The Mullard 5-10 was a circuit for a

valve amplifier A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by sol ...

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...

company,

Mullard Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed thermionic valves for the Admiral ...

in 1954 at the Mullard Applications Research Laboratory (ARL) in Mitcham Surrey UK, part of the New Road factory complex, to take advantage of their particular products. The circuit was first published in

Practical Wireless ''Practical Wireless'' is a British amateur radio magazine, published monthly by Warners Group Publications. History and profile The magazine was founded in 1932 (as a supplement to ''Hobbies'' magazine) by F.J. Camm of George Newnes Publishers. ...

magazine. The amplifier featured five valves and an output of 10 watts - hence '5-10'. Of those valves, one was a

full-wave rectifier A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation (converting DC to AC) is performed by an inver ...

(an EZ80 or EZ81), one was a pre-amplifier

pentode A pentode is an electronic device having five electrodes. The term most commonly applies to a three-grid amplifying vacuum tube or thermionic valve that was invented by Gilles Holst and Bernhard D.H. Tellegen in 1926. The pentode (called a ''tripl ...

EF86 and one a double-triode ECC83 as

phase splitter A phase splitter is a device that separates a signal into multiple phases (or polarities). The term is most often applied to amplifiers that produce two "balanced" voltage outputs: of equal amplitude but opposite polarity (i.e. 180 degrees phase ...

. The power amplification was handled by a pair of

EL84 The EL84 is a vacuum tube of the power pentode type. It is used in the power-output-stages of audio-amplifiers, most commonly now in guitar amplifiers, but originally in radios. The EL84 is smaller and more sensitive than the octal 6V6 that was ...

working in push-pull configuration. The

frequency response In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of sy ...

of the circuit was from 40Hz to 20,000Hz with less than 0.2% THD. In 1959 Mullard published its famous booklet "

Mullard Circuits for Audio Amplifiers Mullard Circuits for Audio Amplifiers is a famous book by the Technical Services Department of Mullard Ltd, a British valve manufacturing company. First published in 1959 and then reprinted several times it contained a number of designs by Mullard e ...

" covering a range of amplifier and pre-amplifier circuits using valves developed within the Receiving Valve Development Department at the New Road factory. The circuit design of the Mullard 5-10, together with the recommended Partridge output transformers, was famous for its unique sound reproduction and many variations of this amplifier (including Mullard's own 20-watt version, the Mullard 5-20 using the

EL34 The EL34 is a thermionic vacuum tube of the power pentode type. The EL34 was introduced in 1955 by Mullard, who were owned by Philips. The EL34 has an octal base (indicated by the '3' in the part number) and is found mainly in the final output st ...

) were in widespread use until the end of the valve era; similar designs are still manufactured as expensive equipment for valve audiophiles.

External links

The original text from Practical Wireless magazine

Book extract
by

FJ Camm Frederick James "F.J." Camm (6 October 1895 – 18 February 1959) was an English technical author and magazine editor. He founded several radio and electronics titles, including ''Practical Mechanics'', ''Practical Motorist'', ''Practical Televisi ...

describing the Mullard 5-10 Valve amplifiers Vacuum tubes {{Sound-tech-stub