This is the main tool for any "respectable" DJ. It is the voice of the DJ, the hands of the DJ and source of the music. Vinyl records are placed on the main platter of the turntable and a needle arm (containing a needle) is placed on the records. This needle fits into the grooves of the records and reads the musical information stored there. Of course, DJs can use other methods for playing music...such as CDs or MP3s but to most DJs, there is a certain style, hands-on feeling or flare about mixing and spinning round pieces of vinyl.

For years, Technics, has made the standard 1200 series turntable . This deck is so popular that almost every turntable company has copied the basic design in an attempt to meet the demands.

The main advantage of a turntable is the direct access to the medium on which the music is maintained. No other musical playback device allows the user to directly access the medium which holds the music. Vinyl records, on the other hand, are large, easily viewable and can be handled easily with a hand. Usually each side of a vinyl record will contain one or two tracks. With such a large surface for a track, the DJ can easily see the grooves in the record. The grooves on the vinyl play an important role in that they show the DJ what will happen in a track. Subtle moments in the music (known as breaks) will be seen as sparsely laid grooves whereas music with lots of frequencies being used will be represented by grooves that are much closer together. By viewing the grooves, the DJ can anticipate changes in the track and act accordingly.

Grooves also play an important part in track selection. When a side of vinyl contains more than one track, the DJ can note the beginning of the sequential tracks by looking for the large dark grooves. If the DJ were to play the third track on a piece of vinyl that contained five tracks on one side, he or she would have to count three grooves in from the beginning of the record and place the needle there. There is a potential for error here as the DJ must correctly place the needle in the proper groove in order to select the correct track. Even after the needle has been placed properly, the DJ must push the record forward a little to find the exact starting point of the track. Each of the dark grooves between each new track consists of a small duration of dead air.

There are other limitations with the turntable. They are listed above.

Perhaps the biggest disadvantage with the turntable is the damage which occurs to both the needle and the vinyl records that are used with the turntable. Each time a vinyl record is played, a (diamond-tipped) needle rubs over the surface of the vinyl. Naturally this causes friction which wears the vinyl down over time. Often the needles become worn as well, resulting in an increased amount of skipping as the needle no longer fits snugly into the groove. The combination of these two forms of damage causes a loss of sound quality over time.

Analysis

The Technic SL1200 turntable (the industry standard) has 5 controlling devices that can effect the music.

1) The power switch is a dial on the bottom left of the unit. It has two modes (on and off) and is operated by turning the dial until it clicks, signifying a change in mode. This is a one dimensional binary task. If the power is switched off when a record is spinning, the record does not come to a complete stop. Instead the power for the motor is turned off and the platter containing the record, continues to revolve until enough friction causes it to stop. This dial is housed on top of the red strobe light which illuminates the sidewall of the platter allowing one to know when the correct pitch has been achieved.


2) A start/stop button is located next to the power dial on the bottom left of the unit. It is used for "instant" starts and stops of the record. Pressing this button when a record is revolving causes a braking mechanism to be used on the platter, halting the record. Pressing this button when a record is motionless causes the platter to start revolving. The Technic SL1200 has a starting torque of 1.5kg-cm and a start up time of 0.7 seconds. This button is a one dimensional binary controller with two modes (start or stop).

3) A speed mode switch is located next to the start/stop button and is used for setting the speed of the platter to rotate at either 33 RPM or 45 RPM. This consists of two button, each with a light to indicate which mode the platter is in. If the light for the 33 RPM mode is illuminated and the 45 RPM button is pressed, the platter switches to 45 RPM. Likewise, if the 33 RPM button is pressed in 45 RPM mode, the platter reduces speed to 33 RPM. If the speed mode button of the current speed is pressed, nothing will happen. Interestingly enough, if the platter is moving at 33 RPM and the 45 RPM speed button is depressed as well as the 33 RPM button, the speed of the platter will speed up to 45 PRM until the 45 RPM button is released and then the platter will resume 33 RPM. This is useful for bending the speed (and pitch) upwards when trying to adjust speeds while beatmatching. If running in 45 RPM mode and both the 33 and 45 RPM buttons are depressed, the effect is to remain in the 45 RPM mode. Thus the modulation can only be acheived upwards from 33 RPM to 45 RPM. This last feature makes the controller a one dimensional binary controller with two modes (33 RPM or 45 RPM) and modulation. We can modulate the speed (and pitch) of a track upwards based on a mode switch and a proportional time modulation. The more we hold the 45 and 33 RPM buttons down at the same time (when in 33 RPM mode), the longer the modulation of the speed (and pitch).

4) A pitch/speed slider is located on the right side of the unit. It controls the speed of the platter within +/-8% of the designated speed. When placed in the middle, the platter should be moving at its exact designated speed. When moved toward the front of the unit, the platter will speed up. When moved towards the rear of the unit, the platter will slow down. This is a one dimensional continuous action that spans +/-8% of either 33 RPM or 45 RPM, depending on the current speed of the platter. If there is no power connected to the platter or the platter has been stopped, this slider has no effect.

5) The platter on the turntable itself can be moved back and forth by hand. This allows the user to have great control over the speed and direction of the music. By placing a hand on the record as it spins around the platter, the user can speed up or slow down the platter and record. When the hand is removed, the platter will resume its designated speed again. This can be useful for positioning the point of a musical track to the desired location or temporarily adjusting the speed of a track to match another. It is also very useful in the art of scratching a record back and forth to produce new and unique sounds. Since the record can only travel back and forth across the needle, this is a one dimensional continuous task.