Science Fair Project Encyclopedia
Usage of these terms is somewhat different in American English and British English; see usage note below. In more modern usage, this device is often called a turntable or record player. In the late 19th and early 20th century, the alternative term talking machine was sometimes used. The phonograph was the first device for recording and replaying sound.
The term phonograph meaning "writing sound", is derived from Greek roots. Similar related terms gramophone and graphophone have similar root meanings.
Arguably, any device used to record sound or reproduce recorded sound could be called a type of "phonograph", but in common practice it has come to mean historic technologies of sound recording.
The earliest known invention of a phonographic recording device was the phonautograph, invented by Leon Scott and patented on March 25, 1857. It could transcribe sound to a visible medium, but had no means to play back the sound after it was recorded. The device consisted of a horn that focused sound waves onto a membrane to which a hog's bristle was attached, causing the bristle to move and enabling it to inscribe a visual medium. Initially, the phonautograph made recordings onto a lamp-blackened glass plate. A later version used a medium of lamp-blackened paper on a drum or cylinder—an arrangement to which Thomas Edison's later invention would bear striking resemblance. Other versions would draw a line representing the sound wave on to a roll of paper. The phonautograph was a laboratory curiosity for the study of acoustics. It was used to determine the vibrations per second for a musical pitch and to study sound and speech; it was not widely understood until after the development of the phonograph that the waveform recorded by the phonautograph was a record of the sound wavelength that needed only a playback mechanism to reproduce the sound.
The first phonograph
Thomas Alva Edison announced his invention of the first phonograph, a device for recording and replaying sound, on November 21, 1877 and he demonstrated the device for the first time on November 29 (he patented it on February 19, 1878; US Pat. No. 200,521). Edison's early phonographs recorded on a phonograph cylinder using up-down (vertical) motion of the stylus. Edison's early patents show that he also considered that sound could also be recorded as a spiral on a disc, but Edison concentrated his efforts on cylinders, since the groove on the outside of a rotating cylinder provides a constant velocity to the stylus in the groove, which Edison considered more "scientifically correct". Edison's patent specified that the audio recording was embossed, and it was not until 1889 that engraved recordings were patented by Bell and Tainter.
The first gramophone
Emile Berliner invented what he called the Gramophone, another device for recording and replaying sound, and patented it in on November 8,1887 (US Pat. No 372,786). It recorded on a disk using side-to-side (lateral) motion of the stylus.
British and American language usage differences
In British English "gramophone" came to refer to any sound reproducing machine using disc records, as disc records were popularized in the UK by the Gramophone Company. The term "phonograph" is usually restricted to devices playing cylinder records
In American English, "phonograph" was the most common generic term for any early sound reproducing machine. Berliner's Gramophone was considered a type of phonograph. "Gramophone" was a brand name, and as such in the same category as "Victrola," "Zon-o-phone," and "Graphonola" referring to specific brands of sound reproducing machines.
The brand "Gramophone" was not used in the USA after 1901, and the word fell out of use there. In contemporary American usage "phonograph" most usually refers to disc record machines or turntables, the most common type of analogue recording from the 1910s on. The word has survived in America based on its nickname form, "Grammy", in the Grammy Awards.
Disc versus cylinder as a recording media
Disc recording is inherently neither better nor worse than cylinder recording in potential audio fidelity.
Recordings made on a cylinder remain at a constant radial velocity for the entirety of the recording, while those made on a disc, have a higher radial velocity at the outer portion of the groove, compared to the inner portion.
Edison's patented recording method recorded with vertical modulations in a groove, Berliner utilized a lateraly modulated groove.
Though Edison's recording technology was better than Berliner's, there were commercial advantages to a disc system:
- The disc could be easily mass produced by molding and stamping, and required less storage space for a collection of recordings.
- The heavy cast-iron turntable acted as a flywheel and helped to maintain a consistant rotational velocity. The cylinder machine, lacking this greater rotational inertia, was suceptable to musical pitch fluctuations, and required more mechanical adjustment and maintainence to avoid this impairment.
Berliner successfully argued that his technology was different enough from Edison's that he did not need to pay royalties on it, which reduced his business expenses.
