Audio Research SP9 MKIII User manual

Owner's Manual
Model SP9 MKIII
STEREO PREAMPLIFIER
audio research
H I G H D E F I N I T I O N®
3900 ANNAPOLIS LANE NORTH/ PLYMOUTH, MINNESOTA 55447-5447 / PHONE: [phone] FAX [phone]

Contents
Model SP9 MKIII
Section Page No.
Preface .............................................................. 1
Warnings .................................................... , ....... I
Packagings ........................................................... 1
Description of Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............... , . . . . . . 3
Installation Instructions . . . . . . . . . . . . . . . . . . . . . . .......................... 3
Operating Procedure ................................................... 4
Tape Dubbing Procedure ................................................ 4
Muting Provisions ... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . 4
Shut Down ........................................... , .............. 5
Input Impedance Adjustment ........................................... 5
Input Capacitance Adjunsment .......................................... 6
Reducing Gain ........................................................ 6
Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Cleaning .................................................................... 6
Warranty Terms and Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Warranty Outside the USA .............................................. 7
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Model SP9 MKIII
Preface
Please take the time to carefully read this Instruction
Manual prior to installation or use ofyour SP9 MKIII
preamplifier. Because it is a highly advanced elec-
tronic instrument, there are several facts and proce-
dures you should know before you place it in opera-
tion.
Just as you would not purchase and attempt to oper-
ate an expensive camera, computer system or high-
performance automobile without first learning some-
thing about performance parameters and correct
operating procedures, so too your preamplifier
requires some familiarization before you make it part
of your music reproduction system. Your reward, in
terms of maximum performance and a long service
life, will be well worth the effort.
In short, the SP9 MKIII hybrid preamplifier is a prod-
uct you can be proud to O\Vll and enjoy for years to
come, without fear that it will soon become techni-
cally obsolete or sonically dated. Taking the time to
carefully read and undersstand the remainder ofthis
Owner's Manual will help insure you get all the
enjoyment your SP9 MKIII is capable of. Happy
Listening!
Warnings
l. To prevent fire, or shock hazard, do not expose
your SP9 MKIII to rain or moisture.
2. This unit contains voltages which can cause seri-
ous injury or death. Do not operate with cover
removed. Refer servicing to your authorized Audio
Research dealer or otherqualified personnel.
3. The power cord on your SP9 MKIII is equipped
· with an 18-guage, 3-conductor cable and a stan-
dard three-prong grounding plug. In addition,
your SP9 MKIII uses an isolating power trans-
former with 4 KV-rated insulation. For absolute
protection. do not defeat the ground power plug.
This provides powerline grounding of the
SP9 MKIII chassis to provide absolute protection
from electrical shock.
4. For continued protection against fire hazard,
replace the fuse only with the same type and rat-
ing as specified at the fuse holder.
Packaging
Save all packaging in a dry place away from fire haz-
ard. Your SP9 MKIII preamplifier is a precision elec-
tronic instrument and should. be properly cartoned
any time shipment is made. You may not have occa-
sion 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 SP9 MKIII from unnecessary dam-
age or delay.
Note that your SP9 MKIII has been shipped with the
vacuum tubes installed in a protective foam block
under the top cover. Using a phillips-head screwdriv-
er to loosen the fastening screws. remove the top
cover and set aside. Install the numbered tubes in
their respective sockets, refasten the top cover and
store the foam block with your carton.
DO NOT ATTEMPT TO OPERATE THIS PREAMPLIFIER BEFORE
INSTALLlt,lG THE VACUUM TUBES IN THEIR PROPER SOCKETS.
TUBE LOCATIONS
TOP VIEW
REAR
FRONT
0
0
l

