April Music Stello AI300 User manual

Owner’s Manual
Stello AI300
INTEGRATED AMPLIFIER
April Music, Inc.

INTRODUCTION
Thank you for choosing the Stello AI300 from April Music.
The AI300 is one of the finest integrated amplifiers available on the market today. It will give the true meaning
to the reproduction of recorded music with high fidelity and musicality.
Natural reproduction of recorded music is not only an elegant way to describe our product, it is a feeling that
captures your full attention from the very first moment you experience the Stello integrated amplifier. You can
feel the subtlety and nuances of the inner details, the lightness of touch within the music which you can only
feel at the concert hall.
The AI300 delivers 150Watts per channel and will power with an extreme ease most of the loudspeaker
systems designed for home audio applications, even those that are very demanding. Your amazement will
also be triggered by an extremely quick transient response where every small micro dynamic signal is
distinctively there!
We designed the AI300 with some very interesting features.
yThe PREAMPLIFIER OUTPUT, for example, allows the use of an independent external amplifier to
be coupled with the preamplifier section of the AI300.
yThe BYPASS input is also prepared to support AI300 as a main power amplifier when used with a
surround processor.
yThe CS3310-based volume control is a very high-end volume control logic which is not usual with
products in such an affordable price range. A 120 steps volume control allows the user to set the
volume with an extreme accuracy.
yThe Remote Control Unit has been designed to operate both Stello products, the AI300 and
CDA200. It is machined in a solid bock of aluminum.
yThe AI300 is fully protected through sophisticated circuits to ensure many years of impeccable and
flawless a non-stop operation.
Stello AI300
1

CAUTION
yThe AI300 is designed to operate at the following voltages; 100, 120, 220, 230V.
The chart below provides the necessary information for the line voltage if needed.
Note: this work must be accomplished by a qualified technician only.
yThe AI300 ‘Mains’ power switch is located on the rear panel. The ‘STANDBY’ switch is located on
the front panel. During a normal daily operation use only the ‘STANDBY’ switch leaving the Mains
switch in the ‘On’ position. The amount of current draw in the standby mode is very small while the
internal circuitry is maintained at an optimal operating temperature. It is, however, recommended to
turn the Mains switch ‘Off’ or unplug the AC power lead when you plan to leave the house for a
prolonged period of time.
yIt is important to maintain proper ventilation around the AI300. Do not put other devices over the
AI300. Improper heat dissipation from and around the AI300 could cause overheating related
problems.
yDo not open the chassis without prior authorization from the manufacturer or from a certified Stello
agent. Do not open the chassis unless you are qualified to do so. Unauthorized repair or tempering
of any type will void the manufacturer’s warranty.
VIEW FROM INSIDE
230V 220V 120V 100V 100V 120V 220V 230V
Yellow Yellow None None None None White White
Blue Brown Blue Brown Yellow Yellow Grey Grey
None None White Red Grey Grey None None
Brown Blue Brown Blue White Red Red Red
Stello AI300
2

FEATURES
Preamplifier Section
of the AI300 makes upgrade and service maintenance a mere formality. This single
feature alone is your long term insurance against built in obsolescence.
he volume control stage is done domain to preserve the quality and integrity of the sound signal using
Cirrus Logic CS3310 integrated circuit.
The following featured circuits and devices are used in the preamplifier section of AI300. All channels are
yMixed design with two pairs of junction FET (J-FET) and two pairs of bipolar transistor on the
tage.
yIndividual and separated Power Supply Section
Power Amplifier Section
The AI300 is transistors for each channel of the power amplifier section. The main
circuit is s maximum quality of sound reproduction and integral
musicality v rve the integrity of the signal and the genuine
playback from he sources used.
nputs.
yProprietary feed-back circuit on the power transistors for an improved base extension and
Main Signal
The main n
The use of OP ictly prohibited at this level.
DC Coupled Signal Path
Connection
l Power Amp)
The modular design
T
dual monaural and individual modules are used for left and right channels respectively.
input differential circuit.
yClass Apush-pull output s
using four bipolar power
de igned to preserve and maintain the
. A ariety of support circuitries are provided to prese
t
yJunction FET i
control.
yPush-pull designed parallel output circuit with SANKEN package type MT-200 power
transistors
Path
sig al path uses exclusively discrete components for an optimal performance.
Amps is str
Preamp Output for Bi-amping or Sub-woofer Application
BYPASS Function input for Surround Processor
(Activated as a 2 Channe
Stello AI300
3

CONNECTION
1. AI300 Integrated Amplifier
The AI300 is equipped with five ‘Unbalanced’ inputs (RCA) and one ‘Balanced’ input (XLR).
For optimal results we recommend to use of the ‘Balanced’ connection whenever the source component is
equipped with a ‘Balanced’ output.
AL-IN
onnection for ‘Balanced’ audio cables between the AI300 and the sources material (for example, the
onnection for tuners for FM/AM broadcasting station
General Connection
B
C
CDA200 CD player)
TUNER
C
Stello AI300
4

AUX1, 2
Connection from Video or TV outputs
ck
put for recording
ection from the main left and right outputs of
e surround processor to this input. This function is activated when pressing the BYPASS button on the
ol handset or directly on the front panel.
r.
onnection for the loudspeaker cables between the amplifiers and loudspeaker system. The loudspeaker
ld be connected to prevent any contact between the plus (+) and minus (-). The plus (+) and
n for the cable, you should follow the recommendations from the
able manufacturer.
TAPE IN
Connection from a cassette tape deck output for playba
TAPE OUT
Connection from cassette tape deck in
BYPASS
This input is used for a multi-channel surround processor. Conn
th
remote contr
The AI300 is then working as a fixed input power amplifie
PRE OUT
This is for preamplifier output. This output of the AI300 can be used for bi-amplification or for a sub-woofer
application (Refer to chapter 2 for details).
SPEAKER OUTPUTS
C
cables shou
minus (-) of the amplifier should respectively connect to the plus (+) and the minus (-) of the loudspeaker
system. If there is a suggested flow directio
c
Stello AI300
5

