2
INTRODUCTION
The
HV sedici
amplifier is the first born in a new family of high performance car
amplifiers and other devices called
THESIS
.
It is endowed with highly innovative technologies and circuit solutions and its realization
required big efforts and investments for research and development.
The purpose was to realize an amplifier that had to be a "milestone" in the evolutive history
of
AUDISON
products.
Its structure in the circuit layout can be identified at two levels: the first one (power) is
entirely on the mother circuit board and it collects all components which handle high
currents and need warmth dissipation; the second one (signal and control) is located on
special surface mounting devices which perform all complex functions of the whole
device.
This peculiar design technique allowed the study and optimization of the signal paths and
the blocking of the interactions among the different stages.
The
HV sedici
amplifier is constituted by three main parts: preamplifier, final power stage
and power supply.
PREAMPLIFIER
HV sedici
amplifier is supplied with an independent preamplifier unit, where the general
sensitivity can be adjusted in the 0.2
÷
1V range.
This unit can be disactivated, allowing the connection with an external preamplifier.
The input signal is applied to ABS (Audison Balanced System) connector in balanced or
unbalanced way, and to MA-1X module through two polypropylene capacitors.
MA - 1X circuit, which constitutes the input interface for audio signals, is characterized
by a FET- BJT hybrid circuitry in CASCODE configuration and it has been superintegrated
in a single chip whose features are: max power supply:
±
50 VDC, S/N ratio: 125 dBA,
Slew Rate: 120 V/
µ
S, Bandwidth: DC
÷
1MHz.
FINAL POWER STAGE
Balanced or unbalanced audio signal (it can be selected) applied to the input can directly
drive the final stage without the preamplifier interposition.
By disactivating, the preamplifier, the final stage sensitivity can be between 1.0
÷
5 V.
The signal coming from the MA-1X module arrives in balanced connection to the
V-AMP 12 LV module which makes the driving of the final stages in voltage and the
thermic stability control.
The internal circuit is characterized by a double complementary differential amplifier in
CASCODE connection with FET-BJT and current mirror combination. This circuit is
integrated in two custom chips (CDAP - CDAN) whose components undergo a laser trim
for the maximum tolerances reduction.
REGULATIONS
All controls are located on top of the device.
- MONO ON-OFF: see MONO connection.
- BALANCED-UNBALANCED: see balanced-unbalanced connection.
- PREAMP ON-OFF: see connection to external preamplifier.
- L-R LEVELS: amplifier sensitivity adjustment , separated for the two channels.
PROCEED AS FOLLOWS
Adjust
the
device
according
to
the
head
unit
requirements,
through
the
above
mentioned
controls and regulations.
1) Set the two L-R LEVELS potentiometers towards minimum (counterclockwise).
2) Turn the head unit volume control to about 3/4 of its maximum volume.
3)
Set
the
two
L-R
LEVELS
towards
maximum
sensitivity
until
you
get
sporadic
lighting
of PEAK R-PEAK L leds with high dynamic musical passages.
IMPORTANT:
if
you
should
hear
distortion
phenomena
without
the
PEAK
L-R
leds
lighting
up,
it
means
that
a
distorted
signal
is
coming
from
the
head
unit.
In
this
case,
turn
the
head
unit
volume
down
until
there’s
no
longer
any
distortion.
Repeat
calibration
operation omitting step 2.
PROTECTIONS
The
device
is
provided
with
several
electronic
protections
which
protect
the
amplifier
from
dangerous
or
wrong
functioning
conditions
,
avoiding
to
interfere
with
the
music
signal in order to get the best performances in every condition.
-
Outputs
protection:
any
type
of
short
circuit
on
the
speaker
wires
,
be
it
between
themselves or to ground , will cause no damages.
-
Temperature
protection:
anomalous
use
conditions
or
high
ambience
temperature
(above
60
°
C),
that
doesn’t
allow
the
amplifier
to
discharge
the
produced
heating
(maximum
working
temperature
of
the
device
80
°
C),
causes
the
protection
intervention.
-
Protection
against
inverted
polarity
of
the
power
supply:
if
the
power
supply
cables
polarities
should
be
mistakenly
inverted,
the
electronic
circuitry
will
be
protected
by
burning the external fuse, that will have to be replaced with an identical one.
- Protection against continuous current in the output.
- Protection against excessively low or dangerous loads.
A
front
red
LED
(SAFE)
indicates
intervention
of
protection
circuits.
Once
the
cause
of
malfunctioning
is
eliminated,
you
need
to
turn
head
unit
off
and
turn
it
back
on
in
order
to have the device function again. The amplifier will function normally.
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