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38-480: At first glance, this technique can be viewed as subtractive synthesis based on a feedback loop similar to that of a comb filter for z-transform analysis. However, it can also be viewed as the simplest class of wavetable -modification algorithms now known as digital waveguide synthesis , because the delay line acts to store one period of the signal. Alexander Strong invented the algorithm, and Kevin Karplus did

76-412: A fractional delay often needed for fine tuning the string below JND ( Just Noticeable Difference ), interpolating filters are used with parameters selected to obtain an appropriate phase delay at the fundamental frequency. Either IIR or FIR filters may be used, but FIR have the advantage that transients are suppressed if the fractional delay is changed over time. The most elementary fractional delay

114-435: A common confusion. While sampled synthesis involves the use of a static digital sample, wavetable synthesis allows for the (optional) evolution of a waveform; this is to say, while wavetable synths can sound like sampled synthesis, the evolving option (which is enabled by default on most classic wavetable sounds) differentiates it. Often they now have displays showing a real time 3d graphs of the wave table being played back with

152-606: A marketing term to their sound card. However, these sound cards did not employ any form of wavetable synthesis, but rather PCM samples and FM synthesis . S&S (Sample and Synthesis) and Digital Wave Synthesis was the main method of sound synthesis utilised by digital synthesizers starting in the mid 1980s with synthesizers such as Sequential Circuits Prophet VS, Korg DW6000/8000 (DW standing for Digital Wave), Roland D50 and Korg M1 through to current synthesizers. Ableton addressed some confusion in an article: Wait, so isn't this just sampled synthesis? Let's pause here to address

190-413: A relatively complex waveform with audible overtones . Only one oscillator is necessary, and the number can vary widely. In this case, two oscillators are used: Pulse-width modulation is applied to both waveforms to create a more complex tone with vibrato : The pulse-width modulated sounds are now combined at equal volume. Combining them at different volumes would create different timbres. The result

228-469: A startup company founded by some of the laid-off Mattel executives. They never got sufficient funding to finish development, and so never brought a product to market either. Eventually Yamaha licensed the patent, as part of the Sondius package of patents from Stanford. It is unknown whether any hardware using the algorithm was ever sold, though many software implementations (which did not pay any license fees to

266-503: A string or bell. Increasing the period sharply after the transient input produces drum-like sounds. Due to its plucked-string sound in certain modes, Alex Strong and Kevin Karplus conjectured that the Karplus-Strong (KS) algorithm was in some sense a vibrating string simulation, and they worked on showing that it solved the wave equation for the vibrating string, but this was not completed. Julius O. Smith III [1] recognized that

304-402: A superior wavetable -modification method for plucked-string synthesis, but only published it as a patent. The first musical use of the algorithm was in the work May All Your Children Be Acrobats written in 1981 by David A. Jaffe , and scored for eight guitars, mezzo-soprano and computer-generated stereo tape, with a text based on Carl Sandburg 's The People, Yes . Jaffe continued to explore

342-460: A wide variety of ways, such as voltage-controlled or low-pass filters . The technology developed in experimental electronic studios which were primarily focused on telecommunications and military applications. Early examples include Bell Labs ' Voder (1937–8). Composers began applying the concept of subtractive synthesis beyond the recording studio in concert music. Henri Pousseur 's Scambi (1957) subjects white noise to filters and uses

380-405: Is a 2-second source sound , which is ready for subtractive synthesis. The combined wave is passed through a voltage-controlled amplifier connected to an envelope generator . The parameters of the sound's envelope (attack, decay, sustain and release) are manipulated to change its sound. In this case, the decay is vastly increased, sustain is reduced, and the release shortened. The resulting sound

418-429: Is a class of sound synthesis methods using the waveform tables by table-lookup , called "table-lookup oscillator" technique. The length of waveforms or samples may be varied by each sound synthesis method, from a single-cycle up to several minutes. The term " waveform table " (or " wave shape table " as equivalent) is often abbreviated to "wavetable", and its derived term " wavetable oscillator " seems to be almost

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456-401: Is a method of sound synthesis in which overtones of an audio signal are attenuated by a filter to alter the timbre of the sound. Subtractive synthesis relies on source sounds that have overtones, such as non-sinusoidal waveforms like square and triangle waves , or white and pink noise . These overtones are then modulated to alter the source sound. This modulation can happen in

494-405: Is audible for half as long as the source sound: With its new envelope, the sound is run through a low-pass filter , which reduces the volume of higher overtones: To better emulate the sound of a plucked string, the filter's cutoff frequency is lowered. Table-lookup synthesis Wavetable synthesis is a sound synthesis technique used to create quasi-periodic waveforms often used in

