The full story of Thermionic Products and Racal-Thermionics is told in A Truvox Product
Founded in 1944 by Alfred Colley and Edward Angold, their first product was Britain's first electronic flash-gun, the 'Mega-Flash'.
They already held patents for cinematographic sound recording which undoubtedly led to their patented improvements to the
Brush "Mail-a-Voice" disc recorder of 1946.
By 1948 they had secured the licence to build the "Mail-a-Voice" in the UK, launching it as the "Recordon
TP503", (right) built in London. This was marketed as an office dictating machine and operated very
much like a gramophone, recording onto a 9" magnetic oxide coated paper disc which could be folded into three and posted
to another office. It proved a most successful product and allowed the company to take up offices in Jermyn Street, London.
It was later produced at Hythe as the improved TP504 along with a deluxe 'Diplomat' version (below)
The Recordon's resounding success allowed Thermionic Products to secure the licence to build the Brush 'Soundmirror'
(lower left) in late 1948. It was the first British-built domestic tape-recorder, whereas the first British
built-and-designed tape recorder was the Wright & Weaire, which appeared a few weeks later (see Terry Martini's superb
history, Built like a Battleship).
Production began in autumn 1948 but the quality of
the paper tape meant it shedded oxide too readily and clogged the heads! While this was being sorted out, Colley made
a fortune producing the drinking-duck novelty solar toys!
The Soundmirror was a single speed machine and one of
the first to use a swinging arm pinch wheel operation. It employed a cross-over belt drive with joy-stick control and 'pop-up'
permanent magnet erase head - the full track head used only the central 2/3rds of the tape. The spools of paper-tape
were driven by flanges on the spool turntable - not the more usual off-set pin or DIN drive seen later. They were sold in
a superbly made walnut veneered cabinet as a piece of domestic furniture at £69.
Production moved to Hythe, Hampshire in 1950. It is said that their Chief Engineer elected to stay in London and
joined Scophony-Baird to help design their first tape recorder, the Scophony-Baird 'Soundmaster'; this 2-motor design
is quite different from the Soundmirror and used an oxide-out spooling and electromagnetic erase and play/record
heads. This model remainded on offer until 1955. However no proof of this move to Baird has been found.
The T-P Soundmirror
was joined in 1951 by a portable model in a wooden case, finished in a yellow/brown fabric, (right)
had provision for extra spools of tape, a large ACOS microphone and cables - and is surprisingly light! It sold for £79.
Production of the Soundmirrors continued to late 1954 by which time Thermionic Products had moved entirely over to multi-track
airfield voice loggers.
A new post-war Convention on International Civil Aviation brought forth a legal demand from 1951 for logging all
Air Traffic Control to pilot communications. This required multi-track machines which Thermionic Products pioneered in the
UK 1950 - they soon became world leaders, but that story is told in A Truvox Product.
In the late 1950s,
T-P were pinning their hopes on a major contract for London Heathrow, but it went to the British Communications Corporation
- a young company owned by Dan Prenn of Truvox fame. The failure to win the contract soon pushed Thermionic Products into
receivership; they were bought by Prenn in 1958 and production of airfield voice-loggers continued at Hythe under T-P while
BCC concentrated on military and police radio communications. T-P were once again world leaders in multi-track recorders and
with expertise gained through Epsylon and Vectron engineers, expanded into instrumentation recorders and digital technology.
In 1967, Dan Prenn made his Truvox audio business a subsidiary of Thermionic Products and Truvox production moved to
Hythe. T-P's expertise in military contracts soon transformed the quality of Truvox's domestic tape recorders. Indeed the
Truvox Series 100 was chosen by T-P for their first portable instrumentation and seismic recorder - the T-P T3000,
(left). This had four speed operation and advanced electronic pcb circuitry. It was superceded by the Series
200 deck and alone survived as the Racal-Thermionic T3000 when Thermionic Products and Racal merged in 1969.
In addition to their multi-channel communication recorders, Racal-Thermionic developed an incredibly versatile and truly
advanced portable instrumentation recorder, the Store 4, which replaced the T3000. This offered optional speed ranges from
15/640ips (for seismic work) to 60ips in 4, 7 and 14 channel formats. Highly regarded for its delicate and accurate tape transport,
it was the machine of choice for replaying fragile aircraft "Black-box" tapes for analysis.
In 1971 Racal bought the Zonal (formerly Ilford-Zonal) magnetic tape business but sold it in the 1980s; Zonal are still
By 1977 the company had become Racal-Recorders and further developed specialist communications and instrumentation recorders,
but these are beyond the scope of this audio web-site! The full story is recorded in A Truvox Product.