26.07.2022, 10:06
Vor einiger Zeit bin ich zufällig auf diese Patentschrift vom Nov. 7, 1994 gestoßen (Patent erteilt am Jan. 21, 1997) :
US5596646.pdf
Autor: James Waller, Jr. et al., Assignee: Rocktron Corporation
Titel: AUDIO TAPE SATURATION SIMULATOR
Darin werden elektronische Schaltungen beschrieben, mit denen man das Verzerrungs- und Tiefpass-Verhalten eines übersteuerten Bandes nachbilden kann.
Die Motivation dazu wird wie üblich unter "Background of the invention" erläutert.
Da die in diesem Zusammenhang von Interesse sein könnte, hier ein auszugsweises Zitat:
"This invention relates generally to audio signal processing and more specifically concerns audio signal processing which simulates analog tape Saturation.
Until recent years, all popular forms of music have been recorded by analog means to magnetic tape. However, the advent of digital technology has revolutionized the industry by providing a much more powerful and precise means of recording. Therefore, an increasing amount of material is now recorded digitally.
While this drastic change in technology provides many advantages over the previous method, digital technology has not been well received among many critical listeners. This is primarily due to the difference in nature of these recording processes. The analog recording process has a very limited dynamic range, typically on the order of 60 dB. Therefore, it has been desirable to record signals as "hot' or high in level as possible in order to obtain the best signal-to-noise ratio. The hotter a signal is recorded, the higher the level of tape saturation that occurs. When tape saturation occurs the amount of harmonic distortion increases and the high frequency information is attenuated. This side effect has been used for years to add a certain sound quality to many recordings. In many cases the recording engineer will purposely overdrive many of the individually recorded tracks, such as vocals and individual instruments, to add this audible characteristic. Conversely, state of the art digital recording has a dynamic range of approximately 100 dB. Therefore, it is not desirable to overdrive digital recordings because the sound is not as pleasant to the ear.
Nevertheless, the benefits of digital recording outweigh those of analog and therefore digital is quickly becoming the most common recording format. There is, however, still a strong desire to provide the sonic artifacts associated with overdriven analog tape. Because of the high efficiency of digital recording components, digitally recorded material contains considerably more audible information, particularly high end information, than can be captured onto magnetic tape. But, when compared, the digital signal sounds much more harsh than the analog signal which has a much smoother high end.
As the industry has moved towards digital recording due to its higher level of control and performance, the absence of any product which provides exactly what analog tape saturation provided for the recording industry has caused people to begin using tube compressors, tube mic preamps
and other products which are tube-based in an attempt to regain at least a small degree of the warmth that the analog tape machine provided. These tube-based products generate considerably higher distortion than their solid state counter parts, although not nearly as much as could be derived from the use of an analog tape machine. In addition, such products do not provide the bandwidth limitations which change dynamically, especially when transients occur. As analog tape is hit with a transient, such as a snare drum, saturation produces a loss of high frequency predominantly on the transient. During the decay of the instrument, the high frequency roll-off diminishes. Until now, the only method
available to derive this effect was through the use of an analog tape machine.
It is, therefore, an object of this invention to provide an audio tape saturation simulator which yields the same auditory results when recording in the digital realm as would be accomplished if recording directly to analog tape."
Noch eine Anmerkung zu Beitrag #42 mit dem Einwand
""dann macht man den Eingangswiderstand der ersten Stufe einfach etwas hochohmiger." - Der Eingangswiderstand ist kein Bauelement."
Man kann den Eingangswiderstand trotzdem hoch-ohmiger (i.e. Röhren-artig) gestalten, zB indem man die erste Stufe mit FETs realisiert (die übrigens Pentoden-ähnliche Kennlinien haben).
MfG Kai
US5596646.pdf
Autor: James Waller, Jr. et al., Assignee: Rocktron Corporation
Titel: AUDIO TAPE SATURATION SIMULATOR
Darin werden elektronische Schaltungen beschrieben, mit denen man das Verzerrungs- und Tiefpass-Verhalten eines übersteuerten Bandes nachbilden kann.
Die Motivation dazu wird wie üblich unter "Background of the invention" erläutert.
Da die in diesem Zusammenhang von Interesse sein könnte, hier ein auszugsweises Zitat:
"This invention relates generally to audio signal processing and more specifically concerns audio signal processing which simulates analog tape Saturation.
Until recent years, all popular forms of music have been recorded by analog means to magnetic tape. However, the advent of digital technology has revolutionized the industry by providing a much more powerful and precise means of recording. Therefore, an increasing amount of material is now recorded digitally.
While this drastic change in technology provides many advantages over the previous method, digital technology has not been well received among many critical listeners. This is primarily due to the difference in nature of these recording processes. The analog recording process has a very limited dynamic range, typically on the order of 60 dB. Therefore, it has been desirable to record signals as "hot' or high in level as possible in order to obtain the best signal-to-noise ratio. The hotter a signal is recorded, the higher the level of tape saturation that occurs. When tape saturation occurs the amount of harmonic distortion increases and the high frequency information is attenuated. This side effect has been used for years to add a certain sound quality to many recordings. In many cases the recording engineer will purposely overdrive many of the individually recorded tracks, such as vocals and individual instruments, to add this audible characteristic. Conversely, state of the art digital recording has a dynamic range of approximately 100 dB. Therefore, it is not desirable to overdrive digital recordings because the sound is not as pleasant to the ear.
Nevertheless, the benefits of digital recording outweigh those of analog and therefore digital is quickly becoming the most common recording format. There is, however, still a strong desire to provide the sonic artifacts associated with overdriven analog tape. Because of the high efficiency of digital recording components, digitally recorded material contains considerably more audible information, particularly high end information, than can be captured onto magnetic tape. But, when compared, the digital signal sounds much more harsh than the analog signal which has a much smoother high end.
As the industry has moved towards digital recording due to its higher level of control and performance, the absence of any product which provides exactly what analog tape saturation provided for the recording industry has caused people to begin using tube compressors, tube mic preamps
and other products which are tube-based in an attempt to regain at least a small degree of the warmth that the analog tape machine provided. These tube-based products generate considerably higher distortion than their solid state counter parts, although not nearly as much as could be derived from the use of an analog tape machine. In addition, such products do not provide the bandwidth limitations which change dynamically, especially when transients occur. As analog tape is hit with a transient, such as a snare drum, saturation produces a loss of high frequency predominantly on the transient. During the decay of the instrument, the high frequency roll-off diminishes. Until now, the only method
available to derive this effect was through the use of an analog tape machine.
It is, therefore, an object of this invention to provide an audio tape saturation simulator which yields the same auditory results when recording in the digital realm as would be accomplished if recording directly to analog tape."
Noch eine Anmerkung zu Beitrag #42 mit dem Einwand
""dann macht man den Eingangswiderstand der ersten Stufe einfach etwas hochohmiger." - Der Eingangswiderstand ist kein Bauelement."
Man kann den Eingangswiderstand trotzdem hoch-ohmiger (i.e. Röhren-artig) gestalten, zB indem man die erste Stufe mit FETs realisiert (die übrigens Pentoden-ähnliche Kennlinien haben).
MfG Kai