Audio Research SP20 Manuale utente
User Guide
H I G H D E F I N I T I O N ®
SP20
Stereo Preamplifier
2Contents
Preface 3
Illustrations 4
Warnings 5
Installation
Installation of Vacuum Tubes 6
In Your System 7
Connections 8
Operation
Power-Up Procedure 9
Front Panel Controls 10
Remote Control Only Controls 11
Interactive Touch Screen Operation 12 - 17
Troubleshooting 18
Maintenance
Servicing 19
Cleaning 19
Disposal and Recycling Guidelines 19
Limited Warranty 20
Specications 21
3
Thank you for selecting the SP20 as part of your music
listening system. The engineers and designers at Audio
Research have spent countless hours of listening and
testing to create a preamplier of the highest caliber for
music reproduction. The SP20 has been designed to
provide you many years of playback.
Please take a few minutes to read through this guide
to help you better understand and optimize your new
preamplier. If you have any questions regarding the
operational functions, contact your dealer or distributor
for assistance.
Sit back and enjoy your new preamplier and the
enhancements it will bring to your system. The SP20 will
bring new life to your entire music collection.
Happy listening!
Preface
4
Front Panel
VOLUME
POWER MUTE
SOURCE
PHONES
SP20 VACUUM TUBE STEREO PREAMPLIFIER HIGH DEFINITION ®SPKR OFF
WARNING
TO PREVENT FIRE AND SHOCK HAZARD, DO NOT
EXPOSE THIS DEVICE TO RAIN OR MOISTURE.
UNIT MUST BE OPERATED IN A HORIZONTAL POSITION.
-DO NOT OPERATE WITH COVERS REMOVED-
UNIT CONTAINS VOLTAGES WHICH MAY BE HAZARDOUS.
+12V REMOTE
TRIGGER
(30mA max)
~
VOLTS
SERIAL
RS-232
IR INPUT
30W MAX
50/60HZ
CAUTION
FOR CONTINUED PROTECTION AGAINST
FIRE HAZARD REPLACE FUSE ONLY
WITH SAME TYPE AND RATING
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
!
STEREO PREAMPLIFIER
PLYMOUTH, MINNESOTA
MADE IN U.S.A.
MODEL SP20
GROUND
SE1PHONO
1.5 A FUSE
SLO-BLO
T630MA
(230V)
SE3SE2 MAIN 2 MAIN 3
RECORD MAIN 1
LEFT INPUTS
RIGHT INPUTS
LEFT OUTPUTS
RIGHT OUTPUTS
SE4 BAL1 BAL2
MONITOR
Illustrations
Back Panel
Remote
MONO
SP20
LOAD SPKR OFF
POWER
BAL L BAL R
MUTE
HOURS
PHONO
SE1 SE2
SE4 BAL1 BAL2
VOL DN VOL UP
SE3
DSP DN
INVERT
DSP UPMON
H I G H D E F I N I T I O N ®
5
Warnings
To prevent re, or shock hazard, do not expose your SP20 to rain or
moisture. Do not place containers with liquid on top of unit.
This unit contains voltages which can cause serious injury or death. Do
not operate with cover removed. Refer servicing to your authorized Audio
Research dealer or other qualied personnel.
The detachable power cord on your SP20 is equipped with a heavy gauge,
3-conductor cable and a standard three-prong grounding plug. For
absolute protection, do not defeat the ground power plug. This provides
power line grounding of the SP20 chassis to provide absolute protection
from electrical shock.
For continued protection against re hazard, replace the fuse only with the
same type and rating as specied at the fuse holder.
The appliance coupler at the rear of this unit must be accessible for
emergency power disconnect.
A note about packaging...
Save all packaging in a dry place away from re hazard. Your SP20 preamplier
is a precision electronic instrument and should be properly cartoned any
time shipment is made. You may not have occasion to return your unit to
the factory for service, but if that should prove necessary, or other occasion
requiring shipment occurs, the original packaging will protect your SP20
from unnecessary damage or delay.
6Installation
Installation of Vacuum Tubes
Before operating the SP20...
This unit has been shipped with the vacuum tubes installed in protective
foam in a separate box packed inside the shipping carton. Remove the
tubes carefully from the protective foam. Using a phillips-head screwdriver
to loosen the fastening screws, remove the top cover and set aside.
After removing the top cover and the vacuum tubes packed in protective
foam, see the accompanying illustrated sheet for instructions on installing
the tubes for your SP20 in their proper locations in the power supply and
audio chassis. Note that the numbers written on each tube correspond to
a ‘V’ number printed on the circuit board next to each tube socket. Insert
each tube rmly, carefully aligning the tube pins with the corresponding
socket holes.
Line
Stage
Phono
Stage
V1
V3
V2
V4
CHANNEL
R L
7
Installation
In your System
While the SP20 does not dissipate an unusual amount of heat, it is important
that it be provided with reasonable airow to assure long, trouble-free
operation. In addition, the following installation guidelines will help insure
maximum sonic performance as well as reliable service:
Operate unit in upright and horizontal position, preferably on solid, non-
metal shelving.
