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TECHNICAL NOTES
Your amplifier is composed of four distinct sections.
Preamplifier
The pre-amplification circuits and the commutation relays are mounted just on the rear panel,
with the aim of the maximum reduction of the distance to the input connectors.
The preamplifier (there six of them) are made of one input buffer, a digital operated attenuator
and an amplification stage.
The stabilized feeding and the optical separating circuits interposed between the logic stage and
the attenuator are placed on the supply board.
Supply board
The energy for the pre-amplification stages is provided by a suitable board, on which is also
placed a toroidal transformer with the secondary coils separated for each channel.
This board also supports the optical separating circuits interposed between the logic stage and
the attenuator, used to reduce at the most the interference between the two stages.
Amplifier
Each of the two independent amplification modules disposes of a 300VA audio dedicated
toroidal transformer.
There are two distinct supply stages for each module; a stabilized one feeding all circuits up to
the drivers; the second one feeding the power output stage.
The stabilized dual supply stage is made of two high-speed capacitors with a total capacity of
13.600μF for each supply line and is designed with discrete technology without feedback, a
choice that from listening sessions proved to be more musical. The stabilized supply stage is
mounted directly on the amplification boards.
The power supply uses six ultra-low ESR 6.800 μF leveling capacitors for a total of 40.800 μF.
Control logic
Hearth of this stage is an 8-bit micro-controller with a ROM of 16 Kbytes that allows managing
the 40 character alphanumeric fluorescent display, the IR receiver, the optical HP encoder, the
buttons, the relays and the communication port.
Notes
Every resistor used in this design is of the “metal film” kind with low noise and a 1% tolerance,
the polystyrene capacitors are from Philips, polypropylene, electrolytic and tantalium ones are
by Roedenstein; all transistors are by Motorola.
All printed boards are made with 70 μm – width copper with an additional 30 μm of metal layer
for an overall of 100 μm.
Balanced input connectors are from Neutrik.
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