user's manual...3 user's manual 15. to prevent electric shock, do not use this polarized...

2

User's Manual

Safety Instructions1. Read Instructions -– All the safety and operationinstructions should be read before the Sunfire Componentis operated.

2. Retain Instructions — The safety and operatinginstructions should be kept for future reference.

3. Heed Warnings — All warnings on the Component andin these operating instructions should be followed.

4. Follow Instructions — All operating and other instruc-tions should be followed.

5. Water and Moisture — The Component should not beused near water - for example, near a bathtub, washbowl,kitchen sink, laundry tub, in a wet basement, or near aswimming pool, etc.

6. Ventilation — The Component should be situated sothat its location or position does not interfere with itsproper ventilation. For example, the Component shouldnot be situated on a bed, sofa, rug, or similar surface thatmay block any ventilation openings; or placed in a built-ininstallation such as a bookcase or cabinet that mayimpede the flow of air through ventilation openings.

7. Heat — The Component should be situated away fromheat sources such as radiators, or other devices whichproduce heat.

8. Power Sources — The Component should be connectedto a power supply only of the type described in these opera-tion instructions or as marked on the Component.

9. Power Cord Protection — Power-supply cords should berouted so that they are not likely to be walked upon orpinched by items placed upon or against them, payingparticular attention to cords at plugs, convenience recep-tacles, and the point where they exit the Component.

10. Cleaning — The Component should be cleaned onlyas recommended in this manual.

11. Non-use Periods—The power cord of the Componentshould be unplugged from the outlet when unused for along period of time.

12. Object and Liquid Entry — Care should be taken sothat objects do not fall into and liquids are not spilled intothe inside of the Component.

13. Damage Requiring Service — The Component shouldbe serviced only by qualified service personnel when:

A. The power-supply cord or the plug has been damaged; or

B. Objects have fallen, or liquid has spilled into theComponent; or

C. The Component has been exposed to rain; or

D. The Component does not appear to operate normallyor exhibits a marked change in performance; or

E. The Component has been dropped, or its cabinet damaged.

14. Servicing — The user should not attempt to servicethe Component beyond those means described in thisoperating manual. All other servicing should be referred toqualified service personnel.

Safety Instructions

3

User's Manual

15. To prevent electric shock, do not use this polarizedplug with an extension cord, receptacle or other outletunless the blades can be fully inserted to prevent bladeexposure.

Pour préevenir les chocs électriques ne pas utiliser cettefiche polariseé avec un prolongateur, un prise de courantou une autre sortie de courant, sauf si les lames peuventêtre insérées à fond sans laisser aucune pariie àdécouvert.

16. Grounding or Polarization — Precautions should betaken so that the grounding or polarization means of theComponent is not defeated.

This apparatus does not exceed the Class A/Class B(whichever is applicable) limits for radio noise emissionsfrom digital apparatus as set out in the radio interferenceregulations of the Canadian Department of Communications.

ATTENTION — Le présent appareil numérique n'émet pasde bruits radioélectriques dépassant las limitesapplicables aux appareils numériques de class A/de classB (selon le cas) prescrites dans le règlement sur lebrouillage radioélectrique édicté par les ministere descommunications du Canada.

Safety Instructions and Table of Contents

Safety instructions ..................................................................................... 2-3Introduction .................................................................................................. 4Features ....................................................................................................... 4Unpacking .................................................................................................... 4Overview ...................................................................................................... 5Front panel features .................................................................................. 6-7Rear panel features ................................................................................... 8-9Installation, AC power and connections ..................................................... 10Care............................................................................................................ 10The Phono stage ................................................................................... 11-12System Configurations ............................................................................... 13

Phono connections ................................................................................ 13CD player connections ........................................................................... 14Tape deck connections .......................................................................... 15Amplifier connections: unbalanced ........................................................ 16Amplifier connections: balanced ............................................................ 17

Specifications ............................................................................................. 18Troubleshooting guide........................................................................... 19-21Appendix .................................................................................................... 22

Changing the phono stage gain ............................................................. 22Changing the phono stage input impedance ......................................... 22Tube type and location .......................................................................... 22

Limited Warranty ........................................................................................ 23Service assistance ..................................................................................... 23

Contents

To find out more about this and other Sunfire products,please visit our website: www.sunfire.com

WARNING: ALWAYS FULLY INSERT THE PLUGINTO THE AC SUPPLY SOCKET.

WARNING: TO REDUCE THE RISK OF FIRE ORELECTRIC SHOCK, DO NOT EXPOSETHIS APPLIANCE TO RAIN ORMOISTURE.

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User's Manual

Your Classic preamplifier should reachyou in perfect condition. If you do notice anyshipping damage, please contact your SunfireDealer immediately.

Gently remove the Classic preamplifierfrom its packing materials with care, so as toavoid damage to or loss of any packingmaterials. This is a precision instrument anddeserves to be treated with care. It has beendesigned to provide years of reliable service,and should you ever need to ship or transportit, the original packing materials will providethe safest means.

Make sure that you keep your salesreceipt. It is the only way to establish theduration of your Limited Warranty and it maycome in useful for insurance purposes.

Please take a moment to fill out and mailthe Sunfire Warranty Registration card. Alsoread the serial number located on the rearpanel and record it here:

Serial Number:

Purchased from:

Date:

Dear Friend,

Congratulations on your purchase of the SunfireClassic Preamplifier. We believe its sophisticatedengineering and meticulous craftsmanship willprovide you with many years of listening enjoyment.

At the heart of the Classic is a high-perfor-mance control preamplifier with extremely low noiseand distortion, wide dynamic range, and a highdegree of control flexibility. An optional phono boardmay be added for precise RIAA phono equalizationof moving magnet and moving coil cartridges. YourClassic will provide remarkable three-dimensionalrealism, with a sumptuous sonic image which canextend beyond the loudspeakers in both breadthand depth.