Model SP9 MKIII
Description o( Controls
GAIN CONTROL: A high-quality, metal-film seg-
mented control with 31 steps and accurate tracking.
Use it to control loudness or volume. Rotation to the
left attenuates gain, rotation to the right increases
gain. Best sonic performance and best signal-to-noise
ratio will result if the input signal and amplifier
input sensitivity allow normal listening when GAIN
is set between 10 o'clock and 2 o'clock.
With some high-efficiency loudspeakers, a high-out-
put source such as a CD player, and with a high-gain
amplifier lacking an input volume control. you may
discover that normal listening is only possible with
the GAIN control barely on, or in the 9 o'clock posi-
tion. In such circumstances it is possible to reduce
the overall gain of the SP9 MK.III by 6dB, by making
a simp1e internal adjustment. See the ADJUST-
MENTS Section of this Manual, or contact your
Audio Research dealer for assistance.
BALANCE CONTROL: When rotated, adjusts the
relative sound levels of the left and right channels.
The 12 o'clock position marks the point of equal bal-
ance. Rotating the knob to the right decreases the
level of the left channel proportionally, shifting the
sonic image to the right. Rotating the knob to the
left shifts the sonic image to the left.
MODE CONTROL: Allows selection of various sin-
gle-channel {mono) and two-channel {stereo) listen-
ing modes. Detents mark each selection option dur-
ing rotation of knob. "Mono• reproduces identical
sonic information in both right and left channels.
"Reverse" switches left-channel information to the
right, right-channel information to the left. "Stereo"
is the n.ormally preferred mode for most program
material, producing the most realistic spacial image.
"Left• cancels all right-channel information and pre-
sents left-channel information to both channels. In
the same way, "Right" cancels all left-channel infor-
mation, etc. ·
INPUT SELECTOR: Detents·mark selection of vari-
ous source material options: "Phono• for phonograph
record turntables; "Tuner• for AM/FM radio tuners;
•co• for compact digital disc players: "Video" for
input from Beta or VHS videotape recorder/players;
and "Spare• fc;ir any additional high level source:
tape, tuner, CD, video, etc.
The signal source chosen by the Input Selector is fed
to the Main and Recorder I/Recorder 2 outputs
2
when the Monitor/Source switch is set to "Source."
.(See description of Monitor/Source switch, next
page.) The source chosen by the input selector is
always fed to the Recorder I/Recorder 2 outputs, and
cannot be overridden.
POWER SWITCH: Supplies power from AC wall out-
let to SP9 MKIII when in "Power" position. Although
not strictly necessary, it is nonetheless good practice
to put the SP9 MKIII in "Mute" before turning on
power for maximum protection ofyour power ampli-
fier(s) and speakers.
MUTE/QPERATE SWITCH: In "Mute" position,
shorts the main outputs of the preamplifier to allow
listening interruptions for telephone answering or
other reasons. This switch should always be activat-
ed between listening uses or switching of inputs, in
addition to turning the Gain (volume) control
counter-clockwise. These two simple precautions
will prevent inadvertent misuse of your SP9 MKllI
and help protect your power amplifier(s) and speak-
ers from unexpected transient signal pulses (tone
arm mishandling, etc). In "Operate" position, this
switch allows the signal to pass normally to the out-
puts.
CAUTION: Do not turn up the gain control beyond
normal listening positions when the SP9 MK.III is in
the Mute mode. Always turn the gain control down
when changing program sources, even when it is
muted. The SP9 MKIII has an extremely wide
dynamic range. and switching to Operate at loud lev-
els may be too much for amplifiers, speakers or ears.
Furthermore, at extremely high signal levels (such as
from a severe blow to the turntable or tone arm) in
the Mute mode, the SP9 MK.III may overload inter-
nally. This will not harm the SP9 MK.III, but it may
take 10-15 seconds to stabilize from the overload. If
you switch to Operate before the SP9 MKIII has
recovered from the overload, you will hear a "pop"
when the mute switch is actuated, indicating the
presence of unwanted subsonic energy that may
damage some amplifiers and poorly-~used speakers,
if the SP9 MKIII is left in Operate. If you hear a
"pop". switch immediately back to Mute, tum down
the gain control and wait 15 seconds or so and try
again. Under normal conditions the SP9 MK.III mut-
ing has no "pops".{Turntable rumble. record warp
wow or other subsonic program energy may also
cause small, harmless mute "pops". These "pops"
may be eliminated by turning down the SP9 MK.III
gain control before muting.}

Model SP9 MKIII
POWER/MUTING CIRCUIT LED: Glows green to
indicate unit is on and receiving power from the
power supply. Note that for approximately 45 sec-
onds after start-up or in "Mute" mode. this LED will
glow more dimly. indicating proper operation of the
muting circuit. In the "Operate" mode (after warm-
up). the LED brightens and your SP9 MKIII is ready
for normal operation.
MONITOR/SOURCE SWITCH: In "Monitor" position
this switch "bypasses" the Input Selector and pre-
sents the signal to the main outputs from sources
(tape recorders. etc.) connected to the "Tape I" or
"Tape 2" input jacks on the rear panel. In the
"Source" position, the program source is controlled
by the Input Selector (Phono. Tuner, CD, etc.).
Connections
INPUT CONNECTORS: All are clearly marked to
indicate use. All high level inputs are 50K ohms
impedance. Remember that impedance of "Phono"
input is controlled by soldered-in resistor values on
the main circuit board (see INPUT IMPEDANCE
ADJUSTMENT).
MAIN OUTPUT CONNECTORS: There is one (1) set
of output connectors, which should be connected to
your electronic crossover or power amplifier.
The input impedance (load) of the power amplifier
or electronic crossover to the SP9 MKIII main out-
puts should be at least 20K ohms for maximum
sonic benefit.
NOTE: At the performance level of the SP9 MKIII,
high-quality audio signal interconnect cables are crit-
ical to preserving maximum fidelity. Audio Research
RFI-shielded or unshielded interconnect cables are
highly recommended for connection to your power
amplifier(s) and to other ancillary equipment. See
your authorized Audio Research dealer for recom-
mended lengths and prices.
RECORDER I/RECORDER 2 OUTPUT CONNEC-
TORS: Two (2) sets are provided. Recorder Outputs
should be connected to your recorder's "AUX or
"LINE" inputs. These outputs supply a source of
whatever is selected by the Input Selector Control.
Level is non-variable and approximately the same as
the selected input source.
All input/output connectors have heavy gold plating
and connect "ground" before "hot". (On disconnect.
"hot" is first.)
Installation Instructions
While the SP9 MKIII does not dissipate an unusual
amount of heat, it is important that it be provided
with reasonable airflow to assure long, trouble-free
operation. In addition, the following installation
guidelines will help insure maximum sonic perfor-
mance as well as reliable service.
1. Upright and horizontal mounting is suggested if
extended operation (longer than one hour) is con-
templated.
2. Do not "stack" the SP9 MKIII on top of a power
amplifier. Not only could this cause overheating.
but "hum" may be introduced into the phono cir-
cuits from the proximity of the amplifier's power
transformer.
3. Do not place or operate your SP9 MKIII on a soft
or irregular surface such as a rug. This willprevent
proper ventilation.
4. Do not operate your SP9 MKIII without the top
and bottom covers installed. These are required
both for safety as well as shielding from interfer-
ence (except in service operations, obviously).
5. If rack mounting is employed, use Audio Research
Rack Mount Ventilators (RMV-3) below and above
your SP9 MKIII.
6. If side-by-side mounting with other equipment is
employed. place the SP9 MKIII to the right of the
other chassis. so as to provide maximum spactng
between another power transformer and the SP9
MKIII's sensitive phono input circuitry.
7. In a cabinet or rack-mount installation which has
an enclosed back. an exhaust fan is desirable so as
not to operate the SP9 MKIII in overheated ambi-
ent air. Operation of vacuum tube equipment for
long periods of time in hot ambient air will short-
en tube life and increase chance of failure of other
component parts.
3

