Coupling Capacitorsįor example, beyond simply providing a link to get the signal from one place to another, coupling capacitors are selected according to their value (which can be considered as the size of their functioning elements) as a means of voicing the amp at these stages, since caps of different values will pass or reject frequencies in different ways. Add them up differently, or stir a different combination of ingredients into the stew, and your guitar comes out the other end sounding somewhat different. Sound Shaping and Infinite VariablesĪs you might already have begun to imagine, every little variable within each sub-stage of the output stage as a whole contributes to shaping your guitar tone. Along with these components, there’s usually also a fair amount of wire used to connect it all together. Plenty of other components do various jobs along the way, of course: resistors help to voice certain stages and deliver operating voltage from the power supply and signal capacitors, also called coupling capacitors, carry the signal from preamp to phase inverter and onward from phase inverter to output tubes. Small, single-ended amps - such as the Fender Champ, Vox AC4 and Epiphone Valve Junior, which carry just one output tube - don’t require a phase inverter, but sometimes have a driver tube to further increases preamp voltage before the output stage.Īfter the phase inverter, the output tubes further amplify the signal and send it along to the output transformer, which converts it to a low-impedance signal that can power a speaker.

Bias guitar amp without probe