| The vacuum tube appears to be the earliest | | | | and Russia did not initially have access to |
| invented amplifier. By pumping all the air out of a | | | | transistor technology, and so they actually carried |
| glass (non-conducting) cylinder, a thin wire inside | | | | vacuum development much further creating tiny |
| (called a 'filament' can be heated very hot by | | | | vacuum tubes so durable they were used in |
| driving an electrical current through the wire. But | | | | Russian space capsules.) |
| because there is no oxygen inside the vacuum | | | | However, the "softer" sound of vacuum tube |
| tube the wire does not burn up. | | | | amplification remained more popular with many |
| This permits the wire to emit electrons without | | | | audiophile applications, including amps used for |
| being destroyed. | | | | electric guitars. Guitarists just liked the sound of |
| At the other end of the tube, the electrons can | | | | electric guitar amplifiers made with vacuum tubes. |
| be "picked up" by a type of plate and thus a | | | | Preamps and Power Amps |
| current is flowing through the tube from the | | | | To make a more powerful amplifier you simply |
| filament to the plate. | | | | use several 'stages' of amplification. First you |
| Between the two another charged plate is placed | | | | amplify the tiny signal from a guitar pickup, and |
| and if there is a small signal on that plate the | | | | then you amplify *that* signal again with larger |
| varying charge on the plate causes a variation of | | | | vacuum tubes that can handle a larger amount of |
| the electron flow between filament and receiver | | | | power. |
| plate. | | | | If you've ever gone to buy guitar amps and were |
| So this electron flow now varies exactly as the | | | | looking at musical instrument reviews, or stores |
| smaller controlling voltage varies on the | | | | which offer musical instrument prices you'll soon |
| in-between plate. | | | | notice that nowadays you can purchase both |
| So the small signal causes the larger flowing | | | | 'preamps' and 'power amps'. The second one -- |
| current to become a larger or amplified signal, an | | | | the power amplifier -- does all the heavy work. |
| exact model of itself as a signal, but now larger | | | | Typical Guitar Power Amplifiers |
| and more powerful. The signal has been amplified. | | | | The 12AX7 Power Amp -- This is not a |
| This brilliant innovation was used in radios, | | | | manufacturer but the name of a vacuum tube |
| telephone companies, televisions and... guitar | | | | model -- the 2AX7 (ECC83) dual triode. Although |
| amplifiers. | | | | this tube has a high gain it is normally used in |
| The Transistor? Nope. | | | | preamps, and the idea of using it for a power |
| Later a solid state device was developed which | | | | amp was an odd one. However a designer named |
| did a similar job but was much smaller and which | | | | Tim de Paravicini undertook the task "because it |
| didn't wear out over time as do vacuum tubes. | | | | was there" and the result was unconventional and |
| This new 'transisitor' was also very durable; it | | | | interesting. The amp he designed uses a battery |
| wasn't made of fragile glass. | | | | of these smaller tubes, and produces a sound that |
| So in most commercial applications, the transistor | | | | handles brilliance well, the sheen of strings and a |
| became the amplifying device of choice, in the | | | | sweet and compliant sound. |
| United States. (For historical reasons, both China | | | | |