Introduction

Introduction

Bob Carver, Amplifier Designer, Physicist

Unpacking Features• High quality vacuum tube design

• 6 L/R pairs of unbalanced inputs

• Optional MM and MC Phono section

• 2 pairs of unbalanced main outputs

• 1 pair of balanced outputs

• 1 pair of tape outputs

• Low frequency contour control

• High frequency contour control

• Tape monitor switch

• Stereo/mono switch

• Motorized volume control

• Balance control

• Remote control of volume, mute andpower

• 3 unswitched AC outlets

• Gold-plated inputs and outputs

• Classic chassis and styling

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User's Manual

Gaincontrol

Poweron/off

Poweron/off

Overview

Overview

The Classic is a preamplifier controlcenter. If you have previous experience withstereo components, you can probably com-plete the input/output connections and makenormal use of the basic preamplifier functionswithout special instructions. We recommend,however, that you read the entire manual atyour earliest convenience. You will find thateven some of the “conventional” parts of theClassic are in fact not conventional at all.

Inputselector

Contour (tone)controls

BalanceMono/Stereo

TapeMonitor

Toneon/off

Mute

TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCKDO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.

WARNING

S/N

PASSIVE PRECISIONINVERSE RIAA PHONO NETWORK

2 AMPAGC

OUTPUTS LINE INPUTS

PHONO/LINE INPUTS

REPLACE WITHORIGINAL TYPEAND RATINGONLY

120 VAC50/60 Hz

R

L

R

L

R

L

MAIN 1 MAIN 2 TAPE TAPE AUX VIDEO CD TUNER

MOVINGCOIL

MOVINGMAGNET

PHONOOUT

LINEIN

PHONO

USE EITHER

INVERSEPHONO

1000WATTSTOTAL

UNSWITCHED

BALANCED

FUSE

ACoutlets

Lineinputs

OptionalPhonosection

XLRouts

Mainouts

Tapeout

Tapein

ACcord

Fuse

Note: The remote controlwill only work when thefront panel power switchis in the ON position.

MM/MCswitch

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User's Manual

Front Panel Features

1 5 6 7 8 11 10 94

2 3


4. Remote windowThis window should be kept clear of obstruction forthe remote control to work.

5. Stereo/Mono SwitchThis sums the left and right inputs so the main outputswill have identical signals. (It does not affect the Tapeoutputs).

The most common use for this switch is in checkingloudspeaker phasing: Play any stereo or monorecording, select Mono and listen. Then reverse thepolarity (+, -) of one speaker connection and recheck.The polarity position which develops a clear centerimage between the speakers with fullest bass contentis the correct “in-phase” position of the speaker wiring.

You should also engage Mono for playback of oldmonophonic sources, since this will cancel mostrumble and noise for quieter playback.

When listening to a single-channel source, you caneither use a “Y” cord at the selected input, or selectMono.

6. Tape Monitor switchThis will connect the output of a recorder to thesubsequent preamplifier circuitry. It may be used fortape playback or record-monitoring with three-headrecorders. Similarly, if a signal processor is connectedto the preamplifier’s Tape inputs and outputs, it will bein circuit whenever the Tape Monitor switch is en-gaged.

1. Power SwitchThis is the main AC power switch. Flip the switch up toapply power to the unit. It is good practice to turn thevolume control down before turning on, and keep itdown until after about 40 seconds of tube warm-uptime (when the MUTE lamp turns off, and the ONlamp stops blinking and turns on continuously).

If you prefer, you may leave this AC power switchpermanently on, and use the remote control to switchthe unit on or off. Turning the power off with theremote will extinguish both the MUTE and ON lamps.

Note: the power switch must be in the up (POWER)position for the remote control to work.

2. On lampDuring normal operation this lamp will be on. Whenyou turn the preamplifier on, this lamp blinks for about40 seconds while the tubes are warming up. After thattime, it will stay on continuously.

3. Mute lampDuring normal operation, this lamp will be off. Whenyou turn the preamplifier on, this lamp stays on forabout 40 seconds while the tubes are warming up,indicating that the outputs are muted and no sound ispassed to your amplifiers. The lamp will also indicatewhenever the remote control MUTE is pressed.

If you accidentally turn off the preamplifier using theremote, you can quickly turn it back on. The preampli-fier will automatically sense that there is no need for a40 second mute because the tubes are alreadywarmed up.

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User's Manual


7. Contour On/OffIn the OFF position, the contour circuits are bypassedand the two contour controls (11) will have no effect.

In the ON position, the signal frequency response canbe adjusted by the contour controls to suit your taste.

8. Input Program SelectorThis rotary switch selects the program source whichwill be heard. The same program source is alsopresented to the Tape outputs for recording. Note thatthere is no Tape selection, you should engage theTape Monitor switch to listen to your tape deck.

If you have the optional Phono input, select either MMor MC using the rear panel switch (depending uponyour phono cartridge), and then select CD/Phono.

To minimize bleedthrough, or an audible signal whenyou select an unused input, it is recommended that“shorting plugs” be inserted in all unused inputs. DoNot install shorting plugs in any OUTPUT jacks, asthis would short-circuit the preamplifier output. If youdo not use shorting plugs, that is perfectly OK., andyou can prevent bleedthrough by turning off or mutingall signal sources not being listened to.

9. Volume ControlThis is the master level control for the stereo system.The control is a continuous taper potentiometer toallow smooth transition from one level to another.

The taper rate of the potentiometer was chosen toprovide maximum flexibility and compatibility withother components. Input signal levels will vary fromone source to the next, as well as from one disc, tape,or FM station to the next, so it is normal to notice thatyour preferred volume control setting varies.

