Phonograph Players

Please note that this chapter is in outline form and will be fleshed out later. Use it to guide you through your own research.

The vinyl phonograph record is obsolete but has a niche market for those who like the particular sound it provides. The unique sound of vinyl recording is largely due to the necessary audio compression and compensation required to put a wide range of sounds on this medium. The dynamic range of vinyl recording is narrow. Therefore, loud sounds must be made quieter and soft sounds must be made louder before recording (dynamic range compression). High frequencies are reduced on playback. This is to reduce clicks and pops caused by the stylus riding over scratches or debris. To compensate, high frequencies are emphasized during recording (RIAA emphasis and equalization). The final result is a sound with an artificially narrow dynamic range and frequency artifacts from emphasis and equalization that many people prefer to the more faithful reproduction of digital audio (many enthusiasts call the sound "warm").

Phonograph recording

Monaural

The groove makes a sinuous path that corresponds to the sound waves recorded on the disk

Stereo

Each wall of the groove carries a separate channel. The walls are angled 90º to each other so that the movement along one wall is easily separated from movement along the other.

Discrete 4-channel

Obsolete

Each wall of the groove carries audio frequencies for one channel and an ultrasonic carrier (like a radio carrier) that is amplitude modulated with a second channel. The audio frequency channel contains the sum of the front and rear channels. The channel on the ultrasonic carrier contains the difference (front channel minus rear channel). The decoder uses the difference information to extract the original front and rear channels from the audio frequency channel.

Phonograph reproduction

Turntable

Must turn at 33-1/3 RPM for long-playing records

Must turn at 45 RPM for singles

Must not introduce vibrations to the record (they will be picked up by the stylus and heard in the speakers).

Stylus

Conical (spherical)

Standard stylus shape

Cone shaped from side view, round from end view, spherical tip

Elliptical

Tighter curve on edges reaches into smaller groove curves for better high-frequency response

Shibata

Designed with a small-radius end view to track the tiny curves of the ultrasonic frequencies

Has a front/back profile with a larger contact area for less record wear.

For discrete 4-channel vinyl recordings from the 1970s

Other shapes

Several designs from the late 1980s onward that improve tracking and contact

Laser

Uses a laser to track the groove without physical contact

Pickup

Piezoelectric (crystal)

Efficient, does not require a preamp

Magnetic

Better frequency response

Requires preamp

Stereo pickups have two transducers, angled 90º to each other. Each transducer picks up vibrations from a different wall of the groove.

Preamplification

RIAA Equalization