13
E
Fig. 3.5: Patchbay configuration around the MAGICIAN
4. TECHNICAL BACKGROUND
4.1 Tube history
Due to many patent litigations, it is difficult to determine exactly when the tube was born. First developments
in tube technology were reported between 1904 and 1906. It was a research task of that time to find a suitable
method for receiving and rectifying high frequencies. On April 12, 1905, a certain Mr. Fleming was granted a
patent for his hot-cathode valve which was based on Edisons incandescent lamp. This valve was used as a
rectifier for high-frequency signals. Robert van Lieben was the first to discover (probably by chance) that the
anode current can be controlled by means of a perforated metal plate (grid), one of the milestones in the
development of amplification tubes. In 1912, Robert van Lieben finally developed the first tube for the amplifica-
tion of low-frequency signals. Initially, the biggest problem was to produce sufficient volume levels, which is
why resonance step-ups (though impairing the frequency response) were used to maximize the attainable
volume. Later, the objective was to optimize the electroacoustic transducers of amplifiers in such a way that a
broad frequency band could be transmitted with the least distortion possible. However, a tube-specific problem
is its non-linear amplification curve, i.e. it modifies the sound character of the source material. Despite all
efforts to ensure a largely linear frequency response, it had to be accepted that tube devices produce a bad
sound. Additionally, the noise floor generated by the tubes limited the usable dynamics of connected storage
media (magnetic tape machines). Thus, a one-to-one reproduction of the audio signals dynamics (expressed
as the difference between the highest and lowest loudness levels of the program material) proved impossible.
To top it all, tube devices required the use of high-quality and often costly transducers and sophisticated
voltage supplies.
With the introduction of semiconductor technologies in the field of audio amplification it soon became clear that
the tube would have to give way to the transistor, as this device featured an enormously enhanced signal-to-
noise ratio, less complex power supply and improved frequency response. Plus, semiconductor-based circuits
can be realized much more easily - for less money. Two decades later, the introduction of binary signal
processing meant the beginning of a new era of recording media that provided plenty of dynamic response and
allowed for loss-free copying of audio signals. As digital media were enhanced, however, many people began
to miss the warmth, power and liveliness they knew from analog recordings. This is why purists still today
consider digital recordings as sterile in sound.
4. TECHNICAL BACKGROUND
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