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Reference Manual
Reference Manual
CE 4000
The amp with an Attitude!
CE 4000
The amp with an Attitude!
Power LED is driven from the low-voltage supply.
Power Supply Operation
AC power enters the amplifier through a power cord equipped
with an IEC (unplugable) connector. It then is passed through
the EMI filter. Circuits that use switching technology will nor-
mally send a small amount of high-frequency noise back down
the power cord and into the power distribution system. This
noise must be removed in order to sell the unit in certain parts
of the world. Since the CE4000 is a worldwide product, the
EMI filter removes this noise so that it does not exit the box.
The power then enters the Power Factor Correction (PFC)
Boost stage. This stage is what allows the CE4000 to be
plugged into any outlet in the world without any modifications
to the amplifier. The PFC stage uses switching power supply
technology to take whatever AC line voltage comes in, convert
it to DC and boost it to 400 Volts. The circuit also uses intelli-
gence to draw the current from the line sinusoidally and in
phase with the line voltage. This reduces the load on the power
companies and also allows the amplifier to pull more peak
power from the power source (the outlet). The power is drawn
in small amounts 62,500 times each second and is used to
provide power to the isolation stage and to fill the large energy
reservoir capacitors.
The power then goes to the “buck” isolation stage. This stage
takes the 400 Volt PFC voltage and, again using switching
power supply technology, converts it down (“bucks” it down)
to the level needed to power the audio output stage. The iso-
lation stage also satisfies a safety requirement by providing
isolation, using a transformer, between the AC mains power
and the power that is delivered to your speakers. The isolation
stage moves power 125,000 times each second from the pri-
mary to the secondary to power the audio output stage and
keep its large energy reservoir capacitors full.
In order to keep the power supply controllers, protection cir-
cuits, and the audio signal path components powered, another
switching power supply is used, this one also running at 125
kHz. This one is also a “buck” type supply in that it takes volt-
age from the 400 Volt PFC bus and converts it down to the low
voltages needed. This circuit also uses a transformer to pro-
vide safety isolation.
Like the audio signal path parts of the amplifier, there are many
ways that the power supply protects itself. Part of the start-up
time delay mentioned above occurs while the power supply is
ramping up all of its voltages (soft-start) so that large inrush
currents are avoided. Current limiters and over-current detec-
tors are used to protect the power supply output devices. The
power supply will also detect severe brownouts and shut off
the supply until the brown-out is over if the line voltage is dras-
tically less than normal.
