Leak
Company Profile[edit]
Harold Joseph Leak was born on January 8, 1907. In the 1920s he first worked in the wine trade, changed jobs and in 1922 found employment in a movie theater where he learned a lot about electronics and audio amplifiers. In 1926 Harold Joseph Leak founded his own company which designed portable wireless microphones. This was followed in 1927 by a 78 rpm phonograph cartridge, a two-stage amplifier and a loudspeaker based on the then new Reis & Kellog moving coil design. At the end of 1920 the company moved to new premises at 124a Dalling Road, Hammersmith, West London. The main focus was on the development and design of amplifiers. 1931 Harold Leak conducts a radio stereo sound test broadcast with D.W. Turpin. 14 September 1934 H.J.Leak & Co is officially incorporated. 1936 H.J.Leak & Co. produces a PA. Amplifier with other exhibits for an exhibition on the occasion of the Olympic Games. The amplifier had an output of 13 watts with push pull PX25 power triode. Frequency range was 40 Hz to 12 kHz ±1dB. Late 1930, Ted Ashley joined the H.J.Leak company and later became chief developer. He remained with the company until the late 1960s. 1940, the company's premises in Dalling Road Hammersmith were destroyed by German bombs. The company moved to 470 Uxbidge Road, Shepherd Bush and continued to produce amplifiers. 1942 Harold Leak marries. In September 1945 the company released the first the "number one" range of amplifiers, so called because the THD was 0.1% at rated power. This represented a major leap forward in accepted standards for high power amplifiers (with 2% distortion generally considered acceptable at the time). This first "number one" amplifier was known as the Type 15, and produced 15 watts of power with 0.1% distortion, using push-pull KT66 tubes connected as triodes, with 26 dB feedback applied across four stages. The amplifier has a similar topology to the Williamson amplifiers (published in Wireless World 1947). In 1948 the original four stage circuit was replaced by a three stage circuit, for the TL/12. This amplifier had the same high performance at reduced cost, and the success of the amplifier was critical in securing the company's future as the dominant manufacturer during the hi-fi boom of the 1950s and 1960s. In late 1940 Leak moved the company to Westway Brunel Road in London. This new factory had a beautiful Art Deco style building in. 1948, the Leak TL/12 was introduced and its quality finally established the company in the high-fidelity field. This was followed in the same year by an S-shaped tonearm, a moving coil cartridge with diamond or sapphire needle and matching transformer. A 25-watt version of the TL/25 was also available. In 1949 Harold Leak travelled the UK to demonstrate his new TL/12 and RC/PA amplifier set live and to make comparisons against other companies' products. The sound was live through the Leak system using an STC4033 microphone, also known as WE639A (produced in the USA). At the 1949 Audio Engineering Society exhibition in New York, Harold Joseph Leak introduces the TL/12 power amplifier. This trip becomes very successful and a US American distributor for Leak products is established. Later a distribution agreement was signed in Australia with "Simon Gray Pty Ltd". Leak also began exporting to other worldwide destinations such as Asia, South Africa and New Zealand.1949 The company has grown to a team of around twenty employees. 1949/1950, the Leak "550" bi-directional moving coil loudspeaker is introduced. In 1951, the BBC places a large order with Leak for TL/12 power amplifiers with specially adapted input attenuator and balancing transformer. 1954 a new pickup with moving coil and a new tonearm follows. 1955 the Troughline FM tuner follows. Leak conducts research with suitable transducers for high quality loudspeakers with a moving coil, 15 cm bass driver and an electrostatic high frequency unit. However, the prototypes never made it to mass production. The new range of TL/12Plus, TL/25Plus and TL/50Plus mono power amplifiers were produced from 1956 with revised mono preamplifiers in stylish cabinets with Diakron plastic front panels The Leak Stereo 20 and 50 amplifiers with new stereo preamplifiers were produced from 1958. Also the Troughline II-FM tuner. Leak hires Dr. Don.A. Barlow in 1959 to develop a new "Piston Action" loudspeaker. Barlow first published the advantages of sandwich speaker construction using the foil diaphragm in Wireless World in December 1958. A new stereo pickup was introduced in 1960, this time using the Variable Reluctance Principle. The first Leak Sandwich loudspeaker was introduced in 1961, over time the Sandwich loudspeakers were very successful. 1963, the Stereo 30, a transistor amplifier with Quasi Complementary Germanium Transistor Output Stage after H.C.Lin became very successful. The production of tube amplifiers continued until the mid 60s. Models with higher output like the TL/50Plus were still available until the end of the 1960s. To meet the increasing demand for sandwich loudspeakers, a separate production facility was built in Norwich, some distance north of London. In 1968 the Stereo 70 transistor amplifier was manufactured using the classic 2N3055 transistors for the output stage in a quasi-complementery configuration. 1969 H.J. Leak & Co. is sold to the Rank Organisation, and Harold Leak retires from the company. 1996 The Leak Westway Factory Estate premises are demolished. Harold Joseph Leak died on 27 August 1989 in Jersey (UK) at the age of. 82. At the beginning of the 1970s there was still a series of receivers with the label LEAK under the direction of Rank: Leak 2000, Leak Delta 30, Leak Delta 70, Leak Delta 75, Leak 2000 and Leak 3200. However, these were not a great success. The quality was no longer that which one was used to from LEAK. In the middle of the 70s the production was finally stopped.
Products[edit]
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