Linn Twin Klimax - Manual (Page 11)

What is switch mode?
In a switch mode power supply the incoming mains is filtered then rectified to generate a very high voltage
dc (direct current) supply. This is usually about 300 to 350 Volts dc, which is far too high to operate audio
circuitry directly, and is still connected directly to the incoming mains supply. Such a high voltage is very
dangerous and is one reason why the Klimax case should never be opened by a customer or a non Linn
Products employee.
This high voltage is chopped up by very fast semiconductor switches and applied to a small transformer
which both transforms the voltage to the value needed by the electronic circuitry and provides a safety
isolation barrier from the mains supply. The size of a transformer reduces as its operating frequency
increases, so a transformer operating at say 60,000 cycles per second is far smaller than one operating at
mains frequency of 50 or 60 cycles per second.
On the output of the transformer, very fast rectifiers, a small coil and small capacitors filter and convert the
high frequency waveform back to dc, ready for the electronic circuitry to use. By controlling the timing of
the switches the output voltage can be held constant or varied, as required, without the need for further
inefficient voltage regulators. This processing all happens well above the range of human hearing which, in
principle, should be good for audio circuitry.
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