• Brand: Ampex / Irish / Quantegy
  • Type:
  • Reel:
  • Lengths Available:
  • Thickness: SP (1.5 mil)
  • Tape Grade / Performance Level: 1-Standard
  • Base Material: Acetate
  • 2024 Advice:
  • Where Produced: USA
  • Mfg Years:
  • Sale Condition: Refurbished - 90 day warranty
  • Description:

    The Ampex 331 / 531 /931 are SP (long play) tapes of the 300 / 500 / 900 Series, first introduced under the Irish brand as the 300 series.  The brown oxide appearance is similar to most other Ampex Ferrosheen tapes made from the 1950s through the 1970s. The “31”  refers to “polyester, standard 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.  They were superior to the Scotch 111/102 and 150, as those did not have the smooth surface of the Ferrosheen tapes. Our tests showed that the performance of the 331, 531 and 931 were virtually indistinguishable and can be considered identical for today’s purposes. Notes:

    • These formulas have withstood the test of time. It is amazing to consider that you can make a high quality recordings on a 60 year old tape, but this is indeed possible.
    • 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.
    • Later versions of 331 were sold with black and silver boxes as “PRT 1200”, an acronym for “Polyester Recording Tape”.
    • Available Refurbished: Yes, you can buy refurbished reels of 331, 531 and 931 in our store.

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