Note: The remote control’s Volume Up function isdisabled when the system is muted or warming up.This is to prevent causing damage to your speakersdue to accidentally high volume levels. The remote’sVolume Down function is available at all times, andyou can still set the volume at any time using the frontpanel control (but make sure it is turned down whilethe preamp is warming up).

10. Balance ControlThis adjusts the relative levels of the two stereochannels. In its center position, the levels are exactlyequal. Clockwise rotation reduces the Left channellevel, while counterclockwise rotation reduces Rightchannel level. Small movements off-center producesmaller shifts in the stereo image per degree ofrotation than near the extreme left and right position.This makes slight trimming of levels more convenient.

11. Contour ControlsThe Sunfire Classic is equipped with a tone-controlstage in the signal path after all input selection andtape switching. These controls are switches whichselect a variety of precise contour curves. In opera-tion, a muted click or pop may be heard when chang-ing switch positions. The controls may be switched inor out of circuit by the contour switch (7), allowing thecontoured signal to be quickly compared with thepreamplifier’s laboratory-flat frequency response.

The contour controls are asymmetrical in boost andcut. They have been designed to be very appropriatefor real music listening situations. The boost exhibitsno shelving, and reaches a maximum of +6 dB at fullclockwise rotation. Bass may thus be boosted withoutthe boom associated with shelving, in order to in-crease deep punch without mid-bass fatness. Trebleboost will field greater definition, without the shrillnesswhich results from treble-boost shelving.

In the cut (counterclockwise) position, treble and bassare not rolled-off, as with most tone controls, ratherenergy output in the upper and lower ranges isreduced while maintaining flat frequency response inthose ranges. Cut does not exceed -10 dB, sincefrequency response attenuation beyond this yields adead sound character which is not musically advanta-geous. Cut is not substantially affected by the tone-turnover frequency switches. This shelving character-istic for the cut mode is very useful, for example, if arecording sounds too bright. The relative harmonicenergy can be reduced without affecting the balanceof the harmonic content. Thus, a violin will still soundlike a violin, retaining its air, sheen and openness,while reducing excessive brightness.

Note: We encourage the routine use of the contourcontrols as this will significantly enhance your listeningpleasure.

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User's Manual

TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCKDO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE.

WARNING

S/N


2 AMPAGC

OUTPUTS LINE INPUTS

PHONO/LINE INPUTS

REPLACE WITHORIGINAL TYPEAND RATINGONLY

120 VAC50/60 Hz

R

L

R

L

R

L

MAIN 1 MAIN 2 TAPE TAPE AUX VIDEO CD TUNER

MOVINGCOIL

MOVINGMAGNET

PHONOOUT

LINEIN

PHONO

USE EITHER

INVERSEPHONO

1000WATTSTOTAL

UNSWITCHED

BALANCED

FUSE

1

2

3

4 5 6 7 8 9 10 11 12 13 14

16

15

Rear Panel Features

1. AC Line CordThis is heavy-duty cord capable ofcarrying large currents required by high-power amplifiers. The Classic itselfrequires only modest power (equivalent tomost light bulbs) and may thus be pow-ered by a conventional extension cord ifrequired. But if you have substantialpower amplifiers connected to one of theconvenience outlets, only use a heavyduty extension cord (16 gauge or thicker).

The line cord should only be plugged inafter completing all input and outputconnections to other components.

2. FuseAlways unplug the power cordbefore inspecting or changing thefuse. Never use a fuse with alarger current rating than 2 A.

3. Accessory outletsThese three unswitched AC outlets areLIVE whenever the unit’s line cord isplugged into an active AC receptacle.They can be used to supply AC power toother components of your system,including your amplifier. The total powerdraw must not exceed 1000W.

Verify that all component power-switchesare OFF before plugging any componentline cords into these or any AC outlets.

If your power amp is not equipped with apower switch, make sure that thepreamplifier’s power switch is OFF(indicator LED is not lit) and its AC line-cord is unplugged, before connecting thepower amp’s line cord to one of theClassic’s outlets.

4. Balanced outputsThese are the left and right outputs whichconnect to the balanced inputs of anamplifier used to drive your speakers.

Balanced outputs offer superior noisecancellation, especially if there is a longcable run to your amplifier.

5. Main 1 and Main 2 outputsMAIN 1 - These are left and right unbal-anced (RCA) outputs which connect tothe unbalanced inputs of an amplifierused to drive your main front speakers.

MAIN 2 - Identical to Main 1. They can beused to drive a second power amplifier,such as in bi-wire or multiple speakerapplications, to drive a subwoofer, or tofeed processed signals to a tape recorderor a time-delay accessory.

Rear Panel Features

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User's Manual

Rear Panel Features

6. Tape outputThese outputs connect to the inputs of atape deck for recording the source whichis currently selected by the preamplifier.

Input jacks on your tape deck may belabeled “Line In”, “Aux”, or “Record”, butdo not use “Microphone.”

It is recommended that DIN-type record/play sockets not be used if conventionalRCA jacks are available at the recorder.

7. Tape inputThis connects to the outputs of a tapedeck for playing your favorite tapesthrough the preamplifier. This input isselected using the TAPE MONITORswitch, not by the Input selector control.

Tape deck output jacks may be identifiedas “Line Out”, “Play”, or “Monitor”.

8. Aux inputThese line-level inputs are electricallyidentical to the other line inputs, and maybe used for signal sources such as asecond tuner, a tape-deck, TV audiotuner, VCR or the output of a microphonepreamplifier.

