Richard Hammond tell us about an extraordinary objects that created with science, art & technologies. Then also he reveal the big ideas and/or inspirations to create that massive masterpiece.
Runtime: 50 minutes
Richard Hammond's Engineering Connections - Leslie speaker - Netflix
The Leslie speaker is a combined amplifier and loudspeaker that projects the signal from an electric or electronic instrument and modifies the sound by rotating the loudspeakers. It is most commonly associated with the Hammond organ, though it was later used for the guitar and other instruments. A typical Leslie speaker contains an amplifier, a treble horn and a bass speaker—though specific components depend upon the model. A musician controls the Leslie speaker by either an external switch or pedal that alternates between a slow and fast speed setting, known as “chorale” and “tremolo”. The speaker is named after its inventor, Donald Leslie, who began working in the late 1930s to get a speaker for a Hammond organ that better emulated a pipe or theatre organ, and discovered that rotating the speaker gave the best sound effect. Hammond was not interested in marketing or selling the speakers, so Leslie sold them himself as an add-on, targeting other organs as well as Hammond. Leslie made the first speaker in 1941. The sound of the organ being played through his speakers received national radio exposure across the US, and it became a commercial and critical success. It soon became an essential tool for most jazz organists. In 1965, Leslie sold his business to CBS who, in 1980, sold it to Hammond. Suzuki Musical Instrument Corporation subsequently acquired the Hammond and Leslie brands. Because the Leslie is a sound modification device in its own right, various attempts have been made to simulate the effect using electronics effect units. These include the Uni-Vibe, the Neo Ventilator, or Hammond-Suzuki's own simulator in a box.
Richard Hammond's Engineering Connections - Sound generation - Netflix
The Leslie is specifically designed, via reproduction of the Doppler effect, to alter or modify sound. As the sound source is rotated around a specific pivot point, it produces tremolo (the modulation of amplitude) and a variation in pitch. This produces a sequence of frequency modulated sidebands. To stop a Leslie's rotor, a special brake circuit was added to the Leslie motor controls, that incorporated an electronic relay by producing a half-wave of direct current. Much of the Leslie's unique tone is due to the fact that the system is at least partially enclosed, whereby linear louvres along the sides and front of the unit can vent the sound from within the box after the sound has bounced around inside, mellowing it. The crossover is deliberately set to 800 Hz to give the optimum balance between the horn and the drum, and is considered an integral part of the speaker. The tone is also affected by the wood used. Tone differences, due to cost cutting using particle board for speaker and rotor shelves instead of the previous plywood, are evident in the Leslie's sound. The thinner ply of the top of the cabinet adds a certain resonance as well. Like an acoustic instrument, a Leslie's tone is uniquely defined by its cabinet design and construction, the amplifier, crossover and speakers used, and the motors — not merely by the spinning of rotors.
Richard Hammond's Engineering Connections - References - Netflix