Model SP9 MKIII
Operating Procedure
Start-Up:
1. Make sure Power switch is set to "Off" position;
Mute switch should be in "Mute" position: and
"Gain" Control should be at minimum (full
counter-clockwise rotation).
2. Secure all rear-panel connections between
SP9 MK.III, power amplifier(s) and input sources.
Note: Given the advanced performance capabili-
ties of the SP9 MKIII. it is extremely important
that high-quality interconnects be used for con-
nection to ancillary electronics. Audio Research
brand interconnects, in either unshielded or RFI-
shielded configurations, are strongly recommend-
ed. Your Audio Research dealer can assist you in
determining optimal lengths for your system.
3. Plug 3-prong powerline cord from rear of
SP9 MK.III into grounded AC wall receptacle.
4. Turn Power switch to "On". Green LED will glow
dlmly for approximately 45 seconds while power
supply stabilizes, indicating operation of automat-
ic muting drcuit. After this warm-up muting peri-
od, the LED will brighten when "Operate" is se-
lected, indicating that your SP9 MK.III is ready for
operation.
Note: For superior sonic performance, a warm-up pe-
riod of at least one hour is recommended. In addi-
tion, your SP9 MK.III may be safely left "On" con-
tinuously for maximum performance at all times.
but at the expense of higher maintenance costs
(more frequent tube replacement).
5. Rotate input selector to source desired: set switch
options to positions desired.
6 If "Phono" has been selected. make sure imped-
ance is properly matched to your phone cartridge
(see INPUT IMPEDANCE ADJUSTMENT).
7. Activate input source, then deactivate Mute
switch and adjust Gain Control as necessary.
Tape Dubbing Procedure
When using the SP9 MKIII as a control center for
recording, the program source to be dubbed must be
connected to one of the five inputs controlled by the
front "Input Selector". This routes the selected pro-
gram to the Recorder I/Recorder 2 outputs, which
should connect to the "Aux" or "Hi-level" inputs on
the recorder(s). (Check to make sure that your
recorder does not short it's inputs when not in
"Record" mode. If it does. it may severely load or dis-
tort the SP9 MK.Ill's output signal.)
4
The Tape I/Tape 2 inputs are for listening or moni-
toring only through the ma1n outputs, and cannot be
routed to the Recorder I/Recorder 2 outputs for dub-
bing. When using these inputs, your tape recorder
should be switched to "Tape" or "Monitor". if it has
separate record and play heads. This allows true "A-
B" comparison of signals before and after recording,
using the Monitor/Source switch on the SP9 MK.III.
Two recorders may be used simultaneously to record
the same program. While dubbing is in process, the
signal from either of the Tape I or Tape 2 inputs
may be listened to by switching to "Monitor" and se-
lecting the appropriate Tape 1 or Tape 2 input.
Switching back to "Source" returns the listener to
the program being dubbed.
Two different programs may be recorded simultane-
ously by routing one program directly from its
source to the recorder (bypassing the SP9 MK.III) and
routing the othersource through the SP9 MK.III and
its Recorder outputs. Then, two different programs
may be monitored through the Tape 1 and Tape 2 in-
puts.
If you wish to use a tape unit both as a program
source to be dubbed and as a recorder with monitor-
ing provisions. then use "Y" connectors to feed both
Spare and Tape I inputs on the SP9 MK.III from the
recorder outputs. Then either function may be se-
lected without changing connections. Remember
that if you accidently select the output of your
recorder as a signal source and send this same signal
back to the same recorder's inputs, you may gener-
ate an "echo loop" or wild oscillations. depending on
the gain settings on the recorder.
Muting Provisions
The SP9 MK.III has several provisions to help protect
against misuse of the exceptional dynamic range and
wide bandwidth that it offers. It is not subject to
damage itself. but some power amplifiers and speak-
ers are more limited in their ability to withstand sig-
nal extremes. These provisions, both manual and au-
tomatic, are designed not to interfere with a flawless
listening experience of unprecedented realism, while
giving reasonable protection against warm-up surges
and power line interruptions. However, for absolute
protection of associated equipment some operator
understanding, and responsibility. is required.
Initial "settling" time of all circuit parameters within
the SP9 MK.III requires approximately 5 to 10 min-