9. Video inputFor connection of the audio output from aVCR, DVD, satellite tuner or TV.

10. CD inputFor connection of the output from a CDplayer. This input is selected using theinput selector’s COMPACT DISC position.If your player has “fixed” and “variable”outputs, use the variable outputs. Thenyou can adjust the output level of the CDplayer so that when you switch fromPhono to CD to Tuner, the volume levelwill remain approximately the same.

11. Tuner inputConnect to the line-level output from a FMor AM/FM tuner.

12. Moving Coil phono inputConnect to the output of a turntableequipped with a moving coil phonocartridge. Push the rear panel MM/MCselector button IN.

13. Moving Magnet phono inputConnect to the output of a turntableequipped with a moving magnet phonocartridge. Push the rear panel MM/MCselector button OUT.

14. Inverse-phono sectionThe Classic preamplifier allows you toplay your CDs or other line level sourcesthrough the phono stage. It can also beused to check the phono stage operation.

The special wiring configuration anddetails for this circuit are described andillustrated on page 12.

15. GroundAttach your turntable’s ground wire to thispoint to prevent hum.

16. MM/MC selectorPush this IN if you are using the MovingCoil (MC) input. Push it OUT if you areusing the Moving Magnet (MM) input.

NoteAn additional line levelinput is available if theoptional Phono stagehas not been installed.This input (or the phonostage) is selected usingthe input selector’s CD/PHONO position.

For more details of thePhono stage, see pages11 and 12.


PHONO/LINE INPUTS

R

L

TUNER

MOVINGCOIL

MOVINGMAGNET

PHONOOUT

LINEIN

PHONOINVERSEPHONO

CD/LINE INPUTLine level only

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User's Manual

Observe the following precautions whenchoosing a location for your Classic vacuumtube preamplifier:

• The Classic is an all-vacuum tubedesign. It may be operated at anyangle, and has modest ventilationrequirements. Do not cover the sideventilation slots.

• It’s location relative to other stereocomponents is not critical, except thatit should not be stacked with, or placedadjacent to, powerful amplifiers whichmay generate external hum fields.

• Typically it is best to locate the Classicclose to the turntable or CD player sothat connection cables may be keptshort. The turntable should be on asolid, vibration-free surface to avoidproblems of acoustic feedback andinstability. In many systems it may beconvenient to locate the preamp withinarm’s length of the prime listeningposition, for which long cables to theamplifier will be necessary; normally,cable runs of up to 30 feet are OK.

• Protect it from prolonged exposure todirect sunlight and other directsources of heat, such as heatingvents and radiators.

• Do not expose the unit to rain ormoisture. If fluid or a foreign objectshould enter the unit, immediately turnoff the power and contact your SunfireDealer.

• Avoid excessive exposure toextreme cold or dust.

• Do not place heavy objects on top ofthe unit.

AC Power ConsiderationsEnsure that the unit is plugged into an outletcapable of supplying the correct voltagespecified for your model.

CareIf you need to clean the front surface, first turnoff the power and then use a slightly damp-ened cloth, rubbing with the grain. Be carefulnot to scratch the front window.

Connection TipsBefore setting up your new system, pleaseconsider the following :

• Before making or changing anyconnections, check the front panel tomake sure the Power switch is DOWN(off), and that the Volume Control isset for no output (full counterclock-wise). The amplifier and all otherequipment should be turned off andthe preamplifier line cord unpluggedbefore making any connections.

• Whenever possible, keep the powercords away from the signal cablesor speaker wires to prevent any humor interference being heard in thespeakers.

• Choose reliable interconnect cables,also called patch cords or RCA cables.They should be fully shielded and asshort as possible for the job.

• If your amplifier has balanced inputs,then we recommend using the bal-anced outputs of the preamplifier asthis will provide superior noise rejec-tion.

• Some patch cords can be a very tightfit and there is usually a preferredmethod of getting them off, some haveto be removed with a twisting action.Be gentle or you may damage thejacks of the amplifier or your othercomponents.

Installation

Installation

11

User's Manual

The optional phono stage contains twoindependent stereo phono preamplifier inputswhich are optimized for specific uses. Thetype of phono cartridge you are using in theturntable will determine which phono input touse. Only a moving coil cartridge should beconnected to the moving coil input, or it maybecome overloaded and distort.

In terms of frequency response, themoving coil and the moving magnet phonoare identical. In terms of gain and sensitivity,however, they differ substantially.

Ground connectionIf your turntable is equipped with a

separate ground lead (usually a single wireterminated with a spade lug), connect it to theground post, (see item #15 on page 8). Inmost cases, this will minimize audible humand buzz in the phono signal. If hum is aproblem with your turntable, refer to thetroubleshooting section starting on page 19.

Normally, these are the only connectionsmade to the ground post, while all othercomponents are grounded through their ownsignal cables.

Moving Magnet phono inputThe rear panel MM/MC selector button

must be OUT for moving magnet cartridges.

The moving magnet phono circuit has atotal gain of 40dB, appropriate for typical highoutput moving magnet and moving ironcartridges.

Its input impedance consists of 47K ohmsresistance in parallel with real capacitance.This prevents the complex input interactionswhich can cause small response shifts insome systems. When plugging the cables intothe Classic’s sockets, be sure each plug isinserted fully into the socket, making a tight fit.

You can plug the turntable line cord intoone of the accessory outlets on the rear panelof the Classic preamplifier.

Moving Coil phono inputThe rear panel MM/MC selector button

must be IN for moving coil cartridges.

The two inputs marked MC are intendedfor use with moving coil cartridges only. ThisPhono circuit employs an additional 20dB oflinear gain (for a total of 60 dB to TapeOutputs), designed especially for the relativelylow voltage output of moving coil cartridges.The Classic employs a built-in “pre-amplifier”,but this design is free of the compromisesusually associated with active gain at thisstage.

