Dynaflex was a type of 12-inch vinyl LP produced by RCA, and introduced in early 1971. It is essentially a very thin LP that was able to flex more without damage, and also claimed to produce a smoother and quieter playing surface.
When introduced, Dynaflex records had a thickness of just 0.03 inches, and a weight of 90 grams (standard LPs were usually around 135 grams).
Their thinness could cause problems with automatic record changers (two discs might drop instead of one for instance) and they needed to be played on a full-size turntable platter otherwise the unsupported section of the record might droop under the weight of the stylus.
There is debate about whether Dynaflex records sound better or worse than standard vinyl, but whatever the truth, RCA stopped using the Dynaflex name sometime in the late 1970s and returned to standard weight vinyl records.
Centre-start (or inside-start) phonograph records date back as far as 1905 with the Pathé vertical-cut disc record, that in addition to other unusual features such as being vertically rather than laterally cut and running at 90rpm, required the stylus to be placed in the area that on other records would be the run-out grooves. In 1915, Pathé switch to a more conventional outside-start.
Later, Electrical transcription discs (1920s – 1980s) often used centre-starts, sometimes on both sides and sometimes alternating with an outside-start on the second side, possibly to reduce changes in sound quality between the end of one side and the start of the other. As the stylus moves to the centre of a record, the linear groove speed decreases and there can be more ‘end-groove distortion’.
Since then, centre-start records have tended to be uncommon, and were usually used as a novelty or promotional feature. A couple of examples include King Kurt’s Destination Zululand 12-inch single (1983) and more recently Jack White’s Lazaretto 12-inch LP (2014), which had a centre-start on side one.
The EV Stereo-4 system (also known as EV-4) was a matrix quadraphonic format, developed by Leonard Feldman and Jon Fixler in 1970 and taken up by Electro-Voice as the first commercial quadraphonic system for vinyl records.
A handful of record labels used the system, including Ovation, Project 3 and Quad-Spectrum, and RadioShack sold compatible decoders and systems in the US.
EV Stereo-4 emphasises front (left to right) and front-to-rear separation, but there is less separation between the two rear channels.
In 1973 Electro-Voice introduced a decoder that could also play SQ and QS quadraphonic records with good results, but despite this Stereo-4 was pushed out of the market by these other systems and nothing appears to have been released on EV Stereo-4 after 1975.
Voice Records were small aluminium phonograph discs, intended to be used to record a personal message.
They were introduced in the 1930s in the UK, to be recorded in automatic booths operated by the Amusement Equipment Co. Ltd. of Wembley. The booths were placed in places were people might want to record a message to family or friends, such as tourist attractions.
The discs were 5-inches in diameter, span at 78rpm, and were double-sided with one side for recording up to one minute of a personal message and the other containing a pre-recorded advertisement (often for cigarettes, but sometimes promoting attractions local to the machine). The discs came with a mailing envelope for posting the recorded message and some wooden needles, since the steel needles used at the time on phonographs would damage the recording.
This most likely the system Graham Greene had in mind when writing Brighton Rock (1938) when Pinkie records his message to Rose.
The machines were withdrawn from service during World War II, when supplies of aluminium were needed for military use. It is probable that many Voice Records were donated as scrap for the war effort.
The Voice-O-Graph was a very similar later concept, but used laminated cardboard.
The Crown name was used by several record labels, but around 1935 was used by the Crystalate company to produce a range of 9-inch (22.5 cm) 78rpm records for Woolworths in the UK.
Woolworths had been selling its Eclipse range of 8-inch records since 1929, but rising raw material costs forced them to try something new and they began selling the Crown range in 1935. Unusually, these were pressed on Bakelite, an early form of plastic, and as this was cheaper than shellac the size could be increased. The grooves could also be packed more closely, allowing more playing time, but Woolworths were still able to sell them for sixpence.
The music on Crown records produced by Crystalate was almost all from UK masters, and included popular bands and singers of the time, including Vera Lynn (though she was uncredited).
By 1937, costs had risen and selling records for sixpence was no longer profitable so Crown records were dropped.
V-Disc was a record label that produced music for US military forces between 1943 and 1949, pressed on 12-inch 78 rpm phonograph discs. Most V-Disc records were pressed on a mixture of Vinylite and Formvar, making it much easier to dispatch records without breakage (many of the brittle shellac records sent by relatives arrived in pieces) although Columbia, one of the companies that pressed V-Discs, continued to use shellac despite it being in short supply during World War II.
