Sound Performance Lab 9842 - Manual (Page 15)

Transient Designer
15
Internal 15 VA torroidal
transformer
Voltage selector
Ground-lift switch
Transformer, power cord and
mains connector with VDE,
UL and CSA approvals.
Fuses (primary voltages):
200 mA/400 mA.
Special care has gone into the design of the power supply of the
T
RANSIENT D ESIGNER . The power supply is the heart of any electronic
system, and the better it is, the better the whole system works. In
an audio system, this translates into better sound quality, lower
noise and lower distortion.
The power supply is based around a 15 VA torroidal transformer
and is designed without an air gap to minimise induced hum and
noise. 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 and a ground-lift switch is fitted for use where ground
loops are causing hum problems. When the G
ND L IFT switch is set
to off, the circuit ground is isolated from the chassis ground.
The detachable power cord is a standard 3-wire type fitted
with an IEC mains connector; the transformer, power cord and
mains connector have VDE, UL and CSA approvals. The fuses have
values of 200 mA/230 V and 400 mA/115 V.
On the secondary side of the power supply, an RC combination
is used to filter out noise and hum. Both half-waves are smoothed
with 2 x 1000 µF capacitors in the positive and 2 x 1000 µF capaci-
tors in the negative voltage supply path, and both lines use preci-
sion voltage regulators for optimum stability. Deviations of only a
few millivolts can impair audio quality, introducing artefacts such
as loss of stereo imaging or a diffuse sound character. Particular
care has gone into the circuit layout and component choice to
minimise crosstalk between the audio circuitry and control
voltages.
Power Supply