Historically, the problem of obtaining theextra gain required for the moving coil car-tridge has been an expensive proposition. Theproblem has been as follows: To obtain lownoise, a step-up transformer has beenrequired, transforming the low cartridgeimpedance up to the 47K ohm input imped-ance of the phono stage. In this process, thenoise floor of the system is generally estab-lished by the 3 to 10 ohm source resistanceassociated with the moving coil cartridge, andis therefore very low. However, in order toobtain signal performance comparable toeven simple active electronic circuits, heroic

The Phono stage


PHONO/LINE INPUTS

R

L

TUNER

MOVINGCOIL

MOVINGMAGNET

PHONOOUT

LINEIN

PHONOINVERSEPHONO

The Phono stage

MM/MCswitch

Groundconnection

12

User's Manual

efforts on the part of the transformer designerare required, and the resulting cost will almostalways be many hundreds of dollars. Lessexpensive transformers will be quiet, but willusually exhibit ringing, phase shift, and somelow frequency distortion. The problems withmost active step-up devices are simplyreversed. Moderate cost, smooth high-frequency response, essentially zero phaseshift and low distortion may almost be takenfor granted, while heroic and expensivedesign techniques, including cryogeniccooling, have been required to even approachthe low noise of a transformer.

A superbly accurate dual parallel input,combined with the use of high current tubeswhich exhibit an almost unheard-of noisefigure at room temperatures, made a new“super-gain” phono stage possible. It yields allthe performance advantages of active circuits,with noise levels within 6 dB of the besttransformers, all at moderate cost and atroom temperature.

To change the gain or the input imped-ance of your phono stage please refer to theAppendix on page 22.

Infrasonic FilterThis circuit corrects for difficulties often

encountered with phono disc playback.

The Infrasonic Filter is an 18 dB peroctave design. Its response is flat down to10Hz, then attenuates the preamp’s frequencyresponse rapidly at lower frequencies. Phonoplayback is inevitably contaminated to someextent by sub-sonic energy, due to normalamounts of record warp, tonearm/cartridgeresonance and turntable motor rumble. If notfiltered out of the audio signal, this sub-audible energy can overload tape recorders,waste amplifier power, and drive woofers intoexcessive cone excursions, causingintermodulation distortion audible as muddybass.

Normally, “group delay”, an unavoidableconsequence of the rapid attenuation of sub-sonic response, can, under certain musical

circumstances, have a just perceptibleconsequence in the audio passband. Infra-sonic filtering is thus often somewhat of acompromise. In order to eliminate this prob-lem, the onset of rolloff has been delayed afull octave below 20 Hz, effectively reducinggroup delay to well below the threshold ofaudibility.

Precision Inverse RIAA NetworkA wonderful and classic pleasure in this

day and age of digital audio is to listen to vinylrecords, which were made using the RIAAequalization curve. Ordinarily of course, withCDs that’s not possible. The next best thing,however, is to use your Sunfire’s PrecisionInverse RIAA network to listen to CDs throughits classic vacuum tube phono stage:

• Connect the output of your CD playerto the line-input of the inverse phononetwork.

• Connect the phono output of theinverse phono network to the input ofthe MM phono stage, using a shortinterconnect cable.

• Make sure that the MM/MC selectorbutton is OUT to select the MM input.

• Set the front panel selector switch toCD/Phono; and “Voila”, RIAA soundfrom CDs!

• This mode also allows a line source tobe used to check that the MM phonostage is working correctly.


PHONO/LINE INPUTS

FROM CD PLAYER

R

L

MOVINGCOIL

MOVINGMAGNET

PHONOOUT

LINEIN

PHONO INVERSEPHONO

The Phono stage

13

User's Manual

Phono Connections

System ConfigurationsThe following pages show some typical

connections that you might make in your installa-tion. They show how the inputs and outputs ofthe Classic preamplifier are connected tovarious audio components.

If your turntable is equipped with a MovingMagnet cartridge, connect its audio outputs tothe preamplifier’s Moving Magnet inputs asshown. Make sure that the MM/MC button isin the OUT position.

If you have a Moving Coil cartridge, usethe preamplifier’s Moving Coil inputs and pushthe MM/MC button inwards.

System Configurations

In most cases, the turntable ground wireshould be connected to reduce any humheard in the speakers.

Never connect a line-level source compo-nent directly to the preamplifier’s MC or MMinputs as they will be overloaded. They arespecially designed to handle only the very lowlevel outputs from a phono cartridge, and notthe higher voltage outputs from CD players orother line level components. (Phono level isusually below 100mV, whereas line level canbe up to 2 volts).

14

User's Manual

CD player Connections

The audio output from your CD player canbe connected to the preamplifier’s CD inputs.

If your CD player has variable outputs,this will allow you to adjust the CD player’soutput volume to match the volume of othercomponents in your system, such as the tapedeck or turntable. When you switch from onecomponent to the next, the initial volumewould then be similar.

If you want your CD player to have anextra special sound, you can use the InverseRIAA circuits as shown on page 12.


CD player

Any of the line level inputs, such asTUNER, CD, VIDEO, AUX and TAPE can beused by any source component with a linelevel output, such as DVD, LaserDisc, VCR,reel-to-reel, DAT, TV or satellite receiver.

15

User's Manual

Tape Deck Connections

The output from your Tape deck connectsto the preamplifier’s TAPE inputs. Theseinputs are only selected by using thepreamplifier’s Tape Monitor switch.

The inputs of your Tape deck connect tothe preamplifier’s TAPE outputs. Theseoutputs are unaffected by the setting of thevolume control or the contour controls.


Tape Deck

An external processor can be connectedin exactly the same way as a Tape deck:

• The external processor outputsconnect to the preamplifier’s Tapeinputs.

