60W Guitar Amplifier PUBLIC

Basic solid-state guitar amplifier with Input Level and Master Volume controls, but no tone controls. Frequency band is limited by the input stage to optimum guitar range, 80 Hz to 18 kHz. Will accept any signal from guitar, effects, preamp, or processor.

Basic guitar amplifier rated 60W RMS into an 8-ohm speaker. No tone control. Response tailored for full guitar range, from 80 Hz, near the lowest natural note on the guitar, to 18 kHz, reaching 3.5 octaves above the highest natural note on a 24-fret guitar. [It is assumed that there is at least one tone control on the guitar and that active devices between the guitar and the amp have their own tone controls.] First in the circuit is an Input Level control, in place of a fixed blocking resistor. IC1 is a TL082 dual op-amp, though any pin-compatible substitute can be used. For example, for least possible noise, an OPA2134 is recommended. However, if the input stage is to be overdriven, an older less costly IC should be used (e.g,, LF353). The input stage is set for a gain of 10, and there is a unity-gain buffer, serving double duty as a driver, between the gain stage and the power IC, which itself has a gain of only 3.2, but need not provide much gain since it will put out up to 60-watts RMS into an 8-ohm speaker at full volume no matter what, given sufficient input. Usually, a buffer is up front, followed by a gain stage as the driver, but I opted for a different tactic in this case, expecting that the input stage may be overdriven (if stomp-box effects are used), so the buffer will act to stabilize the distorted signal going to the output stage. The buffer/driver gets its signal from the Volume control, but there are no other controls in the circuit. IC2 is an LM3886 power-amp IC, chosen for its simplicity of circuit requirements and its perfectly acceptable specifications. It is also readily available should it ever need replacing. [Do not use another power-amp IC in its place unless it is specifically designed for that purpose.]