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TECHNICAL DESCRIPTION
DC POWER AMPLIFIER
In many ways the direct current (DC) ampli¬
fier is the ideal amplifier for audio use. Kenwood
audio engineers have taken up the challenge of
producing this ideal amplifier. The result has been
success in producing a power amplifier which
makes this dream come true.
Characteristics of DC Amplifiers
1.
They make reproduction of low frequencies
down to subsonic and DC levels possible.
The result is to give a greater sense of power
in the audio reproduction which greatly in¬
creases enjoyment of music and reproduces
the low-frequency high-energy sounds of a
live performance as only a DC amplifier can.
2.
There is zero phase difference between input
and output.
Because there are no capacitors
in the signal path to cause phase rotation.
phase distortion is absent.
3. Output waveform is a faithful duplication of
the input waveform.
Although this would seem to be a natural
prerequisite for a hi-fi amplifier, it is a fact
that only
a DC amplifier makes faithful
duplication possible.
The performance of a DC amplifier depends
upon the stability of each individual circuit within
it.
In the input stage, special dual FETs are used,
intended for the most demanding electronic com¬
puter applications (in packs of perfectly balanced
pairs). This is followed by a three-stage differential
amplifier operating in Class A, in which the open
loop gain is high, and in which a fully adequate
degree of negative feedback is applied with a pre¬
driver load circuit in which the power transistor
bias is stabilized by a constant current supply
circuit.
This circuit configuration gives excellent
stability and extremely wide frequency response.
Phase Characteristic
Conventional
DC Amplifier
DC Amplifier
PRECAUTIONS FOR SAFETY
• Switch off the unit and disconnect the power plug
from your AC outlet immediately if the abnor¬
mality (smell, smoke, etc.) should take place.
• When you connect or disconnect the power plug
from your AC outlet, never do it with wet hands
to avoid unexpected accident from electric shock.
Besides, do it by holding the power plug itself,
not the power cord.
•
Disconnect the power plug from your AC outlet
when it begins to thunder terrifically.
Also, dis¬
connect the feeder or coaxial cable for an outdoor
antenna from the tuner, if used together with the
unit.
Do not touch the feeder or coaxial cable
disconnected then.
•
It is desirable to disconnect the power plug from
your AC outlet when you leave your house for
a long time.
•
Never dismantle the case from the unit and touch
the internal part.
Never modify the internal part.
Otherwise,
the danger of electric shock will be
incurred.
• The power cord must not be pulled strongly, nor
bent forcibly, nor scratched, nor extended by con¬
necting an extra cord.
This will damage the cord
and be a cause of electric shock and a fire.
•
Do not put a heavy thing on the power cord.
•
Do not put on and near the unit what contains
water such as a vase, pitcher, etc.
•
Do not put the inflammable (paper, celluloid, etc.)
and the metal (needle, hairpin, coin, etc.) in the
unit.
•
Never close the ventilation holes on the case top
with a table cloth, curtain, etc.
Nothing must be
put on the unit especially when using for a long time.
12
KA-710CHK)
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