Abstract: The device includes a housing containing a dc battery, a microphone, an audio tone signal source, and a speaker and headphone jack which can receive audio signals from either the microphone or the tone signal source, and two multi-pin XLR receptacles or jacks, one of which is male and the other of which is female. The connectors can supply audio signals from the microphone or tone signal source to the input of the speaker and headphone jack, or alternatively, such signals can be outputted by the male connector to a circuit external of the housing, or a source external to the housing can be utilized to supply audio signals via the male or female connector to the speaker. Power from the battery is supplied selectively either to the microphone or to the tone signal source by a switch which can be moved to either of two different operative positions, or by a volume control knob which applies power to the speaker circuits.

Abstract: The device is designed to receive at its input the analog AC output signal of an electric guitar either directly from the guitar, its amplifier or a speaker. The incoming signal is fed to three series connected circuits which successively boost the bass and treble frequencies, and then reduce the signal level between the bass and treble peaks before applying the processed signal to an output circuit. A high frequency adder circuit connected in parallel with the three series connected circuits permits frequencies above a certain level (10 KHz) to be added back to the processed signal at the output circuit. One switch is operable in the bass boost circuit to introduce different resistance selectively to raise or lower the frequency center and gain of the circuit, and another switch at the input of the device is operable to add resistance when the input signal is from a speaker.