A semiconductor integrated circuit includes a first pad provided on one end side of a first resistive element and one end side of a second resistive element externally provided, a second pad provided on a different end side of the first resistive element, a third pad provided on a different end side of the second resistive element and one end side of a third resistive element externally provided, an operation amplifier, a first signal line, wired between an output terminal of the operation amplifier and the first pad, a second signal line wired between an inverting input terminal of the operation amplifier and the second pad, a third signal line wired between the inverting input terminal of the operational amplifier and the third pad, a first ESD protection element, provided to the first signal line, a fourth signal line, through which a voltage signal of the first pad.

A semiconductor integrated circuit includes a first pad provided on one end side of a first resistive element and one end side of a second resistive element externally provided, a second pad provided on a different end side of the first resistive element, a third pad provided on a different end side of the second resistive element and one end side of a third resistive element externally provided, an operation amplifier, a first signal line, wired between an output terminal of the operation amplifier and the first pad, a second signal line wired between an inverting input terminal of the operation amplifier and the second pad, a third signal line wired between the inverting input terminal of the operational amplifier and the third pad, a first ESD protection element, provided to the first signal line, a fourth signal line, through which a voltage signal of the first pad.

Amplifier circuitry that is operative to provide selective control of the amplitude of a musical signal as the signal transitions from the pre-amplifier to power amplifier components of an electric guitar amplifier. According to a preferred embodiment, at least one low variable power amplifier is integrated into the signal path from the pre-amplifier to the power amplifier components of the guitar amplifier. The low power amplifier allows for selective control of the amplitude of the musical signal such that the signal ranges from zero volts to more than 100 DB. Such low power amplifiers may be selectively deployed in guitar amplifiers utilizing either Class A or Class A/B circuitry and enables a musician to have full control of the power amplifier from 0% gain to 100% gain at any tone selection and any power amp wattage, as may be desired.

Amplifier circuitry that is operative to provide selective control of the amplitude of a musical signal as the signal transitions from the pre-amplifier to power amplifier components of an electric guitar amplifier. According to a preferred embodiment, at least one low variable power amplifier is integrated into the signal path from the pre-amplifier to the power amplifier components of the guitar amplifier. The low power amplifier allows for selective control of the amplitude of the musical signal such that the signal ranges from zero volts to more than 100 DB. Such low power amplifiers may be selectively deployed in guitar amplifiers utilizing either Class A or Class A/B circuitry and enables a musician to have full control of the power amplifier from 0% gain to 100% gain at any tone selection and any power amp wattage, as may be desired.