Audison Thesis HV venti Owner's Manual

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a. Unscrew the six screws which fi x the glass panel
b. Reassemble the glass panel. Fasten the six closing screws

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a. Unscrew the two screws which fi x the side handle
b. Reassemble the side handles by fastening the proper screws

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a. Remove the glass panel
b. Remove the side handle above power supply terminal blocks
c. Lift the plexiglass panel which protects power supply terminal blocks
d. Remove the two parts of the fuse to be replaced
e. Eliminate all possible metallic remainders of the broken fuse and install the new one
f. Mount power supply terminal blocks protecting panel
g. Mount the side handle back
h. Reassemble the glass panel

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a. Remove the glass panel
b. Remove the side handle above power supply terminal blocks
c. Lift the plexiglass panel which protects power supply terminal blocks
d. Find the 4 blade mini-fuses
e. Mount power supply terminal blocks protecting panel
f. Mount the side handle back
g. Reassemble the glass panel

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a. Remove the glass panel
b. Set BIAS switch on “L” or on “H”
c. Reassemble the glass panel

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a. Remove the glass panel
b. Remove the bypass module
c. Select the fi lter and the frequency you like
d. Install the crossover module
e. Reassemble the glass panel

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a. Accessories supplied with HV venti
b. How to take the amplifi er out of its inner carton
c. If you like to change DUAL POWER confi guration...
d. If you like to change DUAL BIAS confi guration...
e. If you like to install the electronic CROSSOVER...
f. NON-PROJECTING or SEMI-PROJECTING installation (adhesive template)
g. Remove the amplifi er fi xing plate
h. Secure the fi xing plate
i. Secure the amplifi er to the fi xing plate
j. Connect signal cables...
k. Connect power supply cables...
l. Amplifi er calibration...
m. Mount the grilles which cover connections onto side handles
n. Reassemble both side handles...

a. Fans protecting fi lters cleaning
b. Cooling ducts cleaning

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1 • Project purpose
2 • Project philosophy
3 • Electronics
4 • Chassis and thermal project
5 • Installation method and maintenance

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Safety precautions
Functioning precautions
Maintenance and reliability precautions

MAINTENANCE

12 OWNER’S MANUAL

INSTALLATION

11 OWNER’S MANUAL

CROSSOVER INSTALLATION

10 OWNER’S MANUAL

DUAL BIAS CONFIGURATION

9 OWNER’S MANUAL

DUAL POWER CONFIGURATION

8 OWNER’S MANUAL

MAIN FUSE REPLACEMENT

7 OWNER’S MANUAL

SIDE HANDLES

6 OWNER’S MANUAL

GLASS PANEL REMOVAL

5 OWNER’S MANUAL

CONTROL FUNCTIONS AND PROTECTION

4 OWNER’S MANUAL

CONTROLS PANEL

3 OWNER’S MANUAL

POWER SUPPLY - SWITCHING ON PANEL

2 OWNER’S MANUAL

INPUTS - OUTPUTS PANEL

1 OWNER’S MANUAL

TECHNICAL AND ELECTRICAL FEATURES

1 TECHNICAL DATA

DESCRIPTION

2 INTRODUCTION

GENERAL RECOMMENDATIONS

1 INTRODUCTION

CONTENTS

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i

Safety precautions

• The vehicle electric system must have 12VDC voltage with negative to ground. Make sure your car has it in order to
avoid any damages to your amplifier and to the car itself.

• Suitably fix the amplifier paying utmost attention if you install it into the driver’s compartment. Use extra fixing systems
if you install it inside the bonnet. If the amplifier detaches itself while you are driving, it can severely damage people and
other vehicles.

• Power supply cable must have mechanically resistant and self-extinguishing insulation. Its section has to comply with
what is indicated in this manual. When placing it, avoid to press it against cutting parts or close to mechanical moving
objects. Make sure it is suitably fixed all along its length. Block positive and negative cables just close to the amplifier
respective power supply terminal blocks through a clamping screw.

