21
Power Supply
Custom made torroidal trans-
former with five separate
wirings.
Voltage selector
Ground-lift switch
Mains filter
FUSES (primary voltages):
115 V:1A
230 V:500 mA
Extensive filtering and de-
coupling guarantee stable
power and avoid audible
changes such as a diffuse
sound pattern.
High voltage tube operation
(275 volts)
Special care has gone into the design of the power supply of the
QURE. 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 35VA torro-
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 2x15 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. At 115 V/60 Hz the fuse value for the primary
voltage is 1A and for 230V/50 Hz the fuse is 500 mA.
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 6000 microFarad capacitors
in the positive and negative voltage path (recommended
PREMIUM version: 28.200 microFarad). 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 (275 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 (1microFarad/
400 V/5%) to minimize offset voltages. The tubes are de-coupled
at about 10Hz.
All relays are operated via an individual voltage regulator and
are therefore separated from the audio operating voltage.
