Manley Labs MM/MC GRAMOPHONE CARTRIDGE PREAMPLIFIER User's Manual
Contents
1. MANLEY STEELHEAD ys mS LABORATORIES 3880 MAGNOLIA AY CHINO CA 91710 CONTENTS SECTION INTRODUCTION INSTALLATION PRECAUTIONS FEATURES AND APPLICATIONS OPERATIONAL NOTES TROUBLESHOOTING SPECIFICATIONS WARRANTY WARRANTY REGISTRATION PAGE 12 14 15 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 enjoy ment 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 STEEL HEAD 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 STEE2. setting will ultimately depend on the cartridge in use type of music being heard other downstream equipment and most importantly your personal preference There will no doubt be moments when a technically wrong setting will be musically right for a given situation Do rest assured that in this instance a technically wrong setting is completely harmless for all equipment involved In the case of the MM input the typically higher cartridge output levels allow fixed resistor termination with clockwise most switch setting being the standard 47k ohm load resistance Those MM cartridges capable of properly driving low impedance loads between 25 and 400 ohms should be auditioned through both the MM and MC inputs By doing so you may find the most appropriate sonic character through the use of unconventional input arrangements In short experiment don t let the control labeling stop you On the contrary we invite you to tweak away 4 SWITCH SELECTABLE CARTRIDGE TERMINATION CAPACITANCE on the front panel yet Termination capacitance may be applied to each channel independently in 10 pF steps up to 1100 pico Farads The termination capacitance is present at the gain stage inputs and is not affected by input selector or gain switch changes For best accuracy consult your phono interconnect cable literature or manufacturer to determine how much of the termination capacitance may be attributed to the cable Then subtract at least that
3. amount from the target capacitive termination value If the interconnect manufacturer does not know the amount of capacitance per unit length that their wire presents then refer to the following example for a starting point Typical phono interconnect cables will exhibit self capacitance on the order of about 30 pF per foot If the interconnect cable is 3 feet 1 meter in length you may expect about 90 100 pF of input capacitance to be present due to the interconnect cable alone If the cartridge manufacturer specifies a load capacitance of 150 pF then it is best to subtract the cable s portion 1 90 pF This yields a balance of 60 pF Thus the audition should start with the termination capacitance switches set to 60 pF Page 6 Each cartridge manufacturer s product will work best in laboratory sense when terminated loaded with a certain amount of resistance and capacitance By lab sense it is meant that the signal developed by the cartridge is at maximum power transfer into the pre amp with minimum overshoot and ringing flattest frequency response and gentle roll off characteristics But it is those settings that create the most musically satisfying results for you that are of uppermost importance And your termination preferences may rightly deviate unpredictably from some lab based norm A good place to start is with those values recommended by the cartridge manufacturer less the interconnect cable capacitance A good defaul
4. and the wire link is present between the preamp s green CHASSIS and black CIRCUIT ground mini binding posts on the rear panel Try to position the power supply away from any interconnect cables which may be carrying audio signals BEFORE POWER UP Once placed join the power supply cable to the pre amplifier via the large16 pin circular connector The 16 pin connectors are keyed and can only be mated when both halves are lined up correctly Check and make sure the power supply is switched off then attach the grounded IEC power cable jack to the IEC plug Keep the power off until all other system connections are completed Proceed by connecting the input and output cabling to the signal sources and loads as desired Tie any separate turntable or tonearm ground lead to the gold CHASSIS ground binding Set the GAIN dB control to 55 dB and VOLUME control to about 9 o clock Choose the MM or an MC input as necessary with the INPUT control Place the LOAD Z switch to a value at or near that recommended by the cartridge manufacturer Adjust the LOAD CAP switches to a value at or near that recommended by the cartridge manufacturer less any interconnect cable capacitance Select and clean if necessary your favorite gramophone record Plug the power cable in and place the power supply s mains power switch in the on 1 position The STANDBY switch should glow Push the STANDBY switch The STANDBY switch will go dark selected INPUT and GAIN b
