Harman Kardon A224 User's Manual
Contents
1. ON position You will note how the low frequencies become more apparent while the volume level remains unchanged Balance Contred This control has no function in monaural listening and should be left in the center position If rotated to either extreme position it would completely shut off the preamplifier on that side Mode Switch The only application for this switch in monaural operation is to select he tween the twa preamplifiers This allows for double the usual number of input jacks found on ordinary monaural amplifiers The STEREO NORMAL and MONAURAL RIGHT positions are identically connected and will activate the Right preamplifier therefore awitching on all program material connected to this preamplifier STEREO REVERSE and MONAURAL LEFT are identically con nected and will activate the Left p amplifier For simplicity it is suggested to use only the MONAURAL RIGHT and MONAURAL LEFT positions on the MODE Switch for monaural operation Switch to MONAURAL RIGHT or MONAURAL LEFT as a function of the preamplifier you wish to use Funetion Switch The FUNCTION Switch selects the desired type of program source and has four positions TAPE LO PHONO LO selects the program source plugged into the LOW LEVEL INPUTS which may be either tape or magnetic phono The next position PHONO HI selects either of the two PHONG HL inputs The TUNER position selects your monaural tuner for operation and the AUX TAPE HI selects your tape rec2. INSTRUCTION MANUAL It is essential you rend this instroction booklet carefully before installing your high fidelity system You have invested in an extremely fine clectronic instru ment into which many excellent enginecring developments have been incorpo rated and cach is important for the proper operation of your system This booklet has heen written in simple nontechnical language and if you will take time to Tead it frst before doing anything eke you will find it simple to obtain optimum performance from your Harman Kardon Model A 224 Stereephonic Amplifier Be sure to keep this booklet available at all times lt contains indispensable tecn nical and service information A ifr Mie Horwtew Karcen Serea Spanked fit paar atinaere of caperd nered T GENERAL DESCRIPTION The A 224 stereophonie amplifier is extremely versatile and may be used in any of the following ways 1 Stereophonic amplifier with 12 watts of audio in each channel 2 Monaural amplifier with 24 watts of audio 48 watt peaks 3 Stereophonic conversion amplifier utilizing your present high fidelity amplifier or combination unit for the second channel UNPACKING After unpacking the Trio inspect it carefully for signs of transit damage The unit was subjected to many inspections and tests prior to final packing and it therefore should be in perfect condition If damage is visible notify your dealer at once If the unit was shipped to you notify the tr
3. Control The nature of stereo reproduction is such that it requires two identical channels ta attain the highest degree of faithfulness and spatial distribution Any variation in the efficiency of one channel as compared to the other will distur this relationship Since there may be slight differences between the two speakers tape heads ete the A 224 includes a control te balance one channel against the other Sufficient range is covered by this control to permit rebalancing of the overall system even in cases where major unbalance exists It is entirely to be ex pected that this control will be set anywhere within its range to attain system balance When the BALANCE control is properly set the apparent sound source will lie in a broad area between the two speakers When the BALANCE control is rotated to the right the sound will move to the right and when the control is rotated to the left the sound will move to the left Mode Switch The MODE switch selects between stereo operation where a stereo program source is available and monaural operation utilizing the full power of both chan nels and both speakers when the program source is onai a USING THE MODEL A 224 AS A CONVERSION AMPLIFIER FOR STEREO If you mow own a basic amplifier or an amplifier preamplifier you may utilize the model A224 for the second channel and control the entire sherco sys tem with the A 224 preamplifier For this application the model A 224 is con nected in
