The sound quality and durability of vinyl records is highly dependent on the quality of the vinyl. During the early 1970s, as a cost-cutting move towards use of lightweight, flexible vinyl pressings, much of the industry adopted a technique of reducing the thickness and quality of vinyl used in mass-market manufacturing, marketed by RCA Victor as the "Dynaflex" (125 g) process, considered inferior by most record collectors.[27] Most vinyl records are pressed on recycled vinyl.
New "virgin" or "heavy" (180–220 g) vinyl is commonly used for modern "audiophile" vinyl releases in all genres. Many collectors prefer to have 180 g vinyl albums, and they have been reported to have a better sound than normal vinyl. These albums tend to withstand the deformation caused by normal play better than regular vinyl[citation needed]. 180 g vinyl is more expensive to produce and requires higher-quality manufacturing processes than regular vinyl.
Since most vinyl records are from recycled plastic, impurities can be accumulated in the record, causing a brand new album to have audio artifacts like clicks and pops. Virgin vinyl means that the album is not from recycled plastic, and will theoretically be devoid of these impurities. In practice, this depends on the manufacturer's quality control.
The orange peel effect on vinyl records is caused by worn moulds. Rather than having the proper mirror-like finish, the surface of the record will have what looks like an orange peel texture. This introduces noise into the record, particularly in the lower frequency range. It should be noted that with direct metal mastering (DMM) the master disc is cut on a copper-coated disc which can also have a minor "orange peel" effect. As this "orange peel" originates in the master rather than being introduced in the pressing stage, there is no ill-effect.
While most vinyl records are pressed from metal discs known as 'stampers', a technique known as lathe-cutting is used to create the original discs. A lathe is used to cut microgrooves into an aluminium disc coated with a soft lacquer. This lacquer disc is then electroplated with nickel to form a negative known as a 'master' disc, which has a protrusion rather than a groove. The lacquer disc is destroyed when the nickel impression is separated. This master disc is then electroplated with nickel to form a positive disc known as a 'mother'. Many mothers can be grown from a single master before the master deteriorates beyond use. In their own turn the mothers are nickel plated to produce more negative discs known as 'stampers'. Again a single mother can grow many stampers before they deteriorate beyond use. It is these stampers that are then used to mould the final vinyl discs.[28] In this way several million vinyl discs can be produced from a single lacquer original. For production of discs where a relatively small quantity is required, the first nickel negative grown from the lacquer original is used directly as a stamper. Production by this latter process (known as the 'half process') is limited to a few hundred vinyl discs.
Shellac 78s are brittle, and must be handled carefully. In the event of a 78 breaking, the pieces might remain loosely connected by the label and still be playable if the label holds them together, although there is a loud "pop" with each pass over the crack, and breaking of the stylus is likely.
Breakage was very common in the shellac era. In the 1934 novel, Appointment in Samarra, the protagonist "broke one of his most favorites, Whiteman's Lady of the Evening ... He wanted to cry but could not." A poignant moment in J. D. Salinger's 1951 novel The Catcher in the Rye occurs after the adolescent protagonist buys a record for his younger sister but drops it and "it broke into pieces ... I damn near cried, it made me feel so terrible." A sequence where a school teacher's collection of 78 rpm jazz records is smashed by a group of rebellious students is a key moment in the film Blackboard Jungle.
Another problem with Shellac was that the size of the disks tended to be larger due to the fact that it was limited to 80-100 groove walls per inch before the risk of groove collapse became too high, whereas vinyl could have up to 260 groove walls per inch.
没有评论:
发表评论