• Put a fuse holder close to the battery positive terminal; connect one end of the power supply cable to it after
connecting its other end to the amplifier. The fuse value must be 50% higher than the amplifier built-in one. In case
the cable supplies several amplifiers, the fuse value will have to be 50% higher than the sum of the values of all other
fuses in the system.

• For safer driving, we recommend to adjust volume not to drown external traffic sounds.

• WARNING. When the amplifier works in particularly hard conditions, it can reach 90°C (194°F). Make sure its
temperature is safe before touching it.

Functioning precautions

• Install the amplifier in locations where temperature is between 0°C (32°F) and 55°C (131°F).

• There must be suitable air circulation where you install the amplifier; this area must not be affected by humidity, rain,
external deposits or parts coming from the vehicle mechanical devices. Let the amplifier glass upper part (i.e. the part
where air goes in and out) be at least 10 cm (4”) far from possible walls.

• When installing speakers and the cables that connect them, make sure that non-insulated parts never touch the car
cutting parts. If they do, the amplifier protection intervenes.

• Listening level calibration is made by adjusting the source volume up to 3/4 of its maximum level; then, adjust the
amplifier levels until you can hear distortion and you can see PEAK indicators are occasionally on.

• Avoid to start the car engine with the amplifier on. If the battery isn’t sufficiently charged, in case you start the car with
the audio system on, the amplifier could go in the protection mode.
In this case isn’t sufficient to shut off the audio system and turn it on after some seconds.

Maintenance and reliability precautions

• Periodically clean the amplifier avoiding to use aggressive solvents that might damage it. Dampen a piece of cloth with
water and soap, wring it and clean the amplifier with it. Then, clean the amplifier b y using a piece of cloth dampened with
water only; eventually clean it with a dry piece of cloth.

• Remove dust and solid deposits from the five upper grilles through which air goes in and out. This must be periodically
done by removing the magnetic fixing grilles and by cleaning the filter you can find underneath them as indicated in
this manual. Avoid to use compressed air on the grilles without removing them, since it would push solid parts into the
amplifier. If necessary, please contact a specialised service centre for internal cleaning. Air ducts obstruction makes the
amplifier go in safety.

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GENERAL RECOMMENDATIONS

INTRODUCTION

1

1 • PROJECT PURPOSE

Audison has always pursued the best audio reproduction in all of its products.
The creation of the HR100 in 1991 occurred simultaneously with the achievement of a technological goal. On one hand it

appeared to use all the knowledge attained to this date, yet on the other hand it set a landmark for years to come.
Universally recognized as “The Amplifi er”, the HR100, unlike other car stereo products, set a new standard f or “longe vity;

being produced until year 2003. It identifi ed the Audison brand throughout the world. The worldwide press awarded it
many accolades countless number of times, and today it stays a reference product f or its performance. To car audio fans
worldwide it stands as a legend.

Throughout the HR100 project, Audisons’ mission was to obtain the highest sound quality without compromises. Its
maximum power output was its only limitation, as technology of the time did not allow this reference sound quality with
massive power.

Four years later the THESIS brand was created. Using the latest in technology, Audison once again rewrote the book on
amplifi er performance. In 1995 and in 1996 respectively, HVsedici and HVtrenta amplifi ers came to light.

After the introduction of these amplifi ers, new standards were set as far as the sound quality / power quotient were
concerned. They were also the fi rst to use balanced inputs in a rational way through the worldwide-patented ABS (Audison
Balanced Systems) connectors. HVsedici and HVtrenta became another legend

THESIS line amplifi ers became the most requested products by car audio enthusiasts looking for dynamics and necessary
to anyone in the competition circles requiring maximum SPL without sacrifi cing sound quality

Each of the two projects, THESIS and HR100, keeps its own identity and sonic footprint, which is diffi cult to surpass.
Therefore a new version of these classics may have changed their look, maybe also some of their features, but not their
sound specifi cations.

However there was still a way for Audison to try to improve, by merging these two unique characters into one amplifi er.
This has been the idea of Audison engineers for a very long time.

After several years, obtaining a deeper technological knowledge, this became possible. The project of a new THESIS
amplifi er was launched. After two years of research, by exploiting the technical know-how that has been gathered in the
course of time and by employing the best, most recently introduced electronic components available, today THESIS
HVventi is born.

