An audio system typically consists of one or more source components, one or more amplification components, and (for
stereo) two or more
loudspeakers.
Signal cables (analog audio, speaker, digital audio etc.) are used to link these components. There are also a variety of accessories, including equipment racks,
power conditioners, devices to reduce or control
vibration, record cleaners, anti-static devices, phonograph needle cleaners,
reverberation reducing devices such as speaker pads and stands, sound absorbent foam, and
soundproofing. The interaction between the loudspeakers and the room (
room acoustics) plays an important part in sound quality. Sound vibrations are reflected from walls, floor and ceiling, and are affected by the room's contents. Room dimensions can create
standing waves at particular (usually low) frequencies. There are devices and materials for
room treatment that affect sound quality. Soft materials, such as draperies and carpets, can absorb higher frequencies, whereas hard walls and floors can cause excess reverberation.
Sound sources Audiophiles play music from a variety of sources including
phonograph records,
reel to reel tape,
compact discs (CDs), and
digital audio files that are either uncompressed or are
losslessly compressed, such as
FLAC,
DSD,
Windows Media Audio 9 Lossless and
Apple Lossless (ALAC), in contrast to
lossy compression, such as in
MP3 encoding. From the early 1990s, CDs were the most common source of high-quality music. Nevertheless,
turntables, tonearms, and
magnetic cartridges are still used, despite the difficulties of keeping records free from dust and the delicate set-up associated with turntables. The 44.1 kHz
sampling rate of the CD format limits information loss to frequencies only above the
upper-frequency limit of
human hearing – 20 kHz. Nonetheless, newer formats such as FLAC, ALAC,
DVD-Audio and
Super Audio Compact Disc (SACD) allow for sampling rates of 88.2 kHz, 96 kHz and 192 kHz. Higher sample rates allow greater freedom in choices in playback components such as filters with a less steep roll off in their frequency response. Some audiophiles upsample from the source rate to higher rates which allows different filter properties to be used. CD audio signals are encoded as 16-bit values for each sample. Higher-definition consumer formats such as
HDCD-encoded CDs, DVD-Audio, and SA-CD contain 20-bit, 24-bit and 32-bit audio streams. With a greater number of bits per sample a greater
dynamic range is possible; 20-bit dynamic range is theoretically 120 dB—the limit of most consumer electronic playback equipment. SACDs and DVD-Audio have up to 5.1 to 6.1 surround sound. Although both of these high-resolution optical formats have failed to make an impact in the commercial market there has been a resurgence in high-resolution digital files. SACD can be stored as a DSD file, and DVD-Audio can be stored as an FLAC or ALAC file. FLAC is the most widely used digital format for high-resolution with up to 8 channels, a maximum depth of 32-bit, and 655,350 Hz sampling rate. Uncompressed formats such as WAV and AIFF files can store audio CD data without compression.
Amplifiers A
preamplifier selects among several audio inputs, amplifies source-level signals (such as those from a turntable), and allows the listener to adjust the sound with volume and tone controls. Many audiophile-oriented preamplifiers lack tone controls. A power
amplifier takes the "line-level" audio signal from the preamplifier and drives the
loudspeakers. An integrated amplifier combines the functions of power amplification with input switching and volume and tone control. Both pre/power combinations and integrated amplifiers are widely used by audiophiles. Audiophile amplifiers are available based on solid-state (
semiconductor) technology,
vacuum-tube (valve) technology, or hybrid technology—semiconductors and vacuum tubes. Dedicated amplifiers are also commonly used by audiophiles to drive headphones, especially those with high impedance and/or low sensitivity, or
electrostatic headphones.
Loudspeakers The loudspeaker's cabinet is known as the
enclosure. There are a variety of loudspeaker enclosure designs, including sealed cabinets (
acoustic suspension), ported cabinets (
bass-reflex), transmission line, infinite baffles, and horn-loaded. The enclosure plays a major role in the sound of the loudspeaker. Depending on the frequencies reproduced, the drivers that produce the sound are referred to as
tweeters for high frequencies,
midranges for middle frequencies, such as voice and lead instruments, and
woofers for bass frequencies. Driver designs include
dynamic,
electrostatic,
plasma, ribbon, planar, ionic, and servo-actuated. Drivers are made from various materials, including paper pulp,
polypropylene, kevlar, aluminium, magnesium, beryllium, and vapour-deposited diamond. The direction and intensity of the output of a loudspeaker, called dispersion or polar response, has a large effect on its sound. Various methods are employed to control the dispersion. These methods include monopolar, bipolar, dipolar, 360-degree, horn, waveguide, and line source. These terms refer to the configuration and arrangement of the various drivers in the enclosure. The positioning of loudspeakers in the room strongly influences the sound experience. Loudspeaker output is influenced by interaction with room boundaries, particularly bass response, and high-frequency transducers are directional, or "beaming".
Accessories Audiophiles use a wide variety of accessories and fine-tuning techniques, sometimes referred to as "tweaks", to improve the sound of their systems. These include power conditioner filters to "clean" the electricity, equipment racks to isolate components from floor vibrations, specialty power and audio cables, loudspeaker stands (and footers to isolate speakers from stands), and room treatments. There are several types of room treatment. Sound-absorbing materials may be placed strategically within a listening room to reduce the amplitude of early reflections, and to deal with resonance modes. Other treatments are designed to produce diffusion, reflection of sound in a scattered fashion. Room treatments can be expensive and difficult to optimize.
Headphones Headphones are regularly used by audiophiles. These products can be remarkably expensive, some over $10,000, but in general are much cheaper than comparable speaker systems. They have the advantage of not requiring room treatment and being usable without requiring others to listen at the same time. However, many audiophiles still prefer speaker systems over headphones due to their ability to simulate an immersive, rounded sonic environment. Newer
canalphones can be driven by the less powerful outputs found on portable music players.
Design variety For music storage and playback,
digital formats offer an absence of clicks, pops,
wow,
flutter,
acoustic feedback, and
rumble, compared to vinyl records. Depending on the format, digital can have a higher
signal-to-noise ratio, a wider
dynamic range, less
total harmonic distortion, and a flatter and more extended
frequency response. The
digital recording and playback processes may include degradations not found in the analog processes, such as timing jitter and distortions associated with band limiting filter choices. Vinyl records remain popular and discussion about the relative merits of analog and digital sound continues (see
Comparison of analog and digital recording). Note that vinyl records may be mastered differently from their digital versions, and multiple digital remasters may exist. In the amplification stage,
vacuum-tube electronics remain popular, despite most other applications having since abandoned tubes for
solid state amplifiers. Vacuum-tube amplifiers often have higher
total harmonic distortion, require rebiasing, are less reliable, generate more heat, are less powerful, and cost more. There is also continuing debate about the proper use of
negative feedback in amplifier design. == Community ==