• The external processor inputs connectto the preamplifier’s Tape outputs.

• Select the source you would like tolisten to, such as CD, and then selectthe Tape Monitor switch to listen to theprocessed sound.

16

User's Manual

Amplifier Connections: unbalanced RCA

If your amplifier has RCA inputs, you canconnect them to the preamplifier’s Main 1 orMain 2 outputs. It does not matter which pairyou use, because they are identical.

Main 2 is provided if you want to run asecond amplifier, perhaps to play speakers inanother room, or to drive an active subwoofer.

A third amplifier can be connected to thebalanced XLR outputs if you have another setof speakers in a third room. Note that all theamplifiers would be playing the same musicselection.


If you are using an electronic crossover tobi-amp or tri-amp your speakers:

• Connect a cable from either of thepreamplifier’s main outputs to theactive crossover’s inputs

• Connect the crossover’s High, Mid,and Low outputs, as appropriate, to theseparate power amplifiers in yoursystem.

Amplifier

17

User's Manual

Amplifier Connections: balanced XLR

If your amplifier has XLR inputs, it can beconnected to the balanced audio outputs asshown.

The balanced connections are preferred,as they provide superior noise cancellationand are less susceptible to interference thanunbalanced lines.


Amplifier

18

User's Manual

Phono InputsRIAA curveMoving Magnet input

Gain = 40dB to tape outOverload = 100mV @ 1 kHz.Input Impedance = 47ΩNoise: better than 82 dB, IHF-A,

below 10mVrms at 1 kHzMoving Coil input

Gain = 60dB to tape outOverload = 5.60 mV @ 1 kHz.Input Impedance = 470Ω standard,(setable to 22Ω, 47Ω, 150Ω or 470Ω)Noise: better than 76 dB, IHF-A,

below 1000 µVrms at 1 kHz

High-Level InputsFrequency response

5 Hz to 50 kHz +0/-3dBLine Gain = 12dBInfrasonic Filter

18 dB per octave below 10 HzNoise

better than 96 dB, IHF-A, below 2 Vrms.Distortion

THD: 0.5% or less, below 3 Vrms out.IM (CCIR or SMPTE): 0.5% or less.TIM unmeasurable.

Input Impedance nominally 50kΩ

Power Consumption45 Watts with Phono option25 Watts without Phono option1.4 Watts remote standby (i.e. when it

has been turned off using theremote control)

FinishBlack anodized front panel and cover

Dimensions19” wide x 6.5” high x 18” deep.

Weight25 pounds

Line VoltageUnits built for 110V-120V line voltage can

be converted to 220V-240V by means of amodification. This is not simply a switch, andmust be performed by a Sunfire AuthorizedService Station. Contact Sunfire TechnicalServices for more information.

Muting SystemThe Sunfire Classic employs an electronic

“clamper” to mute the main outputs to elimi-nate turn-on transients. (It will not interrupt thetape outputs).

Muting is accomplished by a shortingrelay which, when it is “open”, is out of thecircuit and hence has no effect on the signal.It is controlled by a toggling device, so mutingcannot be partially “on”.

This muting system will turn off the signalto your power amplifier at these times:

• For about 40 seconds after the initialpower-on, whether by the front panelpower switch or the remote control.

• Immediately at turn-off, whether by thepower switch or the remote control.

• The main outputs will also mute if theline voltage drops below 70 volts. Thisis to reduce thumping.

Output impedanceThe output impedance of the Classic is a

low 1.5K ohms, so it can drive power amplifi-ers having virtually any input impedance.Options include connecting several poweramplifiers to the Classic’s main outputs, toseparately drive different speaker sets, or theuse of extra-long connection cables to drivepower amplifier(s) located close to the speak-ers, or self-powered loudspeakers. Conven-tional cables as long as 30 feet, or speciallow-capacitance cables as long as 60 feet,may be used to drive power amplifier(s)without difficulty.

©2001 Sunfire Corporation. All rightsreserved. Sunfire Corporation reserves theright to improve its products at any time.Therefore, specifications are subject tochange without notice.

Manual Part number : 913-012-00 Rev C

Specifications

Specifications

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User's Manual

In view of the Classic’s input/outputflexibility, the many connecting cables to andfrom the components which may be con-nected to it, and the large number of possibili-ties for mis-set switches both on the Classicand on the various ancillary componentsoperating with it, obviously it is impossible tooffer a complete troubleshooting guide to allof the problems which could, in principle,occur. Most such potential problems will beavoided simply by following the instructions inthis owner’s manual and the instructionssupplied with associated products; and manyother possible problems will be preventedsimply by the excellent reliability of moderncomponents.

So in this section we will provide a guideto some of the most basic and commondifficulties which may arise from time to time,and suggestions as to their probable causes.To illustrate the sort of thought process whichis useful in tracking down problems, we beginwith the most basic: no sound because thepreamp’s power is off. Did you accidentally hitthe Power button when reaching for theStereo/Mono button? Was the preamp’s ACline cord accidentally pulled partially out of itswall socket during housecleaning earlier in theday? Did something else on that samehousehold branch circuit (including the poweramp or other component plugged in thepreamp’s AC convenience outlets) cause acurrent surge which blew the fuse or circuitbreaker protecting that entire branch circuit?In some houses having duplex AC wallsockets, the lower one is permanently livewhile the upper one (intended for lamps) iscontrolled by a wall switch near a doorway;was the preamp’s AC cord accidentallyplugged into the switched socket? Is thepreamp’s AC cord plugged into a clock timerwhich is presently off or unplugged from thewall?

No sound.• The preamplifier’s power may be off,

the amplifier off, line cords unplugged,AC fuses blown, or the power may beoff at the wall socket or power strip.

No sound (the power is on)• Input selector set to an inactive input.

