McIntosh MA 230 - SERVICS BULLETINS Owner'S Manual Download Page 1

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STEREO

PREAMP-AMPLIFIER

MA230

TABLE OF CONTENTS

11
12
12
12
12

GENERAL DESCRIPTION

TECHNICAL DESCRIPTION

Mechanical Specifications
Electrical Specifications

FRONT PANEL INFORMATION

INSTALLATION

CONNECTIONS

AC Connections

Ground Connection

Tape Output Connections

Loudspeaker Connections

AC Power

Input Connections

OPERATING INSTRUCTIONS

GUARANTEE

3-YEAR FACTORY SERVICE CONTRACT

MA23

Summary of Contents for MA 230 - SERVICS BULLETINS

Page 1: ...TION TECHNICAL DESCRIPTION Mechanical Specifications Electrical Specifications FRONT PANEL INFORMATION INSTALLATION CONNECTIONS AC Connections Ground Connection Tape Output Connections Loudspeaker Connections AC Power Input Connections OPERATING INSTRUCTIONS GUARANTEE 3 YEAR FACTORY SERVICE CONTRACT MA230 ...

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Page 3: ...ve enjoyed the outstanding performance of the MA230 you will under stand why Mclntosh products have earned their reputation as THE BEST Your Mc lntosh MA230 stereo preamp amplifier will give you years of the finest possible per formance and will become a highly valued part of your home music system TECHNICAL DESCRIPTION The new Mclntosh MA230 combines for the first time a Mclntosh engineered stere...

Page 4: ... is 250 000 ohms Any conventional tuner or tape recorder may be connected to the MA230 without loss of low frequencies The emitter follower provides the required high input impedance and low output im pedance for feeding the tone control negative feedback circuits The last two stages of the tone control section are two transistors in a Darlington configuration similar to the phono preamplifier The...

Page 5: ...or life The thermistor places slightly more than 25 ohms in the AC circuit when cold As the amplifier warms up the thermistor also warms and its resistance then drops to less than 0 7 ohm The ampli fier then operates at normal line voltages but is protected during the initial warmup period Again Mclntosh care in engineering protects your investment in listening pleasure The combination of these fe...

Page 6: ...h for independent adjustment of each channel Treble Controls 18db at 20 000 cycles with friction clutch for independent adjustment of each channel Comp Compensator Switch RIAA or LP phono equalization Tape Switch Normal or Tape Monitor Phase Switch Normal 0 or reverse 180 Speaker Switch Speakers ON or OFF for headphone listening HF Filter Flat or 5 000 cycle cutoff 12db per octave LF Filter Flat o...

Page 7: ... the back panel PHONO 1 input jacks 5 PHONO 2 Same as PHONO 1 For ex ample PHONO 1 can be connected to a record changer while PHONO 2 is connected to a manual turntable 6 TAPE HD Use the TAPE HD Tape Head position for a tape deck that does not have its own playback preamplifier The Tape Head leads are connected to the back panel TAPE HD input jacks MODE SELECTOR Use the MODE SELECTOR to Listen to ...

Page 8: ...turning the control to the left accents the left channel by reducing the right channel output RIGHT turning the control to the right accents the right channel by reducing the left channel output BASS Figure 5 BALANCE Control The BASS control is a dual concentric control The two are friction coupled The center knob controls the left channel The outer ring controls the right channel With the BASS co...

Page 9: ...s acceptable Tape monitor jacks on the back panel accept a signal from a tape recorder with a monitor head and preamplifier NORMAL the original program source is fed through the power amplifiers and the loudspeakers MONITOR the recorded sound on the tape is fed through the power amplifiers and speakers The PHASE switch corrects for loud speaker or program phasing When this switch is in the 180 pos...

Page 10: ...omatically provides the cor rect amount of bass and treble boost re quired to compensate for this change in response of the human ear at low loudness levels Use the LOUDNESS switch in the COMPENSATED position to listen at low volume and still hear full frequency range HEADPHONE SPEAKER ON POWER ON HEAD PHONE HEAD PHONE OFF OFF Use the HF filter to minimize surface noise when reproducing old or bad...

Page 11: ...ack of the cabinet panel Since the MA230 should rest on a shelf lo cate the cutout from the back of the panel 1A Position the MA230 mounting tem plate on the cabinet panel area to be cutout for the installation 1B On the back of the cabinet panel scribe a vertical line through the exact center of the cutout area Place the template against the back of the panel Match the template centerline with th...

