English company HJ Leak & Co. Ltd was founded in 1934 by Harold Joseph Leake. The company began as a small workshop with a staff of several people. The direction of its activity was the production of amplifiers for cinemas and public address systems. These were typical push-pull devices of that time, built on Osram DA30 triodes.
LEAK founder – Harold Joseph Leak (left)
Profits were reinvested in new developments and production expansion. The result of the work was the appearance in the victorious year of 1945 of the first amplifier of the “Point One” series, so named because the total harmonic distortion coefficient of these devices was only 0.1% at rated power.
The first amplifier in the series, designated TL-12, is capable of delivering 15 W. output power with a distortion of 0.1%, it uses a push-pull stage on KT66 lamps connected in the form of triodes. The amplifier has a circuit design similar to the Williamson amplifier known in those years.
Amplifier LEAK TL-12 (1948)
Perhaps it is to LEAK that we owe the coining of the term “ultralinear amplifier”. The company’s tube amplifiers today have a cult status and are objects of interest to collectors and audio lovers all over the world, and their prices are only rising. Having earned an excellent reputation thanks to its extremely successful tube models, the company confidently stepped into the world of then new technologies and took a leading place among the pioneers of the production of transistor amplifiers, along with such trendsetters of the coming “transistor era” as Rogers, Armstrong, Ferrograph…
Appeared in In the first half of the 60s, LEAK STEREO 30, built on a “germanium” output stage, but also due to its “tube morphology,” immediately became one of the best-selling amplifiers in England. The device has acquired a well-deserved cult status and is a unique example of the classic sound of English audio vintage.
Mr. Lick’s company continued to be successful and the first series of transistor amplifiers was followed by a second, which was called DELTA. The output power and, therefore, the numbers in their names have not changed – 30 and 70, but the design has undergone some changes. And if the first models, in terms of the nature of their sound and partly in terms of the engineering solutions implemented in them, are something between a classic transistor and a lamp, then in their “filling” the Deltas look like quite modern devices and have the sound of a very good and quite powerful “transistor” “in the sense we are familiar with today. These devices are capable of producing undistorted sound even at high volumes. The amplifiers make it possible to pleasantly listen to early heavy metal without feeling any noticeable compromises in presentation. The appearance of the devices has become somewhat more brutal compared to the first models. The front panel is made of solid aluminum with a transparent plexiglass insert. A varnished wooden mac is present. In the amplifiers of the DELTA series, the company began to use a lot of Japanese element base.
LEAK Stereo 30 Plus amplifier (1962)
Mr. Leake and his engineers did not focus exclusively on amplifiers, although amplifiers made the company a world-famous brand. The second successful area of the company’s activity was the design of acoustic systems. And there was some innovation here! The patented diffuser design developed by the company was a multi-layer “sandwich”, the basis of which was light, rigid and durable foam. Driven by powerful (in the first models rare-earth) magnets, these diffusers created a dense and clear bass unprecedented at that time, and complex dynamic passages acquired filigree precision and composure in their execution. Thanks to the design of its diffusers, the acoustics received the marketing name “Leak Sandwich”.