Owners Manual
Model 150.2
audio research
3900 ANNAPOLIS LANE NORTH / PLYMOUTH, MINNESOTA 55447-5447 | PHONE: 763-577-3700 FAX: 763-577-0323
Model 150.2
Section Page No.
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Model 150.2
judio researc
MODEL 150.2
© © ©
800 WATTZ 50/60 HZ ~
O |
150 WPC 802, 300 WPC 442.
150K SE, 300K BAL DIFF
PIN 1 GND, PIN 2+, PIN 3-
MODEL 150.2
audio research
@ ©
Model 150.2
Please take time to carefully read and understand the
following instructions before you install or attempt to oper-
ate this equipment. Becoming familiar with the product
and its correct operating procedures will help assure you of
maximum musical enjoyment and reliable operation. The
effort you invest now will be well rewarded in the years
1. To prevent fire or shock hazard, do not expose this
product to rain or moisture.
2. This unit operates on voltages which can cause serious
injury or death. Do not operate with covers removed.
Any necessary servicing should be carried out by your
authorized Audio Research dealer or other qualified
3. The 14 gauge, 3-conductor power cord on this unit is
equipped with a standard 3-prong grounding plug. If
used normally, it will provide a safe earth ground
connection of the chassis. Refer to section on “AC Power
Connections” for detailed information.
4. For safe operation and protection against fire hazard,
replace fuses only with those of the same type and
rating of fuses as specified.
Save all packaging accompanying this product. You have
purchased a precision electronic instrument, and it should
be properly cartoned any time shipment becomes neces-
sary. It is very possible that this unit could be damaged
during shipment if repackaged in cartoning other than that
designed for it. The original packaging materials help pro-
tect your investment from unnecessary damage, delay and
added expense whenever shipment of this unit is required.
The 150.2 is packed within two cartons (inner and outer)
which have foam supports in between. Because of the
weight of the unit and because it is a precision electronic
instrument it is necessary to take reasonable care during
unpacking and preparation for use.
It is best to have a large, open work area with available
help. Set the carton upright in the center of the work area
and with a small knife carefully slit the taped edges of the
outer carton's top flaps. Fold the flaps to the sides and
while holding the inner carton in place, roll the unit upside
down. You can now lift the outer carton off and set it and
the filler panels aside. Now slit the inner carton's taped
seams on the bottom (now facing upward). Again, fold the
flaps over and while holding the unit in, roll it over as
before. You can now lift the inner carton off to find your
150.2 sitting upright, undamaged and uncartoned. Carefully
remove the plastic wrap. Now, while it is fresh in your
mind, reassemble the carton system for future use.
Spare Fuses:
2 —7 Amp MDX slo-blo (100 & 120v)
2 — T4A Amp slo-blo (220-240V)
Description of Controls
The front panel has:
1 Power line On-Off switch
1 Power “On” LED (Green) indicator
POWER ON-OFF SWITCH: Press the black rocker switch
to initiate or terminate AC line power to the amplifier.
When the LED is illuminated the amp is “on” and ready to
The rear panel has:
2 — RCA input connectors, for single-ended connections,
2 — XLR input connectors, for balanced connection, L & R
4 — Output binding posts, (+) and (-), L & R
1 — Power line fuseholder
1 — Power line cord IEC connector for removable power
cord (supplied)
2 — 12V remote start in and out jacks
2 — Switches for XLR or RCA input operation, L & R
IMPORTANT: Use the best available speaker wires and in-
terconnects. As your system improves in resolution from
the addition of quality components, it becomes increasingly
important to avoid the limitations of inferior system inter-
connections. We recommend Audio Research LitzLink 2®
interconnects and LitzLine 2® speaker cables.
It is important sonically that your entire system be con-
nected so that the audio signal arriving at the speakers has
correct absolute polarity or phase (i.e. is not inverted).
Connect the black or (-) speaker terminal to the wire that
connects to the appropriate-channel (-) gold binding post
on the amplifier. Connect the red or (+) speaker terminal to
the wire that connects to the appropriate-channel (+) bind-
ing post on the 150.2. Tighten the binding posts firmly to
assure good contact for best sonic results.
Model 150.2
For “bi-wired” loudspeaker systems (i.e. running separate
wires to bass and treble speaker terminals), simply repeat
the above instructions, taking care that all connections
have the same (+) or (-) polarity.
AC POWER CONNECTIONS: It is essential that the 150.2
amplifier be connected to a wall AC power receptacle, or a
similar heavy-duty source. If it is connected to convenience
receptacles on preamplifiers, etc., the full sonic
capabilities of both the amplifier and the preamplifier will
be compromised. The AC power source for the amplifier
should be capable of supplying 15 amperes for 100 or 120
volt units, or 8 amperes for 220 or 240 volt units.
For the very best performance on domestic 100 or 120 volt
circuits, the 150.2 should be connected to its own AC pow-
er circuit branch protected by a 15 amp breaker. The pre-
amplifier and other audio equipment should be connected
to a different power circuit and breaker. Avoid the use-of
extension cords. If they must be used on a temporary
basis, use 14-gauge or heavier cords.
