Sound Performance Lab 9523 - Manual (Page 8)

8
Power Supply
Special attention has been paid to the power supply of the
MikeMan. The power pack is the heart of any unit, and the more
accurately it works, the more this improves results.
The power supply is installed around a toroidal-core trans-
former which does not cause any electronic humming or mecha-
nical sounds as a result of its minimum leakage field. The primary
voltage can be switched between 230 V / 50 Hz and 115 V / 60 Hz.
A 3-pole standard IEC mains connection socket serves to
connect a detachable 3-pole mains lead which is included in the
scope of supply. Transformer, power cable and mains connector
comply with the requirements of VDE, UL and CSA.The fuse rating
is 200 mA.
The connection between ground and housing can be sepa-
rated via the GND LIFT switching option. Hum loops can be reme-
died in this way.
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 2000 mF capacitors in the
positive and negative voltage path.
An independent, self-contained power pack is used for the
phantom power supply. It obtains unregulated AC voltage from 2
x 25 V coils in the transformer. This results in +/- 22.5 V DC via
bridge rectifiers which are filtered with 1000 mF. The DC voltage
is adjusted to exactly 48 V in the switching power supply (LM 311)
downstream. It is then smoothed again and stabilized. The power
supply current flows to the intrusion point via the PCB. An RC
combination stabilizes the power supply again at this point. Two
medicinal 6.81 kW resistors with a tolerance of only 0.1% are used
as bridging resistors.
A stable and well-filtered
toroidal-core power supply
provides the basis for good
sound processing.
The GND LIFT switch helps to
remedy hum loops.
Ample filtering, smoothings
and calibrations make for
stable, constant service
voltage.
The phantom supply voltage is
from a separate power supply
with sophisticated filtering
and selected components.