H.J. Leak & Co. Ltd.
124 Dalling Road premises at Hammersmith London (1934 – 1940)
470 Uxbidge Road, Shepherd Bush, London (1944-1946)
Brunel Road, Westway factory estate, London W3. (c1946 -1996)

IAG Group
IAG House, 13/14 Glebe Road. PE29 7DL (2020)

The LEAK brand developed amplifier technology, loudspeakers, pickups, and turntables, amongst many seminal products in a portfolio spanning through the golden years of British audio innovation.

Harold Leak marketed himself as a ‘Sound Engineer – Technician’, and along with Ted Ashley, who joined the company in the late 1930s and who later became Chief Engineer for the company, LEAK became a market leader of affordable but high-performance home audio equipment… for decades upon decades.

During the 1950s and 1960s, the company produced high-quality amplifiers, radio tuners, loudspeakers (the LEAK Sandwich), pickups, tonearms, and a turntable.

In January 1969 the business was sold to the Rank Organisation.

The sale of the business to Rank produced an expanded range of models, and considerable further development of loudspeakers, but Rank was not able to position the brand to counter competition from Japanese electronics manufacturers, so by the late 1970s, electronics and speaker production ceased under the LEAK name.

In 2020, the year of Harold Joseph Leak’s 113th birthday and H.J. Leak & Co’s 84th birthday, IAG Group proudly brings the return of LEAK. Maintaining the art-deco-inspired, classic-styled high-quality home audio format for the modern-day hi-fi enthusiast, LEAK is reborn.

Harold Joseph Leak (1907-1989) founded the seminal H. J. Leak & Co Ltd in 1934 and worked initially as a subcontractor building amplifiers for other firms.

In 1936 H.J. Leak & Co. released a P.A. Amplifier, with exhibits at the Olympia Exhibition. 13 Watts output using push-pull PX25 power triodes. 40Hz to 12kHz ± 1 dB. The cost was 13 guineas. (H.J. Leak does not appear in listings of exhibitors for Olympia, so the company may have used another company’s stand for the exhibit). 

In 1945 he released the first amplifier in the famous Point One series, so named as the total harmonic distortion at rated output measured 0.1%. The first announcement of this astonishing achievement first appeared in an advertisement in the Journal of the British IRE, in September 1945 followed by an advert in Wireless World in February 1946. [1]

In the late 1940s, after the original factory in Shepherd's bush was destroyed by wartime bombing, the seminal LEAK factory was founded on the newly built Westway factory estate, Brunel Road, London.

An epicentre of engineering, named after the famous engineer I.K. Brunel, the art-deco design of this factory estate very likely became part of the industrial design influence that translated through the lifetime of LEAK products.

After years of contract-based amplifier production, the LEAK Type 15 amplifier came to life in 1945 as a gem from wartime efforts. Utilising a four-stage circuit and a groundbreaking ‘negative feedback’ design with ‘push-pull’ triode connected KT66 valves, it achieved a remarkable 15 watts output! The LEAK type 15 would be known as the original ‘Point One Amplifier’, a classic series of stereo amplifiers that evolved right through the 1950s.

In 1948, the future classic, LEAK TL/12 marked the first bold step towards high-fidelity sound reproduction. Soon a tonearm, moving coil cartridge, and a higher-powered TL/25 followed.

The Leak TL/12 amplifier set such improved standards in technical performance and physical layout and construction of its components that it easily became the ‘reference amplifier’ in the sound and broadcasting industry. Leak went on to become one of the dominant names in the audio industry during the 1950s and 60s and was one of the first British manufacturers to successfully export to the USA.

This high-fidelity concept required a unique approach to helping reach the mass market of audiophiles and home music enthusiasts. Therefore, in 1949 H. J., Leak embarked on a nationwide ‘live vs reproduced’ tour. Akin to the marketing campaigns of the great founding fathers of audio, Leak presented a direct comparison of ‘recorded vs live’ music with high-fidelity, LEAK-powered audio systems. The proposed tour was described in Practical Wireless in December 1957.

Mr. Harold Leak to Visit the U.S.A.

MR. HAROLD J. LEAK.  British I.R.E. Chairman and Managing Director of H. J. Leak & Co. Ltd. is to visit New York.

He will spend much time at the New York High Fidelity Fair and will demonstrate some of the Leak equipment exhibited.  Mr Harold Leak is the doyen and leader in the field of Hi-Fi sound reproduction. Having started 23 years ago.

He leads not only in the designing and manufacturing of amplifiers, pickups, and pre-amplifiers. but in the fundamental scientific research on sound reproduction.
Recently he was awarded the " Dr. Norman Partridge Memorial Award " of the British Institution of Radio Engineers, for his paper on " High Fidelity Loudspeakers: The Performance of Moving Coil and Electrostatic Loudspeakers." He is the only Britisher ever to receive the honour of being elected a Fellow of the Audio Engineering Society of America. [2]

In 1949 the Australian company Simon Gray Pty Ltd. was later signed as agents. Leak, also exported to other worldwide destinations such as Asia, South Africa, and New Zealand.

1969 H.J. Leak & Co. sold to the Rank Organization, and Harold retired.

Rank was not able to position the brand to counter competition from Japanese electronics manufacturers, so by the late 1970s, electronics and speaker production ceased under the LEAK name.

In 2020, the brand was reborn by the IAG (International Audio Group) Group.

[1] Wireless World Feb 1946, Page Ad 14.
[2] Practical Wireless Dec 1957, Page 681.