4. ansportation company without delay Check the contents of the carton thoroughly and inspect the folds of the packing material before discarding it Your package should contain the following ibems 1 Trio Model A 224 Stereophonie Amplifier Preamplifier 1 Instruction Booklet 1 Warranty Card 1 Mounting Template WARRANTY POLICY We urge you te completely fill in your warranty card amd mail it te the fac tery without delay te protect your rights under warranty The warranty ecards are carefully filed for reference and should you require information on the use of this high fidelity unit or repair service we will be able to immediately identify your set and reply quickly NOTE It is necessary to receive factory authorization before returning a get for warranty repair cither to the factory or to an authorized station Repairs are to be returned on an Express Propaid basis A letter describing the exact diffi culty mast be enclosed with the unit WARRANTY We warrant each Trio Model A 224 to be free from defects in material and workmanship under normal use and service and in accordance with the canili tions herein below set forth for a period of 1 year from date of delivery to the original purchaser aml agree to replace or repair any part or parts with the exception of tubes which are under the manufacturer s 90 day warranty reburned to us within said 1 year with transportation prepaid and which our examination shall disclose to our s
5. atisfaction to have been thus defective This warranty does net include free labor nor is it applicable to any instrument which shall have been repaired or altered in any way so as in our judgment to affect its stability or reliability nor which has been subject to neglect misuse abuse negligence or accident nor whieh has had the serial number altered effaced or removed Neither shall this warranty apply to any instrament which has heen connected otherwise than in accordance with instructions furnished by us This warranty is expressly in Heu of all other warranties express or implied and of all other obligations or lability on our part and we neither assume nor authorize any representative or other person to assume for us any other liability in connection with the sale of this instrument USING THE MODEL A 224 AS A STEREOPHONIC AMPLIFIER INSTALLATION PROCEDURE Ventilation The unit is well ventilated in itsclf but sufficient space must be allowed around it to permit proper air flow Install the amplifier in a manner to allow for unrestricted circulation Do not pkice books or other objects on the cage or in the immediate vicinity of the instrument Reducing the air flow will result in sharply reduced component and tube life Power Requirements Plug the AC cord into any outlet furnishing LIT volts 50 or 60 cycle AC oir rent The voltage may vary between 15 and 125 volts Two AC convenience outlets are located on the rear of the instru
6. his might cause overloading of the input stage Conmect the recorder output plug to either LEFT or RIGHT TAPE AI AUX jack on the rear panel Connecting Your Tape Recorder To Make A Recording Provision is mide on your Model A 224 ampliber to permit the recording of any program material Connect the input of your monaural tape recorder to either the LEFT or RIGHT TAPE OUT receptacle located on the rear panel TF the program source you desire to record is plugged into the left preamplifier channel use the LEFT TAPE OUT jack and if it is plugged into the right pre amplifier channel use the RIGHT TAPE OUT jack This will enable you to make a recording with the proper recording equalization as determined by your recorder while simultaneoush monitoring the program with the proper tone contrel contour amd boudness setting Connecting Auxiliary Monaural Equipment A TV toner or other similar device with high output levels may be con nected to either the LEFT or RIGHT TAPE HI AUX jock on the rear panel OPERATING THE MODEL 4 224 AS A MONAURAL AMPLIFIER The Model A 234 incorporates the following front panel controls Viewing the instrument from left to right you will note a TREBLE Control on olf switch is incorporated in this control BASS Control LOUDNESS Control BALANCE Control MODE Switch and FUNCTION Switch On the upper left section of the front panel you will note two SPEAKER SELECTOR Switches and on the upper right section a CONTOUR Swi
