Audio research PH8 User Manual

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Owner’s Manual

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Model

PH8

Phono Preamplifier

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Contents

Model PH8 Phono Preamplifier

Illustrations 4

Preface 5

Warnings 5

Packaging 5

Front Panel Controls 5 – 6

Remote Control Functions 6

Connections 6

Installation Instructions 6 – 7

Operating/ Start-up Procedure 7

Servicing 7

Cleaning 7

Disposal and Recycling Guidelines 7

Warranty Terms and Conditions 8

Specifications 8

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Preface

Please take the time to carefully read
this instruction manual prior to installation
or use of your PH8 phono preamplifier.
Because it is a highly advanced
electronic instrument, there are several
facts and procedures you should know
before you place it in operation.
Just as you would not purchase and
attempt to operate an expensive
camera, computer system or high­performance automobile without first
learning something about performance
parameters and correct operating
procedures, so too your phono
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.

Warnings

1.To prevent fire, or shock hazard, do not

expose your PH8 to rain or moisture.

2.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 qualified
personnel.

3.The power cord on your PH8 is
equipped with a standard three-prong
grounding plug. For absolute
protection, do not defeat the ground
power plug. This provides power line
grounding of the PH8 chassis to
provide absolute protection from
electrical shock.

4.For continued protection against fire
hazard, replace the fuse only with the
same type and rating as specified at
the fuse holder.

DO NOT ATTEMPT TO
OPERATE THIS
EQUIPMENT BEFORE
INSTALLING THE VACUUM
TUBES IN THEIR PROPER
SOCKETS.

Packaging

Save all packaging in a dry place away
from fire hazard. Your PH8 phono
preamplifier is a precision electronic
instrument and should be properly
cartooned 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 PH8
from unnecessary damage or delay.
Note that your PH8 has been shipped
with the vacuum tubes installed in a
protective foam blocks under the top
cover. With the PH8 unplugged, use a
phillips-head screwdriver 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 blocks
with your carton.

Front Panel Controls

POWER ON/OFF: The unit is off when no

front panel lights are lit; unit defaults to
‘off’ whenever it is unplugged and then
plugged in. Press the Power switch to
turn unit on: display will light and after
approximately 30 seconds the mute light
will stop flashing and stay on
continuously (along with the power light

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and chosen cartridge loading value)
indicating unit is ready to play.
MUTE: After unit is on and warmed up for
at least 30 seconds, the unit defaults to
mute position indicated by continuously
lit Mute on the display. Pressing the Mute
switch once so Mute is unlit unmutes the
PH8 for play and Operate appears on
the display; pressing the Mute switch
again lights Mute and mutes the PH8.
MONO: Unit defaults to stereo at turn on.
Pressing the Mono switch selects
between stereo and mono operation, as
indicated on the display.
LOAD: Pressing the load switch allows
the user to step through five pre-set
cartridge loading options (47K, 1000,
500, 200, and 100 ohms) with the number
on the display lit for the currently
selected load value. It is suggested that
you select the loading value nearest the
cartridge manufacturers loading
recommendation to begin with and
then listen to alternate loading if desired.
Because all four PH8 front panel
functions are duplicated on the remote,
you may listen to loading sonic changes
from the listening position by repeatedly
pressing the Load button to scroll
through the values. (Note that
depending on the phono cartridge the
volume level may decrease as lower
loading values are selected.)

Remote Control Functions

In addition to all of the front panel
functions, the remote also accesses the
following functions:
DISPLAY: Pressing the display button on
the remote allows you to scroll through
and select from eight levels of display
brightness as well as turning the display
off.
HOURS: Pressing the hours button on the
remote will activate the total
accumulated tube hours on the display
for about seven seconds and then return
to the default load value function.

Connections

INPUT CONNECTORS: There is one set of

RCA input connectors, which should be

connected to your turntable/tonearm
cable.
OUTPUT CONNECTORS: There is one set of
RCA output connectors which should be
connected to line inputs (Direct, Aux,
Spare, Tuner, etc.) of your line
stage/preamplifier. Single ended RCA-to
balanced adapters are available from
Audio Research allowing the PH8 to be
connected directly to a balanced input
preamplifier using single ended RCA
interconnects.
All input/output connectors are gold
plated and connect ‘ground’ before
‘hot’. On disconnect, ‘hot’ is
disconnected first.

Note: A ‘passive’ line stage is not
recommended for use with the PH8 as it
will not provide the gain necessary to
amplify the output of the PH8 to
adequate levels to the power amplifier.

Installation Instructions

While the PH8 does not dissipate an
unusual amount of heat, it is important
that it have a reasonable airflow to
assure long, trouble-free operation.
In addition, the following installation
guidelines will help insure maximum
sonic performance as well as reliable
service.

1.Upright and horizontal mounting is
required if extended operation (longer
than one hour) is contemplated.