5. 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 t
6. undiscovered musical content as you play back your favorites Page 5 3 SWITCH SELECTABLE CARTRIDGE LOAD IMPEDANCE An effective means of varying the load seen by the MC cartridge has been included in the form of a 5 position rotary switch This switch selects various taps on a specially manufactured dual primary bi filar wound high bandwidth low resistance and multiple shielded nickel core step up autoformer A drama to make the autoformer permits the minute MC cartridge signal power to be efficiently and transparently transformed from low volts high current to high volts low current By avoiding conventional parasitic cartridge termination resistors none of the MC cartridge s tiny signal power is thrown away before amplification This results in improved system signal to noise ratio Quite worthwhile provided as in the STEELHEAD the autoformer has the necessary performance for the job This pivotal component has had engineering attention lavished upon it in the only way possible or practical The Manley Labs magnetics department In house transformer prototyping and manufacturing capabilities permit realization of extraordinary transformer designs You may now audition your MC cartridge at or near the manufacturer s specified loading resistance without sacrificing any signal power through a parasitic load resistor And explore the interesting tonal shifts caused by intentional mild or severe mis termination of the cartridge The right
7. 0 Hz to 100 kHz Inter channel differential phase Less than 4 degrees from 20 Hz to 20 kHz any gain setting Typically less than 2 degrees Inter channel differential gain Less than 0 5 dB from 20 Hz to 20 kHz any gain setting Dynamic Range 200 ohm source 47 k ohm input 55dB Gain Maximum Output Output impedance VARIable Output impedance GAIN setting Fixed Ouptut Vari O P MM Noise S N D N D 50 dB 86 dB 108dB 99dB 86dB 200 ohm source 47 k ohm input 55 dB 84 dB 108dB 99dB 85dB A weighted Referred to 2 54 mV 60 dB 80 dB 108dB 94dB 80dB rms kHz 65 dB 75 dB 108dB 89dB 75dB 9 00 12 00 V C FULL MC Noise S N D N D 50 dB 84 dB 108dB 98dB 85dB 100 ohm source 100 ohm input 55 dB 80 dB 108dB 95dB 81dB A weighted Referred to 0 5 mV 60 dB 75 dB 108dB 90dB 76dB rms 1KHz and rated input impedance 60 dB 70 dB 107dB 85dB 71dB 101 dB 1 kHz 1 THD 97 dB 1 kHz 0 1 THD 27dBm 1KHz with 3 THD into 100Kohm load 150 ohms Minimum suggested load greater than 1500 ohms 75 ohms Minimum suggested load greater than 600 ohms Page 14 WARRANTY All Manley Laboratories equipment is covered by a limited warranty against defects in materials and workmanship for a period of 90 days from date of purchase to the original purchaser only A further optional limited 5 year transferrable warranty is available upon proper registration of ownership within 30 days of date of first purchase Proper regi
8. ECT BUTTON The LINE switch routes external line level signals to the top of the feature switch stack and through the VOLUME control In this way an external signal source may be manipulated by the SUM DIM and MUTE switches along with the volume control before transmission to any downstream power amplifiers Notice here that the Steelhead s VARIable internal line driver does not have any voltage gain but does have power gain by virtue of its low output impedance Since most line level gear these days has plent of output level the last thing you probably need in your system is more gain Thus this LINE input allows you to run a CD player for instance into the Steelhead control the volume and let the Steelhead s Variable Outputs go drive your amplifiers Or if you have many LINE level sources you can run the output of another preamplifier or passive switching device such as a Manley SKIPJACK into the Steeelhead s LINE input It s novel Try it In addition when the LINE function is invoked the phono stage remains active and any cartridge signals present will appear in amplified form at the Steelhead s FIXED outputs Thus the preamplifier s dual signal paths may be applied simultaneously 1 listening to the LINE input signal while for example recording material from the phono stages When the LINE feature is not engaged the phono signals travel through the complete path normally as described for the line signal above Notice tha
