The TB-303 (short for "Transistorized Bass") was originally marketed to guitarists for bass accompaniment while practicing alone. Production lasted approximately 18 months, resulting in only 10,000 units. It was not until the mid- to late-1980s that DJs and electronic musicians in Chicago found a use for the machine in the context of the newly developing house music genre. In the late 1980s and early 1990s, as new Acid styles emerged, the TB-303 was often overdriven, producing a harsher liquid acid-like sound. Examples of this technique include Charanjit Singh's 1982 Ten Ragas to a Disco Beat,[1] Phuture's 1987 "Acid Tracks" (sometimes known as "Acid Trax"), Hardfloor's 1992 EP "Acperience" and Interlect 3000's 1993 EP "Volcano". Two simple patterns on the Roland TB-303 Bass Synthesiser. The second pattern has had the filter EG attack level altered. In other instances the TB-303 was extremely distorted and processed, such as Josh Wink's 1995 hit "Higher State of Consciousness". Two simple overdriven patterns on the Roland TB-303 Bass Synthesiser. The second pattern has varying resonance to give a harsh screeching sound. Both patterns have gradual cutoff frequency. The well-known "acid" sound is typically produced by playing a repeating note pattern on the TB-303, while altering the filter's cutoff frequency, resonance, and envelope modulation. The TB-303's accent control modifies a note's volume, filter resonance, and envelope modulation, allowing further variations in timbre. A distortion effect, either by using a guitar effects pedal or overdriving the input of an audio mixer, is commonly used to give the TB-303 a denser, noisier timbre—as the resulting sound is much richer in harmonics. The head designer of the TB-303, Tadao Kikumoto, was also responsible for leading design of the TR-909 drum machine. In 2011, The Guardian listed the 1981 release of the TB-303 as one of the 50 key events in the history of dance music.[2] The TB-303 has a single audio oscillator, which may be configured to produce either a sawtooth wave or a square wave. The square wave is derived from the sawtooth waveform using a simple, single-transistor waveshaping circuit.[3] This produces a sound that is subtly different from the square waveform created by the dedicated hardware found in most analog synthesizers. It also includes a simple envelope generator, with a decay control only. A lowpass filter is also included, with -24dB per octave attenuation, and controls for cutoff frequency, resonance, and envelope modulation parameters. It is a common misconception that the filter is a 3 pole 18dB per octave design when in fact it is 4-pole 24dB per octave.[4] The TB-303 sequencer has some unique features that contribute to its characteristic sound. During the programming of a sequence, the user can determine whether a note should be accented, and whether it should employ portamento, a smooth transition to the following note. The portamento circuitry employs a fixed slide time, meaning that whatever the interval between notes, the time taken to reach the correct pitch is always the same. The accent circuitry, as well as increasing the amplitude of a note, also emphasizes the EG filter's cutoff and resonance, resulting in a distinctive, hollow "wow" sound at higher resonance settings. Roland referred to this as "gimmick" circuitry.[5] The instrument also features a 'simple' step-time method for entering note data into the 16-step programmable sequencer. This was notoriously difficult to use, and would often result in entering a different sequence than the one that had been intended. Some users also take advantage of a low voltage failure mode, wherein patterns that are programmed in memory get completely scrambled if the batteries are removed for a time. There have been many modifications designed for the TB-303 such as the "Devilfish", "Acidlab" and "Borg" modifications. These generally provide additional parameters to the player, or offer alterations to the overall timbre.

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