Operational Manual
3489-24 Kitagata. Iida-shi, Nagano 395-0151. Japan
Phone +81 265-25-8188. Fax: +81 265-25-8250. sales@almarro.com
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The 6SN7 Tube
The 6SN7 (6H8C) is a dual tube designed for
amplification of low frequency voltage. The
6SN7 (6H8C) double triode enclosed in the glass
bulb and provided with an octal base and an
indirectly heated oxide-coated cathode.
The Russian 6H8C is equivalent to the 6SN7
tube.
The driver tubes are 6SN7, renowned for their
linearity and reliability. These comprise the high-
power, low restriction driver/output tube
circuitry for the A318B
The 6SN7 tube has a very open, relaxed and
graceful sound, without sacrificing details.
Introduced by RCA in 1939, this driver tube is
more rugged and sonically consistent.
Power (Output) Tubes
The most interesting aspects of the A318B are
Russian 6C33 output tubes. A version of these
rugged power triodes was applied in MIG-25
fighter aircraft.
"The 6C33C/6C33-B is a high transconductance
indirectly heated triode tube (Where
transconductance is the ratio of the current at the
output and the voltage at the input written as gm.”)
I out = Current at the output
V in = Voltage at the input
Sonically the 6C33C (6C33-B) tube produces a
well-detailed bass and has a very good dynamic
range. They offer a more traditional for tubes
“warm” sound and detailed bass with a very nice
distortion at “clipping” point - where the tube
starts to produce audible distortion at the high
power.
6C33C, 6C33C-B Tubes
The 6C33C's internal resistance is very low, which
works very well with applications which require
low voltage and high current (unlike standard
tubes which are designed as high-voltage, low-
current devices.)
Because of its sonic characteristics and low
internal resistance this tube was the best choice for
the A318B amplifier.
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