9. HINO CA 91710 USA Or you may FAX this form in to 1 909 628 2482 or you may fill in the online warranty registration form found in the Tech Support section of our website www manleylabs com or you can be really diligent and register your warranty three times to see if we get confused Registration entitles you to product support full warranty benefits and notice of product enhancements and upgrades even though it doesn t necessarily mean that you will get them Just kidding You MUST complete and return the following to validate your warranty and registration Thank you again for choosing Manley gear and reading all the way through The Owner s Manual We really mean that sincerely the bit about thanking you for choosing our gear THANK YOU MODEL SERIALNo MODEL 4 4844 SERIAL PURCHASE DATE CM SUPPLIFR 4 40 88480840 NAME OF OWNER ADDRESS CITY STATE ZIP TELEPHONE NUMBER _
10. LHEAD 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 ship ping 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 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 Page 3 INSTALLATION PRECAUTIONS a Avoid locating the preamp
11. al triode CHASSIS GROUND CIRCUIT RFI SHUNT SERIAL ON OFF Please direct any questions to your dealer or MANLEY LABS for further assistance Page 11 TROUBLESHOOTING The STEELHEAD s system architecture is designed with a variety of features so as to allow flexibility in accommodating as many cartridges and as much downstream gear as possible Access to these capabilities rest on the assumption that all STEELHEAD systems are functioning properly If trouble is encountered please review the following short list of symptoms and corrective remedies before contacting your dealer or us Symptom NO lights power Power supply pilot ON HEAD not responding Dim badge lamps LEDs Possible Cause Corrective Action Bad mains fuse Replace with correct fuse Bad or unplugged Check cables and outlets power cable AC outlet not energized Rolling 1 Abandon California elect Libertarians 16 pin connector not seated Check for proper connection Mains Voltage selector Check for proper setting Weak output switch set to 220 V instead of 110 V Be sure of local mains voltage before changing switch setting Tube locator diagram RIAA amp board 7044 7044 Output heard in one channel only Weak or distorted Output in one channel 6922 6922 7044 7044 Bad tube in affected Alternate or replace suspect channel tube Bad tube in affected Alternate or replace suspect channel
12. aving 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 uppe
13. channel preferably with matching manufacturer and date code if possible Page 10 Let the preamp tube s cool down if necessary before handling Tube heater filaments are somewhat more suceptable to damage when warm or hot Each tube should require only moderate force for removal and replacement Gently rock the tube back and forth a bit during removal or replacement Avoid bending the circuit board Notice that the heaters of the 6922s are connected in series and neither channel will function if one of the filaments is open or burned out or unless both of the 6922s are installed Akin to those old Xmas tree lights in the attic no Be careful to straighten any bent tube pins prior to installation pin misalignment will make fitting the replacement tube difficult or impossible and may damage the socket Be careful to put replacement tubes in the proper sockets Never substitute other type numbers of 9 pin tubes without careful research There are literally thousands of types that share the 9 pin mechanical basing arrangement but NOT the internal electrical connections Mechanically compatible tube plugs and sockets by no means indicate electrical compatibility And random experimenting can easily and quickly destroy the substitute tube and other parts of the preamp Three tube types that are electrically and plug socket compatible with the 6922 dual triode are the 7308 6DJ8 and the ECC88 E88CC There is no direct replacement for the 7044 du
14. he 50 60 Hz power line hum frequencies It is of the utmost importance that cables handling the tiny signals from the phono cartridges be of high quality with good screening and connection properties if the single ended signal is to have any chance of being received by the preamp reasonably free from hum and noise intrusions This is especially true formoving coil pickups Please use the shortest practical interconnects and carefully route these away from all possible electrical or magnetic hum or interference sources Page 13 SPECIFICATIONS Vacuum tube compliment 6922 x 2 gain plus 7044 x 4 output buffers 117 VAC 1 5 Amp 3AG slow blow main 0 5 Amp 3AG slow blow logic 234 VAC 0 75 Amp 3AG slow blow main 0 25 Amp 3AG slow blow logic Fuse type and ratings 5 step user adjustable via fixed low noise resistors 25 50 100 200 and 47000 ohms Moving Magnet input impedance 5 step user adjustable via multi tap autoformer 25 50 100 200 and 400 ohms Moving Coil input impedance Variable in 10 picofarad steps from 10 to 1100 pF 1 1 nF Residual input capacitance less than 40 pF Input Termination Capacitance Gain Steps 4 step user adjustable 50 55 60 and 65 dB active gain at 1 kHz referred to FIXED output jack 10 k ohm load Additional gain available via MC step up autoformer Deviation from RIAA curve Less than 0 5 0 3 dB from 20 Hz to 20 kHz any gain setting Typically less than 1 dB from 1