2.Do not ‘stack’ the PH8 on top of other
equipment: not only could this cause
overheating, but ‘hum’ may be
introduced into the phono circuits
from the proximity of the power
transformer of the other equipment.

3.Do not place or operate unit on a soft
or irregular surface such as a rug. This
will prevent proper ventilation.

4.Do not operate unit without the top
and bottom covers installed. These are
required both for safety as well as
shielding from interference (except in
service operations).

5.If side-by-side mounting with other
equipment is employed, place the PH8
to the left of the other chassis, so as to
provide maximum spacing between

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the transformer of the PH8 and the
other component.

6.In a cabinet or rack-mount installation
which has an enclosed back, an
exhaust fan is desirable so as not to
operate the PH8 in overheated ambient
air. Operation of vacuum tube
equipment for long periods of time in hot
ambient air will shorten tube life and
increase chance of failure of other
component parts.

Operating/Start-up
Procedure

1.Secure connections between

turntable, PH8, and line stage
preamplifier. Note: Given the
advanced performance capabilities
of the PH8, it is extremely important
that high-quality interconnects be
used for connection to ancillary
electronics.

2.Plug 3-prong power cord into a
grounded AC wall receptacle.

3.Turn Power switch ‘on’. The display will
light and Mute will flash for
approximately 30 seconds while the
power supply stabilizes, indicating
operation of the automatic muting
circuit. After this warm-up period Mute
will stay on and the cartridge loading
value will appear, indicating the PH8 is
ready for operation.

4.Unmute PH8, select proper cartridge
loading and play.

Note: For superior sonic performance, a
warm-up period of at least one hour is
recommended.

Servicing

Because of its careful design and
exacting standards of manufacture,
your PH8 should normally require only
minimal routine service to maintain its
high level of performance.

CAUTION: Your PH8
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 vacuum tubes inside your PH8 are
6H30 dual triodes and a 6550C. With
normal use they should last
approximately 2,000 to 4,000 hours.

Cleaning

To maintain the visual appearance of
your PH8 phono preamplifier,
occasionally wipe the front panel and
top cover surfaces with a soft, damp
(not wet) cloth 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. A dry 2-inch pure bristle paintbrush
works well to remove dust from bevels,
reliefs and switches.

Disposal and Recycling
Guidelines

To dispose of this electronic product, do
not place in landfill. In accordance with
the European Union Waste Electrical
and Electronic Equipment (WEEE)
directive effective August 2005, this
product may contain regulated
materials which upon disposal require
special reuse and recycling processing.
Please contact your dealer or importing
distributor for instructions on proper
disposal of this product in your country.
Or, contact Audio Research Corporation
(763.577.9700) for the name of your
importing distributor and how to contact
them. Packing and shipping materials
may be disposed of in a normal manner.

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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
responsibility 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 information
necessary for return shipment. The cost
of return shipment is the responsibility of
the purchaser.

Specifications

FREQUENCY RESPONSE: ± .2dB of RIAA, 10Hz

to 60kHz; 3dB points below 0.3Hz and
above 400kHz.

DISTORTION: Less than .005% at .50V RMS 1kHz

output.

GAIN: 58dB at 1kHz (MC & MM compatible).
PUSH BUTTONS: Power, Mono, Load, Mute.
INPUT IMPEDANCE: Selectable 47K, 1000, 500,

200, or 100 ohms with 200pF Unbalanced.

OUTPUT IMPEDANCE: 200 ohms Unbalanced.

Recommended load 50K-100K ohms and
100pF. (10K ohms minimum and 2000pF
maximum.)

OUTPUT POLARITY: Non-Inverting.
MAXIMUM INPUTS: 70mV RMS at 1kHz (180mV

RMS at 10kHz).

RATED OUTPUTS: .50V RMS 10Hz to 60kHz, 100K

ohm load (output capability is 50V RMS
output at 1/2% THD at 1kHz).

POWER SUPPLIES: Electronically-regulated low

and high voltage supplies. Line regulation
better than .01%.

NOISE: 0.2uV equivalent input noise, IHF

weighted, shorted input (74 dB below 1mV
1kHz input).

TUBE COMPLEMENT: (2) 6H30 dual triodes with

JFET input. 6550 and 6H30 as HV regulators.

POWER REQUIREMENTS: 100-135 VAC 60Hz

(200 - 270VAC 50/60Hz) 80 watts maximum.
Line fuse 3A slo blo (1.5A slo blo 230V).
Standby: Less than 1 watt.

DIMENSIONS: 19" (47 cm) W x 5.22" (13.2 cm)

H x 12.0"

(30.5 cm) D. Rear chassis fittings extend 0.6"

(1.5 cm).

WEIGHT: 15 lbs. (6.8 kg) Net; 23 lbs. (10.5 kg)

Shipping.

Specifications subject to change without notice.
©2010 Audio Research Corporation.

3900 Annapolis Lane North

Plymouth, MN 55447

763.577.9700

www.audioresearch.com