[Vintage-Audio] Re Ultra Thin Flex Records

[Robert Nickels]

Here's what wikipedia has on Dynaflex, which was then and still is, 
somewhat controversial:

Dynaflex was a type of vinyl LP album record pressing introduced by RCA 
Records in late 1969. Rather than using the stiff plastic material used 
by conventional vinyl pressings, Dynaflex records used a "flexible" 
formulation that allowed RCA to use less less material, saving money and 
also making the record appear to lie flatter on turntables. At the time, 
many industry record pressing plants were using "reground" vinyl, taking 
old records, removing their paper labels, then melting them down and 
reusing the plastic components to make new records. Such "reground" 
vinyl records typically sounded much noisier than a record made from 
"virgin" vinyl; collectors noted that "reground" records sometimes had 
small remnants of paper embedded in the outer edge of the LP.

Dynaflex records were flexible enough that they literally "flopped" back 
and forth when held in the hand. Their flexibility also gave them 
theoretically more resiliancy in shipping, resulting in fewer returns 
from retailers due to breakage and cracks.

Opinions from record collectors and audiophiles are divided as to 
Dynaflex' sound quality. Some felt that the sound quality actually 
improved, due to better processes for removing impurities in the vinyl 
compounds; others feel that Dynaflex pressings were both noisier and 
lacked bass frequencies compared to conventional records, and also had 
more "rumble" (low frequency noise) than conventional thick pressings. 
While RCA claimed that Dynaflex records would not warp as much as 
conventional vinyl records, due to their flexibility, die hard record 
fans (particularly classical buffs) decried the new technique, calling 
it "Dynawarp," and claiming that Dynaflex records were warping on 
dealers' shelves, just from the pressure of the shrink wrap on the album 
jacket.

RCA eventually discontinued Dynaflex in the late-1970s/early-1980s.

Note that Dynaflex is a completely different process than RCA's 
Dynagroove, which was a technique that introduced a predefined amount of 
distortion during the record-cutting process, in an attempt to 
compensate for mediocre phono cartridges used by consumers in the early 
1960s. Unfortunately, the process detracted from sound quality when 
Dynagroove was used with high quality phono cartridges. RCA discontinued 
Dynagroove in the late 1960s.

73, Bob W9RAN