Like the Fender Rhodes, the Clavinet and to a lesser degree perhaps, the Wurlitzer EP200 and the Mellotron, the Hammond organ is undoubtedly one of the best known keyboard sounds in modern music.

Invented in the mid to late '30s, Laurens Hammond's electric organ is a huge electro-mechanical beast. Comprising no less than 91 constantly spinning 'tone wheels' inside it that make up the Hammond's 'tone generator', each wheel has tiny ridges on their rim which disturb an electro-magnetic field in a nearby magnet. These disturbances create tiny, fluctuating voltages which when amplified, generate something closely resembling sine waves.

The dfferent wheels are used to generate the fundamental frequency and the various harmonics and sub-harmonics used to create the sound.

A series of drawbars (effectively faders much like you'd find on a modern mixer) above the upper keyboard allow you to balance the relative levels of the fundamental and the various harmonics to create a potentially huge range of sounds.

In effect, it was possibly the world's first real-time additive synthesiser!

The drawbars are the key to the sound as they determine the tone of the sound. The nine drawbars represent the different length pipes of a traditional pipe organ. The fundamental drawbar is 'eight foot' (the length of a pipe required to produce middle C) - the other drawbars offer 16-, 4-, 2- and 1-foot drawbars producing one octave below and and consecutive octaves above the fundamental. In addition, there were 5 1/3, 2 2/3, 1 3/5 and 1 1/3 foot drawbars which introduce extra tonal richness and the combination of these harmonics along with percussion effects and chorus and vibrato effects define the sound being played. The sheer number of drawbar combinations and other parameters that are available means that the Hammond was capable of a massive range of tones (although, in fairness, they will all essentially sound like 'an organ').

Many eminent Hammond players defined their 'sound' with their unique combination of drawbar settings but there were also presets which could be recalled using the 'inverted' keys in the bottom octaves of the two keyboards which, although they look like some strange extention of the keyboard range were actually nothing more than switches to select the presets.

But not only was the Hammond a mechanical beast - physically it was a monster too weighing over 400 pounds! At least four people are required to carry one so you were in trouble if you had to negotiate a flight of stairs at your gig!

But the mechanics and operation of the Hammond were only part of the sonic equation.

The Hammond was usually (if not always) amplified through a rotary speaker that literally throws the sound around a room. As the sound 'moves', so it is subject to the Doppler shift - you know the effect ... where the pitch of an ambulance siren changes as it moves towards you, passes by and then moves away from you - and this adds a rich chorus effect to the sound (as well as the distortion created by the valve amplification). The most famous of these speakers was the Leslie speaker and that name is now synonymous with the Hammond.

The speakers themselves don't rotate - instead, baffles in which the speakers are housed spin round powered by a motor and it is these baffles that throw the sound around.

However, the Leslie rotary speaker had two speeds - slow and fast - and both of these produced distinctively different sounds. Furthermore, due to the physical ballistics of the rotary mechanism, you couldn't just switch abruptly between these two speeds - the rotating speakers sped up or slowed down gradually as you switched between the two speeds giving rise to yet another weapon in the mighty Hammond sound.

The '3-series' went into production in 1955 and there were several models in the range. Complete with bench and bass pedal keyboard, the B3 found favour in jazz circles. The model C3 console was similarly equipped but used a different cabinet style. Although it was offered as the "Church Model", the C3 was the Hammond of choice for many rock players. There was also the lesser known "Concert Model" - the RT3 which had a wider C3 cabinet style and built-in amplification.

The 3-series became popular in a wide range of musical environments from home use to gospel. It was also a mainstay of many jazz and rock musicians over several decades from Booker T to Keith Emerson and many, many others - it's a classic sound that defined many different musical genres. The 3-series ceased production in 1974 as its bulk and cost was prohibitive for most especially with the arrival of smaller, lighter electronic organs which although they lacked the powerful sound of a Hammond tonewheel monster in full flight, were cheaper and more convenient.

The sound of the original B3 is also now available new in the form of the authentically modelled B3 from Hammond themselves! Sonically and cosmetically, it is supposed to identical to the original. You can find out more at: