Until the introduction of the germanium transistor in the late 1950’s, there was no alternative form of high quality audio amplification to the thermionic valve (American terminology was always ‘Tube’). The 1960’s, 70’s and 80’s saw a steep decline in the usage of valves for all purposes except audio amplifiers, to the point that, with a few exceptions, they were almost entirely replaced by transistors and integrated circuits. However, since the late 1980’s, valve amplifiers have experienced a renaissance which has, in the last decade grown rapidly year on year.

The unique character of the ‘Tube Sound’ has once again attracted both amateur and professional interest in the areas of High Fidelity (HiFi) amplification, Musical Instrument (MI) amplification (notably the electric guitar) and Audio amplification. The dominance of digital technology now, means that the valve amplifier is seen as new to younger people and as nostalgic to the older generation. Please note it is estimated, that the electric guitar amplification market consume as many as three out of four of the world’s production of audio tubes.

EL34 Valve

Many arguments have been put forward as to why tube amplification ‘sounds’ better than digital. Some differences can be proved using measuring instruments, whilst others are down to the nuances of the human ear. Whatever the reason, evidence shows more and more listeners appear to prefer the sound of a tube amplifier.

The demand for tube amplifiers is rapidly growing, with products ranging from a few hundred pounds to several thousand pounds, depending on quality and output power, with tube sales worldwide currently standing at over $100,000,000. Today vacuum-thermionic devices hold sway over the US $100 million worldwide guitar amp business. One rough estimate shows a 10-percent-per-year growth in demand for tubes used in MI instrument amplifiers and high-end audio since the late 1980s, with no apparent slackening.

However, the problems with existing tube amplifier technology is that the circuits used are based on ‘classic’ designs developed in the 1940’s and 50’s and, although more modern technology has occasionally been applied, this is usually confined to regulating the power supplies. One of the principle disadvantages of existing tube amplifiers is that they are very inefficient in converting electrical power into audio power. This is largely due to the ‘classic’ methods of controlling them. All analogue high power amplifiers require a system known as ‘Biasing’ to be applied to them. This controls the output devices and prevents them from ‘Thermal’ overload and eventual destruction. It does, however, incur a heavy cost in loss of output power and increased heat dissipation. In addition valves also need to be used in ‘Matched’ pairs, in order to control distortion of the output signal. This process is time consuming and expensive when carried out on a commercial basis.

THE SOLUTION IS ……..

EL34