Through experimentation, in 1892 Berliner began commercial production of his disc records, and "gramophones" or "talking-machines". His "gramophone record" was the first disc record to be offered to the public. They were five inches (12.7 cm) in diameter and recorded on one side only. Seven-inch (17.8 cm) records followed in 1895. By 1901, ten-inch (25.4 cm) records being sold by the Victor Talking Machine Company, and Berliner had sold his interests. By 1908, double sided disc recorded records became demanded by the public, and cylinders fell into disfavor. Edison felt the commercial pressure for disc records, and by 1912, though reluctant at first, his movement to disc records was in full swing.
From the mid-1890s until the early 1920s both phonograph cylinder and disc recordings and machines to play them on were widely mass marketed and sold. The disc system gradually became more popular due to its cheaper price and better marketing by disc record companies. Edison ceased cylinder manufacture in the fall of 1929, and the history of disc and cylinder rivalry was concluded.
The dominance of the disc phonograph
Berliner's lateral disc record was the ancestor of the 78rpm, 45rpm, 33⅓rpm, and all other analogue disc records popular for use in sound recording through the 20th century. See gramophone record and vinyl record.
Christmas 1925 brought improved radio technology and radio sales, bringing many phonograph dealers to financial ruin. With efforts at improved audio fidelity, the big record companies succeeded in keeping business booming through the end of the decade, but the record sales plummeted during the Great Depression, with many companies merging or going out of business. Booms in record sales returned after World War II.
The "phonograph", "gramophone" or "turntable", remained a common element of home audio systems well after the introduction of other media such as audio tape and even the early years of the compact disc. They were not uncommon in home audio systems into the early 1990s.
Drive systems: direct and belt
Most turntable designs use a either a belt drive or direct drive system. Earlier designs also used a rubberized idler wheel drive system. However, non-linear wear and decomposition of the wheel introduced noise and speed variations into the desired audio. These systems generally used a synchronous motor which ran at a speed synchronized to the AC frequency of the power supply. Different speeds were obtained by bringing differing diameter wheels into position against the bottom or inside edge of the platter.
Belt drives brought improved motor and platter isolation compared to idler wheel designs. Motor noise heard as low frequency rumble was much reduced. It is difficult to design multiple speed synchronous motors, consequently DC servomotors with electronics providing speed control, have gained favour. On the most sophisticated designs, optical sensors on the platter are used to ensure the speed of the platter remains stable. Many platters have a continuous series of strobe markings machined around their edge to provide these pulses. A strobe effect can be observed by the operator to verify rotational speed. DC servomotors rotate in steps rather than continuously. This is referred to as 'cogging', and can add noise during playback. Helical armature motors can be used to overcome this.
Direct drive turntables, drive the platter directly, without utilizing intermediate wheels, belts, or gears as part of a drive train. The platter functions as a motor armature. This requires good engineering, with advanced electronics for acceleration and speed control. Matsushita's Technics division introduced the first commercially successful direct drive platter, model SP10, in 1969.
An other major component is the pickup or cartridge. Early electronic phonographs used a piezo-electric quartz crystal for pickup, where the mechanical movement of the stylus in the groove generates a proportional electrical voltage. Crystal pickups are relatively robust, and yield a good level of signal which requires only a modest amount of amplification. A crystal's output tends not to be very linear, that is, it introduces unwanted distortion. It is difficult to make a crystal pickup suitable for stereo reproduction, as the stiff coupling between the crystal and the stylus prevents close tracking of the needle to the groove modulations. This tends to increase wear on the record, and introduces distortion.
In all high-fidelity systems, the crystal pickup has been replaced by the magnetic cartridge using either a moving magnet or moving coil. In the moving magnet system, the stylus carries a tiny permanent magnet, which is positioned between a series of fixed coils. As the magnet vibrates in response to the stylus following the record groove, it induces a tiny current in the coils. This current, now a weak alternating current representing the original sound wave from the recording session, is fed to an amplifier which boosts the signal, and then to a loudspeaker where it is converted to sound waves. Because the magnet is so light, and is not coupled mechanically to the coils, the stylus follows the groove far more gently and faithfully. Moving coil systems, are generally more expensive and are preferred by some audiophiles. Here a tiny coil is attached to the stylus, and moves within the field of a permanent magnet. Magnetic cartridges provide a much lower output than a crystal pickup, in the range of a few millivolts, thus requiring a preamplifier stage. Moving-coil cartridges generate an even smaller signal, of a few hundred microvolts, and require additionally a transformer or pre-preamplifier stage. Electrical noise induced by power lines or other EMI are attenuated by various methods, including electromagnetic shielding in the signal cables connecting the pickup to the amplifier.
