Crate Amplifiers V18-212 用户手册

V18-112/V18-212 Tube Guitar Amplifier with Reverb

In 1883, Edison discovered that electrons would flow from a suspended filament when 
enclosed in an evacuated lamp. Years later, in 1905, Fleming expanded on Edison’s discovery 
and created the “Fleming Valve.” Then, in 1907, Dr. Lee de Forest added a third component 
– the grid – to the “Fleming Valve” and the vacuum tube was a fact of life. The door to elec-
tronic amplification was now open.

During World War II, data gleaned from their intensive research on the detectors used in radar 
systems, led Bell Telephone Laboratories to the invention of the transistor. This reliable little 
device gained quick support as the new component for amplification. The death of the vacuum 
tube seemed imminent as designers, scientists, and engineers reveled in the idea of replacing 
large, fragile glass tubes with these small, solid-state devices.

However, there were (and still are) many serious listeners who realized that the sound pro-
duced by a “transistor” amplifier is significantly different from that produced by a tube ampli-
fier with identical design specifications. They considered the sound produced by these new 
solid-state devices to be hard, brittle, and lifeless. It was determined that solid-state devices 
produced a less musical set of harmonics than tubes. When pushed past their limits, they tend 
to mute the tone and emphasize the distortion.

Tubes, on the other hand, produce a more musical set of harmonics, the intensity of which 
can be controlled by the player. This characteristic adds warmth and definition to the sound 
which has become the hallmark of tube amplifiers. When tubes are driven into clipping, the 
harmonic overtones can be both sweet and pleasing or intense and penetrating, depending on 
the musician’s musical taste and playing technique.

Over the years, application engineers have designed a number of outstanding solid-state 
amplifiers that sound very, very good. Some use special circuitry which enables them to simu-
late the distortion characteristics of a tube amplifier. However, the tube amplifier, still held in 
the highest esteem by many musicians, offers a classic “vintage” sound in a contemporary 
market.

Tube amplifiers are based primarily on two types of tubes – preamplifier tubes and power 
tubes. The tubes used in preamplifiers (12AX7, 12AU7, 12AT7, etc.) are smaller than the 
power tubes. These tubes amplify the signal from your instrument and shape the sound. They 
are inherently microphonic (they can mechanically pick up and transmit external noises). Since 
these tubes are used in the critical first stages of a tube amplifier’s circuitry, it is very impor-
tant to use high-quality, low noise/low microphonic tubes for this application. Although tubes 
of this quality may be difficult to find and typically cost more than “off-the-shelf” tubes, the 
improvement in performance is worth the investment. 

Preamplifier tubes are also used to drive the power tubes. When used in this application, a 
12AX7 will produce a more distorted tone than a 12AT7, which produces a clearer, sweeter 
sound. A 12AU7 is even cleaner and brighter than a 12AT7, giving more definition to the 
sound. (In some cases it is possible to change the sound by changing the type of preamp 
and/or driver tubes. When making any modification to your equipment, it is highly recommend-
ed that you consult with a qualified service center.)