The 150.2 utilizes a compatible grounding system that gen-
erally does not require a “ground lifter” adapter plug on the
AC power cord to minimize hum. The power cord on your
150.2 has a standard three-prong grounding plug to provide
maximum safety when it is connected to a grounded wall
receptacle. If there is any question regarding the safety of
grounding procedures, be certain to seek competent help
with the installation. Do not substitute a lighter gauge
power cord for the one supplied with this unit.
If electronic crossovers or other AC powered equipment is
used with the amplifier it may be necessary to use “ground
lifter” adapters on the power plugs of that equipment to
minimize system hum. Generally, the lowest hum is
achieved when the only direct connection between audio
common “ground” and true earth ground occurs in the
preamplifier, through its grounded power cord. Other
equipment in the system should have some form of
isolation to prevent ground loops and associated hum.
Always place the Power On-Off switch on the front of
the 150.2 in the “Off” (left) position before connecting
the power line cord to AC power.
Single-Ended Operation
Single-ended inputs should be used with a preamplifier (or
electronic crossover, etc.) having single-ended outputs
which does not invert overall phase or polarity. When
using single-ended inputs, set two rear-panel toggles to SE
position. Disconnect any balanced cables.
Balanced Operation
Balanced inputs can be used with a preamplifier (or
electronic crossover, etc.) having balanced outputs. When
using the balanced inputs, set two rear-panel toggles to
BAL position. Disconnect any single-ended cables.
The amplifier may be installed in a ventilated cabinet;
observe the following guidelines to maximize the perfor-
mance and service of your amplifier.
With proper installation, the 150.2 may be left on continu-
ously for maximum performance on demand; it will draw
approximately 40 watts of AC power at idle. However, the
150.2 has been designed and engineered to minimize any
“warm up” necessary for best sonics; generally, a half-hour
or 45 minutes of actual playing time will bring the amplifier
around to more than acceptable performance levels, with
some additional improvement noticeable over the next
hour or two. Warm-up characteristics will depend upon
ambient room temperature at start-up, the nature of the
installation and the resolving power of the associated
Operate the 150.2 only in a horizontal (upright) position.
Adequate airflow and proper cooling can be maintained
only if there is no restriction around the unit.
The four (4) non-marring feet provide adequate spacing and
mechanical damping only from a smooth, hard surface.
Never operate the unit while it is sitting on a soft, irregu-
lar surface such as a rug or carpet.
If the unit is to be operated in an enclosure such as an
equipment rack, make certain that adequate air flow above
and below the unit is provided. The “ambient” operating
temperature should never exceed 120° F or 49° C. Improper
installation will cause premature component failure and
will affect your warranty, as well as the service life of
the unit.
It is normal for the 150.2 power amplifier to run moderate-
ly warm to the touch. All components within are operated
at safe, conservative levels and will not be improperly
affected, providing the requirements outlined above are
adhered to.
Remote Turn-on Connections
The 150.2 has a built-in 12VDC remote turn-on/off circuit
for operation by a master control system in a home theater
or large audio system. Use a 3.5mm (.140") diameter mono
mini plug to connect to the +12V IN jack on the rear of the
Model 150.2
150.2. Two identical paralleled jacks are provided to
allow chaining connections to control two or more 150.25
or other equipment.
The +12V IN jack should be connected to the +12VDC
output of the master control system, using a continuous
+12VDC signal at 20mA per 150.2 for the duration of
amplifier on-time. Do not use a momentary or data pulse
control signal.
The front power rocker switch on the 150.2 must be off to
use the remote turn-on. The front power rocker switch may
still be used when the remote turn-on is connected, but the
remote will not turn the 150.2 off if the front power rocker
switch is left on. The front power rocker switch will not
turn the 150.2 off if the remote system is on.
The +12VDC remote jacks have polarity protection, so they
- Will not operate if a -12VDC signal is accidentally connect-
ed, or if the control wires are reversed. The 12V remote
“relay in the 150.2 has click suppression to protect circuits
in the master control system.
Operating Procedure
1. Make sure you have read and followed the INSTALLA-
TION and CONNECTION instructions prior to
attempting operation.
2. Make sure the amplifier is properly connected to a high-
current AC power receptacle via the supplied power cord
3. Your preamplifier should be “On” and muted and/or set
at minimum gain.
4. Turn Power switch from “Off” to “On”. Unit is ready to
play when LED is on. Note: if the power indicator LED
fails to light, turn the Power switch to “Off” and check
the appropriate fuse for possible failure. Extra fuses
for AC power are included with the unit. (On turn off,
the green LED will stay on for a few seconds before
5. Your amplifier should now operate satisfactorily. It may
be played immediately, although best sonic performance
will in most cases not be achieved for an hour or so (see
INSTALLATION for further details.)