• Tape monitor switch is engaged withno tape machine running.

• Input level controls are turned down onthe power amplifier.

• Input or output signal cables may bedisconnected.

• The selected program source is notoperating.

• Output level control turned down atprogram source.

• Program source misadjusted (forexample, the FM tuner is tunedbetween stations.

No sound (phono)• Rear panel Phono MM/MC selector

button in wrong position.

• Internal ribbon cable unplugged

• No phono power jumper in place onpower supply board.

No sound in one channel.• Defective cable from the preamp to the

power amp or from a program sourceto the preamp.

• Speaker wire loose or disconnected.

• Balance control fully clockwise orcounter-clockwise.

• Imperfect contact in a switch (espe-cially any lever or slide switch in aprogram source or signal processor,as well as the various signal-routingswitches in the preamp).

• A speaker’s fuse is blown.

Troubleshooting

Troubleshooting

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User's Manual

Loud howl, squeal, or whistle.• The Tape Monitor switch is engaged

while microphones (in the same roomas the speakers) are connected to atape deck for recording.

• Put the cat out.

Solo voices, or instrumentssound thin, shrill or distorted.

• Phono cartridge is wired out of phase.

HumUnder normal operating conditions you

hear very little hum originating in the circuitryof the Classic. There is one exception to thisrule: If you have a high-gain power amplifierand unusually sensitive (i.e. efficient) loud-speakers, normal listening levels will involveusing abnormally low output levels from thepreamp, and those small signals might thenpick a bit of hum or hiss in the preamp’scircuits. In this case the solution is to turndown the power amplifier’s level controls if ithas them, or consider having its gain reducedby the manufacturer. Contact Sunfire Techni-cal Services for further information.

Except for the condition described above,audible hum will nearly always be found to bedue to problems external to the Classic —usually in the signal source, i.e. the turntableor tape deck. Many turntables, for example,have a hum field in the vicinity of the platterdue to the turntable’s motor or internal powertransformer which is acceptably low withmoving-magnet cartridges but audibly bother-some with moving-coil cartridges. If yourturntable has a non-polarized AC plug, youcan experiment with reversing it to see whichorientation of the plug minimizes the audiblehum. The hum may also vary with the locationand orientation of the turntable with respect toAC wiring in the walls, making it necessary tomove the turntable to another part of theroom.

Turntables and tape decks are sensitiveto the external hum fields created by manypower amplifiers, and sometimes to the humfields of other house appliances (such as arefrigerator on the other side of the wall). It isimportant that signal cables in general, andthe turntable signal leads in particular, shouldnot run close to and parallel with AC powercords, nor close to a power transformer ormotor (including that in the base of theturntable).

As a test, you might try and disconnect allcables which come from outside the room,such as cable TV, satellite TV, or roof topantennas. Make sure that they are discon-nected where they first enter the room, sothey are making no connection to your VCR,TV, or any other component. If you find thatnoise goes away when a cable TV line isdisconnected, then you will need a “ground-loop isolator.” This is an inexpensive devicefitted in line with the coaxial cable feed.

If the hum persists, disconnect all thesource components one at a time from theback of the preamplifier and you may identifythe problem.

In many cases, hum may be eliminated byreversing the Classic’s (unpolarized) ACpower plug in the wall socket. In others it canbe minimized by connecting a heavy strandedwire from the preamplifier’s ground post to atrue earth ground — which may turn out to beany, all, or none of the following: the third(round) hole in an electrical wall socket inmodern U.S. homes, a steam radiator, or acold water pipe. However, if your poweramplifier employs a three-wire power cord,the stereo system may already be groundedthrough that, in which case another groundedwire from the preamp may create a “groundloop” and make the hum worse. As for thevarious components within the stereo system,they are mutually grounded via the shields ofthe signal cables and should not be intercon-nected with additional grounding wires, for thesame reason (except, of course, the turntable;whose grounding wire usually (but not always)should be connected to the preamplifier’sground post).

Troubleshooting

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Finally we come to the other commonsource of hum problems, the signal cablesand their associated plugs. Inexpensivecables often have mediocre wrapped shield-ing, so better cables may make an audibledifference. And it is important that the plug ateach end of every cable makes a good, tightfit in its mating socket. (In this, don’t neglectthe “source” end of the turntable signalcables, which in many tables are plugged intosockets underneath rather than being sol-dered to terminals within the turntable’s base).Crimp the leaves of the phono plug’s skirtslightly inward, if necessary, to ensure that ithas a tight friction-fit on the exterior of thephono jack. When plugging in each cable, usea rotary twisting motion as the plug goes intothe jack, in order to scrape away any invisiblesurface corrosion and make a clean metal-to-metal contact. Finally, in many inexpensivemolded cables, the wire breaks where itmakes contact with the plug; this problem canbe identified by wiggling the cable and listen-ing for an intermittent signal connection orintermittent hum.

Radio Frequency InterferenceRadio Frequency interference (RFI) from

CB, TV, AM, and other radio transmitters is acommon problem, and like hum it usually canbe traced to a condition external to theClassic. Sometimes RFI gets into the poweramp via the signal cables running from thepreamp, and may be cured by substitutingcables with better braided or foil shielding.More commonly RFI enters the power ampthrough its output terminals, with the speakerwires acting as receiving antennas. In thiscase it might be cured by connecting a 0.01 to0.1 microfarad disc capacitor across thespeaker terminals of each channel, but besure to check with the amplifier manufacturerfirst; some power amps become unstable andburn out when certain values of capacitanceare connected at their output terminals. Asimple cure is to place the power amp nearthe speakers and use short wires; then uselong well-shielded signal cables from thepreamp to the power amp. This shouldn’tcause any problems under normal conditions.

