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 interferences, no high current is passed on the main board, with the exception of power
supply terminals; this solution was achieved 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 Power confi guration the amplifi er delivers 400W at 4 ohm and it can also be used at 2 ohms; Hi Power 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 Power
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 very 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
Summary of Contents for Thesis HV venti
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