BYPASS
The AI300 used as a Power Amplifier
yThe AI300 can be activated as a pure power amplifier by pressing the BYPASS button from the
remote control handset or directly from the front panel. In this mode an external preamplifier,
transistor or tube, will be required.
yTo return to normal integrated amplifier mode, just press the BYPASS button again.
Stello AI300
6

Surround Processor Connection
yTo make this connection configuration possible the surround processor should have its own
volume control.
yThe volume control should be done at the surround processor side.
Cassette tape recorder connection
Stello AI300
7

2. Using the AI300 as a Preamplifier
Connection to an external power amplifier
yDisconnect the loudspeaker cables from the AI300
yConnect the PRE OUT of theAI300 to the MAIN IN of the external power amplifier.
Stello AI300
8

Using a self power Subwoofer system
This option will be useful when using a small or medium size loudspeaker system as the main loudspeakers
and using the PRE OUT to connect to a self powered subwoofer for an improved bass extension.
yInstall an interconnect cable between the PRE OUT of the AI300 and the MAIN IN of the
subwoofer controller/amplifier.
yThe following functions, volume, cut-off frequency, phase, etc. should be calibrated directly on the
subwoofer controller/amplifier panel. Please refer to subwoofer manual for operation.
Stello AI300
9

OPERATION
1. Front panel functions
STAN
urning ‘on’ the ‘Mains’ power switch located on the rear panel will activate the amplifier to display APRIL
IC STELLO AI300. Moments later the display will change to the default position showing ‘CD 00.0’.
yThe source selection is accomplished by pressing the INPUT button.
yThe volume level is controlled by pressing the VOL UP and VOL DOWN buttons.
yTo turn off the unit press the STANDBY button. This will switch the amplifier mode to standby.
While in standby a small amount of current flows through the amplifier circuitry to maintain an
optimal operating temperature. In the standby mode the last settings, source and volume level, are
memorized. When pressing the STANDBY button again the display will show the previous source
and volume level settings.
INPUT
yThe initial Power-On mode showing on the display is ‘CD 00.0’. (For example, selected input ‘CD’
yINPUT button selection loop
BAL_IN ÆCD ÆTUNER ÆAUX1 ÆAUX2 ÆTAPE ÆBAL_IN
INPUT BYPASS MUTE DOWN UP
-VOL--
INTEGRATED AMPLIFIER
STANDBY
DBY
T
MUS
volume level 00.0)
YPASS
Refer to ‘BYPASS’ in the chapter ‘Connection’
B
Stello AI300
10

MUTE
ess the MUTE button once to temporarily turn off the music
VOL UP /
s.
yPr
The display will show ‘MUTE’ and no signal will come out from the amplifier.
yTo resume play press the MUTE button again or the VOL UP or VOL DOWN button
VOL DOWN
yThe volume control ranges from 0 to 60 in increments of 0.5 for a total of 120 step
yPress the VOL UP or VOL DOWN button to set the volume level
Stello AI300
11

2. Remote Control Handset
Remote control Handset
yThe remote control handset can control both the Stello CDA200 CD
player and AI300 integrated amplifier.
yCD Players using the RC-5 code like the Stello CDA200 can be
controlled by this remote control unit.
Battery Replacement Procedure
yUsing the suppliedAllen Key Wrench.
Remove the back cover on the remote control handset
yInstall two triple A size batteries following proper polarity
yTest the remote control handset for proper operation
yInstall the back cover
Note: It is strongly recommended to use Alkaline batteries for an extended operation
PREAMP
of the remote control handset but more important to prevent any chemical leakage.
Stello AI300
12

SPECIFICATIONS
Signal to Noise 10-20 kHz, -100dB
Total Harmon
uency Resp 10-35 kHz, +-3dB
Power Output 150W/CH at 8 Ohms
250W/CH
Mains Power Requirement 100/120/230±10% VAC, Selectable
Maximum Power Consumption 500 WATTS
ignal Outputs RCA/REC OUTPUT, 1 PAIR
PREAMP OUTPUT, 1 PAIR
Signal Inputs RCA/UNBALANCED, 5 PAIR
XLR/BALANCED, 1 PAIR
RCA/BYPASS, 1 PAIR
Dimension (WHD) 435 x 94.5 x 345mm
Weight 12.5Kg
Front Panel / Remote Control Function
Standby
Input (CD. TUNER, AUX1, AUX2, TAPE, BALANCED INPUT)
Bypass
Mute
Volume Up – Volume Down (120 Steps)
Display Brightness Control, 4 Levels
Input Sensitivity 0.56V, 150W/8 Ohms
ic Distortion 0.005%, at 30W, 8 Ohms
Freq onse
at 4 Ohms
S
Stello AI300
13

INTERNATIONAL LIMITED WARRANTY
The warranty service is valid only when purchased from an authorized dealer. A valid proof of purchase must
rranty services rk, modification or service rendered on the player
a ty.
ears
be supplied for all wa . Any unauthorized wo
will void the warr n
Warranty Period 2 y
Date of Purchase
Authorized Stello Dealer
Telephone
Serial No.
Autho ed Stello Service Centerriz
APRIL MUSIC, INC
www.aprilmusic.com
Stello AI300
14