Magnetic Reference Lab 21L221
1/4" Multifrequency Calibration Alignment Tape for Open Reel Applications (30"/s, 250 nWb/M)

OUR PART #  21L221

These tapes contain a series of recorded sine-wave signals for general-purpose use for standardizing azimuth, equalization, and sensitivity (usually called "gain" or "level") of open-reel analog audio magnetic tape reproducers.  They are not intended for testing tape reproducer speed, flutter, distortion, or track placement.

The signals on these tapes can be monitored with a voltmeter—either the program level meter in the tape reproducer or an external voltmeter.  Useful auxiliary test equipment includes a loudspeaker or headphones to hear the voice announcements of frequencies and levels, an oscilloscope to observe waveforms, and a level recorder in order to provide a graph of the frequency response.


  • Tape Width: 1/4" (6.3 mm)
  • Playing Time: 6 minutes
  • Tape Speed: 30"/s (760 mm/s)
  • Equalization Standard: AES (IEC2)
  • NOT Fringing Compensated
  • Level of Frequency Response Section: 0 dB
  • Catalog Number for Reference Fluxivity (250 nWb/M): 21L221
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