoustic experience. THIS is what high-end audio is really about!

Noise and Distortion

High quality sound reproduction seeks to convince us that we’re in the environment of the recording, and not the one in which we’re currently located. This is very challenging indeed, as the audio system has to deceive our extremely sensitive and sophisticated hearing system. Humans have depended for their survival on detecting, locating and identifying threats and opportunities in their environment.  This is the role for which the hearing system, consisting of the ears and the brain, has evolved and been honed over millennia.  It processes with extremely high resolution the myriad sounds which surround us, and provides us with a real-time, 3-D acoustic image of the world around us, and the objects and events in it. Thus it has helped our species to survive and thrive despite the innumerable challenges presented by the wide range of environments we have inhabited.

Noise and distortion are two of the main obstacles to realism and emotional impact in sound reproduction. Noise is unwanted sound that is added to the intended sound, while distortion is an undesired alteration of the sound itself. High levels of noise and distortion is clearly audible as such.  No audio product, however inexpensive, should produce such poor sound.  However there are other, more subtle, impairments that we don’t hear directly. Often we perceive them only when they’ve been eliminated, yielding a more natural sound. They obscure the tiny details of level, timbre and timing that are characteristic of natural sounds. When these low level details are masked by noise and distortion, the hearing system recognises the reproduced sound as an artificial copy and not the real thing. The more noise and distortion you can eliminate from your audio system, the closer you can get to the perception of reality, and the more the nuance and richness of your music and movie sounds can shine through and envelop you.

There are many sources of both noise and distortion, some of which you may never have considered. They include imperfections in audio equipment, issues with the electricity supply to the audio system, wireless signals, vibration, unwanted sound reflections, and extraneous sounds from your surroundings. Here we’ll discuss just two of these, the electrical supply and vibrations.

The Importance of Clean Power

Audio systems operate on electrical power, which they almost all get from the commercial electrical power grid. Electricity powers a host of processes within the audio system, many of which are critical not just to its operation, but to the quality of sound produced. When most people consider the quality of the electrical supply to their audio system, they think in terms of protecting the equipment from voltage spikes and overvoltages that can damage it. This is a very important consideration, but it is far from the only issue.

The amazing sensitivity of our hearing system means that issues with the electrical power supply that are insignificant in most other situations cause easily perceptible, negative effects in audio systems, veiling the reproduced sound. Therefore, power conditioning products designed for general use are often unsuitable for the particular demands of high quality sound reproduction. The following video demonstrates that this problem exists, even with very well designed high-end audio components.

Ideally the electrical supply to an audio system should be a pure sine wave of exactly the specified frequency (50Hz or 60Hz, depending on the country), and exactly the specified voltage (110V, 115V, 120V, 220V, 230V, etc.), again depending on the country. The supply should also meet the audio system’s instantaneous electricity demands, up to the specified power limit. Unfortunately, the reality falls short of this ideal in several ways, which can affect the performance of an audio system. Among these are:

• Noise in the power supply: the vast number and range of devices connected to the commercial electrical grid all inject noise into the electrical system, and this noise is present in the electricity delivered to your home. The devices within your home also inject noise into the electricity supplied to your audio system.

• Distortion in the power supply: the constantly changing demand for power from all the devices connected to the power grid, and faults in the power plants and power transmission and distribution networks, cause distortion of the power supplied to you.

• DC voltage on the power line: due to asymmetries in the pattern of demand on the power grid, a DC voltage may be superimposed on the AC power supply, making it also asymmetrical.

• Noise from one component affecting the others: just as devices inject noise into the public power grid, the devices in your audio system also inject noise into the electricity supply of your audio system.

• Energy supply limitations: some electrical supplies are suited to supplying fairly constant demands, but cannot respond effectively to the constantly and rapidly changing energy demands of sound reproduction.

A high-end audio system requires a supply of electrical power that are free of deficiencies, if it is to perform up to its full potential. This requires some form of power conditioning to eliminate or reduce the power quality problems which may exist in the commercial electricity supply. There are several approaches to doing this. We will discuss power conditioning and other power supply approaches in greater detail in a subsequent blog post.

The Need to Control Vibrations

Vibration is inextricably linked with sound. The pattern of air pressure variation of which sound consists is a product of vibration, whether of instrument strings, surfaces or air columns, human vocal cords, or whatever other source. In sound reproduction the desired vibrations of loudspeaker drivers are accompanied by other vibrations in the loudspeaker. These undesired vibrations are themselves sources of noise, which diminishes the clarity of sound reproduction.

Depending on how the listening room is constructed, and the materials used, the parasitic vibrations of loudspeakers can be coupled to the floor, walls and ceiling, causing them also to vibrate. The room surfaces can also be excited into vibration by the reproduced sound itself. These room vibrations become additional noise sources.  The following demonstration of loudspeaker isolators clearly shows the effect of some loudspeaker vibrations on sound reproduction.

The shelves, racks and other pieces on furniture on which audio components are housed are another source of vibrations.  These can be caused by the reproduced sound, or conducted from the floor and the walls on which the furniture is supported. Audio components themselves also produce vibrations, particularly those with motors, such as disc players and turntables, and those with large power transformers.  These vibrations can affect the component itself, and can be coupled to other components that share the same racks and shelves. This all matters because mechanical vibrations can produce distortion and electronic noise in circuitry.

Among the effects of vibration on audio electronic components are:

• Vibration pick-up noise in turntables.
• Degraded performance of laser mechanisms in disc players.
• Vibration-induced distortion and noise voltages in electronic circuits.
• Microphonic effects in tubes.
• Degraded crystal oscillator performance, producing jitter in DACs and other digital audio systems.

These vibrations are generally quite small, as are the audible artefacts they produce. These artefacts are processed by the audio system along with the desired audio signal, adding to the other sources of distortion and noise in the system.  As a result, several approaches are employed to eliminate or minimise vibrations. We shall go into further detail on treating with deleterious vibrations in a subsequent Blog post.

Trifles Make Perfection … But Perfection is no Trifle

Having your audio system perform at its best requires attention to a number of details. Many of these result in a reduction of noise and distortion in the system. Providing a high quality electricity supply to your system, and addressing undesirable vibrations are two of these. It is details such as these which can elevate your listening experience. I shall discuss these issues further in subsequent Blog posts. Until then, I wish you immersive, fulfilling listening.

© Wayne Butcher, 2021. All rights reserved.