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Latest Posts » Archive by category 'Educational'

The Fairlight CMI

Written by v on February 14, 2012 – 12:29 pm -

Fairlight CMI Series II

The Fairlight CMI (Computer Musical Instrument) was the world’s first polyphonic digital sampling synthesiser. It was developed in Australia by Peter Vogel and Kim Ryrie and first released in 1979.

It could record natural sounds from a microphone, then allow the user to view and modify the waveforms on a monitor using a light pen. Sounds could also be constructed from scratch by drawing a waveform on the screen. There was also a large library of pre-recorded samples on floppy disks, which became staples of 80’s pop music.

To understand how revolutionary the Fairlight CMI was at that time, most electronic musicians were still using analogue synthesizers that required manual patching of cables or setting lots of switches and dials.

The Series I Fairlight was equipped with a 73-key velocity-sensitive keyboard and supported 8 voices, each with a sample memory of 16kB, allowing sounds to be sampled at 16kHz with 8 bits of resolution. By the mid-80’s, later models had increased this to allow 16-bit sampling and higher sample rates.

Due to its use of cutting edge technology, the Fairlight CMI was very expensive, with a base price around $25,000 in 1980, and was only affordable by big-name musicians, production studios and universities. Famous users of the Fairlight include Peter Gabriel, Stevie Wonder, Kate Bush and Thomas Dolby.

Here in Australia, the Fairlight was famously used to create the sounds on John Farnham’s hit “You’re the Voice”, released on his “Whispering Jack” album in 1986.

Despite the high price of the Fairlight CMI, it remained popular long after cheaper alternatives like the E-mu Emulator and the Ensoniq Mirage entered the market, and has left a lasting legacy.

Here are my favourite videos of the Fairlight CMI in action

Peter Vogel and Michael Carlos demonstrate the Fairlight CMI on ABC TV in 1980

Art of Noise – Moments in Love

The “Orchestra Hit” sample is a classic sound:

Herbie Hancock demonstrates the Fairlight CMI on Sesame Street

Herbie actually demonstrates quite a few of the capabilities of the CMI, including Waveform decomposition and vocoding. Who says Sesame Street is just for children?

For More Information

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What is Ring Modulation?

Written by v on August 13, 2009 – 8:31 pm -

Ring modulation is an effect  that was introduced in the first analogue subtractive synths. Basically, it involves multiplying two waveforms together, e.g. multiplying a triangle wave and a square wave, to produce a new waveform that was the product of the inputs.

Electronically, this was a simple technique to create a new more complicated sound without requiring new waveform generator circuits.  The resultant waveform would have different harmonics to either of the original inputs and could then be filtered by the musician to create a new sound.

It is called ring modulation because one of the electronic circuits that implemented this operation used 4 diodes connected together in a ring-like configuration, similar to a bridge rectifier.

One of the most famous uses of ring modulation was to create the voice of the evil robots, the Daleks, in the British science fiction TV series Dr Who. The voice actor’s voice was ring-modulated with a 300hz sine wave and then filtered to produce the characteristic warbling sound.

Also, the MOS-6581 (SID) sound chip used in the Commodore 64 home computer implemented a limited form of ring modulation – one of the inputs to the ring modulator was always a square wave.

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Written by v on August 13, 2009 – 8:18 pm -

The vocoder is a very polarising device – it drives some people wild, it drives others nuts, but everyone who’s listened to modern music in the last three decades or watched cartoons had heard one. This is the effect used to produce a robotic voice or talking instrument.

Traditionally, vocoders have been dedicated units – boxes, with two audio inputs – a sound source and a microphone. It analyzes the human voice to measure the formant characteristics  and superimposes them over the tonal qualities of the input sound.

It is very similar in effect to the talk box, where a sound source is fed down a pipe into the user’s mouth and the user moves their mouth, jaw and tongue to modify the sound. The vocoder is also commonly confused with autotune – the quite recently developed pitch correction technology that can also be used for artistic effects.

Nowadays, vocoders are often built into synth keyboards like the Korg MS-2000, Radias and Microkorg series. They are also implemented in software in digital audio workstatation packages including Reason and Ableton Live.

In this article, we’ll talk about the history of the vocoder, how it works, its use in popular culture and how you can use one.


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Low Frequency Oscillator

Written by v on August 13, 2009 – 6:46 pm -

Many synths have a feature known as a Low Frequency Oscillator or LFO. The name is confusing, because usually, an oscillator refers something that makes a sound, like a square wave.

In this case the low frequency oscillator does not generate a sound, rather it is a control that is used to dynamically tweak or modulate  an existing sound to achieve different effects, making the sound more interesting.

It is called ‘low frequency’ because the frequency is usually at or just below the threshold of human hearing, usually less than 50hz, and often set to 20hz or 10hz.

Lets take a look at a few examples:

Imagine playing a note on your keyboard and turning the volume control knob rapidly back and forth with your fingers 10 times a second. By doing this, you are creating a tremolo effect. A 10hz LFO patched to the volume control would allow you to do the same thing without using your fingers.

Now imagine doing the same thing, but instead of turning the volume knob, you move the pitch bend wheel back and forth 10 times per second. This would create a vibrato effect. A 10hz LFO patched to the pitch bend control would do the same thing.

In fact, the LFO can be connected to a whole variety of controls or sound parameters to achieve different effects. The range of parameters you can control of course depends on the capabilities of your synth keyboard.

You can adjust the level (amplitude) of the LFO to determine whether you want a slight or a strong effect and you can raise or lower the frequency for faster or slower ‘throbbing’.

Digital Audio Workstation software and VSTs are usually extremely flexible in what you can control. In fact, you can use multiple LFOs running at different frequencies to control several parameters in parallel.

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