Manley STEELHEAD User Manual

MANLEY

LABORATORIES, INC.

OWNER'S MANUAL

MANLEY STEELHEAD

Version 2

MM/MC GRAMOPHONE CARTRIDGE PREAMPLIFIER

MANLEY LABORATORIES, INC

13880 MAGNOLIA AVE.

CHINO, CA. 91710

TEL: [phone]
FAX: [phone]

[e-mail]

http://www.manleylabs.com

Rev. 8-24-2004 LH

CONTENTS

SECTION PAGE

INTRODUCTION 3

INSTALLATION PRECAUTIONS 4

FEATURES AND APPLICATIONS 5

OPERATIONAL NOTES 9

TROUBLESHOOTING 12

SPECIFICATIONS 14

WARRANTY 15

WARRANTY REGISTRATION 16

INTRODUCTION

THANK YOU!...

...for choosing The MANLEY STEELHEAD phono preamplifier. Please read over this
manual carefully as it contains information essential to the proper operation and maximum enjoy­ment of this fabulous instrument.

The MANLEY STEELHEAD is designed to provide that rare combination of maximized
sonic performance coupled with a generous ability to adapt to any moving magnet, moving coil or
iron vane phono cartridge you may wish to use. With the STEELHEAD’s feature compliment,
you no longer have to settle for what a given cartridge sounds like with a fixed predetermined
preamp load impedance, or wonder what that same cartridge might sound like when presented
with different loading arrangements. What best suits your particular phono cartridge, system,
listening room and personal preference is now merely a flick of a switch away! The STEEL­HEAD adapts to accommodate your situation, rather then the other way ‘round.

To this end you will notice that it is the anticipation of your preamplifier needs which has
driven every detail of the STEELHEAD’s planning, engineering, styling, operating convenience
and adaptability.

UNPACKING

Unpack the preamplifier carefully and make sure that all supplied accessories are present.
Examine all items for any possibility of shipping damage. All six tubes should be standing at
attention in their sockets. If the unit is damaged or fails to operate, notify the shipper or your
dealer or us or your local authorities immediately. Or if you suspect The Shipping People threw it
off the airplane and onto your front porch whilst flying overhead at 30,000 feet, notify the ship­ping company without delay and complain to them as we only guarantee this unit to be able to
survive a drop of 23,487 feet or less.

Your STEELHEAD was packed by Manny Q. with extreme love and each box includes the
following components and accessories:

a) 1 each, 6 foot IEC 3-conductor mains power cable (that you will probably replace with an
expensive audiophile cord anyway.)

b) 1 each, Owner’s Manual per pair (that we hope you will keep reading.)

c) 1 each, Outboard Power Supply Unit with captive grey power cable and big fat connector.

It is prudent to retain the shipping materials for future use, as they are custom-formed for the
preamplifier and will greatly minimize the chance of shipping-related damage should you ever
need to put your precious Steelhead in the careless hands of The Shipping People again.

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INSTALLATION PRECAUTIONS

a) Avoid locating the preamp where it will be exposed to direct sunlight, excessive humidity, dust or moisture.

Extreme environments may temporarily or permanently degrade preamp performance.

b) Keep the preamp housing away from sources of strong magnetic field radiation, such as large video display

CRTs, large power lines or power/audio transformers in nearby equipment. Extra measures have been taken to
shield the magnetically sensitive bits inside the preamp housing. Nevertheless these measures can be
overwhelmed by strong outside influences. Keep in mind that the tiniest disturbance along with the desired
signals will be amplified many hundreds or thousands of times.

c) Locate the preamp away from heat-radiating sources, such as other large amps, political demagogues or

space-heating equipment.

d) Make sure the preamp and power supply is off before making any system connections. Do not remove or

insert the large 16-pin circular power supply connector when the power supply mains switch is in the on (|)
position. Do not hot plug the system.

e) Dissipate any static electric charge build-up on your body by touching the enclosure before making or

changing any system connections. The preamp electronics are fairly robust as far as immunity to damage from
static charge is concerned, but total immunity cannot be had without unacceptable compromise of audio
performance.

f) Be careful to feed only low-level phono cartridge signals to the preamp input connectors. Sustained line-level

signals above 15 volts peak may cause damage to sensitive MC input stages even when the preamp is in the
standby mode or when the power is off.

