Get Preamp Tube Gain Factor Images. For most there's not much they can do with a guitar amp. Gain gain gain gain gain.
Rackmount, 500 series, or desktop . The tube stage itself usually has fixed gain and supply voltages. A tube preamp is an amplifier with one or more tubes (lamps).
Preamp tube gain factor and substitution chart.
Tube preamps have signal levels. You can also use a conventional. How are we defining gain? Changing only the first tube in your amp's gain stage can affect how the rest of the circuit responds to your guitar.