Please see a glossary of technical terms below.
Audio Engineering Society/European Broadcasting Union. A digital audio communication standard most commonly seen in professional audio applications.
An electronic device that increases (or 'amplifies') the power of an electrical input signal.
A type of telecommunications signal (audio or video) that is translated into electronic pulses with varying strength or frequency.
A device on a turntable's tonearm to counteract skating. This sometimes consists of an adjustable spring-loaded device near the tonearm's pivot, or weight on a string (where the torque applied by this arrangement remains constant throughout the range of travel).
aptX has revolutionised the Bluetooth® Stereo listening experience by significantly reducing the bit rate without affecting audio quality or introducing latency issues.
Because the music recorded in the two walls of a ‘V’-shaped record groove, it is obviously essential that the stylus of the pick-up cartridge sits perfectly vertical in the groove, rather than leaning into one or other of the groove walls. This adjustment is called the Azimuth Adjustment and it can be checked in a fairly simple way.
An input consists of two leads, neither of which is common to the circuit ground. This is a “differential pair”, where the signal consists of the difference in voltage between the two leads. Balanced input circuits can offer excellent rejection of common-mode noise induced into the line.
In a classic balanced audio circuit, the output is carried on two leads (high or + and low or -) which are isolated from the circuit ground by exactly the same impedance. A symmetrical balanced output carries the same signal at exactly the same level but of opposite polarity with respect to ground.
Either the range of frequencies which a component can deal with competently (often specified as the range across which the attenuation is no more than 3dB), or the frequency range required to carry a signal.
The number of digital bits a system transfers per second. In general, the higher the bit rate, the higher the quality of the signal. In every case, the higher the bit rate, the more data space required.
Bluetooth is a wireless technology standard for exchanging data over short distances from fixed and mobile devices, and building personal area networks (PANs).
Term used to when converting an integrated amplifier into a power amplifier i.e. bypassing the per-amp stage.
The thin rod within a turntable's cartridge that transmits the movement of the stylus in response to a record's groove to the interior components of the cartridge that generate the electrical signal.
The device that converts the movements of a stylus in the grooves of an LP record to electrical signals. The cartridge is a small, light-weight device, secured to the end of a turntable's tonearm by means of two screws mounted 12.5 mm apart.
A power amplifier in which a sufficient DC bias voltage is applied to the power transistors so that the output signal always operates entirely in the positive or negative part of the cycle, entirely avoiding crossover distortion. This makes them quite wasteful of power since even at idle a considerable voltage is being generated.
A power amplifier in which a certain amount of DC bias voltage is applied to the power transistors so that, at low power outputs, the output signal operates entirely in the positive or negative part of the cycle, avoiding crossover distortion. Thus, at low outputs, a Class A/B amplifier operates in Class A mode.
A very efficient amplifier design. Digital amplifiers use a form of pulse width modulation (with low pass filtering to reduce ultrasonic noise) to drive the loudspeakers. There are some interesting amplifier products appearing that incorporate class D designs.
A form of severe audio distortion that results from peaks of the audio signal attempting to rise above the capabilities of the amplifier circuit. Seen on an oscilloscope, the audio peaks appear clipped off. To avoid clipping, reduce the system gain in or before the gain stage in which the clipping occurs.
The digital audio output signal of a DVD player in an electrical format, rather than optical. The data format accords with the S/PDIF specification.
A system which compresses a signal in some way for storage or transportation and then decompresses it at the point of delivery. Examples are MPEG, Dolby Digital and DTS. These systems use a codec to reduce the amount of data in the signal.
A signal which is referenced to the circuit common point, usually chassis ground.
An acronym for Digital Analog Converter. One of two chips in an A/V receiver that decodes surround-sound formats. The DAC converts digitally encoded music signals into analog signals that a receiver’s amplifier and the surround speakers can understand.
A specification for power amplifiers which suggests the degree of control that the amplifier exercises over a connected loudspeaker. It is the ratio of the nominal impedance of the speaker (and is typically quoted for eight ohms) to the internal impedance of the output stage of the amplifier.
Sound Pressure Level (SPL) measured with an "A" weighting filter.
A unit of measurement of power in an electrical circuit, expressed in decibels referenced to 1 milliwatt. The “m” in dBm stands for “milliwatt.” In a circuit with an impedance of 600 ohms, this reference (0 dBm) corresponds to a signal voltage of 0.775 VRMS (because 0.775 V across 600 ohms equals 1 mw).
The dB is a ratio of quantities measured in similar terms using a logarithmic scale. Many audio system parameters measure over such a large range of values that the dB is used to simplify the numbers.
Digital audio file
Just like any other file on your computer, except they contain digitally encoded music files that you can play back on your computer, on a portable device, or in your home theater.
An inaccuracy in the reproduction of a signal. In the case of audio, it is normally regarded as being composed of harmonic distortion and intermodulation distortion. But used more broadly, it can also encompass frequency response variations and noise.