With HVventi, Audison aims at renewing the HR100 and THESIS legend status. Internally the most current available
technology was employed; therefore it is not dangerous to predict that HVventi is going to remain an absolute reference
product for many years to come.

It could only be overcome when a further technological leap occurs, mostly concerning components. When that technology
is available, Audison will continue to be the legend.

2 • PROJECT PHILOSOPHY

From the start, the vision of the HV venti project was characterised by absolutely no compromises in achie ving maximum
performance. Each stage of the amplifi er was designed employing the most suitable components even if they were hard
to fi nd.

The fi rst unique aspect of the project is the total void of integrated oper ational circuitry. Due to their constructive technology
and the low voltage level that the circuitry can handle, they can deteriorate the signal.

Their elimination permitted the engineers to work at higher voltages and with a Class A biasing of the intermediate stages;
the choice of working in Class A caused the associated heat on the circuits, which might have led to the components
destruction.

Achieving proper operating temperature was a key design component. Cooling all the internal heat sources through
a complex thermal transfer system that directs heat into the main heat sinks assertively attacked the thermal issue.
Employing fi v e controlled fans solved the prob lem of temperature variation, which affects circuit stability, sonic consistency
and also lowers reliability.

Signal commutations were treated using special relays: too complex of a circuit would have led to longer tracks and
parasitic inductances, causing signal deterioration and loss of musical information.

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DESCRIPTION

INTRODUCTION

2

The fi nal power stage uses an innovative topology, which aims at increasing Class “A” polarization as much as possible.
The whole input circuit is balanced up to the fi nal stage “Front End”, while the amplifi er’s confi guration is “Dual Mono”.
In order to avoid electro-magnetic interf erences, no high current is passed on the main board, with the e xception of power

supply terminals; this solution was achiev ed through the use of a second board that is located under the main board. This
second board is used to carry the large power supply current to the fi nal stage.

As in the VRx series, the PWM Sincro confi guration was employed in the power supply stage. It was chosen due to its
response time; obviously, since the confi guration is Dual Mono, four power supplies were employed.

Two more power supplies are used in the signal stage, one for each channel, realised in a high effi ciency confi guration.
An innovative function called “Dual Power “ was introduced which can predict the amplifi er’s output power by choosing

between two distinguished confi gurations called Hi Current and Hi Power.
In the Hi Current confi guration the amplifi er delivers 200W at 4 ohm and can also be used at 2 and at 1 ohm; this

confi guration is recommended when you want the amplifi er to work with really diffi cult loads.
In the Hi Pow er confi guration the amplifi er delivers 400W at 4 ohm and it can also be used at 2 ohms; Hi Po wer confi guration

is recommended for 4-ohm loads.
Obviously , the amplifi er easily drives minimum loads equal to 1 ohm in Hi Current confi guration and to 2 ohms in Hi P o wer

confi guration, but remember, there will necessarily be a slight drop in terms of sound quality.
In order to switch the confi guration, you have to remove the amplifi er’s cover and place four minifuses into the special

slots. This operation can only be made when the amplifi er is off both for technical reasons and for obviously safety
reasons, since inside the HV venti there are voltages over 150V!

You also have to remove the cover in order to insert the crossover module, which is provided as factory option.
In order to manage these unique features, a control unit called ASC (Amplifi er Status Controller) was specially

designed. A separate microprocessor controls this function.
Installing the amplifi er was a v ery important design concern due to the signifi cant weight of the HV venti. In order to install

it, you must fi rst found a solid position to install the bottom mount plate. The amplifi er then mounts to this plate.
Finally we accurately looked after aesthetics, taking functionality into account as well.
In order to satisfy the cosmetic expectations of the potential HV venti owner, the amplifi er was equipped with a special

tempered glass cover and internally lit using white coloured LEDs, recently introduced into the market.
The internal light and ASC display can be turned on in demo mode for demonstration purposes through an external 12

V power supply.
Exuding more exquisite fi t and fi nish, and to make its aesthetics very long lasting, all materials used were treated with

galvanic methods, eliminating painted fi nishes.

