Magnetic Reference Lab 21F101-A Tape, 3.75"-1/4 Open Reel

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.

Magnetic Reference Laboratory 21F101-A Specifications:

• Tape Width: 1/4" 6.3 mm)
• Playing Time: 6 minutes
• Tape Speed: 3.75" per second (95 mm/s)
• Equalization Standard: IEC & NAB
• Fringing Compenstaed? No
• Level of Frequency Response Section: -10 dB
• Reference Fluxivity: 200 - 250 nWb/m