Posted by Elusive Disc on Aug 30th 2017
To truly understand the sounds you elicit from your rare vinyl record collection (and high-end turntables), you need to know a little (or a lot) about the manufacturing process.
In the days of wax and tinfoil cylinders (the late 1800s), sounds were recorded directly onto storage devices. Even when rotating discs replaced rotating cylinders in the early 1900s, engineers recorded sounds directly to discs. Because the wavelengths of bass sounds are so much larger than treble sounds, they dominated early recordings.
With the advent of amplified playback, a balance between bass and treble sounds became the norm. However, skilled recording engineers still navigate the delicate balance between treble/bass (and other factors)
Recording engineers “master” recordings in the studio, but much of the magic takes place in pressing plants. Experts create grooved acetate lacquers that suit vinyl’s limitations as a recording medium. To create the finest recordings, engineers guide the groove-cutting process by hand (or with sophisticated computer equipment).
Vinyl records need flat noise floors, and as much bass response as possible (without causing needles to skip).
Vinyl Record Material
Record pressers create vinyl records from polyvinyl chloride (PVC), the third-most-popular plastic polymer worldwide. This compound is easy to manipulate, chemical-resistant, and resists wear (with proper cleaning and storage, of course.)
Once acetate lacquers exacting standards, they are used to create metal discs for use with cutting lathes. Though older methods are still used, today’s master discs are typically dipped into stannous chloride and then sprayed with atomized silver. Layers of copper and stronger metals (like steel) are added to support this production mold. When the metal disc is strong enough, the lacquer is cracked away from this “matrix.” Successively more durable discs (the “mother” and “stamper”) are created from this matrix.
Cutting, Stamping, and Pressing
Stampers fit into 100-ton presses and can cut thousands of discs before they wear out. They press into “biscuits” of PVC, which are three times thicker than finished records. Though these biscuits are pre-softened, they are treated with 300F steam right before the jaws of the stamping press close.
Trimming and Printing
After stamping, records are cooled off (and hardened) in water baths. Excess PVC is removed from the edges of a record on an automatic trimming tables.
Inspection and Packaging
Before inserting records into sleeves, they are inspected both by eye and by ear. A great number of vinyl records don’t pass muster and are melted back down to create new biscuits.
Flaws in vinyl records are typically created by minor inconsistencies in temperature. If a soft biscuit of PVC doesn’t spread out evenly as it’s pressed, it will show radial lines after cooling. Likewise, if the PVC isn’t heated long enough, gasses don’t have time to escape, creating tiny craters on the surface of the record.
Many boutique companies prefer to manually package vinyl records in sleeves (though machine-packaging is much cheaper). The human touch at this stage of the process provides another layer of quality control – especially when it comes to rough edges (which DJs hate).
The Future of Vinyl Records
As casual music listeners go digital, audiophiles and collectors are moving toward vinyl in large numbers. This increase in demand has spurred the development of new technologies and systems for creating better and better vinyl records. Vintage are rare vintage vinyl records will always be treasures, but tomorrow’s products promise to deliver better sound than ever!