18
TUBE VITALIZER
Power supply
Custom made toroidal transformer
with five separate wirings.
Voltage selector
Ground-lift switch
Mains filter
Fuses (primary voltages):
115 V: 800 mA
230 V: 315 mA
Special care has gone into the design of the power supply of the
Tube Vitalizer. The power supply is the heart of an electronic
system: The better it is, the better the whole system works and –in
an audio system– the better it sounds.
This power supply is based around a custom made 35 VA toro-
idal transformer and is designed to minimize induced hum and
noise due to the non existence of an air-gap. All required voltages
(230 V, 6.3 V and 2 xy15 V, 12 V) have an individual wiring in the
transformer and are smoothened separately afterwords.
The primary voltage may be selected between 230 V/50 Hz and
115 V/60 Hz by means of a recessed slide switch on the rear panel.
The rear-panel ground-lift switch may be used where ground
loops are causing hum problems. When the Gnd Lift switch is set
to off, the circuit ground is no longer connected to the chassis
ground. The power cord connector is a 3-wire, U-ground, standard
IEC mains connector for a detachable power cord (enclosed) with
an inbuilt mains filter.
Transformer, power cord and mains connector have VDE, UL and
CSA approvals. The fuse has a value of 315 mA for the primary
voltage and 500 mA for the secondary when operated at
230 V/50 Hz.
At 115 V/60 Hz the fuse value for the primary voltage is 800 mA
and for the secondary voltage 1000 mA (1A).
On the secondary side of the power supply, an RC combination
is used to filter out noise and hum voltages from the mains side.
Both half-waves are smoothed with 3000 mF capacitors in the
positive and negative voltage path. Both pathes use precision
voltage regulators, as deviations of only a few millivolts can result
in audible changes such as a diffuse sound pattern.
The operational voltage of the tubes (250 V) is heavily smoo-
thened and electronically regulated. The heating voltage (6.3 V) is
supplied by an individuell wiring within the transformer. So-
called »hum-trimmers« adjust the tubes´ heating voltage and
minimize the hum voltages.
Both inputs and outputs of the tubes are smoothened with
condensers of high voltage and condenser values (10 µF/
400 V/5 %) to minimize offset voltages. The tubes are de-coupling
at about 10 Hz.
All relays are operated via an individuell voltage regulator and
are therefore separated from the audio operating voltage.
