Editing Edison Disc Record (section)

==Rise and fall==
Diamond Discs enjoyed their greatest commercial success from the mid-1910s to the early 1920s, with sales peaking in 1920.<ref>{{cite web|url=http://www.mainspringpress.com/edison_kasakove.html|title=EDISON DIAMOND DISC MANUFACTURING PROCESSES – By Paul B. Kasakove / THOMAS A. EDISON, INC.|publisher=Mainspringpress.com|access-date=18 September 2014|archive-url=https://web.archive.org/web/20150915190850/http://www.mainspringpress.com/edison_kasakove.html|archive-date=15 September 2015|url-status=dead}}</ref> Although they arguably had better audio fidelity, they were more expensive than, and incompatible with, other makers' products and ultimately failed in the marketplace. Not least among the factors contributing to their downfall was Thomas Edison's insistence on imposing his own musical tastes on the catalog. As an elderly man who favored old-fashioned "heart" songs and had various idiosyncratic preferences about performance practices, he was increasingly out of touch with most of the record-buying public as the [[Jazz Age]] of the 1920s got underway. It was not until mid-decade that he reluctantly ceded control to his sons.

In 1926, an attempt at reviving interest in Edison records was made by introducing a long-playing Diamond Disc which still rotated at 80 rpm but tripled the standard groove pitch to 450 threads per inch by using an ultra-fine groove, achieving a playing time of 24 minutes per 10-inch disc (12 on each side) and 40 minutes per 12-inch disc (these were the only 12-inch Diamond Discs ever sold to the public). A special reproducer and modified feed screw mechanism were required to play them. There were problems with skipping, groove wall breakdown, overall low volume (about 40% of that of the regular Diamond Discs), and a failure to exploit the format by releasing a limited number of discs. Only 14 different Edison Long Play discs were issued before they were discontinued.

In August 1927, [[Sound recording and reproduction#Electrical|electrical recording]] began, making Edison the last major record company to adopt it, over two years after [[Victor Talking Machine Company|Victor Records]], [[Columbia Records]], and [[Brunswick Records]] had converted from acoustical recording. Sales continued to drop, however, and although Edison Diamond Discs were available from dealers until the company left the record business in late October 1929, the last vertically cut direct masters were recorded in the early summer of that year. Priority had been redirected to introducing a new line of Edison lateral or so-called Needle Type thin shellac records, compatible with ordinary record players, but although their audio quality was excellent this concession to commercial reality came too late to prevent the demise of the Edison Phonograph and Records Division just one day before the [[Wall Street crash of 1929|1929 stock market crash]].<ref>Recent comparisons of late popular-series Diamond Discs with the few released "Needle Type" lateral-cut versions of the same titles indicate that Edison had been splitting their electrical signal during recording to both vertical and lateral lathes since early 1929, as the performances time out identically – the last Diamond Discs are an average of over a minute shorter than 1927-28 releases, fitting the recording time capacity of the ten-inch diameter lateral issues – and have near-identical frequency ranges.</ref>