Audio Research SP-5 User manual

REV. B
10/78
MODEL SP-5 PREAMPLIFIER
INSTRUCTION MANUAL
audio research
H I G H D E F I N I T I O N®
5740 GREEN CI RCLE DRIVE/ MINNETONKA, MINN ES OTA 55343 - 44 24
PHONE 612/939 - 0600 FAX 612/939 - 0604

INTRODUCTION
Congratulations on your purchase. The SP-5 stereo preamplifier was conceived
and designed for audio perfectionists.
11
Analog Module" circuitry provides
unequaled performance under actual dynamic listening conditions.
In addition to the basic audiophile features, the SP-5 has: provisions for
an optional (*) low level head amp, controlled turn-on characteristics for
mi nimimum output
11
thump
11
, 1600 watt relay contra 11 ed power outlets, high
quality anodized aluminum panels, knobs, and handles, and a scuff-resistant
chassis finish. Conservative design and extensive use of high quality
industrial grade components insure many years of trouble-free performance.
WARRANTY
A limited 90-Day Warranty (from the date of purchase by the original purchaser)
is provided by Audio Research Corporation. This warranty is subject to the
conditions and limitations stated within the documents attached to the outer
shipping carton.
LIMITED 3-YEAR WARRANTY
A 3-Year Limited Warranty Application is included with the documents attached
to the outer shipping carton.
THIS LIMITED 3-YEAR WARRANTY WILL NOT BE ISSUED OR EFFECTIVE UNLESS WITHIN
THIRTY DAYS AFTER THE DATE OF SALE THE PURCHASER MAILS TO AUDIO RESEARCH A
LIMITED 3-YEAR WARRANTY APPLICATION FORM WHICH HAS BEEN COMPLETED, DATED AND
SIGNED BY BOTH THE SELLING DEALER AND THE PURCHASER AND A COPY OF THE BILL OF
SALE OR OTHER PROOF OF PURCHASE OF THE PRODUCT.
WARNING - FAILURE TO COMPLY WITH THE ABOVE CONDITIONS WILL RESULT IN THE
WARRANTY BEING RESTRICTED TO THE LIMITED 90-DAY WARRANTY.
PACKAGING
Save All The Packaging - Your Audio Research component is a prec1s1on electronic
instrument and should be properly cartoned any time shipment is made. You may
never have occasion to return it to the factory for service, but if such should
be necessary, or other occasion to ship it occurs, the original packaging may
save your investment from unnecessary damage or delay.
-1 -

ACCESSORIES
The following optional (*) accessories for your SP -5 preamplifier will be
made available through your Audio Research dealer:
* Walnut veneered oiled finish cabinet
* Programable low level head amp electronics
LINE VOLTAGE CONVERSION
This equipment can be operated from either 120 Volts or 240 Volts A.C.,
50/60 Hz. Check the position of the line voltage selector switch on the rear
panel. If necessary, remove the switch safety cover and set the switch to
the proper voltage as indicated below the switch. Secure the switch position
with the safety cover and screws with the word
11
fuse
11
showing. Ins ta 11 the
appropriate fuse as indicated below if the line voltage is different than that
set for at the factory.
WARNING
Voltage
120
240
Fuse
1/4 Amp. Type 3AG or MDL Slo-Blo
1/8 Amp. Type 3AG or MDL Slo-Blo
To prevent fire or shock hazard, do not expose this equipment to rain or
moisture.
This unit contains voltages which may be lethal. Do not operate this unit
with covers removed. Refer servicing to qualified personnel.
CAUTION
For continued protection against fire hazard, replace only with same type
and rating fuse .
-2-

Jl J3 JS
J7
J9 J11
J13
J15
J17 on
OT2
OT3
l= l I I
L1=LL
@1
RIGHT INPUTS r
RIGHT OUTPUTS 1
.... ~
(@ (@
(@ (@ (@ (@ (@ (@ (@
PREAMPLIFIER
. @ MODEL BP · l!S @
0
~
15 WATTS .
~
so .s o Hr
I @
(@ @ @ @ @ (@ (@ @
.,o,o '"""" ,o,.o,., ,o, CA UTION ,o,oo"''""'o 0
MINNEAPO LI S. MINNESOTA. U.S. A. PAOTICTION AO AJNST FIA E @
@I
~:~~ .. T~:l~~c: ... ~~~~ rJ~~ •
LEFT INPUTS L LEFT OUTPUTS
..J
l! AIAL NUMIIEA -- @ S L0 ,8l0
! 11
J2 J4 J6 JS Jl0 Jl2 J14 J16 J18
Fl
S5
REAR PANEL LAYOUT
REAR PANEL FUNCTIONS
Refer to the
11
Rear Panel Layout" diagram above.
Audio Inputs:
Jl - Head Amp* (optional), Right Channel
J2 - Head Amp* (optional), Left Channel
Provision for
11
optional
11
Head Amp electronics have been made within the
SP-5 directly behind the Head Amp input connectors. These inputs and
associated electronics will be required only for low output moving coil
transducers. Consult your dealer for information and use of this special
input feature. These inputs are not connected internally at the factory
and are not used in systems employing moderate or high output magnetic
cartridges.
J3 - Phono, Right Channel
J4 - Phono, Left Channel
Connect to tone arm /car tridge or record player. Nominal input impedance is
47K ohms and 200 PF shunt. Use with magnetic type cartridges requiring RIAA
playback compensation. Note: Normally connect grounding wire from record
player or arm to the
11
Ground Terminal
11
screw located next to and between
Jl and J2. With certain systems this may add hum in which case no ground
wire is required.
Note: The input characteristics and gain of the SP-5 have been factory set
to accommodate most of the high quality magnetic cartridges on ·the market
today. However, the SP-5 phono section can be altered by a technician for
different (gain), input resistance (R), and capacitance (C) , shown in the
schematic di a gram at the back of the manua 1. This feature a 11 ows ''matchi ng
11
of various cartridges to the magnetic preamp section for optimum performance.
Consult your dealer for further information and use of this special input
feature.
JS -Tape, Right Channel
J6 -Tape, Left Channel
High level inputs. Connect to tape recorder line outputs. Nominal input
impedance is 47K in the
11
stereo
11
or
11
reverse
11
mode , 30K in the "l eft " or
11
right" mode, and 20K in the "mono" mode. The input impedance is shunted
by any load connected to the tape outputs Jl5 and Jl6 .
-3-

