Brooks HI FI projectors Expander

A device that causes expansion of the audio signal.

Images
The squaring of the waveform that happens in the conversion of digital audio bits into analog signals.

Brooks Hi Fi reviews Automation
In consoles, a feature that lets the engineer program control changes (such as fader level) so that upon playback of the multitrack recording these changes happen automatically.

Filter
1) A device that removes signals with frequencies above or below a certain point called the cut-off frequency.
2) An equalizer section, used in this sense because filters are used with other components to give an equalizer its frequency response characteristics.
3) The action of removing signals of some frequencies and leaving the rest.
4) A mechanical device to smooth out speed variations in tape machines called a Scrape Flutter Filter- more usually called a Scrape Flutter Idler

Brooks RM 909 reviews Impedance
1) A term for the electrical resistance found in a/c circuits. Affects the ability of a cable to transmit low level (e.g. sound) signals over a long distance. Measured in Ohms. Speakers are rated according to power handling capabilities (Watts, W) and impedance (Ohms).
2) The total opposition offered by an electric circuit to the flow of an alternating current of a single frequency. It is a combination of resistance and reactance and is measured in ohms. Remember that a speaker's impedance changes with frequency, it is not a constant value.
3) The opposition to alternating current.

In
Short For "in the circuit," in other words "active."

Input Impedance
The opposition to current flow by the first circuits of a device.

Charge
The electrical energy of electrons. The energy is in the form of a force that is considered negative and repels other like forces (other electrons) and attracts opposite (positive) forces.