A system is provided to receive a first request to write data to a hard disk drive (HDD) which comprises a plurality of tracks which can be configured as a conventional magnetic recording (CMR) media or as a shingled magnetic recording (SMR) media, wherein an SMR-configured track stores a greater amount of data than a CMR-configured track. The system writes the data to a first CMR-configured track, and classifies data stored in CMR-configured tracks as hot or cold based on a first or a second predetermined threshold. The system copies cold data from the CMR-configured tracks to an SMR zone, and makes available portions of the CMR-configured tracks previously occupied by the cold data.

A magnetic recording head is provided with a main magnetic pole that generates a recording magnetic field to be applied to a magnetic recording medium from an end surface which makes a portion of an air bearing surface, a trailing shield that is placed by interposing a write gap at a trailing side of the main magnetic pole, a spin torque oscillator that is placed within the write gap to be between the main magnetic pole and the trailing shield, and two side shields that are placed at both sides of the main magnetic pole in the cross track direction, and when viewed from the air bearing surface side, at least a portion of the trailing-side end surfaces of the side shields are offset toward a leading-side of the main magnetic pole from the leading-side end surface of the spin torque oscillator.

A sound source processing apparatus uses a magnetic drum to prevent sound quality deterioration and amplify the volume of sound when a sound source transmitted from a primary acoustic device is outputted. The apparatus receives, through an input end, a sound source outputted from the primary acoustic device, records the inputted sound source on a recording part (a magnetic coating surface) of the magnetic drum in a magnetic drum recorder, reproduces, in real time, the sound source recorded on the magnetic drum, and then amplifies it, sequentially passing the amplified sound source through a pre-amplifier and a power amplifier to amplify output and then sending it to a speaker. To prevent sound quality deterioration for repetitive playback, interaction caused by contact between sound sources is removed. Amplifying the volume of sound outputted in real time using the magnetic drum promotes enhanced sound quality.

A sound source processing apparatus uses a magnetic drum to prevent sound quality deterioration and amplify the volume of sound when a sound source transmitted from a primary acoustic device is outputted. The apparatus receives, through an input end, a sound source outputted from the primary acoustic device, records the inputted sound source on a recording part (a magnetic coating surface) of the magnetic drum in a magnetic drum recorder, reproduces, in real time, the sound source recorded on the magnetic drum, and then amplifies it, sequentially passing the amplified sound source through a pre-amplifier and a power amplifier to amplify output and then sending it to a speaker. To prevent sound quality deterioration for repetitive playback, interaction caused by contact between sound sources is removed. Amplifying the volume of sound outputted in real time using the magnetic drum promotes enhanced sound quality.