3 • ELECTRONICS

a) Preamplifi er

It is made of two groups, Front End pre-amplifi er and control unit.
The whole stage is balanced up to the driver outputs.
90 V separate the power supply voltage.
The pre-amplifi er can be bypassed with the PRE ON/ PRE OFF switch. If the pre-amplifi er is bypassed (PRE OFF),
the whole pre-amplifi cation unit is disabled and, as a consequence, also some controls are bypassed, except for IN
MODE and OUT MODE. In this case however you can still insert the factory provided electronic crossover. Of course by
bypassing the internal pre-amplifi er, you will have to use an external pre-amplifi er and it will have to be placed near the
musical signal source. In order to exploit the plus points of an external pre-amplifi er, you will have to carefully choose a
device with higher quality than the one factory provided and to use very high quality cables for the connections.

Front End:

ABS balanced inputs with balanced bypass outputs (available in both PRE ON and PRE OFF confi gurations).
Decoupled input stage through two polypropylene capacitors in each channel (available in both PRE ON and PRE OFF
confi gurations).

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DESCRIPTION

INTRODUCTION

2

JFET differential input stage (available in PRE ON confi guration).
Selectable two level input gain structure adjusted (available in PRE ON confi guration).
Balanced output buffer for control unit (available in PRE ON confi guration).
Thermally stabilized (available in PRE ON confi guration).

Control Unit:

Allows the amplifi er to be properly confi gured and adjusted.

- Sensitivity.
Adjusted using the IN SET switch and ADJUST control.
IN SET allows you to adjust the amplifi er’s sensitivity in 2 levels by changing the pre-amplifi er’s gain.
The fi rst level is used for input gain from 1÷6 V (0 dB Gain), while the second is used for input gain from 0.25÷1.5 V
(13 dB Gain).
The ADJUST control allows adjustment within the indicated values.

- L/R alignment.
Used to increase L or R channels level up to +3dB.
This is useful to balance the output of the two channels.

- IN Mode.
Used to select balanced or unbalanced input mode.

- Out Mode.
It allows the amplifi er to operate in stereo or mono confi guration (R input).
Unlike what occurs with all amplifi ers that have one channel out of phase channel, the HV venti has in phase channels
for perfect symmetry.
Pressing the Out Mode control to confi gure the amplifi er in mono, a phase inversion is activated.
When using in the mono mode, the loudspeaker has to be connected to the positive lead of each terminal. In the mono
mode, if the optional crossover module is installed, the Lo Pass 24 dB confi guration is automatically activated.
When control unit is bypassed (PRE switch on OFF), IN MODE and OUT MODE are the only enabled switches.

b) Crossover

Factory optional module.
In order to insert the module, you have to remove a small bypass module. The crossover module itself contains all the
electronics needed to allow proper adjustment.
The crossover was designed in this wa y so that, in case of passive systems or the use of e xternal processors, there would
be no extra components for the signal to pass through, degrading the signal.
Available adjustments are Hi Pass /Lo Pass 12 dB and Lo Pass 24 dB mono.
Four cut-off frequencies are selectable f or the fi lter (45; 55; 65; 80 Hz). Adjustment can be made by remo ving and rotating
a small module that is on the crossover.
Although this solution is limiting compared to a continuously adjustable cut-off, fi lter linearity is drastically improved and
long signal paths are avoided.
You can install the crossover module both in the PRE ON and the PRE OFF confi guration.

c) Driver

150 V separate power supply.
Thermally stabilized.
Class A biasing.
Balanced input (available in both PRE ON and PRE OFF confi gurations).
First stage, complementary JFET differential.
Second stage, complementary BJT differential.
Cascode voltage amplifi er.
Output buffer to drive output stage.

d) Output power stage

The output power stage is based on an innovative topology similar to IGBT (Insulated Gate Bipolar Transistor) but
employing discrete devices.
The circuit is made from a complementary pair of Hitachi DMOS drivers, usually used as output stage devices (such as
in HR100), which drive two pairs of SANKEN power BJT transistors providing each with 30 A peak current capability and
200 W dissipation.
This solution allowed the use of only two pairs of output devices, thus permitting bias currents to be reduced which
necessarily have to be shared according to the number of output devices in parallel; therefore increasing the bias
current

