April Music Stello AI 320 User manual

Thank you for choosing the Stello AI:320 from April Music.
The AI:320 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.
Although the 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 AI:320 delivers 140Watts 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!
INTRODUCTION
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We designed the AI:320 with some very interesting features
The PREAMPLIFIER OUTPUT, for example, allows the use of an
independent external amplifier to be coupled with the preamplifier section
of the AI:320.
The BYPASS input is also prepared to support AI:320 as a main power
amplifier when used with a surround processor.
The 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.
The Remote Control Unit has been designed to operate both Stello
products, the AI:320 and CDA320. It is machined in a solid block of
aluminum.
AI 320 INTEGRATED AMPLIFIER

The AI:320 is designed to operate at the following voltages; 100, 117, 220, 230(240)V.
The chart below provides the necessary information for the line voltage if needed.
Note: this work must be accomplished by a qualified technician only.
The AI:320 '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.
It is important to maintain proper ventilation around the AI:320. Do not put other devices
over the AI:320. Improper heat dissipation from and around the AI:320 could cause
overheating related problems.
Do 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.
CAUTION
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AI 320 INTEGRATED AMPLIFIER
220V
117V
100V
100V
117V
220V
230/240V
Yellow
Yellow
None
None
None
None
White
White
Blue
B
rown
Blue
Brown
Yellow
Yellow
Grey
Grey
None
None
White
Red
Grey
Grey
None
None
Brown
Blue
Brown
Blue
White
Red
Red
Red
VIEW FROM INSIDE
230/240V

Preamplifier Section
The modular design of the AI:320 makes upgrade and service maintenance a mere
formality. This single feature alone is your long term insurance against built in obsolescence.
The 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 AI;320. All
channels are dual monaural and individual modules are used for left and right channels
respectively.
Mixed design with two pairs of junction FET (J-FET) and two pairs of bipolar
transistors on the input differential circuit.
Class A push-pull output stage.
Individual and separated Power Supply Section.
Power Amplifier Section
The AI:320 is using four bipolar power transistors for each channel of the power amplifier
section. The main circuit is designed to preserve and maintain the maximum quality of
sound reproduction and integral musicality. A variety of support circuitries are provided to
preserve the integrity of the signal and the genuine playback from the sources used.
Junction FET inputs.
Proprietary feed-back circuit on the power transistors for an improved base
extension and control.
Push-pull designed parallel output circuit with SANKEN package type MT-200
power transistors.
Main Signal Path
The main signal path uses exclusively discrete components for an optimal performance.
The use of OP Amps is strictly prohibited at this level.
DC Coupled Signal Path
Preamp Output for Bi-amping or Sub-woofer Application
BYPASS Function input for Surround Processor Connection
(Activated as a 2 Channel Power Amp)
FEATURES
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AI 320 INTEGRATED AMPLIFIER

CONNECTION
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AI 320 INTEGRATED AMPLIFIER
The AI:320 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.
BAL-IN
Connection for 'Balanced' audio cables between the AI:320 and the sources material (for
example, the CDA320 CD player)
TUNER
Connection for tuners for FM/AM broadcasting station
AUX
Connection from Video or TV outputs
TAPE IN
Connection from a cassette tape deck output for playback
TAPE OUT
Connection from cassette tape deck input for recording
1. AI 320 Integrated Amplifier
General Connection
+ -
+ -
HI-FI
AUDIO OUT AUDIO IN
MONITOR
OUT
93.1
CD PLAYER TUNER VCR TV

CONNECTION
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AI 320 INTEGRATED AMPLIFIER
BYPASS
This input is used for a multi-channel surround processor. Connection from the main left and
right outputs of the surround processor to this input. This function is activated when pressing
the BYPASS button on the remote control handset or directly on the front panel.
The AI:320 is then working as a fixed input power amplifier.
PRE OUT
This is for preamplifier output. This output of the AI:320 can be used for bi-amplification or
for a sub-woofer application (Refer to chapter 2 for details).
SPEAKER OUTPUTS
Connection for the loudspeaker cables between the amplifiers and loudspeaker system. The
loudspeaker cables should be connected to prevent any contact between the plus (+) and
minus (-). The plus (+) and minus (-) of the amplifier should respectively connect to the plus
(+) and the minus (-) of the loudspeaker system. If there is a suggested flow direction for the
cable, you should follow the recommendations from the cable manufacturer.
BYPASS
The AI 320 used as a Power Amplifier
The AI:320 can be activated as a pure power amplifier by pressing the BYPASS
fbutton from the remote control handset or directly from the front panel. In this mode
ean external preamplifier, transistor or tube, will be required.
?To return to normal integrated amplifier mode, just press the BYPASS button again.
+ -
+ -
PRE OUT
PREAMPLIFIER

