Abstract: By adding the difference between output and input of the one amplifier section to the output signal by means of a subsequent amplifier section a ring of amplifier sections can be formed which compensate for each other's distortion.

Abstract: An electro-acoustic arrangement comprising a plurality of transducer units including five, seven or nine equally spaced transducers situated in line with the transducers connected to a transmission channel via individual amplitude control devices. The amplitude control devices are adjusted so that the ratios between the conversion factors of the transducer units viewed from end to end are 1:2n:2n.sup.2 :-2n:1 for five transducers to produce an output signal substantially independent of direction and/or frequency. The invention also relates to a combination of five, seven or nine of the foregoing arrangements situated adjacent each other or in line at equal distances with further amplitude control devices connected to a transmission channel. The amplitude control devices are adjusted so that the ratios between the conversion factors of the arrangements, viewed from end to end, form a special relationship.

Abstract: A device for driving an electroacoustic transducer (1) comprising a feedback amplifier and a pickup (2) whose output signal is a measure of the acoustic output signal of the transducer. A by-pass network (4) bypasses at least the transducer and the pickup and produces an output signal that for frequencies outside the operating range of the transducer is large and for frequencies in the operating range (f.sub.1 to f.sub.h) of the transducer is small relative to the pickup output signal. The sum of the output signals of the pickup and the by-pass network serves as a feedback signal. This widens the transducer frequency range and reduces distortion. The device may include a limiter (11) and a network (5) before the transducer. The network has a frequency response inverse to that of the signal path from the electroacoustic transducer to the pickup to provide an additional reduction in the distortion.

Abstract: An arrangement for the transmission of audio signals, comprising a delay line (1) provided with 5, 7 or 9 tappings situated at equal time intervals along the delay line. The tappings are each connected to a common adding circuit (16) via an amplitude control device (9 to 13). The ratios between the amplitudes of the output signals of the amplitude control devices, viewed from one end of the delay line (1) to the other end are 1:2n:2n.sup.2 :-2n:1 for five tappings, 1:2n:2n.sup.2 :n.sup.3 -n:-2n.sup.2 :2n:-1 for seven tappings, and 1:2n:2n.sup.2 :n.sup.3 -n:1/4(n.sup.4 -1)-2n.sup.2 :-(n.sup.3 -n):2n.sup.2 :-2n:1 for nine tappings. This yields an arrangement having a flat frequency response from the input (2) to the output (15). The invention also relates to a plurality of delay lines (for example 31 to 35) connected in series and to a reverberation unit provided with such a transmission arrangement.

Abstract: Artificial reverberation apparatus comprising a delay device (1) provided with a feedback circuit (5) and a feed-forward circuit (6) having a gain equal and opposite to that of the feedback circuit if the gain in the delay device is unity. In order to simulate a second echo having a different delay time using a minimum number of circuit components, the foregoing reverberation circuit is included in cascade with a second delay device (11) and the resulting combination is provided with its own feedback circuit (15) and feed-forward circuit (16). In order to simulate a third echo having yet another delay time, the resulting circuit may be included in cascade with a third delay device (21) with the resulting combination having its own feedback circuit (25 ) and feed forward circuit (26).

Abstract: An artificial reverberation arrangement comprising a number of mechanical units each of which comprises a microphone, an amplifier and a loudspeaker. These units are arranged in such a way relative to each other that the microphone of one specific unit receives substantially less sound energy from its own associated loudspeaker than from all the other loudspeakers of the arrangement.

Abstract: An artificial reverberation apparatus for audio frequency signals, comprises a first delay device preceded by an adder. A feedback circuit couples the output of the delay device to an input of the adder to give a loop signal gain of less than unity. The adder is preceded by a second delay device with the same delay time as said first-mentioned delay device. The signal to be delayed is applied to the input of said second delay device and also to the adder via a transmission path. The ratio of the signal gain of the transmission path to the signal gain of said second delay device is equal to but of opposite sign to said loop signal gain. Preferably the signal gain of the transmission path is equal to but of opposite sign to the signal gain of said feedback circuit. Furthermore, a plurality of apparatuses can be connected in cascade with the delay devices of the different apparatuses all having different delays.