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DESCRIPTION

INTRODUCTION

2

value on every output device is possible, keeping stable the total current absorbed by the amplifi er when in idling status.
All this results in the increase of the output stage to class A value.
This value is the typical car audio amplifi ers’ weak point. Due to installation needs, they always require several output
devices in parallel in order to work on very low loads and in the meantime to have low consumption since the car battery
supplies them.
This confi guration proved to be especially valid both in terms of power performance and of acoustic quality: the DMOS
power transistors used as driver supplies the current that the BJT output needs because their “current gain” decreases
when current increases. Thanks to the DMOS voltage amplifi ers’ specifi c feature, the confi guration used insures that this
gain decrease doesn’t overload in current the previous voltage amplifi er stage and it can have a constant distorsion for
every output load.

Also regarding the output power stage, an innovative solution was adopted.
In any amplifi er high supply currents, power output and return ground current create electro-magnetic fi elds interfering
with our precious audio signal.
In order to avoid this kind of situation, you are often forced to use convoluted wiring which compel designers to accept
compromises. Compromise is not accepted in the HV venti.
Inside the HV venti a six lay er thick copper board was used which gathers all the output stage return currents; the la yout
was created so that each current path comes to close contact with the return current fl owing backwards.
This way the electro-magnetic fi elds are out of phase and nullify each other: this solution could be defi ned as a “balanced
power supply”.

e) Power supplies

There are two Hi power supplies for each channel. They supply power exclusively to the output stage.
Each power supply pair of each channel works in Synchro- PMW mode: an independent circuit controls each of them.
Howev er, they are synchronized with one another and are designed to supply one single po w er source , one supplies the
positive and the other the negative power.
This solution, which has been employed by Audison for a very long time, allows engineers to increase the impulsive
current transient response necessary to the amplifi er.
In HV venti this confi guration was doubled in each of the two channels: the amplifi er is actually set into a Dual Mono
confi guration, reducing interference between the channels.
Furthermore, the two pairs of power supplies were synchronized to reduce radio frequency electro-magnetic
interference.
The use of 4 separate power supplies has a further advantage.
Power split allowed the use of just one MOSFET, although a large power one, for each rail of each power supply, thus
avoiding the paralleled confi guration that is perhaps the main cause of amplifi ers failures.
Each transformer and relative fi lter inductor were enclosed in non-magnetic metallic shells and then fi lled with resin.
This procedure further increases reliability for two reasons: fi rst of all, coils are blocked and therefore made immune to
vibrations; secondly, heat is homogeneously distributed, thus preventing any possible overheated areas.
The resin-fi lled groups were then mounted onto the aluminium thick bottom plate to allow heat to be dissipated through
side heatsinks.
In the Dual Pow er function, each transformer was equipped with two secondary windings that are selectable by positioning
minifuses into the two availab le jumpers. For Hi Current confi guration you need 15A fuses, while for Hi Pow er confi guration
you need 10A fuses; the fuses are factory provided.
All the necessary adjustments for Dual Power confi guration are automatically managed by the ASC (Amplifi er Status
Controller) .
All the rest of the power needed for signal circuits are supplied by two Flayback power supplies, one for each channel.
They have reduced power but are high effi ciency types and are synchronized with the main power supplies. The whole
power supply group is connected to the car battery through two supply terminals equipped with a strip fuse. Two further
terminals are provided to connect an external capacitor.

f) ASC: Amplifi er Status Controller

The ASC unit (Amplifi er Status Controller) is in charge of managing all of the amplifi er’s confi guration functions.
It is equipped with its own proprietary microprocessor. Using the Status Display, you can visualize operational functions
or any possible anomalies of the amplifi er or of the external systems. The ASC also handles the protection circuits and
checks thermal conditions of each component and maximizes the fans to keep things under control. Vumeters are used
to identify output power.

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DESCRIPTION

INTRODUCTION

2

Indications shown on the Status Monitor are:
POWER ON: The amplifi er turn on status.