CONNECTION
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AI 320 INTEGRATED AMPLIFIER
Surround Processor Connection
?To make this connection configuration possible the surround processor should have
iits own volume control.
? The volume control should be done at the surround processor side.
Cassette tape recorder connection
+ -
+ -
3 CHANNEL AMP
SUBWOOFER
(POWERED)
L R C SL SR SUB
MAIN
+ -
+ -
CASSETTE DECK
MONITOR
OUT REC IN
SURROUND PROCESSOR

CONNECTION
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AI 320 INTEGRATED AMPLIFIER
2. Using the AI 320 as a Preamplifier
Connection to an external power amplifier
Disconnect the loudspeaker cables from the AI:320 or press 'SPK OFF' button
on the remote control handset.
Connect the PRE OUT of the AI 320 to the MAIN IN of the external power amplifier.
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.
Install an interconnect cable between the PRE OUT of the AI:320 and the MAIN IN of
the subwoofer controller/amplifier.
The 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.
+ -
+ -
MAIN IN
+ -
+ -
MAIN IN
SUBWOOFER CONTROLLER
POWERED SUBWOOFER
MAIN
LEFT
SPEAKER
MAIN
RIGHT
SPEAKER
CONNECTION
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AI 320 INTEGRATED AMPLIFIER
2. Using the AI 320 as a Preamplifier
Connection to an external power amplifier
Disconnect the loudspeaker cables from the AI:320 or press 'SPK OFF' button
on the remote control handset.
Connect the PRE OUT of the AI 320 to the MAIN IN of the external power amplifier.
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.
Install an interconnect cable between the PRE OUT of the AI:320 and the MAIN IN of
the subwoofer controller/amplifier.
The 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.
+ -
+ -
MAIN IN
+ -
+ -
MAIN IN
SUBWOOFER CONTROLLER
POWERED SUBWOOFER
MAIN
LEFT
SPEAKER
MAIN
RIGHT
SPEAKER
POWER AMPLIFIER

OPERATION
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AI 320 INTEGRATED AMPLIFIER
STANDBY
Turning 'on' the 'Mains' power switch located on the rear panel will activate the amplifier to
display APRIL MUSIC STELLO AI:320. Moments later the display will change to the default
position showing 'CD 00.0'.
The source selection is accomplished by pressing the INPUT button.
The volume level is controlled by pressing the VOL UP and VOL DOWN buttons.
To 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
The initial Power-On mode showing on the display is 'CD 00.0'. (For example,
s selected input 'CD' volume level 00.0)
INPUT button selection loop
CD - TUNER - AUX - TAPE - BAL_IN
BYPASS
Refer to 'BYPASS' in the chapter 'Connection'
MUTE
Press the MUTE button once to temporarily turn off the music.
The display will show 'MUTE' and no signal will come out from the amplifier.
To resume play press the MUTE button again or the VOL UP or VOL DOWN button
VOL UP / VOL DOWN
The volume control ranges from 0 to 60 in increments of 0.5 for a total of 120 steps.
Press the VOL UP or VOL DOWN button to set the volume level.
1. Front panel functions

OPERATION
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AI 320 INTEGRATED AMPLIFIER
The remote control handset can control both the Stello
CDA320 CD player and AI:320 integrated amplifier.
CD Players using the RC-5 code like the Stello
CDA320 can be controlled by this remote control unit.
Using the supplied Allen Key Wrench, remove the
back cover on the remote control handset.
Install two triple A size batteries following proper
polarity.
Test the remote control handset for proper operation.
Install the back cover.
2. Remote Control Handset
Battery Replacement Procedure
Remote control Handset
Note: It is strongly recommended to use Alkaline batteries for an extended operation
of the remote control handset but more important to prevent any chemical leakage.

SPECIFICATIONS
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AI 320 INTEGRATED AMPLIFIER
Warranty Period
2 years
Date of Purchase
Authorized Stello Dealer
Telephone
Serial No.
Authorized Stello Service Center
INPUT SENSITIVITY: 0.56V, 140W / 8 Ohms
SIGNAL TO NOISE: 10-20 kHz, -100dB
THD: 0.005%, at 30W, 8Ohms
FERQUENCY RESPONSE: 10- 35kHz, +-3dB
POWER OUTPUT: 140W/CH a t 8 Ohms
MAXIMUM POWER CONSUMPT ION: 500 WATTS
SIGNAL OUTPUTS: 1 RCA/R EC Output
: 1 PREAMP Output
SIGNAL INPUTS: 4 RCA/Unbalanced
: 1 XLR/Balanced
:1 RCA/B ypass
Front Panel/Rem ote Controller Switches
STANDBY
INPUT(CD,TUNER,AUX,TAPE,Ba lanced Input)
BYPASS
MUTE
SPK OFF
VOLUME UP/DOWN (120 Steps)
DISPLAY/ 4 Steps Brightness Control
POWER REQUIREMENTS : 100/117/220/230V(240V ), 50 or 60HZ
DIMMENSION: 435 (W ) X 105 (H ) X 415 (D ) mm
WEIGHT: 16 Kg
All specifications are subject to improvement without further notice