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{{Short description|British audio manufacturer}} | |||
{{Cleanup|date=January 2007}} | |||
{{Use dmy dates|date=December 2023}} | |||
{{Use British English|date=August 2013}} | |||
{{more citations needed|date=May 2011}} | |||
'''Radford Electronics''' is a British audio manufacturer from ], founded by Arthur Hedley Radford (G6YA) in 1946. Radford's ] ]s enjoyed a reputation for quality that was "second to none", especially because of their output transformers.<ref>{{cite book|last=Hood|first=John Linsley|title=Valve & transistor audio amplifiers|url=https://books.google.com/books?id=YbzBWfTHorQC&pg=PA105|year=1997|publisher=Newness|isbn=978-0-7506-3356-7|pages=105–6}}</ref> | |||
'''Radford Electronics''' is a British audio manufacturer founded by Arthur Hedley Radford in 1961. | |||
==History== | ==History== | ||
Radford began building amplifiers in 1946, and marketed its first hifi-amplifier in 1959.<ref>{{Cite web |url=http://www.radfordaudio.co.uk/ |title=Radford Electronics |access-date=30 January 2007 |archive-date=12 February 2007 |archive-url=https://web.archive.org/web/20070212223126/http://www.radfordaudio.co.uk/ |url-status=dead }}</ref> Reportedly, Radford make amplifiers with such low distortion that they had to build their own test equipment to measure it; their test equipment also acquired a reputation for quality.<ref>{{cite web|url=http://theaudiostandard.net/thread/4776/history-radford-electronics|title=A History of Radford Electronics|last=Bennett|first=Chris|author2=Barry D. Hunt |date=3 July 2010|publisher=The Audio Standard|accessdate=19 February 2019}}</ref> | |||
Radford Electronics began in 1961 with the STA range of amplifiers launched accompanied by the DSM pre-amplifier. The Series 3 STA25, along with other Amplifiers in the STA range, won critical acclaim. As an expert in ] design, Arthur Radford was able to reduce distortion by a factor of ten over the best performing amplifier of the day. The MK11 and Series 3 Amplifiers used a unique pentode phase inverter that was a joint venture between Dr A R Bailey and Arthur Radford and was the subject of a detailed article in Wireless World. | |||
In 1961, the company released the STA range of amplifiers, accompanied by the DSM pre-amplifier. The Series 3 STA25, along with other Amplifiers in the STA range, won critical acclaim. As an expert in ] design, Arthur Radford was able to reduce distortion by a factor of ten over the best performing amplifier of the day. The MK11 and Series 3 Amplifiers used a unique pentode phase inverter, which was the result of a joint venture between Dr A R Bailey and Arthur Radford, and was the subject of a detailed article in Wireless World. | |||
However Arthur Radford’s greatest love was for his ] designs and the rear termination of drivers. After many years of work he eventually took out a patent in conjunction with Dr A R Bailey for the first transmission line loudspeaker. This system was the basis for all his larger designs and is still used by many well-known manufacturers. | |||
<gallery class="center"> | |||
Although today the ]s attract the most attention from enthuiasts, the quality of Radford design continued into the ] age with the "Zero distortion" series of solid state power amplifiers produced in the mid 1970s in which THD was reduced to less than the circuit noise level. These (and later products such as the Quad 405 and Halcro range) achieved the near perfect measured performance for which designers had been striving since the earliest days of the industry. Left with no potential for objective improvements in quality, the industry started to concentrate on subjective analysis of designs and products which has, in some cases, led to a re-interest in valve amplification amongst audio enthusiasts. | |||
File:STA15 MK3 and SC22 pre amp.jpg|alt=A photo of a Radford STA15 MK3 amplifier and an SC22 preamp.|Radford STA15 MK3 and SC22 preamp | |||
File:Glowing radford.jpg|alt=A photo of a Radford STA15 MK3 amplifier with glowing valves.|A glowing example of a Radford STA15 MK3 | |||
At the peak Radford had four factories in Bristol England, employing 160 personnel producing metalwork, painting, printing, transformer design / production Loudspeaker assembly / test and PCB manufacture, all in house. For example another well known Radford product was the "Labpak" low voltage power supply, used in schools and colleges both in the UK and overseas. | |||
File:Radford STA15 MK3 amplifier.jpg|alt=A photo of a Radford STA15 MK3 amplifier with its top cover removed.|A Radford STA15 MK3 amplifier with its top cover removed | |||