Start-Up Following “Protect” Shutdown:
The 150.2 amplifier uses a sophisticated, non-fused sensing
circuit to protect the amplifier from DC at the input, from
thermal overload, and from shorting conditions at the out-
put (e.g. defective speaker leads, etc.). This circuit also
helps prevent damage to your loudspeakers.
When the amplifier senses a fault condition in either chan-
nel from excessive DC or excessive current output, it will
automatically shut off left and right outputs from the
amplifier, and indicate this condition by extinguishing the
green power LED. To resume normal operation, turn off
power to the amplifier for at least 30 seconds to reset the
protection circuits. Check for faulty signals from the pre-
amplifier, or processor and turn the amplifier power on.
If the amplifier fails to resume normal operation after
attempting resetting due to a fault condition, contact your
authorized dealer for further assistance. Normal operation
can be verified by illumination of the green LED on the
front panel.
Because of its careful design and exacting standards of
manufacture, your 150.2 amplifier should normally -
require only minimal service to maintain its high level
of performance.
CAUTION: The 150.2 amplifier contains sufficient levels of
voltage and current to be lethal. Do not tamper with a
component or part inside the unit. Even with the power
turned off, a charge remains in the energy storage capaci-
tors for some time. Refer any needed service to your
authorized Audio Research dealer or other qualified
Additional questions regarding the operation, maintenance
or servicing of your amplifier may be referred to the Cus-
tomer Service Department of Audio Research Corporation
at 763-577-9700 (CST). When ordering a service manual
from Audio Research or an authorized dealer, be sure to
identify the serial number on your amplifier.
To maintain the new appearance of this unit, occasionally
wipe the front panel and top cover with a soft, damp (not
wet) cloth to remove dust. A mild, non-alkaline soap solu-
tion or dilute isopropyl alcohol may be used to remove
fingerprints or similar smudges. Cleaners containing abra-
sives should not be used as they will damage the anodized
finish of the front panel. A small, soft paint brush is effec-
tive in removing dust from bevels, the recessed nameplate
and other features of the front panel.
Model 150.2
Limited Warranty
Audio Research Corporation products are covered by a 3-
Year Limited Warranty, or a 90-Day Limited Warranty
(vacuum tubes). This Limited Warranty initiates from the
date of purchase, and is limited to the original purchaser, or
in the case of demonstration equipment, limited to the
balance of warranty remaining after original shipment
to the retailer or importer.
In the United States, the specific terms, conditions and
remedies for fulfillment of this Limited Warranty are
listed on the warranty card accompanying the product in
its shipping carton, or may be obtained from the authorized
retailer or from the Audio Research Customer Service
Department. Outside the United States, the authorized
importing retailer or distributor has accepted the responsi-
bility for warranty of Audio Research products sold by
them. The specific terms and remedies for fulfillment of
the Limited Warranty may vary from country to country.
Warranty service should normally be obtained from the
importing retailer or distributor from whom the product
was purchased.
In the unlikely event that technical service beyond the
ability of the importer is required, Audio Research will
fulfill the terms and conditions of the Limited Warranty.
Such product must be returned at the purchaser's expense
to the Audio Research factory, along with a photocopy of
the dated purchase receipt for the product, a written
description of the problem(s) encountered, and any infor-
mation necessary for return shipment. The cost of return
shipment is the responsibility of the purchaser.
POWER OUTPUT: 150 watts per channel into 8 ohms,
300 watts per channel into 4 ohms, both channels driven,
1% THD.
POWER BANDWIDTH: (-3dB Points) 5Hz to 40 kHz into
8 ohms, or 4 ohms.
FREQUENCY RESPONSE: (-3dB points at 1W) 5HZ to
120 kHz
INPUT SENSITIVITY: 1.4V RMS for rated output (27 dB Gain)
single-ended or balanced.
INPUT IMPEDANCE: 150K ohms single-ended, 300K ohms
balanced differential.
OUPUT POLARITY: Non-inverting from single-ended inputs.
Balanced pin 2+ (IEC-268).
OUTPUT REGULATION: 0.05dB 8 ohm load to open circuit
(Damping factor 200).
OUTPUT CURRENT: 20 amps peak at protective shutdown.
SLEW RATE: 15 volts/microsecond. (20% maximum duty
RISE TIME: 2.0 microseconds.
HUM & NOISE: 500 microvolts RMS (96dB below rated
output IHF A-weighted).
50Hz) 380 watts at rated output (150WPC 8 ohms), 750 watts
at 300WPC 4 ohms, 800 watts maximum, 40 watts idle.
DIMENSIONS: 19" (48 cm) W (standard rack panel) x 51/4"
(13.3 cm) H x 141/4" (36.2 cm) D (front panel back). Handles
extend 11/2" (3.8 cm) forward of the 1/4" thick front panel.
Output connectors extend 0.9" behind rear panel.
WEIGHT: 30.3 Ibs. (13.8 kg) Net; 43.3 Ibs. (19.7 kg) Shipping.
Specifications subject to change without notice.
©2003 Audio Research Corporation.
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