Audio Analogue Verdi Cento User manual

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Verdi Cento Integrated Amplifier 1 / 7
Issue Date: November 2008
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Research & Development
E-Mail (support):
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Verdi Cento
Integrated Amplifier

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Verdi Cento Integrated Amplifier 2 / 7
Intro uction
Au io Analogue continues in Vacuum Tube/Soli State technology fusion research
intro ucing the Ver i Cento Integrate Amplifier to complete the au io chain begun
with RossiniCD Player REV2.0. We believe vacuum tube technology is, even now, very
vali in treating the au io signal in a preamplifier stage while leaving to soli state
technology the task of the Power stage. So this has been our esign philosophy: a
vacuum tube preamplifier stage to take a vantage of the au io properties of that
technology an a soli state power stage as “transparent” as possible. Other
important innovations concern the Mono/Pre Out an a e use functions.

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Unit escription
1. Power Supply
2. Vacuum Tube Preamplifier Stage
3. Power Stages
4. Protections
5. Mono/Pre utput
6. Pre Phono Stage
7. Functionality
8. Technical Data
3
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5
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6
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1. Power Supply
The Power supply is the basis of every au io evice. The Ver i Cento Integrate amplifier has
a very generous toroi al transformer with a e icate secon ary stage for each section of the
unit. After each secon ary stage there are regulation circuits for every section, let’s see it in
some etail:
Input Selection/Volume control/PrePhono/RECOUT Powers Supply
A e icate secon ary stage an 4 voltage
regulator provi e the supply for the input
selection section, volume control section, Rec
Out output stage an Pre phono section. The
pre Phono power supply is obtaine by further
filtering of the regulator output voltage via a
low time constant RC square.
Vacuum Tube Preamp Power supply
A lot of care has been taken over the Vacuum tube Preamp
power supply, because a Vacuum Tube ifferential pair (that is
the structure we have use in the preamp section) will never be
well matche enough to completely reject the power supply
variations. So we have esigne a iscrete component voltage
regulator to obtain a very stable voltage from the e icate
high voltage secon ary. The voltage regulator output is further
filtere by two very low time constant RC squares, one for each
channel. In such a way we have completely eliminate the
100Hz noise component an using separate RC square for the
channels also ecreases the crosstalk an increases the “soun
stage” efinition.
Vacuum Tube Heater
We eci e to use a e icate secon ary for the
Vacuum tube heater, in this way it is possible to use
a linear voltage regulator for the purpose avoi ing
potentially noisy switching type regulators. The
heather voltage has been selecte to have the best
au io performance from the vacuum tube use .

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Power Amps Power Supply
We have e icate a
secon ary stage for each
power stage channel to
ecrease the crosstalk an
increase the “soun stage”
efinition. The power
amps power supplies take
a vantage of the high
power toroi al transformer
an iscrete high current
rectifier bri ge have been
use to allow high current
peaks. There are four
10000uF capacitors after
the bri ge for each
channel (so 40000uF for
each channel!) an a lot of
capacity has been
istribute close to the
Power amps to provi e the
charge for fast au io
responses. The big capacitors an the iscrete bri ge we have use allow the power stages to
perform very highly in bass repro uction. The particular solutions a opte in the power
supplies allow the realisation of the high signal to noise ratio expecte from the power stage
circuit use .
2. Vacuum Tube Preamplifier Stage
The vacuum tube preamp section is the first active stage the au io signal meets in the unit an
it is place after the input selection circuit an the volume control. The Preamp not only has to
amplify the signal an a apt the impe ances but must also provi e two out of phase signals to
rive the bri ge configure power stage. The unit is base on a “classic” an well-known
scheme that we have evelope to ecrease the output impe ance an match the application.
Moreover, the fact that it pro uces zero fee back is its main outstan ing characteristic. This
means we haven’t mo ifie the vacuum tube istortion characteristics in any way an we have
let the vacuum tube play “as it is” (remember the “philosophy”…). Nevertheless, the overall
istortion is kept low with a higher power stage gain that lets the preamp section work with a
low level signal at all times.

