Hugh Le Caine invented the voltage-controlled synthesizer in 1945, but was never able to successfully market it as a commercial product. This distinction went to the American engineer Robert Moog, whose perfectly made semiconductor synthesizer modules introduced in the mid-1960s were the first to sell with any success. His instruments are classics, as are the Hammond Organ and Rhodes Electric Piano.


Robert Moog synthesizers

The Moog synthesizer was the most used instrument in electronic music studios in the late 1960's and 1970's. The secret of Moog's success was that it solved the three biggest problems with the synthesizer use at the time: size, stability, and control. Transistor and semiconductor elements solved the first two problems by reducing the size of the sound generating elements and producing stable oscillators. Providing the control over the countless number of possible sounds that could be made with a synthesizer was more of a challenge. Earlier electronic musical instruments were controlled by manually adjusting the knobs. Controlling this way was difficult because every separate component of the system, from the oscillators to filters and other special devices, required precise manual adjustments to duplicate any effect. Moog became the first synthesizer designer to popularize the voltage control technique in analog electronic musical instruments.


In a voltage controlled device, a small amount of current is applied to the control input of the component to modify the output signal. This voltage is precisely determined and can be activated, for example, by the synthesizer keyboard, which greatly facilitates the operation of the analog synthesizer. The keyboard sends a certain amount of voltage to the sound-generating synthesizer's oscillator and instructs it to generate a tone of a certain pitch. The Moog synthesizer is designed to be a modular device with independent but connectable components to generate, modify, modulate and play the sounds. Moog managed to create a product that could be manufactured with consistently high quality.


His success gave impetus to various manufacturers who have revolutionized the production of synthesizers using the latest developments in the field of integrated circuits. As instruments became more accessible, they began to be used in the homes of composers and musicians, not just institutional electronic music studios.


A synthesizer is a standalone electronic music system used to generate, modify and play electronically produced sounds. The original Moog Modular Synthesizer was designed to create the sounds to be used in composing for tape. The composer could have used the Moog to collect interesting audio material on tape and then used multi-track mixing to make a musical composition. In the 1970s, synthesizers began to include pre-built "libraries" of sounds, programmable note sequences, and were easy to carry, making them perfect for live performances.


Synthesizers can be grouped into three types of instruments:


• Keyboard instruments for live performance and studio composing.
• Slave modules without keyboards to be controlled by other MIDI keyboards or by a computer.
• Virtual synthesizers that exist in the form of sound modeling software. They can be controlled with a computer or an external MIDI keyboard.


For both analog and digital synthesis, all synthesizers share the same essential elements:


• Two or more oscillators to generate raw sound material. Typically the waveforms offered are sine, sawtooth, square and triangular. You can combine them to create variations of the waveforms.
• Presets of the sounds or instrumental voices are available on all synthesizers. Many of them allow you to create new sounds and save them as new presets.
• Noise generator.
• Waveform amplitude modulation.
• Waveform frequency modulation.
• Envelope controls for modifying the way the sound begins, continues and ends.
Sequencer for recording the note sequences.
High pass and low pass filters for selectively adding and removing frequency ranges.
• MIDI in/out/thru for controlling by one or more keyboards or connecting the synthesizer to a computer in real time.


Moog Synthesizer

Moog built the first complete prototype of his instrument in 1964. He wrote an article entitled "Voltage-Controlled Electronic Music Modules" and was invited to present it at the Audio Engineering Society (AES) convention. The prototype consisted of a module with two voltage-controlled oscillators and two amplifiers, operated by two keyboards. In 1967, Moog named his product "Moog Modular Synthesizer". The earliest Moogs consisted mainly of oscillators and amplifiers. The design kept changing, and after about a year Moog began to introduce other types of sound modulators.

Modular Moog Synthesizer


The keyboards weren't the only controller Moog developed at the time. He also designed a ribbon controller consisting of a thin Teflon-coated metal band that was played by sliding a finger up and down its length. By swiping the finger, you can create the glissando effects similar to those of the Theremin, except that you can have an entire bank of oscillators at your disposal instead of just one fundamental wave.


The basic studio model of the Moog Modular Synthesizer was composed of many independent components that could be connected with each other. The modules were carefully mounted in the racks. But each model could be different than the one previously ordered, as the Moog company wanted the system to be as flexible and modular as the diverse needs of its customers.