532-478: Is especially useful for evolving synth pads , where the sound changes slowly over time. It is often necessary to 'audition' each position in a wavetable and to scan through it, forwards and backwards, in order to make good use of it, though selecting random wavetables, start positions, end positions and directions of scan can also produce satisfying musical results. It is worth noting that most wavetable synthesizers also employ other synthesis methods to further shape

570-409: Is fundamentally based on periodic reproduction of multiple arbitrary, single-cycle waveforms . In wavetable synthesis, some method is employed to vary or modulate the selected waveform in the wavetable. The position in the wavetable selects the single cycle waveform. Digital interpolation between adjacent waveforms allows for dynamic and smooth changes of the timbre of the tone produced. Sweeping

608-428: Is the linear interpolation between two samples (e.g., s (4.2) = 0.8 s (4) + 0.2 s (5)). If the phase delay varies with frequency, harmonics may be sharpened or flattened relative to the fundamental frequency. The original algorithm used equal weighting on two adjacent samples, as this can be achieved without multiplication hardware, allowing extremely cheap implementations. Z-transform analysis can be used to get

646-633: The Atari ST , Mattel 's Intellivision , Sega 's Master System , and the ZX Spectrum . Subtractive synthesis has become a catchall for a method where source sounds are modulated, and it is sometimes applied inappropriately. The following is an example of subtractive synthesis as it might occur in an electronic instrument to emulate the sound of a plucked string . It was created with a personal computer program designed to emulate an analogue subtractive synthesizer. First, an electronic oscillator produces

684-525: The Waldorf WAVE. More commonly, pre-computed wavetables could be added via memory cards or sent to the synthesizer via MIDI. Today, wavetables can be created more easily by software and auditioned directly on a computer. Since all waveforms used in wavetable synthesis are periodic, the time-domain and frequency-domain representation are exact equivalents of each other and both can be used simultaneously to define waveforms and wavetables. During playback,

722-486: The 1990s at the latest, several influential sample-based synthesis products were marketed under the trade names similar to "wavetable synthesis" (including Gravis Ultrasound wavetable card, Creative Wave Blaster wavetable daughterboard , and Microsoft GS Wavetable SW Synth ), and these confusions have further affected industry standards (including MPEG-4 Structured Audio algorithmic and wavetable synthesis , and AC97 optional hw acceleration wavetable synth ). In

760-898: The Karplus-Strong Algorithm, typically known as the Extended Karplus-Strong (EKS) Algorithm, was presented in a paper in 1982 at the International Computer Music Conference in Venice, Italy, and published in more detail in 1983 in Computer Music Journal in an article entitled "Extensions of the Karplus Strong Plucked String Algorithm," by David A. Jaffe and Julius O. Smith, and in Smith's PhD/EE dissertation. Alex Strong developed

798-475: The current waveform highlighted which is the signature feature common in modern wavetable synths. The creation of new wavetables was previously a difficult process unless supported by specialized editing facilities and (near) real-time playback of edited wavetables on the synthesizer. Such editors often required the use of extra hardware devices like the PPG Waveterm or were only present in expensive models like

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836-404: The delay and filter in cascade is − 2 π {\displaystyle -2\pi } . The required phase delay D for a given fundamental frequency F 0 is therefore calculated according to D = F s / F 0 where F s is the sampling frequency. The length of any digital delay line is a whole-number multiple of the sampling period. In order to obtain

874-414: The first analysis of how it worked. Together they developed software and hardware implementations of the algorithm, including a custom VLSI chip. They named the algorithm "Digitar" synthesis, as a portmanteau for "digital guitar". The fundamental frequency (specifically, the lowest nonzero resonant frequency) of the resulting signal is the lowest frequency at which the unwrapped phase response of

912-552: The inventors) have been released. While they may not adhere strictly to the algorithm, many hardware components for modular systems have been commercially produced that invoke the basic principles of Karplus-Strong Synthesis: using an inverted, scaled control system for very small time values in a filtered delay line to create playable notes in the Western Tempered tuning system, controlled with volt per octave tracking or MIDI data. The Inventors were not specifically credited, though

950-525: The late 1970s and published it in 1979. The technique has since been used as the primary synthesis method in synthesizers built by PPG and Waldorf Music and as an auxiliary synthesis method by Ensoniq and Access . It is currently used in hardware synthesizers from Waldorf Music and in software synthesizers for PCs and tablets, including apps offered by PPG and Waldorf, among others. It was also independently developed by Michael McNabb, who used it in his 1978 composition Dreamsong . Wavetable synthesis

988-401: The mid-2000s, confusion in terminology cropped up yet-again. A subclass of generic wavetable synthesis, i.e. McNabb and Palm's multiple wavetable synthesis, tends to be erroneously referred as if it was a generic class of whole wavetable synthesis family, exclusively. As a result, the difficulty of maintaining consistency between concepts and terminology during rapid technological development

