MC302 Power Amplifier Owner's Manual - Stereo Barn

InstallationInstallationThe MC302 can be placed upright on a table orshelf, standing on its four feet. It also can be custominstalled in a piece of furniture or cabinet of yourchoice. The four feet may be removed from the bottomof the MC302 when it is custom installed as outlinedbelow. The four feet together with the mountingscrews should be retained for possible future use if theMC302 is removed from the custom installation andused free standing. The required panel cutout, ventilation cutout and unit dimensions are shown.Always provide adequate ventilation for your MC302.Cool operation ensures the longest possible operatinglife for any electronic instrument. Do not install theMC302 directly above a heat generating componentsuch as a high powered amplifier. If all the components are installed in a single cabinet, a quiet runningventilation fan can be a definite asset in maintainingall the system components at the coolest possible operating temperature.A custom cabinet installation should provide the following minimum spacing dimensions for cool operation.Allow at least 6 inches (15.24cm) above the top, 2inches (5.08cm) below the bottom, 3 inches (7.62cm)behind the rear panel and 2 inches (5.08cm) on eachside of the Power Amplifier, so that airflow is notobstructed. Allow 7/8 inch (2.22cm) in front of themounting1 panel for clearance. Be sure to cut out aventilation hole in the mounting shelf according tothe dimensions in the drawing.1When the MC302 is installed together with other McIntosh Components, check clearances on all componentsbefore proceeding.17"43.18cmOpening for Ventilation14-11/16"MC302 Front PanelCustom Cabinet Cutout37.30cmCabinetFrontPanel6"15.24cmOpeningfor VentilationMC302 Side Viewin Custom CabinetCutout Opening for VentilationSupportShelfMC302 Bottom Viewin Custom ut Openingfor VentilationNote: Center the cutout Horizontallyon the unit. For purposes ofclarity, the above illustrationis not drawn to scale.6Cutout Opening for Custom MountingCabinet Front Panel40.64cm

Rear Panel Connections and SwitchINPUT MODE switchselects between Balancedor Unbalanced InputsUnbalanced INput (LEFT andRIGHT Channels) for an audiocable from a Preamplifier or A/VControl Center audio outputBalanced INputs (RIGHTand LEFT Channels) foraudio cables from a Preamplifier or A/V ControlCenter audio outputPOWER CONTROL INreceives turn On/Offsignals from a McIntoshcomponent.POWER CONTROL OUT1 and 2 send turn On/Offsignals to the next McIntosh Component6.6RIGHT OUTPUT Connectionsfor a 2 ohm, 4 ohm or 8 ohmLoudspeakerLEFT OUTPUT Connectionsfor a 2 ohm, 4 ohm or 8 ohmLoudspeakerConnect the MC302 powercord to a live AC outlet. Referto the rear panel to determinethe correct voltageFuse holder, refer to informationon the rear panel of your MC302to determine the correct fusesize and rating7