Page 12: ...d mounting strip on the other side of the rectangular cutout 6 Left and right metal mounting brackets are packed with the MA230 Fasten these two mounting brackets to the cabinet panel using four of the fillister head screws These screws should pass through the mounting shelf flange through the cabinet panel and then into the mounting strip attached to the inside of the panel Tighten the screws fir...

Page 13: ...e turn table with its own control switch The turn table drives will then be properly disengaged to avoid possible damage Figure 23 AC CONNECTIONS L R OUTPUT Both left and right channel amplifier out puts are combined into a monophonic signal at the L R output jack Connect this jack to an external amplifier for monophonic repro duction through another speaker system Monophonic signals can then be d...

Page 14: ...r leads to the two screws under the lettering marked LEFT SPEAKER Con nect the right speaker leads to the two screws under the lettering marked RIGHT SPEAKER The common or chassis ground tap on each channel is marked C Connect each speaker in an identical manner AC POWER Plug the AC power cord into a 120 125 volt 50 or 60 cycle power line INPUT CONNECTIONS The MA230 provides seven separate pro gra...

Page 15: ...DIRECTIONAL FM ANTENNA ROTATOR 8 OHM SPEAKERS SHOWN TO 12OV AC OUTLET 13 GROUND ...

Page 16: ...t the knob indicators are centered be tween the panel markings L and R 4 Turn the BALANCE control to the cen ter or 12 o clock position 5 Place the LOUDNESS switch in the NORMAL position 6 Place the TAPE switch in the NORMAL position 7 Place the PHASE switch in the 0 position 8 Place the LF filter switch in the FLAT position 9 Place the HF filter switch in the FLAT position 10 Turn the MODE SELECT...

Page 17: ...cators centered be tween the panel markings L and R If you wish to reduce treble in relation to bass for example turn the TREBLE CONTROLS coun terclockwise until the tone balance sounds correct to you These controls will modify tone balance without introducing any unde sirable effects Do not be surprised if you find your preference in tone changing from time to time PHASE If the stereo sound seems...

Page 18: ...n the INPUT SELECTOR to TAPE HEAD 2 Turn the MODE SELECTOR to MONO L R or STEREO depending on the pro gram on the tape 3 Set the PHASE switch to 0 4 Set the HF cutoff filter switch to FLAT See page 15 ADJUSTING FOR SPECIAL EFFECTS 5 Set the LF filter switch to FLAT See page 15 ADJUSTING FOR SPECIAL EF FECTS 6 Set the LOUDNESS switch to NORMAL See page 15 ADJUSTING FOR SPECIAL EFFECTS 7 Set the BAS...

Page 19: ... in the MA230 After extensive use or when tubes have been replaced these ad justments will insure top performance from your MA230 The DC bias of each 7591 output tube can be individually set Test Point jacks and bias adjust controls are conveniently mounted on the chassis next to each output tube The output tubes Test Point jacks and bias con trols are marked V TP and R respectively The bias adjus...

Page 20: ...RESPONSE IN DB 20 10 0 10 20 20 100 1KC 10KC 20KC 0 5 10 15 20 25 30 18 BASS AND TREBLE CONTROL RESPONSE FREQUENCY RUMBLE AND HIGH FREQUENCY FILTERS RESPONSE IN OB 20 100 1KC 10KC 20KC FREQUENCY ...

Page 21: ...LOUDNESS CONTROL FREQUENCY EQUALIZATION CURVES 25 20 15 10 5 0 5 10 15 20 25 20 100 1KC 10 KC 20 KC FREQUENCY 19 20 15 10 5 0 5 10 15 2 0 RESPONSE IN DB RESPONSE IN DB 20KC 10KC 1KC 100 20 ...

Page 22: ...curred during transpor this equipment to be free of defects for a tation to and from Mclntosh Laboratory Inc 3 YEAR FACTORY SERVICE CONTRACT An application for a FREE 3 YEAR FAC fined in the 3 year factory service contract TORY SERVICE CONTRACT is included in the If the application is not mailed to Mclntosh pocket in the back cover of this manual The Laboratory only the services offered under FREE...

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Page 24: ...LABORATORY INC 2 CHAMBERS STREET BINGHAMTON N Y Mods in U S A Phone Area Code 607 723 5491 BE122003 AA133 183 ...

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