7. input to either LEFT or RIGHT TAPE OUT receptacle If the program source you desire to record is plugged inte the left preamplifier channel use the LEFT TAPE OUT jack and if it is plugged inte the right preamplifier channel use the RIGHT TAPE OUT jack This will enable you to make a recording with the proper recording equalization as determined by your recorder while simultancously monitoring the program with the proper tone control contour and lowdness setting Connecting Your Record Player Any type of record player may be used with this amplifier IF your player uses a low level magnetic cartridge plug it into either the LEFT or RIGHT LOW LEVEL INPUT Sct the appropriate PHONO TAPE switch located on the rear panel to the PHONO position IF you are using a monaural ceramic or crystal cartridge plug it inte either the LEFT or RIGHT PHONO HLI input Connecting Your Tape Player Connect your monaural tape deck to one of the LOW LEVEL INPUT acks on the rear panel IF your magnetic cartridge is connected to the LEFT OW LEVEL INPUT connect the tape deck to the RIGHT LOW LEVEL IN FUT or viceversa The PHONO TAPE EQUALIZATION switch correspond ing to the LOW LEVEL INPUT used for the tape deck must be in the TAPE position for proper tone equalization Connecting Your Tape Recorder Since most monaural tape recorders have their own preamplifier it is not desirable to plug the output of the recorder into the LOW LEVEL INPUT jack T
8. ment Auxiliary apima tape deck record player additional amplifier may be plugged inte these outlets and will be controlled by the on olf switeh located on the A 224 REAR PANEL CONNECTIONS LEFT SArARcAS EHT giha FAR Deae 2Qaeae e a if I 5 E E Wf Tare js oH et AEAN P HEL HOOTL Ane Connecting Your Speakers Your two speakers should be matched if possible to obtain optimum results and should be placed approximately amp to 15 feet apart a one wall of your listening room Corner placement is also quite acceptable Facing the speakers straight out or slanting them slightly will depend om your room size scoustle effect and where you will be seated for listening It may be mecessary to experi ment with speaker placement tatil best results are obtained Use any type wire to commect your speakers Lamp cord is excellent and muy be eusily dressed around the molding for an inconspicuous and neat installation Normal Stereo Speoker Arrangement Connect one lead from the left speaker te the 16 ohm terminal on the LEFT SPEAKER output strip and the other lead to the A or B terminal on the same strip Now connect one of the leads from the right speaker to the LA ohm term inal on the RIGHT SPEAKER output strip and the other lead to the A or B terminal on the same strip NOTE A and B terminals on both SPEAKER output strips are strapped together at the factory and should be allowed to remain strapped for this method
9. of steren speaker connection Sec Dingram A The output terminals nsed should be those marked with the same impedance as the speakers The above illustration is for 16 ohm speakers If you are using ohm speakers connect to the 4 ohm SPEAKER output terminals rather than to the 16 ohm terminals The two SPEAKER SELECTOR switches located on the front panel are za P for this method of connection and their setting is therefore not critica IMPORTANT For all methods of stereo operation the POWER PARAL LEL switch mounted on the front chassis support apron to the left of the pilot light must remain in the SEPARATE position The cage if used must be removed to provide acoess to this switch E NORMAL STENE SPEAKER HOOK UP Diagram A Two Independent Stereo Speaker Systems The Model A 224 stereo amplifier incorporates a unique switching arrange ment enabling the user to operate two independent stereo speaker systems bo cated in different rooms Remove the shorting bar between A and B terminals on both SPEAKER out put strips Connect a lead from the left speaker in System A to the 16 ohm term inal on the LEFT SPEAKER output strip and another lead from this speaker to the A terminal on the same strip Connect the right speaker in System A to terminals 16 and A on the RIGHT SPEAKER output strip This complete System A installation E To install System B connect a lead from the left speaker to the 16 ohm terminal on the LEFT SPEAKER o
10. order or other auxiliary monaural equipment Speaker Selector Switch In a monaural installation where more than one set of speakers are installed for example one speaker in the living room and another in the den selection between the two speakers is made by operating the SPEAKER SELECTOR switch on the front panel To operate Speaker A located in your living room set the Left SPEAKER SELECTOR Switch located on the front panel to A and the other SPEAKER SELECTOR Switch to ONE To select Speaker E flocated in another room set the SPEAKER SELECTOR Switch to B and the right SPEAKER SE LECTOR Switch to ONE To operate both speakers simultaneously set the Left SPEAKER SELECTOR Switch to either A or BY and set the right SPEAKER SELECTOR Switch to ALL Rumble Filter At times record changers records and even some turntables produce an ob jectional low frequency signal that is strong enough to be introduced into the sensitive playback system Known as Rumble this unlesirable signal can be climinated by the special RUMBLE FILTER Switeh incorporated in the Model A 234 Whenever rumblo is encountered set the switch to ON