As Arthur approached retirement the company was wound down as there was no one to take it on. After he retired in 1989 Woodside Electronics was formed by John Widgery, who had been apprenticed to Radford Electronics and was responsible for many of the classic designs. Mike Davis joined John as a partner in 1989 and they worked together to launch the ] and update the range of valve equipment as part of the Renaissance series. Arthur died on the 21st of November 1993 and Woodside continued for a while but finally ended production in Llanbedrog, Pwllheli, North Wales in 2004. | |||
Radford ]s are rare today and still command high prices on the secondhand market. Much sought after and enthusiastically rebuilt, they are particularly known for classic and restrained physical design and outstanding and listenable sound quality - including a particular ability to drive, very sweetly, the notoriously difficult Quad electrostatic loudspeakers. 2006 brought hope of a rebirth for the brand, with news of plans to begin manufacture of classic valve based designs like the STA 25 Mk III in 2009 . | |||
The Radford forum, a Yahoo group of enthusiasts from all over the world, maintains substantial files of schematics, pictures and discussions. | |||
== Radford amplifiers == | |||
Below is a (incomplete) list of Radford designs in an attempt at chronological order. | |||
The prefix STA indicates a stereo amplifier. | |||
The prefix MA indicates a mono amplifier. | |||
The number indicates the nominal power rating. | |||
'''Original Radford amplifiers:''' | |||
{| class="wikitable" | |||
|- | |||
! '''Model''' | |||
! '''Information''' | |||
|- | |||
|STA12 | |||
| (1960) Used EL34 output tube and EF86 with ECF82 driver tubes. The rectifier was a GZ34. Produced just over 12 Watts per channel and based on a Mullard 5/20 with good output transformers and some careful LF and HF phase compensation to keep the unit stable. | |||
|- | |||
|MA15 | |||
|power Amplifier. Single channel version of the STA12 with slightly higher power output. | |||
|- | |||
| STA7 | |||
|(1960) Very rare dual channel amplifier giving about 8 Watts from a pair of push-pull ECL86’s. | |||
|- | |||
| STA15 mk2 | |||
| (1962) As above but output = 15 wpc | |||
|- | |||
| STA15 series 3 | |||
| (1962) Uses EF86 input valve, ECF82 phase splitter/driver and 2 EL34s per channel. A single GZ34 provides rectification for both channels. | |||
|- | |||
| STA25 series 3 | |||
| (1965) The first stereo version of the MA25 gave a conservative 25w per channel from EL34 output tubes and EF68 with ECF82 driver tubes. This amp is sometimes confused with the STA15. It can be identified by its manual bias adjustment and solid state rectifier both of which are not present on the STA15. | |||
|- | |||
| ISTA60 | |||
|60wpc. | |||
|- | |||
| STA100 | |||
| (1967) One of the more powerful Radford amps this used KT88s to give two channels at 100w each. The |driver tubes were ECC88 and EF184. A solid state rectifier was used. | |||
|- | |||
| MA15 | |||
| (1961) First monoblock, valve line up = EF86 ECC83 EL34X2 EZ81 rectifier | |||
|- | |||
| MA15 Series 3 | |||
|(~1961) As above but uses EF86 ECF82 GZ34 Valve rectifier. | |||
| | |||
|- | |||
| MA25 | |||
|(1962) Valves used = EF86, ECF82, EL34X2, Diode bridge rectifier. | |||
| | |||
|- | |||
| MA25 mk3 | |||
| (1962) As above. | |||
| | |||
|- | |||
| K25 | |||
|A modified version of the MA25 for use with a BBC monitor loudspeaker manufactured by KEF. It featured a frequency shaping network, to flatten the response of the speaker, and a balanced input. | |||
|- | |||
|} | |||
'''Radford pre-amplifiers/control units'''<br/> | |||
* DSM(~1961) Beautifully made control unit with 3 EF86’s and 1 ECC83’s per channel, a lot of electronics in a very small box. | |||
* SC2 A pre-amplifier with passive tone control system. | |||
* SC3 A three channel version of the SC2.The third derived channel was for a separate centre loudspeaker. | |||
* SC22 Feedback controlled tone controls, transistor disc stage and selective frequency RIAA equalisation network. There was also a switchable feedback rumble filter incorporated around the valve stage. | |||
* SC22p As SC22 with power supply. | |||
'''Radford "Zero distortion" (distortion below circuit noise level) transistor amplifiers'''<br/> | |||
* ZD50 & ZD100 stereo power amplifier | |||
* ZD22 preamplifier | |||
* HD250 stereo integrated amplifier | |||
'''Later Radford hybrid valve & transistor amplifiers'''<br/> | |||
* TT100 stereo power ampliier | |||
'''Woodside Electronics amplifiers'''<br/> | |||
* STA25 renaissance | |||
* STA35 renaissance | |||
* STA50 renaissance (2004) | |||
'''2009 Radford amplifiers'''<br/> | |||
* STA25 mk6 | |||
<gallery> | |||
File:STA15 MK3 and SC22 pre amp.jpg|STA15 MK3 and SC22 preamp | |||
File:Glowing radford.jpg|A glowing example of a STA15 MK3 | |||
File:STA15_mk3_no_top.jpg|A Radford STA15 MK3 amplifier with its top cover removed | |||
</gallery> | </gallery> | ||
