Leak Logo H.J. Leak Timeline  

1907, January 8
Harold Joseph Leak born.

At his school in Middlesex, he formed a Wireless Society

Worked in the Wine trade, but subsequently joined Gaumont British cinemas where he learnt much about electronics and audio amplifiers.

Commenced his own business as a "Wireless Doctor"
Constructed a portable wireless model.

Constructed a pickup for 78 rpm records; an amplifier of two-stage design, and a speaker along the lines of the new Rice & Kellog moving coil design.

Late 1920's
Established himself in new premises at 124a Dalling Road, Hammersmith, West London.
Continued primarily in the design of amplifiers.

Harold Leak conducts a test transmission of stereo sound with D.W. Turpin.

1934, September 14
Founded H.J.Leak & Co- and promotes the company with his own name, adversting himself as "Sound Engineer - Technician".

H.J.Leak & Co. release a P.A.Amplifier, with exhibits at Olympia Exhibition. 13 Watts output using push-pull PX25 power triodes. 40Hz to 12kHz +/- 1dB. 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). This amplifer was supposedly advertised in Wireless World around 1938, although a search has failed to locate the advertisement.)

Late 1930's
Ted Ashley joins H.J.Leak, and was later to become Chief Engineer, and remain with the company until the late 1960's.

Harold Leak marries Muriel.

circa 1940
The Leak 124 Dalling Road premises at Hammersmith were destroyed by German bombs.
Leak moves to 470 Uxbidge Road, Shepherd Bush, and continues to make amplifiers under contract.

Late 1945
The first low distortion amplifier was released as a result of war-time research. This was the original "Point One Amplifier - the "Type 15", a four-stage circuit, with substantial negative feedback, and push-pull triode-connected KT66 valves for 15 Watts output.

Late 1940's
Leak moves to the Westway Trading Estate at Acton, in London. This was a new factory estate (with factories styled with hints of art-deco) in Brunel Road, named after the famous engineer.

The Leak TL/12 was released, heralding a move toward domestic high-fidelity sound reproduction for the company. Leak release a pickup arm and moving coil pickup with diamond or sapphire stylus, and matching transformer. A 25 Watt version, the TL/25 was also available (using tetrode connect KT66's).

Harold Leak travels Britain doing live - versus - reproduced sound comparisons with his new TL/12 and RC/PA amplifier set. The live sound is reproduced via the Leak system using an STC4033 microphone (also known as the WE639A in the USA).

During 1949 he travels at short notice, and attends the Audio Engineering Society exhibition that was held in New York. He demonstrates the TL/12 to amazed Americans. This trip establishes highly succesful American distribution of Leak products via the British Industries Incorporation.

In Australia "Simon Gray Pty Ltd" were later signed as agents. Leak also exported to other world-wide destinations such as Asia, South Africa and New Zealand.

In 1949 the company has grown to a team of around twenty staff.

The Leak "550" two-way moving coil loudspeaker was released. This loudspeaker was used in the many live-versus reproduced sound demonstrations Harold Leak conducted.

The BBC place large orders for the TL/12 power amplifier (specially modified with input attenuator and balancing transformer).

New moving coil pickup and arm released.


Troughline FM tuner released.
Leak undertakes research into suitable transducer for a high quality loudspeaker, and settles on a moving coil 15 inch bass unit, and electrostatic high frequency unit, but the prototypes never make it to mass-production.

The new range of TL/12Plus, TL/25Plus and TL/50Plus mono power amps is released, with revised mono preamps featuring the stylish diakron plastic front panel.

The Stereo 20 and Stereo 50 amplifiers, with new stereo pre-amps are released.
Troughline II FM Tuner is released.

Leak engages Dr. Don.A. Barlow to develop a new "piston action" loudspeaker.

A new stereo pickup is released, this time using the variable reluctance principle.

The highly successful Leak Sandwich loudspeaker was released.

The "Stereo 30" transistor amp using a quasi-complementary germanium transistor output stage is released (after H.C.Lin). Valve amplifier production continued into the mid 60's, and higher power models such as the TL/50Plus were still available in the late 1960's.

Downnham Market factory established (in Norwich, some distance north of London) to cater for demand for the Sandwich speaker.

Stereo 70 transistor amplifier released, using the classic 2N3055 transistors for the output stage, in quasi-complementery configuration.

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

The Leak premises at the Westway Factory Estate, Acton, are demolished.

August 27 1989
Harold Leak dies.

Reference and Acknowledgment
Many factual details for the above are from:

"The Beginnings of Hi Fi - A History of H.J. Leak & Co.", HiFi World, October 1996.

Obituary for "Harold Joseph Leak", by Raymond Cooke, OBE, (of KEF fame), Journal of the Audio Engineering Society, Vol 37, No 10, October 1989.

"Point One Amplifers" by H.J.Leak.

"High Fidelity Loudspeakers: The Performance of Moving Coil and Electrostatic Transducers" by H.J.Leak. British Institute of Radio Engineers, December 1955.

Other miscellaneous sources.


Designers and Manufacturers of Specialised Electronic Instruments for the Communications Industries