J7 - Tuner , Right Channel
J8 -Tuner, Left Channel
High level inputs. Connect to the output of an AM and/or FM tuner component.
Nominal input impedance is 47K in the
11
stereo
11
or
11
reverse
11
mode, 30K in the
11
left
11
or
11
right
11
mode, and 20K in the
11
mono
11
mode. The input impedance is
shunted by any load connected to the tape outputs J15 and Jl6 ,
J9 - Aux. 1, Right Channel
JlO - Aux. 1, Left Channel
Provides high level inputs for any auxiliary system component . Nominal input
impedance is the same as the "tuner" inputs J7 and J8 above.
Jll -Aux.2, Right Channel
J12 -Aux.2, Left Channel
Same as above. Allows use of a second auxiliary component.
Jl3 -Monitor, Right Channel
J14 -Monitor, Left Channel
High level inputs. Connect to tape monitor or main outputs of tape recorder
if tape monitoring feature is desired. Permits tape monitoring during
recording from front panel toggle switch (S2). If tape playback only is
required, connect the tape recorder outputs to the tape inputs (JS and J6)
which will instead be selected by "source" switch (S4).
Audio Outputs:
J15 -Tape, Right Channel
Jl6 -Tape, Left Channel
Connect to tape recorder line inputs. Provides a program source for tape
recording. Output signal is independent of "volume" control setting and
equal to the source input level, i .e.
11
tape
11
,
11
tuner
11
,
11
aux . l
11
,
11
aux . 2
11
,
or magnetic phono preamplifier output. Nominal output impedance is 50 ohms
plus the output impedance of the selected source. In general. the load
impedance should be greater than 20K for optimum performance.
J17 - Main, Right Channel
J18 - Main, Left Channel
Connect to power amplifier (or electronic crossover) inputs. Nominal output
impedance is 50 ohms. In general, the load impedance should be greater than
lOK for optimum performance. The outputs are AC coupled through a 5 MF
capacitor.
-4-

Power Circuits:
OTl -Switched AC Convenience Outlet
OT2 -Switched AC Convenience Outlet
OT3 -Switched AC Convenience Outlet
Connect to system components {power amplifier(s), tuner(s), electronic
crossover, etc.) that are to be turned on by the front panel power
switch (Sl). Will accept 2 or 3 prong line plugs. Outlets are switched
by an internal power relay. Capacity is 1600 watts total including the
unswitched outlet (OT4) . The outlets are not fuse protected.
Note: An internal .01 MF/1600 Vcapacitor is connected (for arc
suppression) across the internal power relay contacts . If an Audio
Research RPR-1 (Remote Power Receptacle) is used in the system to
remotely turn on the power amplifier(s), the .01 MF capacitor must be
removed . The small 60 Hz current passed by the capacitor is sufficient
to turn- on the RPR -1 transmitter electronics continuously even with the
SP-5 power switch (Sl) off .
Since relay contact arcing is not a problem when using the RPR-1 (power
amplifiers are instead connected to the RPR-1 outlets), this capacitor
can be safely removed. To accomplish this, remove the SP -5 top cover
and 8 holding screws. CAUTION: UNPLUG SP-5 POWER CORD BEFORE REMOVING
TOP COVER AND CAPACITOR. Locate the .01 MF/1600 V capacitor nested
between the power relay contacts -towards the rear panel next to the
power transformer. Clip the leads off close to the solder joints, remove
the capacitor, and replace the top cover. The SP -5 is now ready for use
with an RPR-1 .
OT4 - Unswitched AC Convenience Outlet
Connect to record player, turntable. or tape recorder where power should
be controlled by the component on - off switch only . This insures proper
11
cycling
11
and mechanism disengagement.
Note: The
11
grounding
11
type convenience outlets are provided to accommodate
power amplifiers with 3 prong {grounded) line plugs. To avoid
11
system
11
ground loops, the ground circuits of the rear panel outlets are connected
to the ground conductor of the SP -5 line cord only. The preamplifier
chassis~ not connected to the convenience outlet or line cord/plug
ground circuit.
Fl -Preamplifier Line Fuse Receptacle
Provides protection for preamplifier electronics only. Refer to page 2
for fuse replaceme nt information.
S5 - Line Voltage Selector Switch
Selects for 120 or 240 volt input power. Refer to page 2 for
11
Line
Voltage Conversion
11
procedure.
- 5-

