The turntable has dominated as the most popular physical device used by DJs for controlling pre recorded music. There are many types of turntables but the SL-1200 model produced by Technics has remained the leading type of turntable controller since its creation. It is the industry standard.

Why has the turntable succeeded as the leading controller for music? It has many great advantages over other controllers such as CD players, tape players and 8-tracks.

Features:

1. Direct contact with the musical medium (vinyl)
2. Ability to adjust the pitch and tempo of a track
3. Fast access to sections of a track
4. Plays music backwards and forwards
5. Ability to scratch a vinyl record thus producing new sounds
6. Ability to see track information such as length and lulls (breaks) in sound
7. Produces a "warmer" analog sound

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 summarized as follows.

Limitations:

1. Needles become damaged and need replacing
2. Needles damage vinyl records resulting in lower sound quality
3. Heavy vibrations can cause the needle to skip resulting in an interruption in music
4. Large amounts of vinyl are needed for a set. A large volume of vinyl can become heavy and cumbersome to transport
5. Track selection may be difficult when trying to find the right groove
6. Relatively high cost
7. Limited pitch control
8. Control of pitch and tempo are not separate. Altering one, affects the other

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 Technics SL-1200 turntable, the industry standard, has six controlling devices that can affect the music. The first three are the primary controls of the turntable as they are used the most often.

1) The record on the turntable itself can be moved back and forth by hand. This provides 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 record, affecting the tempo and pitch of the song. A felt slipmat is placed between the record and platter to maintain the platter’s forward circular motion while the record is held. When the hand is removed, the record resumes its designated speed. A relationship between the movements of the record and the playback of the song is formed from this straightforward mapping. Due to the slipmat, the same relationship does not exist between the turntable platter and the music playback.

Manipulating a record can be useful for positioning the playback point of the music or temporarily adjusting the speed of one 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.

Control intimacy is defined by Moore as the compatibility with the performer and his/her instrument when regarding the performer’s psychophysiological capabilities versus the desired sound produced. To clarify, control intimacy provides a satisfying feeling of control from the correct production of a desired sound, via the instrument and the performer’s abilities to use it. Fels explores this concept further and suggests that direct interfaces promote control intimacy. We believe that the direct tangible nature of the turntable provides a high level of control intimacy when used as an instrument.

2) A pitch/speed slider is located on the right side of the unit. It provides a modulation of the platter’s speed within +/-8%. When placed in the middle, the platter should be moving at exactly 33 RPM or 45 RPM, depending on the speed mode; the 33 RPM setting is actually 33 1/3 RPM. 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 limited range continuous action that spans +/-8% of either 33 RPM or 45 RPM, depending again on the speed mode. If there is no power connected to the platter or the platter has been stopped, this slider has no effect.

3) The needle on the turntable provides random access within a song and temporal position feedback when it is placed in a groove. Placing the needle is a one dimensional limited range linear task.

4) 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 that illuminates the dotted sidewall of the platter. The strobing effect causes the dots on the sidewall to move back and forth, allowing the DJ to determine if the velocity of the turntable platter and the position of the pitch slider are calibrated correctly.

5) A start/stop button is located next to the power dial on the bottom left of the unit. It is used for ‘instant’ starting and stoping of the record. Pressing this button when a record is revolving engages a braking mechanism on the platter, halting the record. Pressing this button when a record is motionless causes the platter to start revolving. The Technics SL-1200 has a starting torque of 1.5kg-cm and a start-up time (from full stop to 33 RPM) of 0.7 seconds [1]. This button is a one-dimensional binary controller with two modes: start and stop.

6) 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 buttons, each with a light to indicate the mode of the platter. 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 achieved 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).