Model SP9 MKIII
utes. The automatic muting circuitry timer is adjust-
ed for about 45 seconds. (This is because recurrent
interruption "settling" time is much less. You would
not want to wait for 5 to 10 minutes each time such
an interruption occurred.)
The Mute/Operate Switch allows manual disabling
of the SP9 MKIII outputs during any moving of the
tonearm or switching of equipment. Use of this
switch will minimize stress on your amplifier even if
it is "Off". It is also highly recommended that manu-
al muting be employed during the initial 45 second
warm-up period as well as during tum-off for maxi-
mum protection.
While it is true that the automatic muting will pro-
vide reasonably adequate protection against speaker
burnout during these periods. it has limitations. At
the 45 second point the automatic timer "releases"
the output, and since full subsonic stabilization has
not yet occurred, some sonic unpleasantness may oc-
cur. Although this is normally adequate protection.
utilization of the manual mute provision will com-
pletely avoid this stress to your speakers, as well as
the associated sonic unpleasantness.
Some solid-state power amplifiers have a DC offset
present at their input connections. (This, of course.
should not be.) Operation of the manual muting
switch with such an amplifier connected will result
in a "click" or "pop" in your loudspeaker (commensu-
rate in level with the amount ofthe offset) each time
the switch is activated. Repair or replacement of
such amplifiers is suggested.
The automatic muting operates as follows:
1. The manual mute switch always disables both
"Main" outputs and overrides any automatic provi-
sions. even when the SP9 MKIII is turned off.
(The "Operate" position of the manual mute
switch is functional only when the unit is not in
the automatic mute mode.)
2. The 45 second warm-up timer will restart auto-
matically and the LED will dim if the power is
temporarily interrupted for 0.1 second or more.
Note: Power supply regulation ofthe SP9 MKIII is ef-
fective down to lO0VAC without serious sonic de-
gredation.
3. The automatic muting of the SP9 MKIII is de-
signed to be effective only against power supply
interruptions and power line failures. It will not
mute against subsonic signal transmissions from
your turntable, etc. Proper Fusing of speakers ls
essential to protectagainst excessive audlo level
or power amplifier faults.
Shut-Down
1. Set "Mute" switch to "Mute" position.
2. Rotate "Gain" control counter-clockwise to
minimum setting.
3. Deactivate power amplifier(s).
4. Deactivate all input sources.
5. Set SP9 MKIII Power Switch to "Off" position.
Input Impedance Adjustment
For the best sonic performance of your phono pick-
up cartridge, it should connect to the proper load im-
pedance recommended by the cartridge manufactur-
er. Your SP9 MKIII comes wired with a standard
load of 47K ohms for most high-output moving-coil,
or moving magnet cartridges. A kit of precision load
resistors is supplied with your SP9 MKIII for the
more common low-impedance load requirements of
10, 33 or 100 ohms for typical low to medium output
moving-coil cartridges. Consult your cartridge manu-
facturer or dealer to determine the optimum load im-
pedance for your needs. You may wish to connect
the load resistors at the output of your turntable,
rather than in the SP9 MKIII. especially if you may
be using more than one turntable or cartridge, with
different load requirements.
The use of precision fixed resistors provides better
load accuracy and sonic performance at lower cost
than most adjustable or switchable loads. Audio Re-
search can supply audiophile grade non-standard
load resistor and capacitor values upon request ac-
companied by $10.00 to cover order processing costs
(certified funds or money order).
Solder the desired resistors to the turret terminal
posts on the bottom of the main circuit board near
the phono inputs (see illustration). First wrap the re-
sistor leads around the posts 1/2 to 3/4 tum. Then
solder using the special alloy solder supplied with
the resistors. Connect one resistor between the left
and center posts and the other resistor between the
center and right posts.
5

Model SP9 MKIII
For 10 ohms use brown-black-black-gold resistors.
For 33 ohms use orange-orange-red-gold resistors.
For 100 ohms use brown-black-black-black resistors.
NOTE: All SP9 MKIII's have two 560 picofarrad ca-
pacitors mounted on the impedance loading pegs.
one for each channel. When using moving coil car-
tridges these capacitors should not be removed
when adding load resistors. The load resistors
should be installed in parallel with these capacitors.
Input Capacitance Adjustment
The SP9 MKIII has a total input capacitance of 600
picofarrads with the 560 picofarrad capaciators in-
stalled and 40 picofarrads without them. Different
value capacitors can be installed to match the re-
quirements of your moving magnet cartridge. Ob-
serve the polarity as shown in diagram below when
adding capacitors.
Reducing Gain
When using the SP9 MKIII with high-output car-
tridges or high-sensitivity power amplifiers or high-
efficiency speakers, you may find that you typically
set the SP9 MKIII Gain control at 9-11 o'clock,
where the detented gain increments may be too
large for setting the desired listening volume. For
more precise setting of the desired listening level.
The SP9 MKIII includes a simple internal provision
to reduce the gain of the line section by 6dB. This af-
fects all signal sources. when using the normal Main
Output jacks. The signal level at the Recorder Out-
put jacks is unaffected.
NOTE: The CD input of the SP9 MKIII has a built-in
gain reduction of 12dB. Other line inputs have nor-
mal gain. To reduce the gain by 6dB, merely remove
the bottom cover and unsolder the gain change con-
nection for each channel. These connections are lo-
cated in the central area of the bottom of the main
SP9MKIII
BOTTOM VIEW,
REAR CORNER.
0
circuit board near V2, where the pads identified by
the letter "A" connect to the large central ground
path.
To restore the SP9 MKIII to its original gain, merely
resolder across these small gaps at "A". For best re-
sults use special alloy solder supplied with the car-
tridge load resistor kit.
Servicing
Because of its careful design and exacting standards
of manufacture. your SP9 MKIII should normally re-
quire only minimal routine service to maintain its
high level of performance.
CAUTION: Your SP9 MKIII contains sufficient levels
of voltage and current to be lethal. Do not tamper
with a component or part inside the unit. Refer any
needed service to your authorized Audio Research
dealer or other qualified technician.
The two (2) vacuum tubes inside your SP9 MKIII are
quality 6922 types, and with normal use should not
need to be changed for approximately 5,000 to
10,000 hours of use. Replacement 6922 tubes need
not be low-noise or matched for gain characteristics.
and are available from Audio Research.
Should service be necessary. please contact your
Audio Research dealer. or Audio Research Customer
Service [phone].
Cleaning
To maintain the visual appearance of your SP9 MKIII
preamplifier. occasionally wipe the front panel and
top cover surfaces with a soft. damp (not wet) doth
to remove dust. A mild. non-alkaline soap solution
may be used to remove fingerprints or similar
smudges. Cleaners containing abrasives should not
be used as they will damage the "brushed" grain of
the front panel finish.
I~
I 1 + + \__ 560 pF CAPACITORS.
0
6
WRAP, SOLDER RESISTORS
TO TURRET TERMININALS.

