Harman Kardon CD301 Owners Manual - Page 4

Cassette Tape Handling • Be sure to remove the cassette tape from the cassette compartment after the end of operation to keep the tape quality and maintain the deck performance for a long time. • Store cassette tapes off from a strong magnetic field such as near a TV set, amplifier and speakers to prevent adverse effect on the recorded sound. • Before a cassette tape is played back or recorded, be sure to eliminate tape slackness. A slackened tape, if used, may cause jamming in the tape running mechanism. 0 If the sound recorded on the tape is desired to be protected from accidental erasure, remove the erase-prevention tabs. With these tabs broken out, accidental erasure can be prevented even if the RECORD button is inadvertently pressed. Remove the tab with e screwdriver. Remove tape slackness by winding with a pencil. 0 If it is later desired to record on a cassette tape protected in this way, cover the holes with adhesive tape. Doi by C-Type NR System Your deck provides the Dolby C-Type Noise Reduction system, which is said to be the ultimate in noise reduction system. Also, you can work the standard Dolby B-Type Noise Reduction System by changing the B-C select switch. The Dolby NR System is one of the methods for reducing the noise that is created during the play back of a tape, and is now widely and internationally used. The noise which this system reduces largely emits from the tape itself and this system cannot reduce the noise which comes from the program which is being recorded. Therefore, in order for the Dolby NR System to function more effectively, it is important to avoid recording from signals either from records or FM radio that contain a lot of noise, i.e., it is important to choose signals with as little noise as possible. Principle Any magnetic tape used on a tape recorder contains native noise. In particular, among these noises, the middle and high frequency noises, which we can easily pick up by hearing, are called "hiss noises", and they are said to be caused by the size of magnetic particles on the tape. Hiss noises decrease if the magnetic particles are small, and also decreases if the tape is played at a higher speed. In other words, the high speed of the tape playing, and the small size of the magnetic particles produce the same effect as regards the hiss noise. In this respect a cassette tape played at a low speed, will produce more hiss noise. Function of the Dolby Noise Reduction When the recording input signals are lower than the standard level, those middle and high frequency sounds among those signals are gradually strengthened and recorded. The signals will return to the original state if a tape is played back opposite to the way it was recorded, i.e., if it is played back with middle and high frequency sounds above the standard level being gradually weakened. At the same time tape hiss sounds, which are middle and high frequency noises, created during the play back are reduced accordingly, as the signals become smal ler_ Noise reduction is achieved in this way. While the Dolby B-Type NR System has only the noise reduction capacity of the noise level of 10 dB, the Dolby CType NR System has a capacity of 20 dB. This C-Type NR System, in comparison, has an improvement in its function in the high frequency range so that it can be used for 0 dB recording. The Dolby C-Type NR System assures enough dynamic range and SN ratio to record a HI-FI program source. 50 40 30 (dB) 20 NR OFF 8-Type 10 0 20 C-Type 50 100 200 500 1000 2000 5000 10000 20000 (Hz) NOISE SPECTRA 4