The following "warning regarding LP Mode" was condensed from JVC's service manual for the GY-DV300 camcorder: It applies equally to all MiniDV format equipment.
The track width in SP mode is 10 microns (approximately 1/10 the width of a human hair). In LP this is reduced to approximately 5 microns. In both modes the head drum spins at 9000 rpm and has to be able to accurately position each head over it's respective track on a moving tape. The requirements in LP mode are right at the limit of manufacturing and mechanical tolerances. Block noise may be generated in the LP mode depending on the tape being used or the usage environment. Please take note of the following points:
Compatibility of LP tapes recorded on another unit
Reliable playback is possible only with tapes recorded on the same unit (self recordings). Block noise and sound errors may occur when playing an LP tape that has been recorded using another unit due to minute differences between units.
Compatibility of LP with environmental conditions
When playing back at normal temperature a tape that has been recorded in a low or high temperature environment, block noise and sound errors may occur. This is due to expansion/contraction of mechanical parts and thermal tolerance of electronic parts and circuits. The same may occur in the opposite situation as well.
80 minute tapes & LP mode
If an 80 minute tape is used, block noise may occur during playback, even on self recordings. Use of 80 minute tapes is strongly discouraged.
Head Drum replacement
When the head drum is replaced, compatibility with LP tapes made previously is lost and block noise may occur during playback. Valuable tapes should be recorded in, or dubbed to SP mode. If you have LP tapes recorded on a camcorder brought in for service, please supply at least one "sample" so the technician can confirm LP performance. In some cases, it will not be possible to play your LP tapes after head/drum replacement due to variances caused by manufacturing tolerances.
Courtesy Halle's Service, Inc.
Last modified: March 31, 2007