However, Arthur Radford’s greatest love was for his ] designs and the rear termination of drivers. After many years of work he eventually took out a patent in conjunction with Dr A R Bailey for the first ]. This system was the basis for all his larger designs, and is still used by many well-known manufacturers. | |||
== Radford loudspeakers == | |||
Radford also manufactured loudspeakers, tuners and other audio gear. An (incomplete) list of these is below: | |||
*Bookshelf | |||
*Beaumonde | |||
*Tristar T90 | |||
*Studio S90 | |||
*Monitor M180 | |||
*Studio S270 | |||
*Studio S360 | |||
*Monitor 90 | |||
]Although today, the ]s attract the most attention from enthusiasts, the quality of Radford's designs continued into the ] age with the "Zero distortion" series of solid state power amplifiers produced in the mid 1970s, in which THD was reduced to less than the circuit noise level. These, and later products such as the Quad 405<ref>{{cite web | url=http://www.keith-snook.info/QUAD-405-mods.html | title=~ A Home away from home ~ }}</ref> and Halcro range, achieved the near perfect measured performance for which designers had been striving since the earliest days of the industry. Left with no potential for objective improvements in quality, the industry started to concentrate on subjective analysis of designs and products which has, in some cases, led to a revival of interest in valve amplification amongst audio enthusiasts. | |||
== Radford Tuners == | |||
At its peak, Radford had four factories in Bristol, England, employing 160 personnel producing metalwork, painting, printing, transformer design / production Loudspeaker assembly / test and PCB manufacture, all in house. Another well known Radford product was the "Labpak" low voltage power supply, used in schools and colleges, both in the UK and overseas. | |||
*FMT1 | |||
*FMT2 | |||
*FMT3 | |||
*FMT4 | |||
*FMT5 prototype produced, but never manufactured | |||
As Arthur approached retirement, the company was wound down as there was no one to take it on. After he retired in 1989, Woodside Electronics was formed by John Widgery, who had been apprenticed to Radford Electronics and was responsible for many of the classic designs. Mike Davis joined John as a partner in 1989, and they worked together to launch the ] and update the range of valve equipment as part of the Renaissance series. Arthur died on 21 November 1993, and Woodside continued for a while but finally ended production in Llanbedrog, Pwllheli, North Wales in 2004. | |||
== Radford CD-Players == | |||
??? | |||
Radford ]s are rare today, and still command high prices on the secondhand market. Much sought after and enthusiastically rebuilt, they are particularly known for classic and restrained physical design and outstanding, listenable sound quality - including a particular ability to drive, very sweetly, the notoriously difficult Quad electrostatic loudspeakers. 2006 brought hope of a rebirth for the brand, with news of plans to begin manufacture of classic valve based designs like the STA 25 Mk III in 2009. | |||
== Radford Lab power supples (specifications approximate) == | |||
Small scale production is now carried on by Radford Revival, a UK craft business dedicated to replicating the classic amplifiers of the company's heyday. | |||
Model ?? 0-24V output switchable in 0.2V increments @ 2.0A and 240V @ 100mA</br> | |||
Model ?? Continuously variable 0-24V output with current limit variable up to 2.0A</br> | |||
== Radford test gear == | |||
Arthur Radford was designing such high specification amplifiers for the time period that he was having problems measuring their performance due to limitations of the test gear. Radford set about designing new ultra-linear measurement and test tools to solve this problem. | |||
{| class="wikitable" | |||
|- | |||
! Model | |||
! Information | |||
|- | |||
| DMS Series 3 | |||
| LF Total Harmonic Distortion (THD) analyzer, to 0.003%, 10Hz-50k, 1mV-50v, portable. | |||
|- | |||
| LDO series 3 | |||
| Low Distortion Oscillator. The instrument harmonic distortions are about 120 dB below the fundamental. | |||
|} | |||
==See also== | ==See also== | ||
* ] | * ] | ||
==References== | |||
FERRARI Pier Paolo - Italy - "RADFORD - Hi-Fi Legend" - SANDIT Editor, Bergamo - Italy - ISBN-10 : 8869283135 | |||
==External links== | ==External links== | ||
* | * | ||
* | |||
* | |||
] | ] | ||
] | ] | ||
] | |||
] | ] |
Latest revision as of 20:58, 2 December 2024
British audio manufacturer
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Radford Electronics" – news · newspapers · books · scholar · JSTOR (May 2011) (Learn how and when to remove this message) |
Radford Electronics is a British audio manufacturer from Bristol, founded by Arthur Hedley Radford (G6YA) in 1946. Radford's hi-fi amplifiers enjoyed a reputation for quality that was "second to none", especially because of their output transformers.
