In the world of vintage Blues instruments, the Hammond Organ is ultra high-tech. It requires electricity, which is not mandatory for many roots instruments. It requires motorized transportation, it weighs 400+ pounds. It also requires one of the most unique speaker systems ever conceived, the Leslie Speaker. This combination of organ and speaker renders the sweet sound that is so familiar in Blues music. It has also infiltrated most other music genres as its beauty is undeniable.
Clock maker Laurens Hammond came up with the basic A-model design in the 1930's. Over the years Hammond produced dozens of models of organs. Three models have emerged as the favorites, the B3, C3, and the A-100. In fact they are the same organ, the only real difference being the cabinets.
The organ works like an electric guitar. A metal object is placed right next to an electromagnet. As the object vibrates, it disrupts the magnetic field of the electromagnet. This fluctuation is then sent to an amplifier where it is converted to sound waves you can hear. On a guitar, the vibrating object is the plucked string,. On a Hammond, small discs with notched edges rotate near the electromagnet.
Many of the great recordings were done on a C3, which is the church version of the B3.
To get different notes (vibrations), each disc has different notches so all the discs can rotate at the same speed but create a different vibration for each disc. There is one disc for each basic note. This mechanism is called the Tone Generator.
The next ingenious step the Hammond takes is to take all the basic tones and mix them together, one on top of the other, to create the signature sound. To do this, there are controls above the keys that are called drawbars. Each drawbar controls a basic tone. By adjusting the 9 drawbars that are assigned to one sound, an astounding range of tones can be achieved. Most Hammonds have two manuals (keyboards) and a set of bass pedals on the floor.
This astounding versatility make the Hammond a self-contained band. A player can solo with his right hand, comp with his left, and kick the pedals for bass. Add a drummer and you've got a band! In most Blues bands though, the Hammond is not used to such an extent. It is used to mimic horn parts, to solo, and to pad (holding a chord).
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