Do not stack the preamp on top of a power amplier: not only could this
cause overheating, but hum may be introduced into the preamp from the
proximity of the amplier’s power transformer.
Do not stack components or other objects directly on top of the SP20.
Do not place or operate your preamp on a soft or irregular surface such as
a rug. This will prevent proper ventilation.
Do not operate your preamp without the top and bottom covers installed.
These are required both for safety as well as shielding from interference
(except in service operations by qualied personnel).
Ensure a minimum of 8-10” clearance above the unit when placed on
shelving.
8Connections
Analog Connections
Input Connectors: The SP20 provides ve pairs of single-ended input
connectors: SE1 - 4, PHONO and MONITOR. Please note that input SE4
can be selected as a unity gain input; in this case, SE4 should only be
connected to a component with a volume control (such as a home theater
processor). For further information about the SE4 unity gain (PROC mode),
see the section ‘PROC Mode’ on page 16. In addition, there are two pairs
of balanced input connectors: BAL1 and BAL2.
Never connect a source with a xed level output (DVD player, tuner, CD
player, etc.) to the unity gain input. This could cause serious damage to the
ampliers or speakers in your system.
Output Connectors: Two pairs of balanced and one pair of single-ended
main outputs are provided.
Record Output: The tape outputs should be connected to your recorder’s
‘Record’ or ‘Line’ inputs. These outputs provide a xed-level two-channel
signal (L, R) to your recorder from whichever input is selected. The xed
output level will be the same as the output of the selected source.
It is possible to dub or copy from one recorder to another by connecting the
output of the source recorder to an unused set of stereo inputs (e.g. SE2 or
BAL1). The signal will then be routed to the Record Out connectors when
that input source is selected.
RS-232 Connection: The RS-232 connection allows for remote control via
systems such as Creston or other automation systems.
IR Input: The IR input can be used to link the SP20 to an IR repeater
system with a standard mono 1/8” connector.
12V Trigger Jack: The +12V DC output connector provides the ability to
remotely turn on and off other linked components such as power ampliers
having similar capabilities.
9
Operation
Power-Up Procedure
• Secure all rear-panel connections between SP20, power amplier(s) and
input sources.
• Plug three-prong power cord from rear of chassis into grounded A.C. wall
outlet. The Power switch defaults to ’off’ when the unit is plugged into a
power receptacle.
• Press power switch (either on the remote or front panel). The screen will
begin the warm-up sequence, rst displaying the Audio Research logo,
followed by SP20 and a series of dots (g. 1 + 2). The home screen will
then appear, and the unit will be muted. Depress the front panel MUTE
button (right button) or the Mute button on the remote to initiate normal
operation.
• Select input source and adjust the volume as necessary.
Shut-Down
• Activate ‘Mute’ function.
• Set Volume level to 0.
• Turn off power amplier(s).
• Press Power switch to ‘off’.
• Turn off input sources.
g. 1 g. 2
10 Operation
Front Panel Controls
The SP20 has two microprocessor-driven rotary controls and three buttons
(Power, Mute and Speaker Off).
Left Rotary control (Input Select): Select input by rotating the control to
the left or right. The screen displays the current input by factory-set and
user-denable name at the top right.
Right Rotary control (Volume): Adjust volume (output level) up or down for
both L and R channels. Volume control is also selectable via Vol UP and Vol
DN buttons on the remote control. Volume adjustment is indicated in the
display window by numeric digits on 0–103 scale.
Do not turn volume up beyond normal listening levels when ‘mute’ is
engaged to avoid unexpected or possibly damaging sound levels. Reduce
volume level whenever changing input sources, even when muted.
Power On/Off: Supplies power from A.C. wall outlet to preamp; indicated
by active display window. The SP20 requires approximately 30 seconds to
warm up; this time is required to stabilize the power supply. See ‘Power-Up
Procedure’ on the adjacent page for details.
Mute: When activated, electrically mutes all output of the preamplier;
indicated by ‘Mute’ in display window. This control should be activated
before switching inputs, changing connections or shutting down your audio
system to help protect your amplier and speakers from unexpected signal
pulses. When deactivated, ‘Mute’ disappears from the display window
allowing normal operation.
The SP20 also has automatic muting to help protect system components
in the event of low line voltage. When sensing low line voltage, the preamp
displays ‘Low Line’ and automatically goes into ‘Mute’. This condition will
persist until the line voltage returns to a safe operating level; please note the
unit will remain in ‘Mute’ even after ‘Low Line’ no longer appears.
Note that automatic muting is only designed to protect against power line
interruptions or severe voltage drop. It will not mute in the event of subsonic
transmissions from a faulty input source, amplier failure or speaker
malfunction.
Spkr Off: Toggles between the main outputs on the back of the unit and the
headphone jack mounted adjacent to the Speaker Off button.
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