3-Year Limited Warranty
Terms and Conditions
1. LIMITED WARRANTY
Audio Research warrants the product designated herein to be
free ofmanufacturingdefects inmaterial and workmanship. sub-
jectto the conditions hereinaftersetforth. for a period ofthree
(3) years from the date ofpurchase by the originalpurchaser or
no later than five (5) years from the date of shipment to the
authorizedAudio Researchdealer. whichevercomesfirst. except-
ingvacuum tubes which arewarrantedfor 90 daysonly (See 6).
2. CONDITIONS
ThisWarrantyis subjectto the following conditions and limita-
tions. TheWarranty is void and inapplicable if the producthas
been used orhandledother than inaccordance with the instruc·
tions in the owner'smanual. abused. or misused. damaged by
accidentorneglect or inbeingtransported. or the defect is due
to the productbeingrepaired or tampered with by anyoneother
than Audio Research or an authorized Audio Research repair
center. The product must be packed and returned to Audio
Research or an authorizedAudio Research repair center by the
customer at his or her sole expense. Audio Research will pay
return freight ofits choice. A RETURNED PRODUCT MUST BE
ACCOMPANIED BY A WRITTEN DESCRIPTION OF THE
DEFECT AND APHOTOCOPY OF THE ORIGINAL PURCHASE
RECEIPT. This receipt must dearlylist model and serialnumber.
the dateofpurchase. the name and addressof the purchaserand
authorized dealer and the price paid by the purchaser. Audio
Researchreserves the righttomodify the design of anyproduct
without obligation to purchasers of previously manufactured
products and tochange the pricesorspecifications ofanyprod-
uct without notice or obligation to any person.
3. REMEDY
In the event the aboveproductfails to meet the aboveWarranty
and the above conditionshave been met. the purchaser's sole
remedy under this LimitedWarrantyshall be to return the pro-
ductto Audio Research or an authorizedAudio Research repair
centerwhere the defectwill be rectified withoutchargefor parts
or labor. exceptvacuum tubes (See 6).
4. LIMITED TO ORIGINAL PURCHASER
ThisWarrantyis for the solebenefitof the originalpurchaserof
the covered product and shall not be transferredto a subsequent
purchaser of the product.
5. DURATION OF WARRANTY
This Warranty expires on the thirdanniversary of the dateofpur-
chase or no later than the fifth anniversary of the date ofship-
ment to the authorizedAudioResearchdealer. whichevercomes
first.
Warranty Outside the U.S.A.
Audio Research has authorizeddistribution in many countries
of the world. Ineachcountry. the authorizedimporting retailer
ordistributorhasaccepted the responsibilityfor warrantyofour
products. Warranty service should normally be obtainedfrom
the importingretailer ordistributor from whom you purchased
your product.
6. VACUUM TUBES
Vacuumtubesarewarrantedfor the original90-dayperiodonly.
7. DEMONSfRATION EQUIPMENT
Equipment used by an authorizeddealerfor demonstrationpur-
poses is warranted to be free of manufacturing defects in
materials and workmanship for a periodofthree (3) yearsfrom
the dateof shipment to the dealer. Vacuum tubesarewarranted
for 90 days. After the first year. demo equipment needingwar-
rantyservice must be packed and returnedtoAudio Research by
the dealer at his sole expense. Audio Research will pay return
freight ofits choice. A returned product must be accompanied
bya writtendescription of the defect on an AUDIO RESEARCH
RETURNED GOODS AUTHORIZATION form. Dealer-owned
demonstration equipment sold at retail within three (3) years of
date of shipment to the dealer is warranted to the first retail
customer to be free of manufacturing defects in materials and
workmanshipfor the durationof the 3-Year Limited Warranty re-
maining(as measured from the date of shipment of the equip-
ment to the dealer). Vacuum tubes are not warranted for any
period under theseconditionsofsale. In the eventwarrantyser-
vice is needed under these conditions. the owner of the equip-
ment must providea copy of his purchasereceipt. fulfilling the
requirementsdescribed under "2. Conditions"above. The pro-
duct must be packed and returned to Audio Research or an
authorizedAudio Research repaircenterby the customer at his
or her soleexpense.Audio Researchwillpayreturnfreight of its
choice.
8. MISCELLANEOUS
ANY IMPLIED WARRANTIES RELATING TO THE ABOVE
PRODUCT SHALL BE LIMITED TO THE DURATION OF THIS
WARRANT~THEWARRANTYDOESNOTEXTENDTOANY
INCIDENTAL OR CONSEQUENTIAL COSTS OR DAMAGES TO
THE PURCHASER. Somestates do not allowlimitations on how
long an implied warranty lasts or an exclusion or limitation of
incidental or consequentialdamages. so the above limitations
or exclusions may not apply to you. This Warranty gives you
specific legal rights. and you may also have other rights which
vary from state to state.
9. WARRANTOR
Inquiriesregarding the aboveLimited Warrantymay be sent to
the following address:
Audio Research
5740 Green Circle Drive. Minnetonka. Minnesota 55343-4424.
ATTN: Customer Services
In the unlikely event of service required beyond the capability
of the importer. Audio Researchwillfulfill the conditions of the
warranty. Suchproduct must be returned at the owner's expense
to the Audio Researchfactory. together with a photocopy of the
bill ofsalefor thatproduct. a detailed description of theproblem.
and any information necessary for return shipment.
7

