An audio preamplifier (1) for a microphone, including: a chassis (2) with at least one audio input (17) and at least one audio output, a control panel (3) including a gain selector (10) being arranged on one of the sides of the chassis (2), the chassis (2) further including a receiving compartment inside which a first connector is arranged; and a cartridge (6) comprising a preamplification circuit and a gain control circuit, the cartridge (6) further having a second connector complementary to the first connector, the cartridge (6) being configured for being inserted in a removable manner into the receiving compartment of the chassis (2) so as to connect the first and second connectors. An audio preamplification kit includes an audio preamplifier (1) and a plurality of additional cartridges.

In live music performances it is desirable for a mixing console operator to be able to hear the result of all the processing of a single input signal provided by the various processing steps without the other input signals being present. This is achievable by providing a console (10) which processes an input signal independently of other input signals to produce an operator output signal (210), wherein the processing is arranged to be identical to that applied in combination to the same signal as it is processed, in combination with other signals, for the creation of an output mix (180).

In live music performances it is desirable for a mixing console operator to be able to hear the result of all the processing of a single input signal provided by the various processing steps without the other input signals being present. This is achievable by providing a console (10) which processes an input signal independently of other input signals to produce an operator output signal (210), wherein the processing is arranged to be identical to that applied in combination to the same signal as it is processed, in combination with other signals, for the creation of an output mix (180).

According to aspects of the present disclosures, an acoustic signal processing device includes a sound pressure measurement section configured to measure a sound pressure of a sound output from a speaker, a recording level obtaining section configured to obtain a recording level of an audio signal which is a signal representing the sound, and a gain increasing section configured to increase a gain to the audio signal when the sound pressure measured by the sound pressure measurement section is equal to or larger than a first threshold and the recording level obtained by the recording level obtaining section is less than a second threshold.

According to aspects of the present disclosures, an acoustic signal processing device includes a sound pressure measurement section configured to measure a sound pressure of a sound output from a speaker, a recording level obtaining section configured to obtain a recording level of an audio signal which is a signal representing the sound, and a gain increasing section configured to increase a gain to the audio signal when the sound pressure measured by the sound pressure measurement section is equal to or larger than a first threshold and the recording level obtained by the recording level obtaining section is less than a second threshold.

An amplification circuit includes a first amplifier provided between an input terminal and an output terminal and a second amplifier connected in parallel with the first amplifier between the input terminal and the output terminal. The first amplifier includes a transistor and a transistor, which are cascode connected with each other. The second amplifier includes a transistor. The transistor has a gate connected to the input terminal, a source connected to ground, and a drain. The transistor has a gate, a source connected to the drain of the transistor, and a drain connected to the output terminal. The transistor has a gate connected to the input terminal, a source connected to ground, and a drain connected to the output terminal.

Bidirectional variable gain amplifiers (VGAs) for radio frequency (RF) communication systems are provided. In certain embodiments, a bidirectional VGA includes a first amplifier having an input coupled to a transmit/receive port, a second amplifier having an output coupled to a transmit port, a third amplifier having an input coupled to a receive port, a fourth amplifier having an output coupled to the transmit/receive port and to the input of the first amplifier, and a switch circuit that connects an output of the first amplifier to an input of the second amplifier in a transmit mode, and that connects an output of the third amplifier to an input of the fourth amplifier in a receive mode.

A variable gain circuit includes: input/output terminals P1 and P2 configured to input/output a high frequency signal; a transistor having a signal terminal “a” connected to the input/output terminal P1, a signal terminal “b” connected to the input/output terminal P2, and a control terminal; bias terminals B1, B2 and B3, and a reference voltage terminal respectively set to a first variable voltage, a second variable voltage, a third variable voltage, and a fixed voltage that are independent of one another; an impedance element connected between the bias terminal B1 and the signal terminal a; an impedance element connected between the bias terminal B2 and the signal terminal b; an impedance element connected between the bias terminal B3 and the control terminal; and a first switch configured to switch between connecting and not connecting the reference voltage terminal and the control terminal.

A variable gain circuit includes: input/output terminals P1 and P2 configured to input/output a high frequency signal; a transistor having a signal terminal “a” connected to the input/output terminal P1, a signal terminal “b” connected to the input/output terminal P2, and a control terminal; bias terminals B1, B2 and B3, and a reference voltage terminal respectively set to a first variable voltage, a second variable voltage, a third variable voltage, and a fixed voltage that are independent of one another; an impedance element connected between the bias terminal B1 and the signal terminal a; an impedance element connected between the bias terminal B2 and the signal terminal b; an impedance element connected between the bias terminal B3 and the control terminal; and a first switch configured to switch between connecting and not connecting the reference voltage terminal and the control terminal.

A variable gain circuit includes: input/output terminals P1 and P2 configured to input/output a high frequency signal; a transistor having a signal terminal a connected to the input/output terminal P1, a signal terminal b connected to the input/output terminal P2, and a control terminal; bias terminals B1, B2 and B3, and a reference voltage terminal respectively set to a first variable voltage, a second variable voltage, a third variable voltage, and a fixed voltage that are independent of one another; an impedance element connected between the bias terminal B1 and the signal terminal a; an impedance element connected between the bias terminal B2 and the signal terminal b; an impedance element connected between the bias terminal B3 and the control terminal; and a first switch configured to switch between connecting and not connecting the reference voltage terminal and the control terminal.