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Laserdisc: Laserdisc was the first commercial optical disc, an analog video format providing 425 lines of resolution. Pioneer Electronics was the biggest backer of the format, which provided the best video quality of its time but never escaped nice status due to high prices for the players and movies, as well as the large size of the discs. Later Laserdiscs had Dolby Digital audio tracks recorded as an RF signal. Laserdisc was phased out within a few years of the introduction of DVD.
LCoS: Liquid Crystal on Silicon. Projection television technology using reflective silicon panels, lenses and a lamp to create the image. See D-ILA, SXRD.
Leaf Tweeter: Tweeter using a thin, flat “leaf” driven by an intense magnetic field. Leaf tweeters are known for tremendous detail and transparency and are typically found only in exotic or expensive speakers. See Tweeter.Lens Flare: Reflections within a lens or on the outside element which manifests as multicolored spots across the image or fogging of an area of the frame. Lens flare occurs when a strong light source shines into the lens at an angle that causes reflection. Lens hoods and multicoating reduce or eliminate lens flare. See Lens Hood, Multicoating.
LED: Light Emitting Diode, a light-emitting semiconductor used as a light source used in a variety of applications such as receiver displays, LCD TV backlights and the light source for DLP televisions. LEDs are extremely power efficient and can be tuned to emit specific wavelengths of light.
LFE: Low Frequency Effects. The .1 channel in multichannel recordings. See .1.
Light Meter: Photographic device that measures light levels to aid in setting exposure for film and video. Light meters are most commonly an integral part of a camera or camcorder, but many photograhers use a hand-held meter for improved accuracy and flexibility. See Exposure, Flash Meter, Spot Meter.
Line Level: Low voltage signal for transferring audio between components, such as between a VCR’s audio outputs and the audio inputs of a receiver. Other examples of line level signals are DVD player analog audio outputs and cassette deck analog outputs. A phono cartridge’s signal is NOT line level, but far below it, which is why turntables must be used with components having a phono input, or a phono preamp . The phono preamp increases the voltage of the cartridge’s signal to line level, so that it may be used with a line level input.
Lines of Resolution: The number of vertical lines in a video image. The more lines, the information and the better the picture. The numbers in resolution figures such as 480i, 720p and 1080p refer to the lines of resolution.
Logic 7: Matrix surround format developed and marketed by Harman Audio. Logic 7 creates discrete multichannel surround sound effects from 2 channel or matrix surround sources and is found in audio components and automobiles. See Matrix Surround.
Lossless Audio: Audio formats (usually found on Blu-ray Discs and HD DVDs ) that have no loss of sound quality due to compression. Lossless audio can be PCM recordings or lossless compression formats such as Dolby TrueHD, and DTS-HD Master Audio. Lossless audio is highly desirable and will often make a noticeable difference in sound quality when played on a good sound system.
Lossless Compression: Compression which reduces digital file size with no loss in quality from the compression process. Some examples of lossless compression are Apple Lossless Compression, Dolby TrueHD, DTS-HD Master Audio, and compression used in digital cameras producing RAW files. See Compression, RAW.
Lossy Compression: Compression in which digital file size is reduced, but some sound or image quality is lost through the compression process. The amount of quality lost varies based on the quality of the compression codec, complexity of the source material and the amount of compression applied. For example, a blank white wall could be heavily compressed with very little loss in quality. A flock of fast-moving birds would have a great deal of fast-moving detail and would require much less compression to render it clearly. Some examples of lossy compression are AAC, AVC, Dolby Digital, MP3, MPEG-2, and VC-1. (Currently all the video codecs are lossy, though advanced codecs such as AVC and VC-1 are often able to produce results indistinguishable from the original if adequate bitrates are used and the person performing the compression is highly skilled.) See Bitrate, Compression.
Loudness Compensation: Tone adjustment on receivers and preamplifiers, meant to boost bass volume at low listening levels.
Loudspeaker: Transducer the converts electrical energy into audible sound.
Loudspeaker, 2-way, 3-way, etc: The terms 2-way and 3-way refer to the number of drivers in a loudspeaker. For example, a speaker with a woofer and tweeter is a 2-way, a speaker with a woofer, midrange and a tweeter is a 3-way. Please note that a speaker with two identical woofers operating together in tandem along with a tweeter is a 2-way speaker, despite having three drivers, as the two woofers produce identical sounds.
Loudspeaker Driver: Any speaker component that produces physical sound, such as a woofer, tweeter, planar magnetic driver, or Walsh driver.
LPCM: Linear PCM, a form of PCM recording optimized for audio use. See PCM.