Specification
Model SP9 MKIII
FREQUENCY RESPONSE:
High Level Section: ±.5d8, 5Hz to 50kHz, -3d8
points below 1 Hz and above 200kHz.
Phono: ±.3dBof RIAA, 30Hz to 40kHz.
DISTORTION: Less than .01 % at 2V RMS output.
(Typically less than .005% in midband)
GAIN: Phono input to tape output: 46d8
Phono input to main output 67d8
High level inputs to tape output: OdB
High level inputs to main output 21dB
G.D. input to main output: 9dB
INPUT IMPEDANCE: 50k ohms line inputs; 47K
phono. (Phono provisions f?r any value bel?w 47K
ohms or added input capacitance for matching cer-
tain magnetic cartridges.)
OUTPUT IMPEDANCE: 250 ohms main output; 850
ohms recorder output. Recommended load 60K
ohms and 100pF. (20K ohms minimum and 1000pF
maximum.)
MAXIMUM INPUTS: Phono, 200mV at 1 kHz
(1000mV RMS, 10kHz). High level inputs essentially
overload-proof.
RATED OUTPUTS: 2V RMS 5Hz to 50kHz, all out-
puts, 60K ohm load (main output capability is 50V
RMS output at 1/2% THO at 1kHz into a 100K ohm
load with 5V RMS high level input.)
POWER SUPPLIES: Electronically-regulated low and
high voltage supplies and electronic decoupling.
Shielded toroid transformer. Line regulation better
than .01%.
NOISE: (High Level) (1) 70uV RMS maximum resi_d-
ual unweighted wideband noise at main output with
gain control minimum (98dB below 5V RMS output).
(2) More than 100dB below 1V RMS input (less than
7uV equivalent input noise).
PHONO: 0.12uV equivalent input noise, IHF weight-
ed, shorted input (78dB below 1mV input).
8
TUBE COMPLEMENT: 2-6922 dual triodes, (Hybrid
FET/Tube audio circuit, solid-state power supply)
POWER REQUIREMENTS: 100-135VAC 60Hz
(200-270VAC 50/60Hz) 55 watts. max.
DIMENSIONS: 19" (48 cm) W x 5¼" (13.4 cm) H
(standard rack panel) x 10¼" (26 cm) D. Handles ex-
tend 1 ½" (3.8 cm) forward of the front panel. Rear
chassis fittings extend 7 /a" (2.3 cm).
WEIGHT: 12 lbs. (5.5 kg) Net; 21 lbs. (9.5 kg)
Shipping.
Specifications subject to change without notice.
©1993 Audio Research Corporation.

audio research
H I G H O E F I N I T I O N®
57 40 GREEN CIRCLE DRIVE / MINNETONKA, MINNESOTA 55343-4424 / PHONE [phone] FAX [phone]
8-5-93
SP9MKI II PREAMPU FI ER .
· SCHEMATIC
AND PARTS LI ST

ISP9MKIII PREAMPLIFIER - (PHONO CIRCUITRY) - PAGE 1of 4 PAGES
.-----e----------.--------------ti~--..,. B+ 275
PHONO
INPUT
. T-~i .
!Tin CHASSIS
46dB Gain at lkHz
RIM Equalized ·
01
R3
75K
RB
150K
+11.1
R18A+BIIC
15.7K
cs
.0048uf
AUDIO RESEARCH CORPORATION
5740 GREEN CIRCLE DRIVE
MINNETONKA, MINNESOTA 55343-4424
+4.9
8-5-93
R10
54.9
R9AIIB
20.6K
+174 __ '\/Vl,---------------t
ZD2
+
1N5245B
cs
27pf
015
1N916B
G
A61
15K
06
C35
6.8pf
To Se
Switc~
COMMON
R17
R15
475K
C7 562K
.0156uf
PROPRIETARY NOTICE: THIS DRAWING CONTAINS PATENTED, PATENT PENDING,
PATENT APPLIED FOR, AND/OR OTHER CIRCUITRY CONSIDERED PROPRIETARY BY
AUDIO RESEARCH CORPORATION AND IS FURNISHED ON A CONFIDENTAL BASIS
FOR IDENTIFICATION PURPOSES ONLY. .

FROM GAIN
CONTROL ·
I SP9MKIII PREAMPLIFIER - (LINE SECTION CIRCUlfRY) - PAGE 2 of 4 PAGES
------41._., __________ ,._ ______ 8+285
R23
75K
G
R25AIIB
186.5
G
-+46.1 2(7)
C29 1--.0-1 _..,__.1\/V\J~.-- ....... \-a;_;:-----+-
G
5.0 ..
.01
C9 ,47
166
. 010 .
A20 · . 56pf /
475K . · /R21
·. +26.7 200 ·
A
COMMON
A22A+B .
13.7K
+26.4
R31AIIB+CIID
2.40K .
R59A+B
3.64K ·
A30
3.92K
C11
56pf
NOTE: DE-SOLDER "A"
FOR -6 dB GAIN
NORMAL GAIN: 20dB
8-5-93
Q9
A27AIIB
21.5K
A28
475K
A29
200
MUTE-
OPERATE
RELAY
o NORMALLY
CLOSED
TO MUTE
CIRCUllAY
MAIN
OUTPUT
CHASSIS
AUDIO RESEARCH CORPORATION
5740 GREEN CIRCLE DRIVE
MINNETONKA, MN 55343-4424
PROPRIETARY NOTICE: THIS DRAWING CONTAINS PATENTED, PATENT PENDING,
PATENT APPLIED FOR, AND/OR OTHER CIRCUITRY CONSIDERED PROPRIETARY BY
AUDIO RESEARCH CORPORATION AND IS FURNISHED ON A CONFIDENT AL BASIS
FOR IDENTIFICATION PURPOSES ONLY.

