A drum machine is an electronic musical instrument that creates percussion. Drum machines may imitate drum kits or other percussion instruments, or produce unique sounds. Most modern drum machines allow users to program their own rhythms. Drum machines may create sounds using analog synthesis or play prerecorded samples.
Drum machines have had a lasting impact on popular music. The Roland TR-808, introduced in 1980, significantly influenced the development of dance music and hip hop. Its successor, the TR-909, introduced in 1983, heavily influenced techno and house. The first drum machine to use samples of real drum kits, the Linn LM-1, was introduced in 1980 and adopted by rock and pop artists including Prince and Michael Jackson. In the late 1990s, software emulations began to overtake the popularity of physical drum machines.
Drum sound synthesis
A key difference between such early machines and more modern equipment is that they use sound synthesis rather than digital sampling in order to generate their sounds. For example, a snare drum or maraca sound would typically be created using a burst of white noise whereas a bass drum sound would be made using sine waves or other basic waveforms. This meant that while the resulting sound was not very close to that of the real instrument, each model tended to have a unique character. For this reason, many of these early machines have achieved a certain "cult status" and are now sought after by producers for use in production of modern electronic music, most notably the Roland TR-808.
Programmable drum machines
In 1972, Eko released the ComputeRhythm (1972), which was the first programmable drum machine. It had a 6-row push-button matrix that allowed the user to enter a pattern manually. The user could also push punch cards with pre-programmed rhythms through a reader slot on the unit.
Another stand-alone drum machine released in 1975, the PAiA Programmable Drum Set was also one of the first programmable drum machines, and was sold as a kit with parts and instructions which the buyer would use to build the machine.
In 1975, Ace Tone released the Rhythm Producer FR-15 that enables the modification of the pre-programmed rhythm patterns. In 1978, Roland released the Roland CR-78, the first microprocessor-based programmable rhythm machine, with four memory storage for user patterns. In 1979, a simpler version with four sounds, Boss DR-55, was released.
The Linn LM-1 Drum Computer (released in 1980 at $4,995) was the first drum machine to use digital samples. It also featured revolutionary rhythmic concepts such as swing factors, shuffle, accent, and real-time programming, all of which have since rooted themselves in beat box technology. Only about 500 were ever made, but its effect on the music industry was extensive. Its distinctive sound almost defines 1980s pop, and it can be heard on hundreds of hit records from the era, including The Human League's Dare, Gary Numan's Dance, Devo's New Traditionalists, and Ric Ocasek's Beatitude. Prince bought one of the very first LM-1s and used it on nearly all of his most popular albums, including 1999 and Purple Rain.
Many of the drum sounds on the LM-1 were composed of two chips that were triggered at the same time, and each voice was individually tunable with individual outputs. Due to memory limitations, a crash cymbal sound was not available except as an expensive third-party modification. A cheaper version of the LM-1 was released in 1982 called the LinnDrum. Priced at $2,995, not all of its voices were tunable, but crash cymbal was included as a standard sound. Like its predecessor the LM-1, it featured swappable sound chips. The LinnDrum can be heard on records such as The Cars' Heartbeat City and Giorgio Moroder's soundtrack for the film Scarface.
It was feared the LM-1 would put every session drummer in Los Angeles out of work and it caused many of L.A.'s top session drummers (Jeff Porcaro is one example) to purchase their own drum machines and learn to program them themselves in order to stay employed. Linn even marketed the LinnDrum specifically to drummers.
Oberheim DMX (1981)
SCI Drumtraks (1984)
Following the success of the LM-1, Oberheim introduced the DMX, which also featured digitally sampled sounds and a "swing" feature similar to the one found on the Linn machines. It became very popular in its own right, becoming a staple of the nascent hip-hop scene.
Other manufacturers soon began to produce machines, e.g. the Sequential Circuits Drum-Traks and Tom, the E-mu Drumulator and the Yamaha RX11.
In 1986, the SpecDrum by Cheetah Marketing, an inexpensive 8-bit sampling drum external module for the ZX Spectrum, was introduced, with a price less of than £30, when similar models cost around £250.
Programming of drum machines varies from product to product. On most products, it can be done in real time: the user creates drum patterns by pressing the trigger pads as though a drum kit were being played; or using step-sequencing: the pattern is built up over time by adding individual sounds at certain points by placing them, as with the TR-808 and TR-909, along a 16-step bar. For example, a generic 4-on-the-floor dance pattern could be made by placing a closed high hat on the 3rd, 7th, 11th, and 15th steps, then a kick drum on the 1st, 5th, 9th, and 13th steps, and a clap or snare on the 5th and 13th. This pattern could be varied in a multitude of ways to obtain fills, break-downs and other elements that the programmer sees fit, which in turn could be sequenced with song-sequence — essentially the drum machine plays back the programmed patterns from memory in an order the programmer has chosen. The machine will quantize entries that are slightly off-beat in order to make them exactly in time.
If the drum machine has MIDI connectivity, then one could program the drum machine with a computer or another MIDI device.