User Guide

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Jimmy Page strikes the guitar strings on "Stairway to Heaven" and Angus Young of AC/DC's "Back in
Black" share one common attribute– It is the vacuum tube that powers their guitars’ souls that express what
they want to sound like and what the listener likes to hear.
How The Vacuum Tube Works
Let’s take a look at the fundamentals of how the vacuum tube works. In a modern vacuum tube, there are
four principal elements that work together to make a tube work. The Filament (heater), Cathode, Grid and
Anode (or plate). When the filament is connected with voltage that boils the cathode, the cathode then emits
electrons that pass through the grid and hits the Anode. Through this electron flow, the tube will amplify a
small AC signal into a larger AC voltage, thus amplifying it. By controlling the grid voltage, the current flow can
be regulated and thus creates the desired electronic characteristics, while amplifying the signal (source).
Today, most electric guitar and bass amplifiers are tube-based. Professional audio equipment also
deploys the tube as a preferred amplification device. One can even find tubes in digital-to-analog converter
designs. The vacuum tube is a natural choice for these music-associated vehicles to depend on.
What's that Silver Stuff on the Glass?
The silver deposit is called the "getter" and is there to help increase the vacuum in the tube. Its color may
vary slightly. Sometimes the getter will flow with use, even to the point of becoming evenly and thinly deposited
over the entire envelope. The edge of this flow may have a brown color. None of this is important as long as the
tube biases correctly and stability.
If you see the getter receding leaving a whitish profile the tube is loosing vacuum and should be removed
from service.