Output TerminalsWhen connecting the Loudspeaker Hookup Cables tothe MC452 Power Amplifier Output Terminals pleasefollow the steps below:1. Rotate the top of the Output Terminal Post counterclockwise until an openingappears. Refer to figures A andB.2. Insert the Loudspeaker hookupcable into the Output TerminalOpeningPost opening or the cable spadeFigure BFigure Alug around the center post ofthe Output Terminal. Refer tofigure C.3. Rotate the top of the OutputTerminal Post clockwise until itis finger tight. Refer to figure D.4. Place the supplied McIntoshFigure C Figure DWrench over the top of the Output Terminal and rotate it onequarter of a turn (90 ) to securethe Loudspeaker Cable Connection. Do not over tighten. Referto figure E.Figure Emanner. For additional information refer to “Connector and Cable Information” on page 4.1. For Remote Power Control, connect a power controlcable from the Audio Preamplifier or A/V Control Center Power Control Output 1 to the MC302POWER CONTROL IN.2. Connect XLR cables from the Balanced Output 1(L&R) of an Audio Preamplifier or A/V ControlCenter to the MC302 Balanced INput (RIGHT andLEFT). Place the INPUT MODE Switch in theBALANCED Position.Note: An optional hookup is to use unbalancedcables and place the INPUT MODE Switch inthe UNBALANCED Position.This McIntosh MC302 Power Amplifier is designedfor Loudspeakers with an impedance of 2 ohms, 4ohms or 8 ohms. Connect a single Loudspeaker onlyto the Right and Left Output Terminals.When connecting Loudspeakers to the MC302 itis very important to use cables of adequate size, sothere is little to no power loss in the cables. The size isspecified in Gauge Numbers or AWG (American WireGauge). The smaller the Gauge number, the larger thewire size:Loudspeaker Cable Distance vs Wire Gauge GuideHow to ConnectCaution: Do not connect the AC Power Cord to theMC302 Rear Panel until after the LoudspeakerConnections are made. Failure to observe thiscould result in Electric Shock.The connection instructions below, together with theMC302 Connection Diagram located on the separatefolded sheet “Mc1A”, is an example of a typical audiosystem. Your system may vary from this, however theactual components would be connected in a similar8LoudspeakerImpedance25 feet(7.62 meters)or less50 feet(15.24 meters)or less100 feet(30.48 meters)or less2 Ohms8AWG12AWG10AWG4 Ohms14AWG12AWG10AWG8 Ohms16AWG14AWG12AWG3. Prepare the Loudspeaker Hookup Cable for attachment to the MC302 Power Amplifier:Bare wire cable ends:Carefully remove sufficient insulation from thecable ends, refer to figures 2, 3 & 4. If the cableis stranded, carefully twist the strands togetheras tightly as possible.Figure 2Figure 3Figure 4Notes: 1. If desired, the twisted ends can be tinnedwith solder to keep the strands together.2. The prepared bare wire cable ends may beinserted into spade lug connectors.3. Banana plugs are for use in the UnitedStates and Canada only.Banana Plugs are for use in the United States andCanada only:4. Attach the previously prepared bare wire cable endsinto the banana plugs and secure the connections.Refer to figure F.5. Rotate the top of the Output TerminalPost clockwise until it is finger tight.Refer to figure G. Then using theMcIntosh Wrench, rotate the top of theFigure FOutput Terminal one quarter of a turn(90 ). Do not over tighten. Refer tofigure E.6. Referring to figure H, connect theLoudspeaker hookup cables withbanana plugs into the hole at the topFigure Gof the terminal to the MC302 COM(Negative) Output Terminal and Positive OutputTerminal indentified asFigure HFigure orF2Ω (ohms), 4Ω (ohms)8Ω (ohms) connection tomatch the impedance of the Loudspeaker, being

Output Terminals and How to Connectcareful to observe the correct polarities.Note: The illustration on separate sheet “Mc1A”isconnections for 8Ω (ohms) Loudspeakers.If the Loudspeaker’s impedance is in-betweenthe available connections, use the nearest lowerimpedance connection. Refer to “General Information” Note 4 on page 3 for additional information.WARNING: Loudspeaker terminals are hazardous live and present a risk of electricshock. For additional instruction onmaking Loudspeaker Connections contact your McIntosh Dealer or McIntosh Technical Support.7. Connect the MC302 power cord to an active ACoutlet.Note: The illustration on separate sheet “Mc1A”isconnections for 8Ω (ohms) Loudspeakers.If the Loudspeaker’s impedance is in-betweenthe available connections, use the nearest lowerimpedance connection. Refer to “General Information” Note 4 on page 3 for additional information.WARNING: Loudspeaker terminals are hazardous live and present a risk of electricshock. For additional instruction onmaking Loudspeaker Connections contact your McIntosh Dealer or McIntosh Technical Support.9. Connect the MC302 power cord to an active ACoutlet.Spade Lug or Wire Connections:8. Connect the Loudspeaker hookup cables to theMC302 COM (Negative) Output Terminal andPositive Output Terminal indentified as 2Ω (ohms),4Ω (ohms) or 8Ω (ohms) connection to match theimpedance of the Loudspeaker, being careful toobserve the correct polarities. Insert the spadelug connector or prepared section of the cable endinto the terminal side access hole, and tighten theterminal cap until the cable is firmly clamped intothe terminals so the lugs or wire cannot slip out.Refer to figures 7 and 8.Figure 7Figure 89