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3. Power Stage
Our purpose was to have a soli
state power stage as “transparent”
as possible, able to provi e/supply
100W in an 8Ohm loa . So we have
chosen the National Semicon uctors
LM3886 Power pack as a buil ing
block an we have esigne a
“parallel/bri ge ” power amplifier.
We have eci e to use such a
component (we are not the first in
this, see Jeff Rowlan ’s Concentra
Integrate Amplifier as an example)
for its overall electrical
characteristics (high power
capability, high signal/noise ratio…),
its reliability an very goo overall
au io performance. The
“parallel/bri ge ” structure we have
use requires 4 LM3886 for each
channel an allows sharing of the
current eman e by the loa
among the 4 components. It also
allows the use of a lower power
supply voltage. In such a way we
can obtain more than 100W on an
8Ohm loa an more than 170W on a 4Ohm loa . The signal to noise ratio obtaine is very
goo : for a loa of 8Ohm with a 100W output power we have 99 B with no filter an 106 B A-
weighte (with a noise gate of 0-500KHz for both the measurements)!
4. Protections
Every sensitive part insi e the unit has been protecte to increase the reliability expecially in
respect to the temperature increasing ue to the high power capability of the pro uct. As an
example the LM3886 use in the power stage is a very reliable component (that’s one of the
reasons why we have choosen it!) protecte against shortcircuits an overcurrent an it has
two ifferent temperature protection systems: one against instantaneous overtemperature an
one against average overtemperature. We have intro uce a termal protection into the
toroi al transformer too to isconnect the primary if the temperature rises too much. An we
have even intro uce a thermost close to the power stage heathsink to etect the internal
overall temperature an isconnect the lou speakers if the temperature becomes too high,
protecting in such way all the components in the unit.
5. Mono/Pre ut
Ver i cento has a Mono/Pre Output. This means the output
can be set to be a Mono Out or a Preamplifier output. If you
set it as Mono Out you can use it to rive a passive
subwoofer. If you set it as preamp out you can use the Ver i
Cento preamp Stage to rive a Power Amplifier to realize a
“bi amplifie ” system or just to use the Ver i cento as
Preamplifier. The Mono/Pre Out is easily set changing the
position of Jumpers on the boar with the only simple but
essential recommen ation of to not o it with the unit on.

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6. Pre phono stage
Ver i cento has a pre Phono section able to treat both MC an
MM signals. You can easily set the Pre Phono Mo e changing
the position of Jumpers on the boar . We have chosen this
kin of Mo e selection because it permits you to perform the
Pre Phono settings without increasing the track’s length an it
avoi s the low level signal from the cartri ge passing through
selectors.
7. Functionality
Ver i Cento has a new set of functions that makes it very flexible. Besi es the tra itional
integrate functions it can be set in bypass mo e to work as a Power Amplifier. Moreover, you
can change the “volume scale” of the integrate amplifier to match it with your lou speaker’s
efficiency an have the best volume resolution. Four ifferent scales are available inclu ing a
1 B step scale an a scale a juste for high efficiency lou speakers! Furthermore, the Ver i
Cento has the balance function as well.
All the components use are high quality an low tolerance. The Boar that is often a
neglecte “component” has been esigne respecting all possible noise re uction techniques
especially for the current return parts an power supply traces.
8. Technical Data
103 x 448 x 405 mm
Dimensions (Nota 1) 4,0 x 17,6 x 15,9 “
12,5 Kg
Weight 27,5 Lbs
Line Gain 4,6 B
Power Amp Gain 32,5 B
Phono Gain 60 B (MM), 80 B (MC)
Line Input impedance 40KOhm
Phono Input impedance 56KOhm (MM), 100Ohm (MC)
1W @ 0.03% THD + N
10W @ 0.05% THD + N
100W @ 0.15% THD + N
Power on 8 hm load:
110W @ 0.16% THD + N
[email protected]% THD + N
Power on 4 hm load: 170[email protected]% THD + N
Frequency responce (Note 2) 150KHz
Vout: 80Vpp
Responce to a Square Signal (Note 4) Rise time: 2.8uS
106.20 dB (A weighted)
Signal Noise Ratio (Note 3) 99.30 B (No filter)
Noise level (Nota 5) -100 B
Inputs 1 Phono Input + 5 Unbalanced Input
utputs 1 tape ut + 1 Pre/Mono utput
Notes:
Nota 1 - Height x Wi th x Depth
Nota 2 - Attenuation 0 B, -3 B ban
Nota 3 - Attenuation: 0 B A weighte reffere to 8 Ohm loa nominal power
Nota 4 - 8 Ohm loa nominal power
Nota 5 - Ban limits 0Hz-40kHz