If the interference disappears when youmute the output of the preamp, then theinterference is part of the signal and probablyis entering the preamp from one or more ofyour signal sources. Use the Input Selectorand Tape Monitor controls to identify whichsignal sources are picking up the interference,or unplug the sources one at a time. Usuallyturntables and tape decks are most vulner-able to RFI. If the RFI is coming in through thephono signal leads, cables with better shield-ing might help. Other options include wrap-ping the signal cables with aluminum foilwhich is then connected to the Ground post;or forming a loop in the cables, adjusting thesize of the loop to tune out the interference,and taping it in place. And as with hum, trytightening all phono plugs and twist them intheir sockets to get good metal-to-metalcontact.

RFI in tape decks may enter via signalcables, but more commonly the interferenceis picked up directly in the playback head andits associated internal wiring, so a cure islikely to involve a trip to the factory or serviceshop for approved modifications. Or you mightbe able to reduce the interference to tolerablelevels simply by turning the tape deck 90degrees or moving it to another location in theroom. A signal-processor, such as an equal-izer, may be connected between either Mainoutput set and the inputs of the power ampli-fier which drives the speakers you wish toequalize.

Troubleshooting

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User's Manual

Changing the phono stage gainThe following gain changes may be

performed by experienced electronic techni-cians. Your Sunfire Dealer may be able torecommend a good service/repair shop.

Factory set gain of MM Phono is 40 dB.The gain may be changed as follows:

36 dB - change R 11 and R 35 to 3.9 K ohms

40 dB - R 11 and R 35 are 2.4 K ohms

44 dB - change R 11 and R 35 to 1.5 K ohms

These resistors are located on the circuitboard close to the Phono stages. They areidentified by white ink lettering. Changingthese resistors will simultaneously increasethe gain of the moving coil phono stage, i.e.,by the same four dB increments.

Factory set gain of MC Phono is 60 dB.The gain may be changed independently ofMM Phono as follows:

60 dB - Stock R4 and R28 are 62ohms, 1/2W

65 dB - change R4 and R28 to 33 ohms,1/2W

70 dB - change R4 and R28 to 18 ohms,1/2W

Changing the input impedanceof the phono stage

Change the jumper position on theheaders labeled J6 & J9 to the value recom-mended by your phono cartridge manufac-turer. Most moving magnet cartridges workbest at the 47k setting. Moving coil cartridgestypically work best at a lower setting.

Tube type and locationPhono Board

V1 6DJ8 or 6922 MC amp



V4 12AX7 MM amp

V5 12AX7 MM amp

V6 6DJ8 or 6922 Infrasonic amp

Line Board

V1 6DJ8 or 6922 Contour amp

V2 6DJ8 or 6922 Line amp/Bal amp

V3 6DJ8 or 6922 Line amp/Bal amp

Note: 6922 Tubes are preferred as theyhave less noise and microphonics than 6DJ8s

Appendix

Appendix

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User's Manual

Limited Warranty

Sunfire Corporation is proud of its prod-ucts which have been built with care usingadvanced technology and premium compo-nent parts. Your unit has been crafted toperform properly for many years. SunfireCorporation offers the following Warranty toyou, the owner of a new Sunfire product:

The Sunfire Corporation Warranty for theClassic vacuum tube preamplifier is in effectfor FIVE years from the date of original retailpurchase. The Sunfire Corporation Warrantycovers defects in materials and workmanship.The following, however, are excluded:

a) Damage caused during shipment

b) Damage caused by accident, misuse,abuse of operation contrary to theinstructions specified in the SunfireCorporation user’s manual

c) Units where the serial number hasbeen defaced, modified or removed

d) Damage resulting from modification orattempted repair by any person notauthorized in writing by Sunfire Corpo-ration.

The Sunfire Corporation Warrantyextends to the original owner or subsequentowner(s) during the five year warranty periodso long as the original dated purchase receiptis presented whenever warranty service isrequired.

All implied warranties, including warran-ties or mechantability and fitness for particularpurposes, are limited in duration to the fiveyear length of this Warranty, unless otherwiseprovided by state law.

Sunfire Corporation’s liability is limited tothe repair or replacement, at our option, ofany defective product and shall not in anyevent include property or any other incidentalor consequential damages which may resultfrom the failure of this product.

Some states do not allow limitations on howlong an implied warranty lasts and/or do notallow the exclusion or limitation of incidental orconsequential damages, so the above limita-tions or exclusions may not apply to you.

This Warranty gives you specific legalrights, and you may also have other rightswhich vary from state to state. We suggestthat you attach your purchase receipt to thisWarranty and keep these in a safe place.Thank you for your choice of a SunfireCorporation product.

Service AssistanceWe suggest that you read the Limited

Warranty completely to fully understand yourWarranty/Service coverage.

If your Sunfire Corporation product everrequires service, write to us or call:

Sunfire CorporationTechnical Services DepartmentP.O. Box 1589Snohomish, WA 98290Tel (425) 335-4748Fax (425) 335-4746

You will be directed to an authorizedSunfire Corporation Service Station or receiveinstructions to ship the unit to the factory.Please save the original shipping carton andpacking materials in case shipping is required.Please do not ship Parcel Post.

NOTE: Before sending in your unit for repair,you must call Sunfire for return authorization.

Include a complete description of theproblem, indicating how you have it con-nected, the associated equipment in yoursystem and a copy of your purchase receipt.Initial shipping costs are not paid by SunfireCorporation; return ground shipping costs willbe prepaid if repairs were covered by thescope of this Warranty.

©2001, Sunfire Corporation. All rights re-served.

Limited Warranty

Manual Part number : 913-012-00 Rev C

user's manual...3 user's manual 15. to prevent electric shock, do not use this polarized...

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