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Things We Lose

by Allan Wyatt, February, 2017.
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At the age of 13 in 1963 I built my first radio set. This was a one valve design from Fun With Radio1025 by Gilbert Davy that had a 1T4 as the active device. Listening was on a pair of S G Brown Type F headphones. Also at this time I was looking after the school PA system. The school hall was too small and some classes listened to the school assembly in their classrooms. My main task was the replacement of quarter inch jack plugs that were fitted to the classroom speakers as the connection into the school 100 Volt line system. Jack plugs were in demand by the pupils for guitars.

Our metalwork teacher, Mr Gillam, was probably a seargent major during the war and outside school was a celebrated semi-pro sound recordist. In about 1965 he offered me a valve amplifier, a large heavy chassis with seperate pre-amp. The main chassis and transformers were covered in gold paint and the output valves were a pair of PX25s. I was told that this amplifier had been owned by Johnny Dankworth.

The amplifier worked, but only just, but the volume was low. Pocket money was insufficient to buy new valves and the amplifier was put aside for later use. However, in 1969 when I went to college, my mother insisted that I dispose of my 'toys' and so the amplifier and assorted radios and a working TV22 went to the dump. My brother borrowed an air rifle and broke all my valves - even the delightful PX25s. This museum is in part atonement for that act of vandalism.

Some 45 years later I saw a picture of the Leak pre-amp and it reminded me of the PX25 amplifier. The only Leak product that used PX25s dates to 1936 and is very rare. Much of our heritage went into a skip during the 1960s drive to modernise UK industry.

This is all I have found so far about that elusive Leak amp.

In 1936: 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.)

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