15. he 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 FEATURES 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 h
16. hunts are not part of the signal path 10 DISCRETE SYSTEM COMMON AND EARTH GROUND POINTS Breakable link between electronics common zero volts point and chassis ground allows great flexibility in grounding arrangements 11 REMOTE HIGH PERFORMANCE POWER SUPPLY Multiple channel power supply in separate enclosure eliminates supply proximity based noise intrusions into the signal path Robust and regulated ultra quiet high voltage rail maintains electrical quiet of sensitive input stage amps Each voltage channel is conveyed to the preamplifier via separate source and sink lines no common supply points except at the star grounding point on the amplifier boards Multi core interconnect cable is screened via tinned overall shield braid Page 8 OPERATIONAL NOTES INPUT o VOLUME lt N _ STEELHEAD GAIN dB 2 SY PREPARATION FOR INSTALLATION Budget a suitable space in which to place the preamplifier power supply and associated interconnect cable This space should be free of strong external magnetic and RF fields and reasonably removed from strong loudspeaker generated acoustical fields This space should also be free of excessive heat or dust and large enough to permit easy flow of cool air to the top bottom and sides of the preamp and power supply Make sure the power supply s mains voltage selector switch is set to match the local line voltage
17. lue LED s will illuminate the MUTE switch lamp will start flashing and the power supply pilot LED and the MANLEY STEELHEAD badge will light up Page 9 The winking MUTE lamp indicates the beginning of a 30 second warm up mute delay during which time the muting relay 15 engaged no output will be heard from the preamp DURING OPERATION Once audio is heard from the STEELHEAD the exploration for the ideal control settings can begin However it would be best to allow about 15 minutes of warm up time for the system to reach thermal equilibrium Again notice that the MUTE function operates over both FIXED and VARIable outputs while the DIM and SUM functions are only available at the VARIable output jacks RETURNING TO STANDBY MODE At the conclusion of your listening session press the STANDBY switch again to cut power to the preamp Notice that effort has been made to keep power engagement and cessation noise generated by the preamp to a minimum Nevertheless it is wise to remove power mains and signal feed to your power amps when the preamp is undergoing a power state change Additionally it is best to return the STEELHEAD to the STANDBY mode when not in use rather then leaving the power on indefinitely This will enhance tube and system life The tubes should last thousands of hours under normal conditions REPLACING A TUBE OR ILLUMINATED BADGE LAMP Yes there are user servicable parts inside But as with other vacuum tube based produc
18. r 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 low feedback 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 1 tolerance components are used throughout the RIAA equalization network Add to that the factory set variable capacitors and the result 15 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
19. stration is made by filling out and returning to the factory the warranty card attached to this general warranty statement along with a copy of the original sales receipt as proof of the original date of purchase or registration can be made online in the Tech Support section of www manleylabs com This warranty is provided by the dealer where the unit was purchased and by Manley Laboratories Inc Under the terms of the warranty defective parts will be repaired or replaced without charge excepting the cost of tubes Vacuum tubes and meter or badge lamps are warranted for six months provided the warranty registration is completed as outlined above If a Manley Laboratories product fails to meet the above warranty then the purchaser s sole remedy shall be to first obtain a Repair Authorisation from Manley Laboratories and return the product to Manley Laboratories where the defect will be repaired without charge for parts and labour The product will then be returned to customer via prepaid insured freight method and carrier to be determined solely by Manley Laboratories All returns to the factory must be in the original packing accompanied by the Repair Authorisation and must be shipped to Manley Laboratories via insured freight at the customer s own expense Factory original packaging can be ordered from Manley Labs Customer will be charged for new factory original packaging if customer fails to ship product to Manley Labs in non original factor
