Each family comprises a range of tube models possessing different performance specifications. Tubes (called valves in other parts of the world) can be divided into three families: preamp, poweramp and rectifier. What’s more, once armed with this knowledge, you’ll be better equipped to troubleshoot amplifier problems and to improve your guitar tone. In reality, the various functions and characteristics of tubes are easily understood. Yet few musicians seem to have even an elementary knowledge of this rather low-tech device. The basic technology behind the modern vacuum tube has been around since 1906. And as grandma used to say about grandpa, it may take him a while to get warmed up, but he makes sweet music like no one else. That sound has been at the heart of countless blues and rock songs. The result is a tone that “sags” slightly before it comes crashing out of the speaker with a pleasantly crunchy rumble. When a tube reaches “saturation,” it contains a veritable swamp of electrons. Why does a guitarist’s favorite electrical component rely on technology more than 100 years old? And why aren’t vacuum tubes used in anything else today other than specialized music equipment? The answer to both questions is: Because they don’t work very well and sound wonderful trying to do it. Today, the vacuum tube has evolved to include a complex assembly of plates, grids and heating elements that produce a more efficient part. In 1906, inventor Lee de Forest added a third element to the bulb and found that the resulting triode could be used as both a switch and an amplifier. Fleming added a second metal element to the bulb, thereby creating the first diode, or-to use a name more familiar to guitarists- rectifier. This discovery, named the Edison Effect, remained a minor phenomenon until another scientist, John Fleming, found that these electrons could be used to detect radio waves and convert them into electricity. He then sheathed the filament in a glass bulb and extracted the oxygen, thus creating a vacuum to prevent the filament from burning up.ĭuring further experiments in 1883, Edison detected electrons flowing from the filament, through the vacuum and over to a metal plate he had placed inside the bulb. And then pay your respects to Thomas Edison, the Wizard of Menlo Park, New Jersey.Įdison produced an incandescent light bulb in the late 1870s by feeding an electric current to a filament until it burned bright red. What is a vacuum tube? - If the link between a light bulb and a raging Marshall stack doesn’t seem obvious, take a glance at those vacuum tubes glowing inside your amp.