Block Diagram of Disc Recording System | New Topic

In this note, we are going to learn about the Block Diagram of Disc Recording System. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.

Author Name: Arun Paul.

Block Diagram of Disc Recording System

Audio signals in the output of a microphone are processed and amplified to drive a disc-recording unit to cut grooves in the lacquer compound of the disc. The figure depicts the block diagram of a disc-recording system.

This is the disc recording system block diagram, and below we will discuss the function of each block in the block diagram –

• Microphone: A high-grade microphone, like a condenser microphone or a specially designed cardioid microphone, is used to convert the sound waves into electrical variations called audio signals.
• Pre-amplifier: It amplifies the weak output of the microphone. It is a low noise, high-gain amplifier to get high signal -to -noise ratio.
• Processing Circuit: The amplified signals are processed to de-emphasise low-frequency signals and emphasize high-frequency signals to eliminate the chance of over-modulation for low frequencies and improve the signal-to-noise ratio for high frequencies.
• Driver Amplifier: The processed signals are further amplified for voltage amplification, so that a high output voltage is available to drive the next stage to give adequate power.
• Power Amplifier: It provides power amplification to the signal. Its internal resistance is low, and the output circuit has a matching transformer to match the source and load impedance with each other.
• Recording Unit: The output audio power from the power amplifier is used to drive the recording unit to convert audio signals into mechanical vibrations.
• Cutter Stylus: It cuts spiral grooves on the disc, producing a wavy pattern in the horizontal plane when audio signals cause the stylus to vibrate laterally. The stylus moves radially on a rotating disc, and hence, cuts spiral grooves from the edge of the disc to its centre.
• Disc: It consists of a wax or lacquer coating on a metal disc. Grooves are engraved on the coating by the vibrating stylus.
• Turntable: The turntable carries the disc over itself. When the turntable rotates, the disc placed on it also rotates.
• Motor: It is used to drive or rotate the disc at a constant speed. A synchronous motor is used because the speed of a synchronous motor remains locked to the frequency of ac mains, which is very stable. The steady speed is necessary to reduce wow and flutter noise during playback. The connection between the motor and the turn-table may be means of gears, friction drives, and belts.