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The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a ...
Early 78 rpm phonograph discs had a dynamic range of up to 40 dB, [24] soon reduced to 30 dB and worse due to wear from repeated play. Vinyl microgroove phonograph records typically yield 55-65 dB, though the first play of the higher-fidelity outer rings can achieve a dynamic range of 70 dB. [25]
Database Services No. of tracks No. of releases No. of artists Notes License Full free access AllMusic: Music information and reviews. ~20,000,000 [7] ~2,200,000 [7] Song samples only. Discogs • Database: user-generated cross-referenced database of physical & digital releases, artists, and labels. With catalogue numbers, codes, and other ...
A graph of the A-, B-, C- and D-weightings across the frequency range 10 Hz – 20 kHz Video illustrating A-weighting by analyzing a sine sweep (contains audio). A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. [1]
Though the values vary widely between units, a typical analogue cassette might give 60 dB, a CD almost 100 dB. Most modern quality amplifiers have >110 dB dynamic range, [6] which approaches that of the human ear, usually taken as around 130 dB. See Programme levels. Phase distortion, Group delay, and Phase delay
where b is the number of quantization bits, and the result is measured in decibels (dB). [10] [11] Therefore, 16-bit digital audio found on CDs has a theoretical maximum SNR of 98 dB, and professional 24-bit digital audio tops out as 146 dB.
The first true graphic equalizer was the type 7080, an active tube device developed in the 1950s by Davis's Cinema Engineering company. It featured six bands, each 1.5 octaves wide, with a boost or cut range of 8 dB. It used a slide switch to adjust each band in 1 dB steps. Three summing amps smoothly restored the gain lost in the filter circuits.
A typical British quasi-PPM. Each division between '1' and '7' is exactly four decibels and '6' is the intended maximum level. A peak programme meter (PPM) is an instrument used in professional audio that indicates the level of an audio signal.