Output TerminalsWhen connecting the Loudspeaker Hookup Cables tothe MC452 Power Amplifier Output Terminals pleasefollow the steps below:1. Rotate the top of the Output Terminal Post counterclockwise until an openingappears. Refer to figures A andB.2. Insert the Loudspeaker hookupcable into the Output TerminalOpeningPost opening or the cable spadeFigure BFigure Alug around the center post ofthe Output Terminal. Refer tofigure C.3. Rotate the top of the OutputTerminal Post clockwise until itis finger tight. Refer to figure D.4. Place the supplied McIntoshFigure C Figure DWrench over the top of the Output Terminal and rotate it onequarter of a turn (90 ) to securethe Loudspeaker Cable Connection. Do not over tighten. Referto figure E.Figure EHow to Connect for Bi-AmpCaution: Do not connect the AC Power Cord to theMC302 Rear Panel until after the LoudspeakerConnections are made. Failure to observe thiscould result in Electric Shock.The connection instructions below, together with theMC302 Connection Diagram located on the separatefolded sheet “Mc1B”, is an example of a typical audiosystem. Your system may vary from this, however theactual components would be connected in a similarmanner. For additional information refer to “Connector and Cable Information” on page 4.101. For Remote Power Control, connect a power controlcable from the Audio Preamplifier or A/V Control Center Power Control Output 1 to the MC302POWER CONTROL IN Amplifier One.2. Connect a power control cable from the AudioPreamplifier or A/V Control Center Power ControlOutput 2 to the MC302 POWER CONTROL INAmplifier Two.3. Connect XLR cables from the Balanced Output 1(L&R) of an Audio Preamplifier or A/V ControlCenter to the MC302 Balanced INput (RIGHT andLEFT) on Amplifier One. Place the INPUT MODESwitch in the BALANCED Position.Note: An optional hookup is to use unbalancedcables and place the INPUT MODE Switch inthe UNBALANCED Position.4. Connect XLR cables from the Balanced Output 2(L&R) of a Audio Preamplifier or A/V ControlCenter to the MC302 Balanced INput (RIGHT andLEFT) on Amplifier Two. Place the INPUT MODESwitch in the BALANCED Position.Note: An optional hookup is to use unbalancedcables and place the INPUT MODE Switch inthe UNBALANCED Position.This McIntosh MC302 Power Amplifier is designedfor Loudspeakers with an impedance of 2 ohms, 4ohms or 8 ohms. Connect a single Loudspeaker onlyto the Right and Left Output Terminals.When connecting Loudspeakers to the MC302 itis very important to use cables of adequate size, sothere is little to no power loss in the cables. The size isspecified in Gauge Numbers or AWG (American WireGauge). The smaller the Gauge number, the larger thewire size:Loudspeaker Cable Distance vs Wire Gauge GuideLoudspeakerImpedance25 feet(7.62 meters)or less50 feet(15.24 meters)or less100 feet(30.48 meters)or less2 Ohms12AWG10AWG8AWG4 Ohms14AWG12AWG10AWG8 Ohms16AWG14AWG12AWG5. Prepare the Loudspeaker Hookup Cables for attachment to the MC302 Power Amplifiers:Bare wire cable ends:Carefully remove sufficient insulation from thecable ends, refer to figures 2, 3 & 4. If the cableis stranded, carefully twist the strands togetheras tightly as possible.Figure 2Figure 3Figure 4Notes: 1. If desired, the twisted ends can be tinnedwith solder to keep the strands together.2. The prepared bare wire cable ends may beinserted into spade lug connectors for usein outside the United States and Canadaonly.3. Banana plugs are for use in the UnitedStates and Canada only.Banana Plugs are for use in the United States andCanada only:6. Attach the previously prepared bare wire cable endsinto the banana plugs and secure theconnections. Refer to figure F.7. Rotate the top of the Output Terminal Post clockwise until it is fingerFigure F