Direct Stream Digital. The digital audio format used in the SACD. Unlike the PCM system normally used, DSD uses a stream of single bits of information. The momentary level of the analogue wave form being represented by the bitstream is determined by the density with which the bits are 'on' rather than 'off'.
When pertaining to audio CDs, the difference between the softest and loudest musical passages on a compact disc. The range between the maximum and minimum sound levels that a sound system can handle. It is usually expressed in decibels as the difference between the level at peak clipping and the level of the noise floor.
EBU stands for the European Broadcasting Union, an alliance founded in 1950 and best-known for producing the musically dubious Eurovision Song Contest!
File formats used for converting digital content (audio and video files) to smaller file sizes. Some audio encoding formats include MP3, WMA, and AAC. Some video encoding formats include WMV and MPEG.
The number of times an event repeats itself in a given period of time. Generally the time period for audio frequencies is one second, and frequency is measured in cycles per second, abbreviated Hz, honoring the physicist Dr. Heinrich Hertz.
A specification for a receiver that is measured in Hertz (Hz). The lower frequency ranges (for bass sounds) require more amplifier power than the higher frequency ranges.
The measure of how much a circuit amplifies a signal. Gain may be stated as a ratio of input to output voltage, current or power, such as a voltage gain of 4, or a power gain of 1.5, or it can be expressed in decibels, such as a line amplifier with a gain of 10 dB.
An amplification point in a signal path, either within a system or a single device. Overall system gain is distributed between the various gain stages.
Also called earth. Ground is defined as the point of zero voltage in a circuit or system, the reference point from which all other voltages are measured. In electrical power systems, ground connections are used for safety purposes, to keep equipment chassis and controls at zero voltage and to provide a safe path for errant currents.
A ground loop occurs when the technical ground within an audio system is connected to the safety ground at more than one place. This forms a loop around which unwanted current can, and does flow, causing noise in the audio system. Never disable the safety ground in an attempt to solve hum problems.
The difference between nominal operating level and peak clipping in an audio system.
A specification for an amplifier that measures electrical resistance. Most amplifiers are rated at 8 ohms impedance. The A.C. resistance, capacitance, and inductance in an electrical circuit, measured in ohms.
A measure of the efficiency with which loudspeakers turn the electrical energy provided by a power amplifier into acoustic energy. The more sensitive, the greater the volume for a given amount of power.
An amplifier consisting of both a preamplifier and a power amplifier. If properly designed, an integrated amplifier should offer better sound qualities, due to less connectors and cables between components.
Short-run cables that you use to connect home theater components that are located within a few feet of each other (or in the same room).
Top-end Hi-Fi equipment such as CD players, amplifiers and loudspeaker mountings / feet require complete Isolation to perform at the highest level.
The phenomenon of a drift in the digital audio data delivered so that it does not precisely match the sampling frequency, causing confusion in the receiving equipment as to the appropriate value of the sample. A host of audible problems with CDs and other digital formats have been laid at the feet of jitter.
A signal whose level falls between -10 dBu and +30 dBu.
An MC phono is a phono stage amplification boost needed to connect a Moving Coil cartridge used with a vinyl record replay system. Moving Coil designs are lower in output than a MM or Moving Magnet but sound more detailed.
An MM phono is a phono stage amplification boost needed to connect a Moving Magnet cartridge used with a vinyl record replay system. Moving Magnet designs are higher in output but lower in price than a MC or Moving Coil but often sound a little less detailed.
A magnetic cartridge in which the stylus moves a coil via the cantilever, while the magnet is fixed in position. Moving coil cartridges tend to have lower moving mass than moving magnet cartridges, but also tend to be lower in output by an order of magnitude.
A magnetic cartridge in which the stylus moves a magnet via the cantilever, while the coil is fixed in position. Moving magnet cartridges tend to have a higher output than moving coil cartridges, but also tend to have a higher moving mass (possibly reducing their ability to deliver fine detail from record).
The residual level of noise in any system. The lower the noise floor and the higher the headroom, the more usable dynamic range a system has.
A unit of electrical resistance or impedance. In a DC circuit, the number of ohms of resistance offered by a component can be calculated by dividing the voltage across the component by the current (in amps) flowing through it.
A method of communicating digital audio between components using light carried on optical fibre. See TOSLink. The data format accords with the S/PDIF specification.
A dynamic effect in which the phase relationship between the fundamental and overtone components of a sound is continually changing. This is done by passing the signal through an automatically sweeping filter. The effect is often simulated by mixing original signal with a delayed (1 to 10 ms) version of itself.
Short for RCA phono plug.
Phono Stage (RPP)
The aim of the RPP was to further develop the sonic achievements of the renowned previous Roksan Reference Phono Stage. The highest possible quality components are used throughout the circuit to ensure the best possible sound quality.
The amount of energy expended per unit time. The common unit is the watt. Power (in watts) in a DC circuit equals voltage times current (in amps). Things are a bit more complicated with AC.