SYSTEM CONN E CTION
Before connecting the SP -5 into your system, familiarize yourself with the rear
panel functions by referring to the diagram and description of the rear panel in
the previous section.
Use only high quality shielded phono cables when interconnecting the SP -5 with
any signal sources, power amplifiers, or electronic crossovers. Avoid inexpensive
cables which use "weak" or soft metal grounding shells as they may introduce hum
and/or noise into the system. Keep audio cables neatly dressed and away from all
power cords for minimum hum and noise interference .
It should be noted that the SP -5 line cord grounds the convenience outlet grounds
only. The preamplifier chassis is not connected to the line cord ground in order
to minimize system ground loops .
-6-

Rl R2 SJ 54
0 V
OL U M •
OAL tNC E -~-•O ~o
~-
I =o~
0 0
~PO-A==::J
1111111 l'llllll'CII
(
<a>
©
~
)
.. OO H D E., INITION , ..
BP •II PAII AMPt..l .. l•A
0 1-
51
LED
52
FRONT
PANEL LAYOUT
FRONT PANEL FUNCTIONS
Refer to the "Front Panel Layout" diagram above.
Rotary Controls:
Volume ( Rl) -Controls preamplifier " main output" level . Power amplifier or
source gain controls (if available) should be set such that
normal listening levels occur at approximately al or 2 o'clock
setting. This will provide ideal volume control "resolution".
Balance (R2 ) - Controls the relative volume of each channel. Equal channel
volume occurs when the control is centered at the indicator mark.
Clockwise rotation from center position decreases left channel
output. Counter-clockwise rotation decreases right channel
output.
Rotary Switches:
Mode ( S3 ) - Switch selects one of five "main output" modes :
"Mono" - Combines the left and right input channels internally
to provide a monaural output (common output for both left and
right main outputs) .
"Reverse" - Provides stereophonic operation except channels are
reversed, i .e. left input to right output, right input to left
output.
"Stereo" -Provides normal stereophonic operation without channel
reversal, i .e. left input to left output, right input to right
output.
''Left" -Left channel input sources are coupled to both the left
and right "main outputs" simultaneously. The "balance" control
functions as normal.
- 7-
0
0

"Right" - Same as above except right channel inpu t sources are
coupled to both the left and right "main outputs" simultaneously.
Note: The "tape outputs" are unaffected by the position of the
11
mode
11
switch.
Source (S4) -Switch selects one of five rear panel inputs (program sources)
as marked. The selected source is also switched to the "tape
outputs" . All unused inputs are shorted to ground.
Note: Provisions for optional (*) Head Amp electronics have
been made within the SP -5 directly behind the Head Amp input
connectors . These inputs and associated electronics will be
required only for low output moving coil transducers. Consult
your dealer for information and use of this special input
feature. These inputs are not connected internally at the
factory and are not used in systems employing moderate or high
output magnetic cartridges.
Toggle Switches:
Power (Sl) -Preamplifier on-off switch. Move handle up for power
11
on
11
•
Also turns on the "switched" rear panel outlets. Green indicator
(LED) illuminates when preamplifier is on.
Monitor (S2) - Allows instantaneous monitoring of tape recordings (inputs Jl3 and
Jl4) in the "monitor" position. In the "source" position, selector
switch (S4) controls the program source to the loudspeaker. Source
switch (S4) is bypassed when (S2) is in the "monitor" position.
Indicator:
LED - Green light emitting diode. Illuminates when preamplifier power
switch, Sl , is
II
on
11
•
-8-

GENERAL OPERATION
Before operating, familiarize yourself with the front panel control functions
by referring to the diagram and control description in the previous section.
To operate your music system proceed as follows:
l. Set "volume" control at minimum (full counter-clockwise),
2. Turn power switch "on" -green LED i ndi ca tor should i 11 umi nate.
Note : A controlled warm - up (10 second nominal) is initiated at power
turn- on. This minimizes warm - up pulses or thumps that would otherwise
be heard through the speaker system.
3. Turn on desired source (record player, tuner, tape recorder, etc.).
4. Set
11
source
11
switch to program source desired,
11
mode
11
switch to "stereo",
"balance" control to a 12 o'clock position, and the monitor toggle switch
to the right of the power sv,itch in a down position.
5. Turn "volume" control clockwise to desired listeninq level.
6. The tape monitor switch allows a recording monitor function for one
recorder. The normal position is down when a tape recorder is not in use.
7. Refer to the previous section for a detailed description and operation of
the front panel controls.
-9-