SPARE
VIDEO
C-O
TUNER
I. SP9MKHI · PREAMPLIFIER - (MUTING & SWITCHING CIRCUITRY) • PAGE 3 of 4 PAGES I
+22.7
R47
7&.BK
+15
6
4
U2
NE555
+ 014
1N916B
C23
.22
8
C24
33mfd
4 8
6
U3
· 2
NE555
R50
1
10M
+ 013
1N916B
R51
3
1K
---~,/\J\ro--+13
POWER ON AND
MUTE INDICATOR
I
TO MUTE
RELAYS
3
+.2
SW-2
+.4
C22
.22
. R53
'IM
499
R56
¥Mt
54.9
1
0
0
. 0
TOPHONOCKT
COMMON
TP 1
TP2
SW6 SW4
R57
MON
499
REC
OUT
(2)
AUDIO RESEARCH CORPORATION
5740 GREEN CIRCLE DRIVE
MINNETONKA, MN 55343-4424
45 SECOND WARMUP DELAY
R52
5.11K
COMMON
I INPUT &CONTROL CIRCUITS!
MODE SWITCH
LEFT
BALANCE
RV2
ccw ... ~
•' '
.• '
CHANNEL
TO
RIGHT
LEFT O
RIGHT O
cw
CHANNEL
sws
8-5-93
COMMON
PROPRIETARY NOTICE : THIS DRAWING CONTAINS PATENTED , PATENT PEl;JDING ,
PATENT APPLIED FOR, AND/OR OTHER CIRCUITRY CONSIDERED PROPRIETARY BY
AUDIO RESEARCH CORPORATION AND IS FURNISHED ON A CONFIDENT AL BASIS
FOR IDENTIFICATION PURPOSES ONLY.

T1
BLU
SW1
WHT
0
ON-OFF
I sPeMKm PREAMPLIFIER. (POWER suPPLY sEcTIONJ. PAGE 4 or 4 PAGEs I
RED
02
· D1
03
+395V
C33
.01
---~...--19--------.
RED
D4
D5 -
GAN
06
07
GAN
08
C37
.22
+22.7V
039
1.0
R64
54.9
. .
R63 R32AIIB
(2) LM329 1 N5359A
1N916B
158K
COMMON
204
1N4740A
+273.2V
A42 C19
R43
100K
+
208
220
+265V
A45
10M
COMMON
+275V
C16
.22
co
~
2
~ +
,...
D11
R40
332
C17
.01
+ 1N916B
038 }
1gis .__,..__..__._t __ ...,... ________ +~lSV .· TO MUTING CIRCUIT
VA1 +22.7V
R41
1.0
C18
2.0
8+2
COMMC
+zo10
220
D12
1N916B +
+2
CHASSIS
8-5-93
.005 .005
BLK GAN WHT
100·1 . 35 VAC 50/60Hz
AUDIO RESEARCH CORPORATION
5740 GREEN CIRCLE DRIVE
MINNETONKA, MINNESOTA 55343-4424
PROPRIETARY NOTICE: THIS DRAWING CONTAINS PATENTED, PATENT PENDING,
PATENT APPLIED FOR, AND/OR OTHER INFORMATION CONSIDERED PROPRIETARY
BY AUDIO RESEARCH AND IS FURNISHED ON A CONFIDENTIAL BASIS FOR
IDENTIFICATION PURPOSES ONLY.

PARTS UST
As of AUG 16 93
PRODUCT: SP9MKIII NOTES:
Schematic Symbol
Quantity ARC Part It Description
a TRANSISTORS
O1A,1B
4
30006535
FET, WHITEORAN. GE GREEN
02 · · 2
30007006
FET, GRAY BLUE
03
2
30006704
FET, ORANGE YELLOW
04,6,8,9 8 30005901 FET, RED BROWN
05,10 4 ·
30006706
FET, ORANGE BLUE
07
2
30006503
FET, WHITE ORANGE
.. :
011
1 30006761 FET, ORANGEYELLOW BROWN
012
1
30007102
FET, YELLOW RED
013 2 30003101 2N5210 NAT. ONLY
R RESISTORS
R4C{1RIM),258 2 42267203 RES. 267OHM 1% MK-3 SOPPM
R48{1RIM) 2 42182203
RES. 182OHM 1% MK-3 SOP PM
R4A{1RIM) 2 42150203
RES.150 OHM 1% MK-3S0PPM
R1,10,56,62,63,64 9
42549103 RES.54.9 OHM 1% MK-3 SOPPM
R2 2
42499403 RES. 49.9K 1% MK-3 50PPM
R3,23 4
42750405
RES. 75K 1% MK-8 S0PPM
R5 2
42121303
RES•. 121K 1% MK-3 SOPPM
RGA,68 4
42100403 RES. 10K+/-1% MK-350PPM
R6C 2
42100503
RES. 100K+/-1% MK-3 SOPPM
R7A 2
42121403 RES. 12.1K 1% MK-3SOPPM
R78,26
4
42215403 RES. 21.SK 1% MK-3 50PPM
R8 2
42150514 RES. 150K1% MK-5 1W SOPPM
R9A,13,27A 6
42274405 RES. 27.4K 1% MK-8 SOPPM
R9B 2
42825405
RES. 82.5K 1% MK-8 S0PPM
R11
2
42357203 RES. 357OHM 1% MK-3S0PPM
R12 2 42274103 RES. 27.4OHM1% MK-3 SOP PM
R14 2 42150414
RES. 15K1 % MK-5 S0PPM
R15,20,28
6 42475503
RES. 475K 1%MK-3 SOPPM
R16 2 43375200
RES. 375 OHM 3W 1% w.w~
R17 2
42562513
RES. 562K 1%MK-4SOPPM
R18A,2SA 4
42619203
· RES. 619 OHM 1% MK-3S0PPM
.R18B 2 .
42274403 · RES. 27.4K 1% MK-3 S0PPM
R18C 2
42357403
RES. 35.7K 1% MK-3 S0PPM
R19A,198,40
5
42332203
RES ~332 OHM 1% MK-3 50PPM
R21,29,32A,32B
6 42200205
RES. 200 OHM+/-1%· MK8 S0PPM
R22A,22B
4 42681303
RES. 6.81 K 1% MK-3 SOPPM
R24.27B.35,36,42,43
8
42100505
RES.100K 1% MK-8 S0PPM
R30 i
42392303
RES. 3.92K 1% MK-3 SOPPM
R31A,31B
4
42221303
RES. 221K 1% MK-3 SOPPM
R31C . 2
42237303
RES. 2.37K 1% MK-3 SOPPM
R310 2
42287303
RES. 2.87K 1% MK-3 SOP PM
R33 1
42158513
· RESa 158K 1% MK-450PPM
R34A;348
2
42392403
RES. 39.2K 1% MK-3 S0PPM
R37 1
42499303
RES. 4.99K 1% MK-3 S0PPM
R38A,61 3
42150403
RES. 15K 1% MK-3 SOP PM
R388 1 42432503
RES. 432K 1% MK-3 SOPPM
R39 1
42280513
RES. 280K1% MK-4 S0PPM
R41 1 43100002 RES: 1 OHM 2W 5% W.W.
R44,45 2
42100703
RES.10 MEG 1% MK-3 S0PPM

