| Home | Audio Magazine | Stereo Review magazine | Good Sound | Troubleshooting Departments | Features | ADs | Equipment | Music/Recordings | History |
|
Wow and Flutter Limits Q. If a tape deck has a wow and flutter specification of, say, 0.06% wtd. rms, and if a tape is recorded and played back on this deck, what would be the wow and flutter? Would it be the same 0.06%, or 2 x 0.06%, or some other figure? Is it additive? When does it become objectionable? -Leonard Ross, Los Angeles, Cal. A. Wow and flutter can be additive or subtractive. When additive, the maximum level, using your example, would be s 2 x 0.06%. The point at which W & F becomes discernible, and therefore objectionable--tending to impart a grainy or coarse character to the program material--varies from one person to another and depends on the nature of the sound source; it is more perceivable on a single sustained note. At one time it was considered that it should not exceed 0.25%. Today, about 0.1% is considered the safe limit, or perhaps as low as 0.05%. Some decks do get below 0.05%. Head Materials Q. While shopping recently for a new cassette deck, I was overwhelmed by the variety of materials that are used in tape heads. Could you please describe the advantages and disadvantages of ferrite, permalloy, sendust, cobalt amorphous, glass, etc.? -Jeff Jacobsen, Austell, Ga. A. Your question demands an extensive answer that goes beyond the limitations of this column. Therefore, only a few general comments follow. Each of the head materials you describe has its advantages and disadvantages. For example, ferrite has the advantage of resistance to wear and therefore of long life. But this is not always a preferred material for recording when its distortion characteristics are considered. Within each type of material, there are variations of quality, according to manufacturer or according to which of several grades is used. This mitigates against my giving a statement as to which type is best for a given purpose (recording, playback, erasure). The price of a deck tends to reflect the quality of the heads employed. It is not uncommon to find that a given deck uses different head materials for the several heads, each chosen for optimum performance. New Shell Q. I've noticed some mechanical vibration picked up by the playback head when playing older prerecorded cassettes. Is there any way I can cure this? Is it practical to remount the tapes in new shells? -Gerald Pasternack, Colts Neck, N.J. A. If you are not all thumbs, you can transfer a tape to a new shell. If your audio dealer doesn't carry it, try Radio Shack (Cat. No. 44-626, $1.19). (Source: Audio magazine, Nov. 1991, HERMAN BURSTEIN) = = = = |
Prev. | Next |