The V-Disc label came about as a way to boost morale among the forces. A strike by the American Federation of Musicians over royalty payments from the major record labels meant an agreement that the V-Disc records were not to be sold commercially, and the masters were disposed of. The V-Disc project meant the forces could hear newly recorded music they would not otherwise hear due to the strike, and these included big band, swing, jazz and marches, often by famous performers who also put spoken greeting into the recordings.
Because of the larger disc size, and closer groove spacing, each side of the disc could hold up to 6 minutes, so performances could be longer and jams could be extended. Discs were sent in sets of 30, and included phonograph needles, lyric sheets and feedback forms to gauge which material was most popular.
After the war ended, the cost of producing V-Disc records meant that the project was gradually run down, with smaller consignments of discs, or longer intervals between them, though they continued to provide entertainment to forces stationed overseas as part of the Marshall Plan. The last consignment of 10 discs was sent in May 1949, and after this many masters and discs were destroyed as part of the agreement with the American Federation of Musicians.
Over 900 V-Disc record titles were issues, and over 8 million discs were produced.
Kid Kord was a record label in the UK, that produced records for children around the 1930s.
The records themselves were shellac, played at 78rpm and were 8-inches in diameter. Each disc contained about 2¼ minutes per side, and form part of an album of six discs. The colourful centre labels depicted the contents of the record.
Most of the records contained nursery rhymes and children’s songs, though there is a series of zoological records with descriptions of animals, and pictures of them on the centre label.
The National Library Service for the Blind and Physically Handicapped (NLS/BPH) began distributing magazines and books on flexible discs running at 8⅓ rpm in the early 1970s in the US. Machines capable of playing this very slow speed had already been made available a number of years previously when model AE-1 was introduced in 1965, and existing machines were also converted by volunteers. Standard ‘rigid’ records running at 8⅓ rpm had been available via the NLS/BPH since 1969.
Magazine titles available included Readers Digest, National Geographic, Sports Illustrated, and U.S. News & World Report.
The flexi-discs were 9-inches in diameter and had Braille centre labels. They also had narrower grooves than a standard record, so a finer stylus is required to avoid damage. The use of a slow speed and fine grooves allowed very long playing times, but lower fidelity. The discs could be produced quickly and cheaply, meaning audio magazines could be distributed as soon as possible after the print copy. Their success meant the NLS/BPH stopped using rigid records by the late 1980s.
After 1994, audio magazines on flexible disc began to be phased out in favour of Compact Cassettes, and the final discs were sent out in 2001.
Whilst the vast majority of Long Play records were played at 33⅓ rpm, a few records were made to be played at half that speed, 16⅔ rpm (usually listed as 16 rpm). Many of these were spoken word, since the slow speed meant lower fidelity reproduction, but despite this there were a few music releases, mainly from South Africa.
Even though 16 rpm records were rare even at the time, many record decks of the 1950s, 1960s and even into the 1970s came with a 16 rpm speed setting.
The current system for creating stereophonic (2 channel) phonograph discs date back to 1933 when Alan Blumlein, a senior sound engineer at EMI in London, demonstrated a single-groove system in which the stylus moves both horizontally and vertically.
When the 12-inch Long Play record was launched in 1948, it was initially monophonic, and it wasn’t until 1957 that stereophonic LPs were released, by now using a refined version of the EMI system developed by Westrex (a division of Western Electric) called Westrex 45/45 in which each channel drives the cutting head at a 45 degree angle to the vertical.
In late 1957, Audio Fidelity Records and Bel Canto in the US released demonstration stereo LPs, with the the Bel Canto release on multicoloured vinyl. The first mass-produced stereophonic LPs were released in early 1958.
Mono LPs continued to be released alongside stereo LPs for the next ten years or so with major labels ceasing production in 1968, but 7-inch singles continued to be mono for longer, into the 1970s in some cases.
Stereo records produced using the Westrex system played well on a mono record player, and mono records could be played on a stereo system.
In the 1970s, quadraphonic (4 channel) LPs were produced, but were not a great success partly because there were several competing and incompatible systems.