• Brand: Ampex / Irish / Quantegy
  • Type: 311, 321
  • Reel: 5" (13cm), 7" (18cm), 10.5" (26.5cm)
  • Lengths Available: 600' (180m), 1200' (360m), 1800' (550m), 2400' (720m), 3600' (1100m)
  • Thickness: SP (1.5 mil), LP (1.0 mil)
  • Tape Grade / Performance Level: 1-Standard
  • Base Material: Acetate
  • 2024 Advice: Playback Only - Do Not Record, Acetate Vinegar Syndrome Possible, Wavy Tape - Possible Tape to Head Contact Challenges
  • Where Produced: USA
  • Mfg Years: Early 1950s - Early 1970s
  • Sale Condition: Used - At your own risk
  • Description:

    The Ampex 311 / 511 /911 are SP (standard play) tapes and the 321 / 521 /921 are LP (long play) of the 300 / 500 / 900 Series, first introduced under the Irish brand as the 300 series, with Acetate backing.  The brown oxide appearance is similar to most other Ampex Ferrosheen tapes made from the 1950s through the 1970s. The “11”  refers to “acetate, standard play”, and the “21” refers to “acetate, long play”.  In general, we recommend any of theses Ampex or Irish tape for Standard (type 1) applications made with their Ferrosheen process due to their longevity, low oxide shedding, and excellent frequency response for the time – but only with polyester backing.  They were superior to the Scotch 111 and 150, as those did not have the smooth surface of the Ferrosheen tapes. Our tests showed that the performance of the 300, 500 and 900 Series were virtually indistinguishable and can be considered identical for today’s purposes. Notes:

    • As with any Acetate backed tape, these present long term usage and storage challenges. The Ampex acetate tapes seem to hold up better than other brands but should not be considered reliable choices for daily use going forward. Their quality today is directly rated to the way they were stored, and their quality and longevity can not be guaranteed.
    • Tapes of this vintage have a tendency to shed oxide more than modern tapes. This is not a sign that this tape is degrading, it should be considered normal. Ampex tapes made with their Ferrosheen process seem to shed less today than their counterparts, and should be considered to be at the top of the quality chart for tapes made at the time.
    • The general quality of these tapes increased over their production run as general improvements were made, particularly with oxide shedding and smoothness.
    • Ampex tapes included the formula code on the tape hold down tab, supplied when new. Many users kept the tab or stuck it to the box, so this might help you identifying a formulation.
    • Available Refurbished: No, we do not sell these tapes, because of the acetate backing, as refurbished – but you can buy refurbished reels of the 300, 500 and 900 Series with polyester backing in our store.

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