Magnetic Reference Lab 231-570-480-107

These test tapes contain a recording of a 3150-Hz sine wave, for use in measuring weighted peak flutter and tape speed according to current national and international standards.

According to IEC Standard 368 and other standards [1],[2], the measurement of the weighted peak flutter of normal recording and reproducing systems should be made on one element only of the system—either the recorder or the reproducer, but not on both at the same time.  This is for two reasons: First, it is desirable to separate the flutter due to the recording system from that due to the reproducing system because professional recordings are usually played on a different system from the one that they were recorded on.  Second, the recording system flutter adds vectorially to that of the reproducing system, and under some practical (but not too common) conditions, the flutter measured while simultaneously recording and reproducing may be anywhere from nearly zero to twice the true flutter for one element.

One convenient way to separate the recording flutter from the reproducing flutter is to reproduce a flutter test tape whose flutter is less than the value specified for the reproducer to be tested.  The weighted peak flutter inherent in MRL Flutter and Speed Test Tapes [3] is listed in the table below.  This value is adequate for routine measurements of most professional audio transports, to determine that the weighted peak flutter meets the specifications given by the manufacturer and those given by the IEC Standard 94-1 [4].  For professional applications, this Standard calls for the weighted peak flutter of the recorder or reproducer at 190 mm/s (7.5"/s) to be less than ±0.15%.

In general you should not measure flutter while simultaneously recording and reproducing, for the reasons given above.

Specifications:

• Tape Width: 1/4" (6.3 mm)
• Tape Speed: 7.5"/s (190 mm/s)
• Weighted Peak Flutter: +/- 0.05%
• Duration: 4 minutes