AC VOLTAGE SELECTION

The STEELHEAD system may be set to operate on either 117 or 234 volts A.C. by means of a rotary switch
located on the power supply P.C. board. The power supply's mains-voltage selector switch is normally preset to the
mains voltage at the customer's location prior to shipment. If, however, the preamp provenance is unknown then the
mains-voltage selector switch should be checked and reset to the correct voltage if necessary. The mains fuses must
also be checked for proper ratings and changed if necessary. Failure to correctly set the mains selector switch or use
properly rated fuses can cause extensive damage to the system which is of course not covered by the warranty.
The mains fuse may be checked by first disconnecting the IEC mains cord from the power supply’s power inlet plug.
Then gently press the small leaf spring on the side of the rectangular gray fuse retainer cap. The fuse and cap should
spring outward toward your fingers. Inspect the fuse for the proper rating; change if necessary. Refer to the fuse-rating
chart in the specifications section of this manual.

To inspect or adjust the mains-voltage selector switch it will be necessary to remove the top cover of the
power supply enclosure. For this you will need a #1 Philips screwdriver, and a 3/16 inch flat blade driver to change
the selector switch setting.

Before opening make sure that the power supply is unplugged from mains power and the STEELHEAD
preamp. Once inside you will see tall cylindrical high voltage energy-storage capacitors, which can be a shock
nuisance even when the supply is not energized. Therefore, if the supply has been recently power cycled, let the
supply capacitors discharge for 15 minutes prior to opening. Then remove 8 Philips 4x40 retaining screws from the
cover, followed by the cover. Locate the voltage selector switch near the mains power entry / fuse / power switch
module. The switch face is the black round object, about 1/2 inch in diameter, with white voltage numbers “110” and
“220” on the rotor and a white triangular selection indicator on the stator. Notice that the “110” and “220” markings
on the switch should not be interpreted as being the precise voltage needed to operate the preamp system. Using the 3/
16 inch screwdriver rotate the switch, if necessary, so that the mains voltage you intend to feed the power supply lines
up under the selection indicator. Be sure to replace all screws when reassembling.

Page 4

FEA TURES AND APPLICATIONS

1. HIGH PERFORMANCE FRONT END

The STEELHEAD preamplifier makes the best use of active and passive component and
circuit developments generated over the past half-century. The hybrid cascode gain blocks
simultaneously deliver wide-band high-gain, low noise and low distortion performance without
having to resort to heavy-handed amounts of negative feedback. Or overly complex circuit
topology. The multiplicative aspect of the cascoded device’s output (anode) impedance means that
the most important characteristics of each gain stage are preserved even though the local negative
feedback present in each block is very small. This approach makes the amplification factor of each
stage insensitive to tube gain or transconductance variations which occur due to device production
tolerance allowances or aging.

Other uncommon traits include high quiescent and operating current in each gain stage. This
lowers the static and dynamic impedances found within each stage and raises system bandwidth.
Musical material which would cause a cave-in of the typical current-starved 12AX7-based
preamplifier circuit are conveyed unflinchingly by these amplifier stages.

2. ACCURATE “4-CORNER” RIAA EQUALIZATION

In the spirit of high fidelity, all four RIAA phono equalization corner frequencies or time
constants have been specifically addressed in the STEELHEAD preamplifier. Historically most
designs have concentrated on the “big three” time constants of 3180, 318 and 75 microseconds.
This ignores the fourth corner of about 3.2 us, which when ignored causes most phono stages to
continue rolling off the highest octave signals coming from the phono pickup, rather than turning
the final “corner” and shelving to flat response at about 50 kHz. Careless removal of upper octave
bandwidth causes the recovered audio to become somewhat lifeless and remote, with needless loss
of impact, detail and percussiveness. Ironically this signal content is precisely what is omitted from
all currently popular digital audio delivery formats, and is one of the chief culprits behind the
homogenous upper octave sonic characteristics of those formats.

As with all equalizing amplifiers intended to correct a given form of frequency-selective
emphasis curve, care must be used when building the restorative compensation networks. Great
care must be exercised if the goal is to produce a highly accurate passive network coupled to low­feedback amplifiers. And experience has shown that the effort spent in faithfully adhering to the
inverse RIAA equalization curve produces results that easily justify the additional procurement and
manufacturing costs. To this end, only hand-selected and/or1% tolerance components are used
throughout the RIAA equalization network. Add to that the factory-set variable capacitors, and the
result is very high equalization accuracy where small component and circuit layout variations that
other manufacturers ignore are netted out. This yields impeccable inter-channel phase and gain
matching at any gain setting. In short, the STEELHEAD will magnify the differences in the
character and personality of your vinyl recording collection, cartridge, tonearm and turntable. A
microscope for the ear! Be prepared to hear previously undiscovered musical content as you play
back your favorites!

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