History
Radford began building amplifiers in 1946, and marketed its first hifi-amplifier in 1959. Reportedly, Radford make amplifiers with such low distortion that they had to build their own test equipment to measure it; their test equipment also acquired a reputation for quality.
In 1961, the company released the STA range of amplifiers, accompanied by the DSM pre-amplifier. The Series 3 STA25, along with other Amplifiers in the STA range, won critical acclaim. As an expert in transformer design, Arthur Radford was able to reduce distortion by a factor of ten over the best performing amplifier of the day. The MK11 and Series 3 Amplifiers used a unique pentode phase inverter, which was the result of a joint venture between Dr A R Bailey and Arthur Radford, and was the subject of a detailed article in Wireless World.
- Radford STA15 MK3 and SC22 preamp
- A glowing example of a Radford STA15 MK3
- A Radford STA15 MK3 amplifier with its top cover removed
However, Arthur Radford’s greatest love was for his loudspeaker designs and the rear termination of drivers. After many years of work he eventually took out a patent in conjunction with Dr A R Bailey for the first transmission line loudspeaker. This system was the basis for all his larger designs, and is still used by many well-known manufacturers.
Although today, the valve audio amplifiers attract the most attention from enthusiasts, the quality of Radford's designs continued into the transistor age with the "Zero distortion" series of solid state power amplifiers produced in the mid 1970s, in which THD was reduced to less than the circuit noise level. These, and later products such as the Quad 405 and Halcro range, achieved the near perfect measured performance for which designers had been striving since the earliest days of the industry. Left with no potential for objective improvements in quality, the industry started to concentrate on subjective analysis of designs and products which has, in some cases, led to a revival of interest in valve amplification amongst audio enthusiasts.
At its peak, Radford had four factories in Bristol, England, employing 160 personnel producing metalwork, painting, printing, transformer design / production Loudspeaker assembly / test and PCB manufacture, all in house. Another well known Radford product was the "Labpak" low voltage power supply, used in schools and colleges, both in the UK and overseas.
As Arthur approached retirement, the company was wound down as there was no one to take it on. After he retired in 1989, Woodside Electronics was formed by John Widgery, who had been apprenticed to Radford Electronics and was responsible for many of the classic designs. Mike Davis joined John as a partner in 1989, and they worked together to launch the CD player and update the range of valve equipment as part of the Renaissance series. Arthur died on 21 November 1993, and Woodside continued for a while but finally ended production in Llanbedrog, Pwllheli, North Wales in 2004.
Radford valve amplifiers are rare today, and still command high prices on the secondhand market. Much sought after and enthusiastically rebuilt, they are particularly known for classic and restrained physical design and outstanding, listenable sound quality - including a particular ability to drive, very sweetly, the notoriously difficult Quad electrostatic loudspeakers. 2006 brought hope of a rebirth for the brand, with news of plans to begin manufacture of classic valve based designs like the STA 25 Mk III in 2009.
Small scale production is now carried on by Radford Revival, a UK craft business dedicated to replicating the classic amplifiers of the company's heyday.
See also
References
FERRARI Pier Paolo - Italy - "RADFORD - Hi-Fi Legend" - SANDIT Editor, Bergamo - Italy - ISBN-10 : 8869283135
External links
- Hood, John Linsley (1997). Valve & transistor audio amplifiers. Newness. pp. 105–6. ISBN 978-0-7506-3356-7.
- "Radford Electronics". Archived from the original on 12 February 2007. Retrieved 30 January 2007.
- Bennett, Chris; Barry D. Hunt (3 July 2010). "A History of Radford Electronics". The Audio Standard. Retrieved 19 February 2019.
- "~ A Home away from home ~".