Abstract: In signal sources having a high impedance, typically a capacitive “signal source” such as capacitor-microphone capsules, it is common practice to use amplifier circuits that include means for coupling signals and determining operating points in addition to the actual amplifier having a high-resistance, non-inverting input. For setting the operating points of the signal source and the amplifier, separate bias-voltage sources are provided; these are coupled to the signal source and the non-inverting input, respectively, of the amplifier via a coupling impedance. At least one coupling capacitance is disposed in the signal path between the signal source and the non-inverting input of the amplifier. To attain a considerable noise gain without the disadvantage of very high idle times in this type of amplifier circuit, it is proposed that the coupling impedances be formed from a nonlinear resistance (D1, D2 or D3, D4) and an ohmic resistance (R3 or R4) connected thereto in series.

Abstract: With a method for converting an analog input signal (S1) to a digital output signal (S7), the analog input signal (S1) is amplified in a first signal path (2, 3, 5) and is subjected to an analog-to-digital conversion (5). In a second signal path (4, 6), another analog signal (S4) is obtained for transmitting larger signal amplitudes and is subjected to an analog-to-digital conversion (6). The signal (S5) digitized in the first signal path (2, 3, 5) and the signal (S6) that is digitized in the second signal path (4, 6) are fed to a digital signal processor (7), which generates the digital output signal (S7). To avoid an abrupt reduction in the signal resolution and achieve the highest possible dynamic scope, it is suggested that the analog signal fed to the second signal path (4, 5) be distorted non-linear and counter to the amplified analog signal (S2) in the first signal path (2, 3, 5).

Abstract: To facilitate direct conversion to digital form of an acoustic signal acting on the acoustic receptor of an acoustic receiver while satisfying requirements of dynamic range, noise and adequate quantization, the following is proposed: the acoustic receptor should be exposed to a counter-signal when the acoustic signal acts on it in such a way that the acoustic receptor is largely maintained in its rest state despite the action of the acoustic signal. The counter-signal is derived from the control variable of a control circuit which is a component of the acoustic receptor. The control variable contains the information on the acting acoustic signal. Any deviation of the receptor from its rest state immediately generates a digital “nought” or “one.

Abstract: A boundary-layer microphone may obtain a frequency independent, hemispherical directional characteristic with a high tonal quality. The geometrical configuration of the mounting plate and the installed location of the membrane within the surface of the mounting plate are chosen so that a flat frequency response is obtained at the installed location of the membrane, i.e., the superposition of the incident primary sound field on the secondary sound field created by diffraction will not cause any deviation from a flat frequency response and a smooth, hemispherical polar pattern. The mounting plate may be triangular. The membrane may be installed in the vicinity of the center of gravity of a scalene triangle.

Abstract: An electroacoustic transducer system comprises a microphone working into a low-frequency amplifier for the energization of an a-c load such as, for example, a loudspeaker or a volume indicator at a control panel. Biasing voltage for the microphone and operating current for the amplifier are derived from a d-c source, via a phantom circuit including the output leads of the amplifier and through a coupler in cascade with a chopper; the latter includes a transistor conducting intermittently under the control of an adjustable pulse generator whose pulse width is varied by negative feedback from the integrated chopper output. An output transformer with a primary in series with the transistor has several secondaries each connected across a storage capacitor through a diode for the generation of a relatively high biasing voltage for the microphone, a relatively low driving voltage for the amplifier and, possibly, a further voltage used to vary the directional pattern of the microphone.

Abstract: A system for controlling the mean depth and spacing of V-grooves cut by a stylus in a phonograph disk for recording stereophonic sounds comprises a processing stage deriving first and second signal components, designed for the vertical and lateral deflection of a stylus support, from advanced left and right preview signals picked up from a storage medium about half a disk revolution ahead of the actual modulation signals.