Preamp out is the stereo (left and right RCA) outout from a preamp or integrated amp to connect a power amplifer.
The part of the motor on a turntable that the drive belt is driven by.
An acronym for root mean square, a conventional way to measure the effective average value of an audio signal or other AC voltage. Most AC voltmeters are calibrated to read RMS volts, though on many meters that calibration is accurate only if the waveform is sinusoidal.
Low frequency noise, usually from a turntable. Given that RIAA equalization boosts the bass signal from a cartridge by an enormous amount (17dB at 50 hertz), the highest quality bearings and excellent isolation from the turntable's motor are required to control rumble.
Sony/Philips Digital Interface Format. A widely used digital audio protocol. It is used as the protocol for all consumer home entertainment equipment. It is distinguished from the professional AES/EBU protocol by incorporating the clock timing information in the main signal.
This is the rate at which an analog signal is sampled during the analog-to-digital conversion process. The sampling rate used for compact discs is 44.1 kHz, but professional recordings are often sampled at higher sample rates, such as 96 kHz or even 192 kHz (that’s 192,000 samples per second!).
A measure of the degree to which leakage from one channel of sound to another channel (crosstalk) is limited. This is typically measured in decibels (e.g. -90dB at 1kHz). While great emphasis is placed on this figure, the reality is that very modest figures like -20 or -30dB (typical of LP records) provide excellent stereo separation and imaging.
Signal-to-noise ratio (S/N)
This is a specification that describes how much noise an audio component has compared to the signal. It is usually expressed in dB below a given output level.
A movie set where audio is recorded along with video. But in the home entertainment (audio) context, the sound stage is area between a pair of stereo speakers from which they appear to make the various sounds appear.
Speed control (RPM)
The RPM is the new high-specification, ultra-accurate statement speed control for use with the Xerxes 20+. The RPM represents a signi cant upgrade from the previous and long-established reference speed control as featured in the discontinued DX2.
Stop Band Rejection
The amount of attenuation given to unwanted signals occurring outside of the test passband region.
A method of sending audio or video content in which the content plays while it is delivered over your home network, the Internet, or both.
A small diamond on the end of a cartridge's cantilever. This sits within the groove of an LP and picks up the vibrations recorded therein. The stylus is generally spherical or elliptical in shape, although other variations have been developed, all with a view to more accurately tracking the groove while reducing damage to it.
All the harmonic distortion components added together to give a summary measure, though often misleading. The imperfection resides in the fact that, audibly, some of the harmonic components are worse than others.
Position the attached cartridge in the correct alignment to play an LP record. Is normally pivoted at the back and provides for an adjustable tracking weight by the use of a spring-loaded or weight-loaded mechanism; and usually have a damped cueing lever to allow the stylus to be gently lowered to the surface of the record.
An optical audio interconnect cable used in home theaters to connect DVD players, HDTV tuners, video game consoles, and more to the A/V receiver or controller. Toslink cables use fiber optics that carry the digital signal as pulses of light.
The correct downforce and anti-skate setting to a cartridge, so it reads the most information possible from the record wall without causing damage to the cartridge or the record.
A device used to alter the voltage of AC electricity. This typically consists of an iron ring of some kind with two coils of wire wound around it. The input current is fed to one of the coils, which generates a magnetic field in the iron ring and which, in turn, generates a voltage in the other coil.
A device to rotate at the correct speed a vinyl LP recording. More generally, the word can refer to the turntable itself along with an installed tonearm and cartridge. The platter on the turntable (the rotating part) is powered by a small electric motor. Different types of turntables are defined by the drive mechanism used to connect motor to platter.
A subtle change to home audio or A/V intended to improve the sound. This could range from merely adjusting the system's controls, through replacing cables and experimenting with speaker positions, to all kinds of damping and isolating procedures.
An electrical circuit in which the two legs of the circuit do not have the identical impedance to ground. Often one leg is also at ground potential. Unbalanced circuit connections require only two conductors (signal “hot” and ground). Unbalanced audio circuitry is less expensive to build, but under certain circumstances is more susceptible to noise pickup.
When an original record master is cut, the cutter sits at a slight angle to the record surface because the cutter head needs to be lifted slightly above the record surface. This angle is called the Vertical Tracking Angle (VTA) and can vary from record to record.
Wow and Flutter
A defect affecting analogue audio signal sources that rely on rotating the medium, particularly LPs and compact cassettes. Wow is a slow, repetitive speed variation, typically repeating at less than once per second. If an LP or audio cassette undergoes this, it produces slow variations in the playback frequency.
An XLR connector is a type of electrical connector used mostly in professional audio and video electronics cabling applications such as for stage microphones and other analog sound equipment, as opposed to home audio/video equipment using RCA connectors.
The XLR connector was an incremental variant that started from the Type O connector made by Cannon (ITT Cannon), which featured an oval-shaped body and receptacle with three prongs and a latch locking mechanism.