Dolby tloise-reductio1l ing several small panes of glass.
Dividend. (Math.) A number or quantity divided or to be divided intoequal parts.
Dividers. Compasses for measuring
or setting off distances.
Dividing head. (Mach.) A mechanical device which provides for the dividing of the circumference or perimeter of a piece of work into equal parts or spaces, as in the spacing of gear teeth.
Divisor. (Math.) That by which a number or quantity is divided.
Doctor. (Shopwk.) Local term for adjuster or adapter so that chucks from one lathe can be used on another. Sometimes used in the same way as the term dutchman. A common shop expression meaning to repair, remedy, or patch up. To doctor up.
Dodger. (Print.) A small printed circular or handbill such as is distributed form door to door.
Doeskin. (Leather.) The dressed s'kin
of a doe.
Dog. (Mach.) The carrier of a lathe. One of the jaws of a chuck. (Woodwkg.) A small piece of metal with two or more points for bind
ing pieces of wood together while being worked.
Dogtooth. (Arch.) A type of early English decoration in the form of a four-leaved flower, probably so named from its resemblance to the dog-tooth violet.
Dolby-A. Professional version of ~olby covering whole audio fre
quency range. .
Dolby-B. Domestic version of Dolby covering HF only. Particularly suitable for reducing tape hiss in cassette recordings.
Dolby-C. The latest development from Dolby Laboratories for consumer use. Similar to Dolby-B in action but offers an extra 10 dB of noise reduction, is compatible with Dolby-B. .
Dolby HX. A circuit designed to be complementary to Dolby - B. Literally means headroom extension. The circuit varies the level of bias applied to the record head, simultaneously adjusting equalisation when high frequency information is detected. The effect is to give
more headroom at high frequencies (above 10 kHz). It is single
ended (encode) system only.
Dolby level. Tape magnetisation corresponding to 200 n Wb/m, used as reference'level for calibrating the
Dolby noise-reduction system.
Dolby noise-reduction. Invented by Mr. Ray Dolby, it was the first noisereduction system commercially available. Split into two sections (as all present NR systems are), Encode and Decode, the system splits
Do~ysu"ounddecoder and input signal into several frequency bands and boosts the high frequencies (which is where the hiss is) well above normal level. On playback, in Decode mode, the process is reversed, with the high frequencies being reduced to original strength, resulting in the hiss being brought down to inaudible levels. Some engineers swear by Dolby, others curse it. I personally fed that thedbx noise reduction system (if well lined up) offers a slightly better end result; this conclusion is based on my theory that you shouldn't mess about with a signal more than you have to and tthe Dolby system of splitting the sound into preselected frequency bands, going through a process of level emphasis and then sticking them all back together again, is a bit long winded, DBX takes the signal as a whole, compresses it as a whole and then expands it as a whole. However, my remarks should under no circumstances be taken as law without you yourself experiencing and using the effects of the more professional multitrack and mastering machine Dolby units.
Most HiFi cassette decks now have two Dolby systems to choose from; Dolby - B and the better Dolby - C. The Type A units are the most
widely used in the professional recording field.
Dolby surround decoder. A patented process for decoding the special (rear-channel) audio track found on the soudtracks of Dolby-encoded l1ovies. Pro-Logic takes the sur158
Dome round information and steersjt to the various channels with greater accuracy.
Dolby system. One form of noisereduction system, now very widely used with cassettes to reduce background hiss. The DBX system is similar and more powerful, but not so popular.
Dollu. (Mech.) A tool held against heads of rivets while riveting.
Dolly. Wheels on the feet of a tripod; also the action of moving a camera toward or away from a scene, as to dolly in or dolly out.
Dolly blocks. (Sheet-Met. Wk.) Oddshaped steel blocks used as seaming irons for irregular shapes and for reshaping and straightening fenders.
Dolomite. (Mineral.) A limestone containing a high percentage of magnesia. (Min.) Used as a refractory in the steel industry principally for the bottom and sides of open-hearth furnaces. Found in many sections 'of the United States.
Domain. A small area in a piece of metal, such as iron, which behaves like a tiny magnet.
rotunda; a cupola.
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