The earliest detailed concept of a sound recording device is Edouard-Leon Scott's Phonautograph. His design used an animal hair bristle as a recording head, and traced a groove into a cylinder of carbon-coated paper. Thomas Edison refined this design, and in 1877 produced the Phonograph. It replaced the paper cylinder with a foil-wrapped wax cylinder. A clockwork mechanism rotated the cylinder as the stylus rested upon it, and the speaker simply spoke into a large cone mounted to the back of the stylus.
Much like later competition between audio cassette and 8-track, or VHS and Beta, there was a battle for superiority regarding the dominant format for recorded sound. Edison's cylinder went unchallenged for the first few years, until the appearance of gramophone discs. They did little to improve sound quality, but they could be easily mass produced. They were more resilient to damage and were capable of storing more material, though there were no standard sizes or speeds at first. Different voltages in different parts of the world caused turntable motors to spin at different speeds. The industry and public eventually settled on seven-inch, 78 RPM discs, reflecting the most commonly available motors and gear components.
Mechanical recording remained the standard until World War I, but recordings lacked depth and longevity. The fact that the cutting stylus had to be physically moved by the force of the sound wave meant high-pitched instruments such as flutes and violins were almost impossible to record. With the technological advances in electronic technology made during The Great War, namely electronic condenser microphones and triode vacuum tubes, electronic gain could be used to boost the strength of the signal before it was committed to disc, widening the frequency range and transferring more of the sonic details to the recording.
The concept of using a magnetized strip of motorized tape to imprint electronic data was first attempted in the 1920s, initially using paper tape covered with iron oxide -- essentially powdered rust. The results were not promising and the idea was shelved until some impractical and dangerous reel-to-reel tape recorders were produced using vast reels of razor sharp steel tape. Their tendency to shear and fling shrapnel across the room meant they also failed to catch on. It wasn't until the 1930s that audio engineers at BASF in Germany hit upon the idea of using acetate tape coated with a magnetic oxide solution. The resulting product was affordable, high-quality, convenient and durable. Magnetic tape became the standard for professional recording until the advent of digital technology several decades later.