While 8 - tracks and cassette are as relevent to the digital world as wax piston chamber , the vinyl group LP is still being steadily produced and roll up despite , or perhaps thanks to , their imprecise strong analogue acoustic . Here ’s how LPs get their unique sound .
Thomas Edison is credited with cook up the phonograph , the first gimmick to both immortalise and play back audio , in 1877 . It recorded sound directly as indentations on a canvass of tin foil wrap around a well-grooved cylinder , which could then be play back by rotating the cylinder , which would moved the phonograph needle across the indentations , vibrate the mechanical diaphragm accordingly and procreate the strait . By the 1880 ’s Volta Labs had devise a ranking wax - coat composition board piston chamber whose stylus vibrated laterally , like a seismometer , to inscribe the wax with recorded sound rather than vertically , known as the “ hill - and - dale ” method acting , like Edison ’s . It was n’t until the other 20th century that the piston chamber was finally exchange by the categoric disc record we use today . But even then , sound were recorded like a shot , automatically onto the disk . “ acoustic ” recordings like these trust on a large horn connect to a style . As the profound undulation caused the car horn to oscillate , so too did the stylus , which transcribed the vibration to a hand - crank wax disk . As you ’d expect , these lo - fidelity recordings go like a cat yelling into a hooter — the maximal mass was severely limited to the acheivable physical effects of the trump and the cut style . The extra endeavour required to generate additional volume qu8ickly put on down both the record and the stylus .
The problem is that the amplitude of a bass bill is so much magniloquent than that of a higher - slant note , the down in the mouth - frequency sound takes up more physical quad in each grove , literally crowd out the mid and upper range sounds that would be lose during playback . This resulted in a deformed , bass - heavy playback . It was n’t until about 1925 that the audio input was run through a mic and amp to boost the active mountain range and intensity without trust on the physical attributes of a horn and the era of “ electrical ” transcription start . These transcription designedly rescale ( read : boosted ) upper cash register sounds and inhibit the bass , “ equalizing ” the sounds during playback . 78s — record book that spun at 78 RPM — were image as a neat technological leap over the hand - crank herald . Per Compton Pakenham of The New York Times in 1930 ,
The time has hail for serious musical unfavorable judgment to take account of performance of heavy euphony reproduced by substance of the records . To claim that the records have succeeded in exact and complete reproductive memory of all details of symphonic or operatic performance … would be extravagant … [ but ] the article of today is so far in advance of the former machine as hardly to take classification under the same name . Electrical transcription and reproductive memory have combined to retain vitality and color in recitation by procurator .
That quality only increase in the 1950 ’s with the introduction of 33 revolutions per minute discs , which retain about 25 minutes of music per side , and audio tape recording , which could be easy edited and its audio optimized in office yield , then knight onto a master phonograph record for replication . This master magnetic disc is have intercourse as a laquer or acetate rayon disc . Acetate is really a bit of a misnomer as the discs are actually lacquer coated with cellulose nitrate . And unlike mickle get vinyl radical records which are mold , the master disc is physically geld , its groove gouged out on by a record - cutting machine ’s needle whose mechanically skillful move is guided by an audio input signal . The groove are routinely check during the cutting summons to secure a proper depth of cold shoulder and to adjust bulk and pitch on the playback . Once the audio has been transcribed and the playback quality verified , the cut laquer is commit to a product company .
The laquer is far too maleable to be used in the actual production process , so a metallic element cast must be made of it . Originally , the laquer was coated in an exceedingly fine stratum of electrically - conductive graphite to which silver or Ni was then plated . Once the denture was thick enough , the wax was plunder away leaving a sturdier metal mold . Modern proficiency postulate dip the phonograph record into a solution of stannous chloride and then spray on atomized ash gray . The conventional metal plating bath technique is also still widely used but is not as acoustically accurate .
After the initial silver metal plating has indurate , a layer of all right - grain fuzz is applied , followed by a layer of more full-bodied , coarse - cereal metal like steel . Fine - grain metal , wherein the case-by-case grains are relatively small ( packing 85 or more grains per substantial column inch at 100 diam magnification ) and have ameliorate strength and toughness than coarse grained blade , which is more easily machinable . Once enough metal has been applied to plunk for the facile plate , the laquer is smashed innocent of the mold , leaving the metal negative , or “ matrix . ”
The ground substance is still somewhat maleable so it must be remold once more before it can begin pressing vinyl . A metal record known as “ the female parent , ” is thin from the matrix and then replated to create another negative make out as the “ stamping machine . ” And since the mother is burn from a metallic element such as cop , it can stand firm multiple recastings to roil out multitudes of stampers , which are then used to campaign the actual production records .
Each stamping machine , which is attached to an self-directed 100 - short ton hydraulic military press , works essentially like a waffle iron and can churn out thousands of records before involve refilling . A flat solid of preheated vinyl approximately half the domain but 3 times the heaviness of a ruined saucer , known as the biscuit , is slipped between the jaw of the press , 300 degree F steam is applied to further yield the fabric before the jaws close , and squeeze the hot vinyl into its last shape while imprint the sound recording . The disk is then cool and hardened in a water bath and labelled — all of which is done automatically , the only human input is the payload of the two disc label sandwiched around the biscuit .
Once it come off the stamper , the record ’s ragged edge are trimmed into a neat circle on an automatize trimmer joist tabular array and the phonograph recording is inspect , both visually and audibly . Many , many , pressings do n’t pass muster and are afterwards dethaw back down into biscuit for another go . But the LPs that are quality enough are then box and ship out to your local main music retailer .
[ Eil – Yale – Core 77 – Modern Mechanix – Wikipedia – How Stuff Works – transcription History – Record Collectors Guild – Infill Plane – Image : Jim Hughes/ Shutterstock ]
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