Palmer FAB5 Bedienungsanleitung Seite 9

3) WHAT DOES A RECTIFIER DO?
The Palmer FAB5 has a EZ81 rectifier tube.
Rectifiers convert the alternating current from the mains connection into
direct current, which is required by the amplifier circuitry.
Early "classic" tube amplifiers used rectifier tubes that produce an
elastic feeling when playing. The advent of transistor technology result-
ed in the increasing use of silicon diodes as rectifiers, which produce
a direct, "crisp" response. They are cheaper, more efficient, and easi-
er to integrate in amplifier circuits than tube rectifiers are. Today,
one finds both tube and diode rectifiers in guitar amplifiers and has a
choice; many models even use diode rectifiers that emulate the response
and tone of a tube rectifier.
As a rule, diode rectifiers react more quickly to the high voltage re-
quirements of heavily played notes and chords. The significantly longer
rise time of a tube rectifier at first produces a voltage drop when the
strings(s) are plucked, which is often referred to as "sag" in English.
When the signal decays, the direct voltage increases again. This results
in essentially the same effect as that of a compressor/sustainer. Many
guitarists prefer tube rectifiers because of their quasi "breathing"
response and the possibility of controlling the tone by means of the at-
tack.
The maximum voltage and the rise time, i.e., the duration until the maxi-
mum voltage is generated, vary depending on the rectifier tube and type.
A different tube type or a diode plug-in that plugs into the tube socket
can change the playing feel, sound, and performance of an amplifier.
ALWAYS CONSULT A QUALIFIED TECHNICIAN BEFORE ANY CHANGE - A DIFFERENT
TUBE TYPE OR DIODE RECTIFIER COULD DAMAGE YOUR AMPLIFIER!
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