1026-539: The musical and technical possibilities of the algorithm in Silicon Valley Breakdown , for computer-generated plucked strings (1982), as well as in later works such as Telegram to the President, 1984 for string quartet and tape, and Grass for female chorus and tape (1987). The patent was licensed first to Mattel Electronics, which failed as a company before any product using the algorithm was developed, then to

1064-414: The output waveform, such as subtractive synthesis (filters), phase modulation , frequency modulation and AM (ring) modulation . On Csound , it is called f-table (function table), and used for various purposes including: wavetable-lookup synthesis, waveshaping , MIDI note mapping, and storing ordered pitch-class sets . Table-lookup synthesis (or Wavetable-lookup synthesis ) ( Roads 1996 )

1102-462: The pitches and decay times of the harmonics more precisely, as explained in the 1983 paper that introduced the algorithm. A demonstration of the Karplus-Strong algorithm can be heard in the following Vorbis file. The algorithm used a loop gain of 0.98 with increasingly attenuating first order lowpass filters. The pitch of the note was A2, or 220 Hz. Holding the period (= length of the delay line) constant produces vibrations similar to those of

1140-464: The production of musical tones or notes . Wavetable synthesis was invented by Max Mathews in 1958 as part of MUSIC II . MUSIC II “had four-voice polyphony and was capable of generating sixteen wave shapes via the introduction of a wavetable oscillator.” Hal Chamberlin discussed wavetable synthesis in Byte 's September 1977 issue. Wolfgang Palm of Palm Products GmbH (PPG) developed his version in

1178-536: The pulse wave will appear to change over time. As the early Ensoniq wavetable synthesizers had non resonant filters (the PPG Wave synthesizers used analogue Curtis resonant filters), some wavetables contained highly resonant waveforms to overcome this limitation of the filters. In 1992, with the introduction of the Creative Labs Sound Blaster 16 the term "wavetable" started to be (incorrectly) applied as

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1216-432: The resulting sounds to create montages. Mikrophonie I (1964) by Karlheinz Stockhausen uses a tam-tam and a microphone as the primary sound source which is then filtered extensively by two sound projectionists. Until the advent of digital synthesizers , subtractive synthesis was the nearly universal electronic method of sound production. Its popularity was due largely to its relative simplicity. Subtractive synthesis

1254-661: The same as " table-lookup oscillator " mentioned above, although the word "wave" (or "waveform", "wave shape") may possibly imply a nuance of single-cycle waveform. However, the derived term " wavetable synthesis " seems slightly confused by the later developments of derived algorithm. On the above four terminologies for the classes of sound synthesis methods — i.e. , (1) Wavetable synthesis , (2) Wavetable-modification algorithm , (3) Multiple wavetable synthesis , and (4) Sample-based synthesis — if these had been appropriately used to distinguish each other, any confusions could be avoided, but it seems failed historically. In

1292-458: The sound produced can be harmonically changed by moving to another point in the wavetable, usually under the control of an envelope generator or low frequency oscillator but frequently by any number of modulators (matrix modulation). Doing this modifies the harmonic content of the output wave in real time, producing sounds that can imitate acoustic instruments or be totally abstract, which is where this method of sound creation excels. The technique

1330-540: The term "Karplus-Strong Synthesis" is referenced in some of the manuals. Hardware components capable of Karplus-Strong style synthesis include the Moog Clusterflux 108M, Mutable Instruments Elements and Rings, 4ms Company Dual Looping Delay, 2HP Pluck, Make Noise Mimeophon, Arturia MicroFreak , Non Linear Circuits Is Carp Lust Wrong?, and the Strymon Starlab. Subtractive synthesis Subtractive synthesis

1368-454: The transfer-function of the KS, when viewed as a digital filter, coincided with that of a vibrating string, with the filter in the feedback loop representing the total string losses over one period. He later derived the KS algorithm as a special case of digital waveguide synthesis , which was used to model acoustic waves in strings, tubes, and membranes. The first set of extensions and generalizations of

1406-453: The wavetable in either direction can be controlled in a number of ways, for example, by use of an LFO, envelope, pressure or velocity. Many wavetables used in PPG and Ensoniq synthesizers can simulate the methods used by analog synthesizers , such as pulse-width modulation by utilising a number of square waves of different duty cycles . In this way, when the wavetable is swept, the duty cycle of

1444-538: Was so prevalent in analog synthesizers that it is sometimes called "analog synthesis". It was the method of sound production in instruments like the Trautonium (1930), Novachord (1939), Buchla 100 (1960s), EMS VCS 3 (1969), Minimoog (1970), ARP 2600 (1971), Oberheim OB-1 (1978), and Korg MS-20 (1978). Programmable sound generators (PSG) relied heavily on subtractive synthesis. PSGs were used in many personal computers, arcade games, and home consoles such as

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