QuestionI listen to a lot of books on tape in my car and at home. It may be related to the tape, rather than the player, but do you know what causes a tape's volume to rise and fall during playback?
Also, I have had some tapes that seem to have dual tracks of the same thing that play concurrently, but one timed just slightly later than the other, and much softer, almost as if it were an echo (without sounding echo-y) of the first track. Thanks for your help!
AnswerThe first problem - varying volume - could be either the player or the tape. If its only with some tapes, then its just old tapes. If it only happens in the car tape deck or only the home tape deck then its got to be that particular unit. Volume by itself, expecially unacompanied by a varying tone called "warbling", could be anything.
There are indeed two tracks on a tape, one for the left and one for the right tracks of stereo sound. What you may be hearing is a sign that the tapehead isn't tracking the two at the same time, but to hear a distinct echo they'd have to be seperated by at least 40mS - not very likely. If it is the tapehead or the electronics behind it then you've got a VERY problematic tape deck.
What may be more likely is that when a tape reel is coiled up, especially in the heat of a car, sometimes it can become annealed.
The tape records sounds as changes in magnetic polarity. When the tape is coiled around one of the two reels (and all but three inches of it always are) some of the magnetic information on one layer of tape can be imprinted on its nearest neighbors, causing an echo effect (or sometimes a "reverse echo" where you can faintly hear a "ghost" of something before it plays). Anealing can also weaken the strength of the magnetic polarity in certain sections of the tape, reducing the strength of the signal (volume) in those sections. This can be doubly true if the tapes are exposed to heat AND sunlight.
To test I would suggest buying a tapehead cleaner and a test tape - this could be a brand new audio tape or an actual test standard tape.
Tapehead Cleaner:
http://www.jr.com/JRProductPage.process?Product_Id=21341&JRSource=googlebase.dat...
Test Tape:
http://www.jvc-victor.co.jp/english/media/testm/audio.html
Tape decks are surprisongly robust, but eventually everything wears out. You can test your luck by cleaning the tape head and see if things improve. Either way you may need to brace yourself for a replacement of your tapedeck(s) or tape(s) soon.
I wish you luck!
