Kenwood XD-9581MD instruction manual MD system, CaseImportantof difficultyItems

In caseImportantof difficultyItems 77

XD-9581MD (En)

MD system

The Mini Disc system has the features as summarized in the following.

1Like CD (Compact Disc), playback can be started from any position. (Random access)

2 It uses a disc with a diameter of 64 mm that is accommodated in a cartridge.

3 Two types of discs can be used.

4 Up to 74 minutes of recording or playback is possible using high-efficiency coding technology. 5 Countermeasure against vibration is taken using semiconductor memory chip.

Two Mini Disc types

There are two types of Mini Disc, the one designed exclusively for playback and the other which is both recordable and playable.

Playback-only Mini Disc

This type of MD can be used only for playback, and is used by the commercially-available music MD software packages. The playback-only MD is an optical disc like the Compact Disc (CD). The signals are recorded as the presence or absence of small pits and read out by an optical, non- contact pickup.

High-efficiency coding technology “ATRAC”

The Mini Disc has only a half the size of the Compact Disc but provides the same recording time. This is made possible by ATRAC*, a newly developed high-efficiency coding technology.

* ATRAC: Adaptive TRansform Acoustic Coding

The ATRAC compresses the music data to about 1/5 the amount of data which would be obtained with conventional technology, by cutting off the sound components which do not pose problem in audition even when they are not present. This has made it possible to record or play up to 74 minutes.

Recordable Mini Disc

This MD is a magneto-optical disc which can be recorded by magnetic field modulation. To record signals, laser light is irradiated from the bottom side of the magneto-optical disc and magnetic field is applied from the upper side of it.

Sound-skip prevention memory

During playback, this unit always stores signals in memory temporarily to prevent sound from being skipped in case of vibration. As a result, even when the data from the optical pickup is interrupted due to vibration, etc., the music will not be interrupted because the memory holds the data for several seconds.

Mini Disc

Preparation section

Basic section

Sound does not af- fect the sensitivity of ears

Lowest and highest frequencies are not audible unless the sound has a certain level of volume.

Sensitivity of ears

During normal
playback	ofdata
The sound data for	sec.
several seconds is al-
ways stored during	Several
playback.
	Digital memory

Application section

Lowest fre-	Highest fre-
quencies	quencies

Reproduced sound

Small sound near large sound

A small sound is not audible to human ears if it is produced at the same time as a large sound. (Masking ef- fect)

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In case of vibration

Even when the read- out from disc is inter- rupted momentarily due to vibration or shock, the repro- duced sound from the memory will not be interrupted.

Reproduced sound

Knowledge sections