The basic components that could be ordered as part of the Moog Modular Synthesizer included:


• Five-octave monophonic keyboard for triggering voltage control signals. It could function as a chromatic keyboard with a twelve-note scale or be adapted to altered pitches and microtone systems. Only one tone could be played at a time, represented by the highest voltage - the highest key pressed on the keyboard at any given time.
• High Range Voltage Controlled Oscillators (VCO). They had a frequency range of 0.01 to 40,000 Hz. The range of human hearing is only about 20 to 20,000 Hz. Moog has provided frequencies above (ultrasound) and below this range that can be used as control voltages to modulate audible tones. The original Moog included two VCOs as sound sources. Larger studio models such as the Moog 55 had up to seven VCOs. Each VCO was switchable to sine, sawtooth, triangular, rectangular (square /pulse) waves.
• Voltage controlled amplifier (VCA). VCA can be used to amplify any voltage. Most often it was used in conjunction with an envelope generator to change the volume of a wave during an attack-sustain-decay sequence.
• Voltage Controlled Filter (VCF). The voltage controlled filter was one of the system's most cleverly designed components. Its design was so unique that several other synthesizer manufacturers copied it until the Moog company forced them to stop. The ARP 2600 used this filter, as did the Crumar synthesizers.
• Envelope generator. It controlled the rise, sustain, initial fall and final fall durations of the output signal.
• Tape controller. This was available as an optional triggering device. It consisted of a teflon tape with a wire on the underside, suspended slightly above the contact strip. Pressing the tape against the contact strip at any point along its length closed the circuit and generated the corresponding voltage. This voltage was used to trigger the oscillators. A knob was used to set the frequency range of the ribbon controller.
• Patch cords to connect different modules. RCA phono connectors were used on the front panel of the instrument, which created a great tangle of cables required to set up the patch to create the desired sound or modulation type.
• Popular accessories including spring reverb, ring modulator, pink and white noise generators, vocoder (analog voice processor).



While the Moog Modular Synthesizer was best suited for studio use, there was a growing demand for a portable version that could be easily taken on a trip. In 1969, Moog set another precedent with the introduction of the Minimoog, a simple, compact mono synthesizer designed for a live performance. With a sale of around 12,000 units, this model has become the most popular synthesizer of all time. Most of the connections between the modules were permanently fixed and controlled by rocker switches and knobs. The keyboard featured two unique controls that were widely imitated: a "pitch wheel" to deflect the pitch of the notes and a "mod wheel" to adjust the degree of modulation of the output signal. The original Minimoog was produced until the end of the 1980s.



Buchla Synthesizer

Engineer Donald Buchla, like Robert Moog and Hugh Le Caine, believed that the voltage control was the most practical concept for producing a synthesizer that could be operated effectively by a composer. Unlike Moog, Buchla was a musician and had a strong, natural attachment to the composer's needs.


Originally, the Moog synthesizer was designed solely as a studio tool.

Buchla, on the other hand, envisioned an instrument that could be used during live performances. In 1963, at the same time when Moog was working on the voltage-controlled synthesizer project, Buchla built an instrument he called the "Buchla 100 series Modular Electronic Music System (MEMS)".



Buchla placed an emphasis on two aspects of synthesizer design to meet the needs of composers. First, he offered a great flexibility in modifying the tone timbres. He then provided a way to "program" a series of repeatable sounds using a sequence of repeated control voltages. It was the first sequencer available on a commercial synthesizer.


The semiconductor MEMS was equipped similarly to the Moog with regard to the use of voltage controlled oscillators, amplifiers and filters. Instead of the keyboard, Buchla used different sets of the touch-sensitive pads. These capacitive-sensitive pads could trigger sounds that were manually programmed using the connection cables on the control panel, or could be set to emulate an actual keyboard tuned to a chromatic scale.


The Buchla's synthesizer has undergone several improvements over the years. In 1970 he introduced the "200 series Electric Music Box", which became one of the main instruments at the Mills Center for Contemporary Music. A year later, he built the first hybrid, digitally controlled analog synthesizer, the "500 series".Buchla instrument  In 1972 he introduced the Music Easel synthesizer, of which about twenty five were produced. In the mid-1970s, Buchla built several analog-digital hybrid instruments and a model with a keyboard (Touché, 1978). In the mid-1980s, MIDI was so widespread that Buchla shifted his focus from designing synthesizers to creating unique MIDI-compatible controllers for musicians other than keyboardists. Then, in 1987, he introduced the 700 model with a MIDI control.

Buchla continued the development of touch pad controllers, and in 1990 produced the Thunder, a MIDI compatible touch pad controller. In 1991, he introduced Lightning, an optical MIDI controller that used infrared beams to transfer control data from hand-held wands to any MIDI compatible synthesizer equipped with a receiver. The speed and position of the wands can be used to trigger various MIDI parameters, including pitch, but also audio panning and volume level. In 2000, the Lightning II model was introduced with the added feature of a thirty-two voice synthesizer, making it a complete playable instrument.


Other commercial synthesizers

Following the success of the Moog and Buchla systems in the late 1960s, many new manufacturers entered the market with the modular voltage-controlled synthesizer's variants. Japanese manufacturers in particular have developed an innovative and less costly technology. Instrument manufacturers included ARP, Oberheim, Korg, Yamaha, Roland, EMS and Crumar, some of whom still make electronic music products today. Over the years, the analog technology has evolved to the hybrid analog/digital technology, then to the microcomputers with sound cards, and finally to the purely digital performance instruments. One of the dominant trends is the "virtual analog" instrument: digital keyboards using sound-generating algorithms and controls that imitate the manual controls and timbres of the classic analog instruments.