HI POWER: When on Dual Power is in Hi Power mode, if turned off it means it is in Hi Current mode.
In the case of wrong fuse positioning, master protection activates.
FAN ON: Cooling system is active.
TEMP GOOD: If solidly illuminated, it indicates the best operating temperature f or maximum listening pleasure; if it blinks,
please wait.
LEFT CH: If it blinks intermittently, the left fan is active. Intermittence can vary depending on the three lev els of f an speed.
If it doesn’t blink, it means that left channel has gone in protection mode.
RIGHT CH: Same operation as left channel.
BATT PRT: Protection activated because battery voltage is lower than 11 V or higher than 16 V.
THERM PRT: Thermal protection is on at 90°C ( 194° F) .
CHECK SPK: One output is in short circuit state with the car chassis. Check loudspeakers and cables.
SAFETY PRT: A certain protection is on. Check the other leds to identify the cause.
CHECK FAN: One of the four side heatsink fans or the drivers central f an is not functional. Check fans and air pathways.
SERVICE: The amplifi er is faulty, please go to the nearest after sales service centre.
LEFT (VUmeter): It indicates the signal level on Left output.
RIGHT (VUmeter): it indicates the signal level on Right output.
PEAK (VUmeter L/R): It reveals the amplifi er’s distortion limit. It usually turns on when the VUmeter is fully on, indicating
Clipping mode. It may occasionally turn on, but if on solid, power needs to be reduced. If it turns on when VUmeter isn’t
fully on, there must be anomalous distortion. Possibly the applied load is too high (low impedance) or has anomalies.

g) Lighting system

For cosmetic effect, the HV venti is equipped with three styles of lighting: the Thesis logo and glass perimeter red, the
Audison logo blue, and the internals of the amplifi er are lit white.
If the user removes the glass top plate, there are no electric wires to disconnect or reconnect, as electric contact
automatically occurs through spring loaded contacts; the white light for the internals are the result of various white
coloured LEDs.
In order to avoid current consumption, near the battery terminal connections on the amplifi er, there is a LIGHT ON-GND
terminal. If you connect this terminal to the car chassis, all the internal lights turn on. You can also control the internal
lights remotely through a switch. You could also connect the terminal to the trunk light ground switch so when the trunk is
opened the amplifi er lighting comes on.
Near this connection, there is a DC terminal to connect a small external 600 mA, 12 V power supply to turn on all the
internal lights, including the Status Controller. In this case the ACS activates in the demo mode . This function is useful f or
exhibitions and doesn’t require the LIGHT ON-GND terminal to be connected to the car chassis.

4 • CHASSIS AND THERMAL PROJECT

The HV venti was designed to dissipate the heat generated by the amplifi er, and to make the system thermally stable.
Generally speaking, the system consists of a 5 mm thick aluminium plate that connects to two side cooling ducts; on the
top of the amplifi er two fans are placed at the end of each side. One pulls the air in, the other pushes it out, thus creating
a fl ow inside the underlying tunnel.
The aluminium plate bears all the various internal parts and also acts as heat-gathering element: internal heat generating
parts such as transformers and the energy management modules are attached to this plate.
This solution not only helped to eliminate the high heat generated by the HV venti internal circuits class “A” biasing,
but it also allowed excellent circuitry layout, by not forcing the designers to place the biggest heat sources next to side
heatsinks.
As well, as explained in the previous section, all po w er wiring runs on a board underlying the main one and is electrically
connected to it through screws and soldered bushes; this two layer thic k copper power board is in touch with but electrically
insulated from the bottom plate: as a result, the whole power layout exhausts heat through the side ducts.
We turned to a different solution for the drivers and preamplifi er section.
The side ducts prevent the temperature from o vercoming certain values but are nev ertheless affected by the environmental
temperature and the time needed to reach the best working temperature. Instead, the drivers and preamplifi er circuitry
needs constant temperature.
In order to solve the concern, a further small tunnel for the central cooling system was designed. This tunnel is internally
combined with a fi fth autonomous fan.

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DESCRIPTION

INTRODUCTION

2