The stylus is typically a conical diamond tip on an aluminum tubular cantilever for a monophonic sound or rugged use, and an elliptical diamond tip for a stereo or binaural signal. Some very expensive styli have ruby, boron, or carbon fiber cantilevers chosen for their exceptional stiffness.
Phonograph recordings are made with high frequencies boosted. Then during playback the high frequencies are rescaled to the initial level, which reduces groove background noise including clicks or pops. This is accomplished in the amplifier with a 'PHONO' input that uses a standardized RIAA equalization curve.
Basic arm design has changed relatively little. S-Type tone-arms can be found on even the 1925 Victor Orthophonic phonograph. Originally, even though the tone-arm was light for earlier electric pickup, the full weight rested on the record. Right through to the crystal pickup, this was required to create sufficient tracking force to follow the grooves adequately with the relatively stiff styli. Naturally, record wear was not given much consideration. With the advent of the better technologies, including more powerful rare-earth magnetic cartridges, far lighter tracking forces became possible, and a balanced arm came into use. Many use a counterweight to offset the weight of the arm. The addition of a calibrated dial on the weight, provides for quick change of stylus pressure. Stylus pressure of 1 to 2 grams are currently the standard.
Two types of tracking error incident to a standard arm can affect the sound. As the tone arm tracks the groove, the stylus drag tangent to the disc surface and resistance along the arm the combine to create a horizontal skating force towards the center of the disc. Modern arms provide a spring-loaded or hanging weight bias which offsets this force, so as to leave the net horizontal force near zero. The second error occurs as the arm sweeps in an arc across a disc recording, causing the angle between the cartridge head and groove direction to change slightly. A change in angle, albeit small, may have an audible effect by creating a differential force on the groove walls. Making the arm longer so as as to reduce this angle is one solution. Some arms have been manufactured with an auxillary arm which pivots the cartridge head on the main arm to maintain a constant angle.
If the arm is not pivoted at a fixed point, but travels horizontally along a radius of the disc, there will be no skating force and no cartridge angle error. The arm is driven along a linear track using a servomechanism to position it properly. Matsushita's Technics division developed one such practical system with its model SL-10 turntable in 1979, ten years after the introduction of the first direct-drive turntable. Early Edison phonographs had utilized similar but spring powered drives to carry the stylus across the record at a pre-determined rate. In practice the linear tracking system is not widely used today due to its complexity and attendant expense. However some of the most sophisticated systems do employ this technique.
A brief mention could be made of one attempt to make the use of records more convenient, in the dawning age of the compact disk. In the early 1980s, one manufacturer designed an upright (front loading) record playing music centre, in which the record was placed in a door which hinged downwards to accept it. The door retracted automatically and the record was spun in the vertical plane. A pair of linear-tracking arms traversed the disk, one on each side, meaning that the whole record could be played without stopping and turning it over. The whole system was mechanically and electronically exceedingly complex, and while it worked, the system as a whole was aimed at the mass market and had only mediocre sound quality. The large physical size of the hinged door made it vulnerable to damage, and the retraction motor was barely able to lift its weight, especially after some years of use.
The phonograph in the 21st century
Phonographs or disc record turntables continue to be manufactured and sold into the 21st century, although in much smaller numbers.
Updates to the 1970s era Technics SL-1200, have remained an industry standard for DJs to the present day. Turntables and vinyl records remain popular in techno music, where they allow great latitude for physical manipulation of the music by the DJ. The turntable is also useful in "scratching" in hip hop or rap music, though for recording use it has largely been replaced by the sampler. "Turn Tables" or "Turntablism" is a 'technique' of manipulating music recorded by artists. It is not considered by some to be original music. However, music may be defined as an 'organized sound', and organized manipulation of sound (music) can still be music.
The laser turntable—using a laser as the pickup, rather than a stylus in physical contact with the disk—was conceived of in the late 1980s, although the first examples were not of usable audio quality. Practical laser turntables are now being manufactured by ELPJ. They are favoured by record libraries and audiophiles since they minimize wear on the recording. In fact, the turntable or record player is still the source of choice in high end audio systems.
Experimentation is in progress in retrieving the audio from a record by scanning the disc and analysing the scanned image, rather than using any sort of turntable, by Ofer Springer at the Hebrew University of Jerusalem.
- Invention of the Phonograph
- The Phonograph vs. the Gramophone
- Phonograph technology in 1958
- Record scanning - Ofer Springer
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