11. perating controls menali normally be doubled This would make operation un necessarily cumbersome For convenience the duplicate controls are mechanically tied zelian or ganged to be operated hy ane knob Boss and Treble The BASS and TREBLE controls on the Model A 224 provide the full range of tonal adjustment necessary for high fidelity listening These controls can either boost or ent the bass and treble tones of the stereo system The controls ahould be set in accordance with your hearing preference speaker characteristics and room acoustics Loudness Control This control adjusts the volume level of any program material fed into your stereo system Its effect can be modified by the CONTOUR switch Contour Switch One of the Limitations of human hearing is its tendency to lose sensitivity to the very low pitched sounds as the program sound level is reduced It is this characteristic known as the Fletcher Munson effect which causes one to play music programs at high listening level in order to experience the full rich tone available from fine modern recordings The Harman Kardon CONTOUR switch compensates for the Fletcher Munson effect thos eliminating high listening levels as a requisite for full enjoyment of reproduced music For low level listening throw the CONTOUR switch located on the front panel to the ON position You will note how the low frequencies become more apparent while the volume level remains unchanged Balance
12. room is vory quiet The setting for minimum hum is attained only when the two power tubes have been exactly balanced and this is the comelition for absolute minimum distortion Hum Adjustment One HUM ADJUST HIGH LEVEL control and one HUM ADJUST LOW LEVEL control are located on the chassis behind the electolytic condenser and in front of the LAUT tube Each operates simultaneously to adjust both left and right channels To adjust for minimum hum set the FUNCTION switch to TUNER tum the tuner olf if porinactes and turn the LOUDNESS control full on While listen ing to either s neaker adjust the HIGH LEVEL hum enatrol for minivan Wir Now set the FUNCTION switch to the TAPE LO position and set the LOW LEVEL hum control for minimum hom System Hum or Noise in any high fidelity installation hum may be couse by the interconnection af a record changer tuner and amplifier as a result of the cables and different groumds A 1 way to climinate this problem is to first disconnect everything but the speakers from the amplifier and listen for hum Lf the hum persists make the hum and balance adjustments described above Try reversing the ampli fer power plug Now plug in the record player Hf hum appears try reversing the record player power plug and try connecting a wire from the record player chassis to the amplifier chassis In this way connect the tuner tape deck and other de vices in ture Note that hum may be picked up by defecti
13. should be left that way IF you are using an amp ohm speaker tie the two 16 ohm terminals together instead of the 32 ohm terminals as cescrited The SPEAKER SELECTOR Switch on the front panel may be placed in any position since it is inoperative for this method of installation Connect Speaker B te the G and 16 ohm speaker terminals on your other monaural amplifier SREAKES HOON UF POM STERED COVES Diogram E Connecting Both Amplifiers For Stereo Operation Connect a shielded lead not longer than 3 or 4 feet between the LEFT PREAMP OUT jack on the rear of the A 224 and the Aux or Tuner input on your other amplifier Connect the AC power cord from your monaural amplifier to the AC cem venience outlet on the rear of the Model A 234 The on off switch on the A 224 will now control the power for both amplifiers Contour Switch One of the limitations of human hearing is its tendency to lose sensitivity to the very low pitched sounds as the program sound level is reduced It is this characteristic known as the Fletcher Munson effect which causes one to play music programs at high listening level in order to experience the full rich tone available from fine modern recordings The Harman Kardon Ci INTOUR Switch compensates fer the Fletcher Munsen effect thus climinating high listening levels ag a requisite for full enjoyment of reproduced musie For low level listening throw the CONTOUR Switch located on the front panel to the
