Thermionic Culture Ltd. 2021
4
2 Controls
&
Meters
2.1 Drive
This control is really in 2 parts, a switch and a rotary pot.
The switch gives a coarse control and the pot a fine control
of the signal input level. At the first position
'
Normal’ (for
line level signals) the frequency response is flat. The ‘+10’
position increases the gain by 10dB and adds some top
end for extra bite.
'
Overdrive’ is 30dB above
'
Normal’ and
can be used for extreme distortion effects at line level, also
guitars and other low-level sources.
The ‘Drive’ pot controls the amount of signal you are
feeding to the 2
nd
valve, so the higher it
’
s set the more
effect. It should be used in conjunction with the ‘Output
Level’ control to keep overall levels where they are desired.
2.2 Output Level
Again, this control is in 2 parts, a switch (-10dB) and a
rotary control. This controls the signal going to the output
valve. Usually, it’s advisable to set the rotary control at 8-12
(check test report) with the ‘-10dB’ switch down for low
distortion at line level. Set the switch to ‘-10dB’ and reduce
the rotary control when pushing the distortion valve at other
than P3, which always requires maximum ‘Output level’.
2.3 Bias (and meter use)
This control varies the current through V2 by changing the
positive voltage on its cathode. The actual current is shown
on the milliammeter. When the Vulture is starved of current
the sound is thinner and when over-fed it becomes fatter,
but current above 0.6 mA will shorten valve life. The best
setting for low distortion is usually 0.25 - 0.3 mA (see test
report for exact figures with valves supplied).
Summary of Contents for The ULTRA Vulture
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