Editing Edison Disc Record (section)

==Unusual characteristics==
Like cylinder records, the sound in a Diamond Disc's groove was recorded by the vertical method, as variations in the depth of the groove cut. At that time, with the notable exception of [[Pathé Records]], which used yet another incompatible format, a disc's groove was normally of constant depth and modulated laterally, side-to-side. The vertical format demanded a perfectly flat surface for best results, so Edison made his Diamond Discs almost one-quarter of an inch (6&nbsp;mm) thick. They consisted of a thin coating of a phenolic resin virtually identical to [[Bakelite]] on a core of compressed [[wood flour]], later also [[china clay]], lampblack for color, all in a rabbit-hide glue binder.<ref name="Gracyk1"/> With very rare exceptions, all were about ten inches in diameter, but they used a finer groove pitch (150 threads per inch, or "TPI") and could play longer than lateral ten-inch records—up to {{frac|4|1|2}} minutes per side.

Among their advantages over the competition, they were played with a permanent conical diamond stylus, while lateral-cut records were played with a ten-for-a-penny steel needle that quickly wore to fit the groove contour and was meant to be replaced after one use. A feed screw mechanism inside the Phonograph moved the reproducer across the record at the required rate, relieving the groove of that work and thus reducing record wear. This design was in response to the patent held by the Victor Talking Machine Company that states that the groove of the record itself is what propelled the reproducer across the surface of the record via the needle. The playing speed for Diamond Discs was specified at exactly 80 revolutions per minute, at a time when other makers' recording speeds had not been standardized and could be as slow as 70&nbsp;rpm or even faster than 80&nbsp;rpm, but were typically somewhere around 76&nbsp;rpm, leaving users who cared about correct pitch to adjust the playback speed for each record until it sounded right. Above all, there was, and still is, general agreement that the Diamond Disc system produced the clearest, most 'present' sound of any non-electronic disc recording technology.

Although [[Victor Talking Machine Company|Victor]]'s Victrolas and similar record players could not play Diamond Discs (at best, only very faint sound would be heard, while the crude steel needle seriously damaged the groove) and Edison Diamond Disc Phonographs could not play Victor or other lateral-cut discs, third-party suppliers came up with adapters, such as the Kent adapter, to defeat this incompatibility, but typically with less than optimal sound quality.<ref>{{cite web|url=http://pat.kagi.us/main.php?g2_itemId=15243|title=Very rare reproducer made for Victrola machines to play Edison DD records.|publisher=Pat.kagi.us|access-date=18 September 2014|archive-url=https://web.archive.org/web/20110824025507/http://pat.kagi.us/main.php?g2_itemId=15243|archive-date=24 August 2011|url-status=dead}}</ref> The [[Brunswick Records|Brunswick]] Ultona, the Sonora, and the expensive "Duo-Vox" phonograph made by the piano manufacturer [[Bush and Lane]] were the only non-Edison machines that came from the factory equipped to play Diamond Discs as well as Victor and other 'needle-type' records, along with [[Pathé Records|Pathé's]]  sapphire ball stylus hill-and-dale format that used a vertical groove that was U-shaped in cross-section. Edison discouraged all such alternatives by cautioning on some of the record sleeves: "This Re-Creation should not be played on any instrument except the Edison Diamond Disc Phonograph and with the Edison Diamond Disc Reproducer, and we decline responsibility for any damage that may occur to it if this warning is ignored."<ref>{{cite web|url=http://www.gracyk.com/brunswick.shtml|title=Tim Gracyk's Phonographs, Singers, and Old Records – Brunswick Phonographs and Records|publisher=Gracyk.com|access-date=18 September 2014|archive-date=7 September 2011|archive-url=https://web.archive.org/web/20110907054210/http://www.gracyk.com/brunswick.shtml|url-status=dead}}</ref> The very good reason for such discouragement was that Diamond Disc grooves were too narrow and fragile to propel a soundbox across a record surface, as lateral machines did; Edison's precise mechanical feed system on the Disc Phonograph for its weighted "floating" reproducer replaced that stress on its records.

[[Image:EdisonDiscLabelBunk.jpg|thumb|Edison Records "Diamond Disc" label, early 1920s, featuring [[the Happiness Boys]], [[Billy Jones (singer)|Billy Jones]], and [[Ernie Hare|Ernest Hare]]]]