The word turntable is the modern term used to describe what is known as the phonograph, gramophone, or record player. The first turntable was invented by Thomas Edison in 1877. It was the first device used for recording and playing back sounds. Modern turntables have the same fundamental components as their ancestors, albeit slightly more sophisticated in design. This paper covers the fundamental technical aspects of modern turntables.
A modern turntable basically works like this: A platter (on which the record sits) is spun by a drive system. The drive system spins the record at specific revolutions per minute (RPM). A pickup system in the form of a stylus and cartridge converts the audio on the record into an electrical signal. A tracking system in the form of a mechanical arm connects the cartridge to the turntable and also enables the pickup system to track the record grooves smoothly and steadily.
In short, there are three components of a modern turntable that need to be inspected in order to understand how one works. These three components are:
* Drive system
* Pickup system
* Tracking ststem
The drive system is the part of the turntable that rotates the platter in order to spin a record. There are two types of drive systems in common use today:
* Belt Drive
* Direct Drive
Belt Drive Systems
Belt drive systems consist of a motor and a belt that is connected to the platter on which the record sits. The motor spins the platter at a specific RPM. The most common rotation rates for modern turntables are 33 1/3 RPM and 45 RPM. Motors for belt drive systems are usually isolated or separated from the body of the turntable in order to reduce vibrational noise. However, the drawback to belt drive systems is that the torque is relatively low, so the amount of time it takes the platter to get to its proper velocity is much greater than a direct drive system.
Direct Drive Systems
Direct drive systems consist of a motor that is directly connected to the platter (sometimes the platter is even considered to be part of the motor). There is an almost instantaneous change in rotational velocity of the platter because of this direct connection (absence of a belt), with starting and stopping times of around 0.5 seconds. Another result of this direct connection is that the torque is much higher than in the belt drive models. Higher torque means the platter speed is less susceptible to outside forces, which is another reason why the platter will accelerate to its proper speed faster. This feature is one of the main reasons why direct drive turntables are so popular with DJs today.
A pickup system consists of a stylus and a cartridge. These are the components of the turntable that convert the sound waves etched on a record into an electrical signal. Two types of pickup systems are:
* Piezo-electric pickup systems
* Magnetic pickup systems
Piezo electric pickup...