How Are Recordings Played Back?
To play back phonographic recordings, you place a needle in the groove on the flat or cylindrical recording. The needle vibrates at the frequency of the waves inside the groove. In older mechanical phonographs, these vibrations transfer from the needle to a diaphragm in the phonographic cartridge. Those sounds transmit through a mechanical amplification system that ends with a mechanical speaker called a horn. In electrical and electronic systems, such as those with modern phonographs, the vibrations of the needle are converted in the needle cartridge into electrical signals that are subsequently amplified by other equipment. Types of Needles Early phonographs used steel needles. In some cases, a new needle is needed after each record. Needles that are more modern are made with a diamond tip. Some models of mechanical phonographs, especially Edison, used a sapphire or diamond-tipped needle. Diamond needles are much more durable and may last for years without replacement. With modern ne