14. t permanently in that setting Sa the tone controls amd contour switch to Hat the rumble and scratch filter switches to off and the funetion selector to AUX or TUNER depending on which input receptacle was used for connecting to the A 224 Set the VOLUME control on your old amplifier to minimum and mljust the BALANCE Control on your Model A 224 to the mid point Play a stereo rec ord of tape and turn the LOUDNESS Control on your A 224 up te a mormal lis tening volume The left channel will be inoperative since the volume control on your old amplifier is set at minimum Now slowly rotate the volume control on this amplifier until the loudness of the two channels is equal Allow the volume control on your second amplifier to remain in this pesition permanently ADJUSTMENTS Output Balance Individual OUTPUT BALANCE controls for Left and Hight channels are located between the EL 84 output tubes These controls balance the two output tubes of each channel for lowest power hum and distortion Adjustment is quite simple With the amplifier turned on for a sufficient length af time to be thor oughly warmed up tum the LOUDNESS control to minimum Now while lis tening carefully to the left speaker adjust the LEFT OUTPUT BALANCE con trol for minimum hum Then while dstening to the right speaker only adjust the RIGHT OUTPUT BALANCE control for minimum hum Due to the ex tremely low hum level of the A 224 this is best done at a time when the
15. t pug Connect one plug to the LEFT LOW LEVEL INPUT jack located on the lower rear of the Daan and the other apn ping to the RIGHT LOW LEVEL INPUT jack Place both PHONO TAPE switches located directly above the LOW LEVEL INPUT jacks down in the TAPE position Since the Model A 224 has anly one pair of low level input receptacles for stereo use cither a magnetic cartridge or a tape head may be plugged in It beth types of program sources are desired it is suggested a ceramic cartridge be used instead of a magnetic type The tape head can then be plugged inte the two LOW LEVEL INPUT jacks and the ceramic cartridge can be plugged into the two PHONO HI jacks Connecting Your Stereo Tape Recorder Since most sterco tape recorders have their own preamplifiers it is mot de sirable to plig the autput of the recorder into the LOW LEVEL INPUT This might canse overloading of the input stage Connect one of the output plugs into the TAPE HI AUX jack on the RIGHT HIGH LEVEL INPUT strip and the other inte the TAPE HI AUX jack on the LEFT HIGH LEVEL INPUT strip Connecting Your Tape Recorder To Make A Recording Provision is made on your Model A 224 to permit the recording of any pro gram material Connect the left input of your stereo tape recorder to the ra ceptacle marked LEFT TAPE OUT on the rear panel and the right input of your stereo tape recorder to the receptacle marked RIGHT TAPE OUT To con nect a monaural tape recorder connect its
16. tch and RUMBLE FILTER Switch TECHNICAL EXPLANATION OF THE CONTROLS Bass and Treble These controls provide the full range of tonal adjustment necessary for high fidelity listening These controls can either boost or cut the bass and treble tomes of your monaural system The controls should be set in accordance with your hearing preference speaker characteristics and room acoustics Loudness Contra This control adjusts the volume lovel of any program material fed into your high fidelity system Its effect can be modified by the CONTOUR Switch OPERATING THE MODEL A 224 AS A STEREOPHONIC AMPLIFIER Every control on a well designed and honestly considered high fidelity in strument has a specific useful function related to each of the other benm Af brief explanatory note on the relationship of the various front panel controls will doubtless prove useful in organizing and clarifying them for you The Model A 234 incorporates the following front panel contrels Viewin the instrument from left to right you will note a TREBLE control on oll switch is incorporated in this control BASS control LOUDNESS contr BALANCE eontral MODE switch and FUNCTION switch On the upper left section of the front panel you will note two SPEAKER SELECTOR switches and on the upper right section a CONTOUR switch and RUMBLE FILTER switch TECHNICAL EXPLANATION OF THE CONTROLS Since a stereo amplifier is actually two amplifiers in one the number of o