PARTS UST
As of AUG 16 93
PRODUCT: SP9MKIII NOTES:
Schematic Symbol Quantity ARC
Part# Description
R48 1 42324403 RES.
32..K 1% MK-3 S0PPM
R49 1 42100603 RES. 1
MEG 1% MK-3 50PPM
RSO
41100702 RES. 10 MEG 1/4W 5%
R51
42100303 RES. 1K 1% MK-3 SOPPM
R52 1 42511303 RES. 5.
11 K 1% MK-3 50PPM
R53;54,57
6 42499203 RES. 499
OHM 1% MK-3 S0PPM
R58 2 42464303 RES. 4.
64K 1% MK-3 S0PPM
R59A,598 4 42182303 RES. 1.82K 1% MK-3 50PPM
R60A,608,60C,60D 8 42100203 RES. 100 OHM 1% MK-3 S0PPM
RV CONTROLS
RV1 1 45100528 1 OOKDUAL GAIN POT
RV2 1 45100529 100KDUAL BALANCE POT
RY RELAYS
RY1
2 64101000 RELAY,
12V REED S1 P 1200 OHM
SW SWITCHES
SW1 1 24100730 TOGGLE SWITCH
Sil VER. SATJN
SW2,3,4 3 24100430 TOGGLE
SWITCH GOLD, SA TIN
SWS 1 24000700 5 POS MOOESWITCH,SP11
SW6 1 24002200
SWITCH,5POS.SOURCE
T TRANSFORMERS
T1
. 1 60007700
XFR SP9/14 {120V) TOROID
u INTEGRATED CIRCUITS
U1 1 31002200 MC34071P
U2 ,3 2 . 31000800 NE555N TIMER
U4 1 31001900 J FETINPUTOP-AMP
v VACUUM ruses
V1,2
2 32001150 VAC.TIJBE6922 RUSSIAN
VR
VOLTAGE REGULATOR
VR1
1 31002000 MC7815CT
2D
ZENER DIODES
201 2 30504400 IN52408
. 202
2 30501800 IN52458
203
1 30504210 IN5535A (KNOX ONLY}
ZD4 1 30500300 IN4740A
ZD5,6 2 31000703 LM329DZORANGE
207
1 30503500 IN5359.B
208,9,10 3 30503700 DIODE. 220 1 O"/o

PARTS LIST
As of AUG
1693
PRODUCT: SP9MKIII NOTES:
Schematic Symbol
Quantity
ARC Part#
Description
C CAPACITORS
C1,2,10,11 8 53560103 CAP. 56
PF+/-2°/o 630V DPN
C3 2 53100101. CAP. 10 PF +/-1 PF 630V PPN
C4 2
53150202 · CAP. 150
PF 2 112% 630V PPN
cs 2 53270101 CAP. 27 PF+/-1PF 630V PNP
C6,12 4 53500607 CAP. 5
UF200V
Cl
2 53156400 CAP
•. 0156 UF +/-2% 630V
ca
2 53480300 CAP. :0048 UF+/-2%
630V
C9 2 53470514 CAP. 0.47UF400V MIT
C12,28,29 6 53100412 CAP
•. 01UF600V ·
C13,40 2 .. 50100802 CAP. 100 UF 450V
C14,15,16, 19,37
5 53220507 CAP• .22
UF 10%160V
C17,33,32,34
4 53100406 CAP
•. 01UF+/-10"/4630V
C18,20 2 53200602 CAP. 2 UF +/-10"/4 450V
C21
1 50150904 CAP. 1500
UF 35V ·
C22,23 2 53220506 CAP•.22 MFO 1 OOV
C24 2 51330702 CAP. 33 UF+/-10"/o 16V
C25,26 2 52500300 . CAP: .005
UF 20% CERAMIC DISC
C27 2 52100300 CAP. 1000
PF 20% 1000V .
C31,39 2 53100608 CAP. 1.0
UF 1-20% 425VTYPE V
C35 . 2 52680000 CAP. 6.8
PF +/-1J2PF1000V
C36 2 53560201 CAP. 560 PF+/-2.5%. 630V
C38 1 53100505 CAP
•. 1 UF 10% 63V
D DIODES-
01,2,3,4
4 30502200 IN4006
05,6,7,8
4 30500400 IN4005 GENERAL INSTRUMENT
09-19
16 30500910 lN916B
F FUSES
F1(120) 1 34500250 FUSE. MOO
6/1 oA
F1(240) 1 34500121 FUSE. MOO
3/1 O SL BL220
J CONNECTORS
Jl-10
20 23202101 GOLD PHONOJACK.SD.CONN.
L INOUCTOR.S
L1,2,3 3 61000160 CHOKE, 2.7 UH +/- 10%
LE
PANEL INDICATOR
LEl
1'
34300102
LED. COLLAR & RETAINING A.ING