20. t the line signal is subject to a fairly demanding 500 ohm termination resistance not a short circuit when the LINE feature is not engaged This helps cut down on crosstalk between the line and phono signals inside the STEELHEAD enclosure 8 BUFFERED VOLUME CONTROL The STEELHEAD is equipped to drive external power amplifiers directly via low output impedance VARIable line drivers Purists may easily bypass other outboard preamplifier circuitry by connecting power amplifier inputs directly to the STEELHEAD s VARIable output jacks SEPARATE BUFFERED FIXED AND VARIABLE OUTPUTS Choice of constant level source for interconnection to a line level only pre amp or recorder and variable outputs for direct connection to power amplifiers 9 TWO STAGE RF INTERFERENCE SHUNTS One set of dual dip switches per channel for selective shunting of annoying radiofrequency energy to the STEELHEAD chassis or earth ground These switches are located on the rear apron nested within each channel s cluster of RCA jacks These switchable shunts effectively connect the signal ground to the chassis ground at high frequencies only Switch the shunt switches on as needed if RFI 15 encountered Notice that the shunts are made switchable for those installations where having a permanent shunt connection would due to innumerable saftey and signal grounding arrangements provoke unacceptably audible buzz current ground loops for some users Notice that these s
21. t the pre amp gain is about 20 dB higher 10 times at 20 Hz and about 20 dB lower 0 1 times at 20 000 Hz The MC step up autoformer may also provide approximately 2 to 12 dB of additional voltage gain depending on cartridge source impedance and load switch setting 6 PUSH BUTTON SWITCH FUNCTIONS Four feature switches have been provided for a variety of utility functions STANDBY toggles the STEELHEAD between normal operating state and a near zero power sleep mode No operating voltages are present when in sleep mode except for some keep alive CMOS system control logic energized by a separate small mains transformer in the power supply SUM combines the amplified audio into a binaural signal present at the VARIable outputs only Monophonic or the lateral only modulation content of your stereo records may now be heard True mono may be experienced if the feed to one of your two loudspeakers is cut DIM reduces the output level by 20 dB or about 1 4 previous volume The DIM function is effective at the VARIable outputs only Notice that preamp specifications at the VARIable output may be slightly compromised with the DIM feature engaged This feature should be treated as a convenience for use when for example cueing up a record System menacing pops and thumps due to needle drop are held at bay yet sound from the pick up may still be heard MUTE kills audio signals present at both the FIXED and VARIABLE outputs Page 7 7 LINE INPUT SEL
22. t value if the recommended cartridge load capacitance is unknown is 150 pF the sum of cable and termination capacitance switch settings This value reflects a de facto standard as used by pre amp manufacturers past and present From there we encourage you to scrutinize a range of switch settings until you find those values which best suit you and your accompanying components Also notice that the audible affects of varying the termination capacitance can differ substantially between cartridge types and brands This is to be expected due to the greatly varying source impedance characteristics of the cartridges available today In general you may expect the termination capacitance value to alter at one extreme subtle imaging and spatial cues and at the other high frequency content forwardness and speed of the reproduced sound As with the load Z switch feel free to tune the termination capacitance switches for maximum sonic satisfaction even though the final setting differs from the cartridge manufacturer s specs gt gt SWITCH SELECTABLE AMPLIFIER GAIN Cartridge output levels and downstream line level interconnect drive voltage requirements can vary greatly between manufacturers Hence a four step amplifier block gain control has been included to accommodate these differences as well as differing cartridge sensitivities You may select from 50 to 65 dB of gain in 5 dB steps The gain figure is referred to amplifier gain at kHz Notice tha