17. the manner described below INSTALLATION PROCEDURE Connecting Your Speakers Your two speakers should be matched if possible to obtain optimum results and should be placed 8 to 15 feet apart against one wall of your listening room Comer placement is also quite acecptable Facing the speakers straight out or slanting them slightly will depend on your room size acoustic effect and where you will be seated for listening It may be necessary to experiment with speaker placement until best results are obtained Use any type wire to connect your speakers Lamp cord is excellent and miay be easily dressed around the molding for an inconspicuous and neat installation Speaker Connection For Conversion Arrangement Set the POWER PARALLEL Switch located on the front chassis support apron to the left of the pilot light to the PARALLEL position and strap the appropriate Speaker Output terminals together IMPORTANT Whenever the POWER PARALLEL Switch is in the PARALLEL position the Speaker Oul put terminals must be strapped together and conversely whenever the Speaker utput terminals are strapped together the POWER PARALLEL Swibely must be in the PARALLEL position Connect Speaker A refer to Diagram E to either 2 ohm terminal on the Speaker Output strip and the other lead to either A terminal Now tie the two 32 ohm terminals together The A and B terminals on both output strips have been strapped together at the factory and
18. utput strip and another lend to the B term inal on the same strip Now connect the right speaker in System B to the 16 and B terminals on the RIGHT SPEAKER output strip This completes System B in stallation See Diagram 1 The above illustration is for 16 chm speakers IF you are using 8 ohm speak ers connect to the 8 ohm terminals on the SPEAKER OUTPUT strip rather than to the 16 If one pair of speakers is 8 ohms and the other pair 16 ohms then connect appropriately For this type of installation the SPEAKER SELECTOR switches located on the front panel are operative See Stereo Operating Instructions IMPORTANT The POWER PARALLEL switch located on the front chassis support apron to the left of the pilot light must remain in the SEPA BATE position The cage if used must be removed to provide access to this awitch Army ATRAPA HOO uP OF TE INDEPENDENT STEREO SPEAKER SYSTEMS Diagram B No further connections need be mule to your old monaural amplifier Pro gram sources such as tuner tape phonograph ete are connected to the appro priate receptacles on the A 234 as deseribed under stereo installation OPERATING YOUR MODEL A 224 AS A CONVERSION AMPLIFIER Operation of the model A 234 as a stereo conversion amplifier is identical with ils operation as a normal stereo amplifier The controls of the old monaural amplifier now being used as one channel of your new stereo system must be properly set however amd then lof
19. ve interconnecting cables and by interconnecting cables running too close to power cables Connecting Your Tumir The FM output of your Harman Kardon stereo tuner should be connected to the LEFT TUNER input jack on the HIGH LEVEL INPUT strip located om the rear panel The AM output should be connected to the RIGHT HIGH LEVEL INPUT jack The same method of installation applies if you are using separate FM and AM tuners Plug the AC line cord of your tuner into one of the AC com venience outhets located om the rear panel of the Model A 224 amplifier Connecting Your Stereo Record Player A stereo cartridge is essentially two cartridges in ome amil uses two ouput connecting plugs If yeu are using a low level maguetic cartridge phig one output lead into the LEFT LOW LEVEL INPUT locatel on the lower left rear of the chassis and the other plug into the RIGHT LOW LEVEL INPUT jack Both PHONO TAPE switches located directly above the LOW LEVEL INPUT jacks must be placed in the up or PHONO position Stereo crystal or ceramic cartridges may also be used with this amplifier They must be plugged into the LEFT and RIGHT FHONO HI jacks located on the HIGH LEVEL INPUT strip on the rear panel Plug the AC line cord of your record player into one of the AC convenience outlets located on the rear panel of the Model A 224 amplifier Connecting Your Stereo Tape Player A steresphonic tape deck utilizes two pliyback heads Each head has its own outpu
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