23. ts there is also high voltage present Therefore caution must be used when covers are removed otherwise there could be shock hazard As with all mains powered gear make sure the mains power is off and mains cords are unplugged Then unplug the power supply from the preamp If the preamp has been powered up within the last 15 minutes stop and let the large internal capacitors finish discharging Wait about 5 minutes before opening the preamp once the 16 pin connector is unplugged You will need a 1 Philips screwdriver and a small slot driver FUSE LAMP REPLACEMENT After removing the cover use the small slot driver to help pry the badge s fuse lamp out of the clip holder Use one hand only when reaching into the enclosure or touching any components inside Keep the other hand away from the preamp preferably in your pocket TUBE REPLACEMENT Increased noise level whether gradual or abrupt can generally be attributed to aging tubes Gradual noise increase from weakened tube cathode emission is the chief symptom of an aging tube which may be accompanied by exaggerated distortion or loss of headroom The noise may be a variation in the level of hiss or the noise may develop a more granular large curd quality Should these symptoms appear unplug the tubes in the offending channel and replace with new devices of known good quality If the front end 6922 tube is being replaced in one channel it is wise to replace the same tube in the alternate
24. tube s Page 12 Symptom Lights ON no output either channel after warm up delay times out Hum heard on unused MM or MC inputs Hum heard on active inputs No or bad sound heard on MC2 input Possible Cause Corrective Action cont d Open 6922 filament either Check for glowing 6922 channel 6922 unplugged filaments Replace if necessary Output MUTE function UnMUTE the preamp activated Input connectors are non Avoid unused inputs install shorting shorting plugs Ground link between CHAS SYS and CIRCUIT open jumper if necessary Turntable tonearm ground Establish inter chassis link to CHASSIS open connection Open cartridge leads Check lead head shell continuity Phono plugs not fully in Check for proper connection serted Table lines close to hum Keep source lines away from magnetic field transformers motors etc Ground loop between Break ground connection of STEELHEAD and turntable one or two of the three or downstream pre amp system elements power amplifiers Experimentation may be necessary Faulty shield connection Roll or swap cables or input or output interconnect replace cables cables Check DIN plug wiring Re wire plug for continuity Left Ihigh 4 low Right 3 high 5 low Shield 2 earth chassis Remarks on hum pick up Please be aware that the STEELHEAD can develop voltage amplification factors as high as 30 000 times or 90 dB at t
25. 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 Locate the preamp away from heat radiating sources such as other large amps political demagogues 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 1 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
26. y packaging Charges for unauthorized service and transportation costs are not reimbursable under this warranty and all warrantees express or implied become null and void where the product has been damaged by misuse accident neglect modification tampering or unauthorized alteration by anyone other than Manley Laboratories The warrantor assumes no liability for property damage or any other incidental or consequental damage whatsoever which may result from failure of this product Any and all watrantees of merchantability and fitness implied by law are limited to the duration of the expressed warranty All warrantees apply only to Manley Laboratories products purchased and used in the USA Some states do not allow limitations on how long an implied warranty lasts so the above limitations may not apply to you Some states do not allow the exclusion or limitation of incidental or consequential damges so the above exclusion 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 MANLEY LABORATORIES INC 13880 MAGNOLIA AVE CHINO CA 91710 USA TEL 909 627 4256 FAX 909 628 2482 for Tech Support email service manleylabs com website www manleylabs com 15 WARRANTY REGISTRATION We ask grovel and beg that you please fill out this registration form and send the bottom half to MANLEY LABORATORIES REGISTRATION DEPARTMENT 13880 MAGNOLIA AVE C
Download Pdf Manuals
Related Search