Output Terminals and How to Connect for Bi-Amptight. Refer to figure G. Then usingthe McIntosh Wrench, rotate the topof the Output Terminal one quarterof a turn (90 ). Do not over tighten.Refer to figure E.Figure G8. Referring to figure H, connect theLoudspeaker hookupcables with banana plugsinto the hole at the top ofthe terminal to theFigureMC302Figure HFCOM (Negative) OutputTerminal and Positive Output Terminal indentifiedas 2Ω (ohms), 4Ω (ohms) or 8Ω (ohms) connectionto match the impedance of the Loudspeaker, beingcareful to observe the correct polarities.Note: The illustration on separate sheet “Mc1B”isconnections for 8Ω (ohms) Loudspeakers.If the Loudspeaker’s impedance is in-between theavailable connections, use the nearest lower impedance connection. Refer to “General Information”Note 4 on page 3 for additional information.WARNING: Loudspeaker terminals are hazardous live and present a risk of electricshock. For additional instruction onmaking Loudspeaker Connections contact your McIntosh Dealer or McIntosh Technical Support.observe the correct polarities. Insert the spadelug connector or prepared section of the cable endinto the terminal side access hole, and tighten theterminal cap until the cable is firmly clamped intothe terminals so the lugs or wire cannot slip out.Refer to figures 7 and 8.Figure 7Figure 8Note: The illustration on separate sheet “Mc1B”isconnections for 8Ω (ohms) Loudspeakers.If the Loudspeaker’s impedance is in-betweenthe available connections, use the nearest lowerimpedance connection. Refer to “General Information” Note 4 on page 3 for additional information.WARNING: Loudspeaker terminals are hazardous live and present a risk of electricshock. For additional instruction onmaking Loudspeaker Connections contact your McIntosh Dealer or McIntosh Technical Support.11. Connect the MC302 power cord to an active ACoutlet.9. Connect the MC302 power cord to an active ACoutlet.Spade Lug or Wire Connections:10. Connect the Loudspeaker hookup cables to theMC302 Negative Output Terminal and PositiveOutput Terminal indentified as 2Ω (ohms), 4Ω(ohms) or 8Ω (ohms) connection to match theimpedance of the Loudspeaker, being careful to11

Front Panel Displays and ControlsMeter indicates theLeft Channel Outputof the amplifierLED indicates when the LEFTChannel Amplifier POWERGUARD circuit activatesMETER Switch selectsthe display modes of thePower Output Meter andMeter Illumination12Standby PowerOn IndicatorLED indicates when the RIGHTChannel Amplifier POWERGUARD circuit activatesMeter indicates theRight Channel Outputof the amplifierPOWER Switch Turns AC Power Off,Remote, AC Power On

How to OperateHow to OperatePower OnTo have the MC302 automatically turn On or Offwhen a control center turns on or off, rotate the powerswitch to the Remote position. For manual operation,rotate the power switch to the Onor Off position as desired. Refer tofigure 8.Note: There must be a powercontrol connection betweenthe MC302 and the AudioPreamplifier or A/V Control Center, in order for theremote power turn-on tofunction.Input Mode SwitchThe Input Mode Switch, which is located on the RearPanel of the MC302, allowsselection of either the Balanced or Unbalanced Input.Refer to figure 11.Figure 11Figure 10Figure 8Meter SelectionRotate the meter mode switch to select the meteroperation mode you desire.Refer to figures 9 and 10.Lights Off - Meter lightsare turned offand the meterwill continueto indicatethe poweroutput.Figure 9Note: WhenPower Control Input of the MC302is connected to a Audio Preamplifier or A/V Control Center withRemote Meter Illumination Control, the Meter Illumination willautomatically be remotely controlled (On/Off) with the METERSwitch set to the WATTS or HOLDposition.Watts- The meters respond to all the musical information being produced by theamplifier. They indicate to an accuracyof at least 95% of the power output withonly a single cycle of a 2000Hz toneburst.Hold - The meter pointer is locked to the highest power peak in a sequence of peaks.It is electronically held to this powerlevel until a higher power peak passesthrough the amplifier. The meter pointer will then rise to the newer higherindication. If no further power peaksare reached, the meter pointer willvery slowly return to its rest positionor lower power level. The decay rate isapproximately 6dB per minute.6.613

Technical DescriptionMcIntosh Laboratory, the company who introducedthe world’s first amplifier that could be called “HighFidelity”, has done it again. The McIntosh engineeringstaff has created a power amplifier without compromise, using the most advanced McIntosh circuit designconcepts.The MC302 has a continuous average power outputrating of 300 watts per channel, with a peak outputcurrent of 60 amperes, making it one of the mostadvanced amplifiers available today. The distortionlimits for the MC302 are no more than 0.005% atrated power output for all frequencies from 20Hz to20,000Hz. Typical performance at mid frequencies isless than 0.002%. The true distortion readings on theMC302 are so low, it takes special measuring techniques to make accurate readings. The MC302 candeliver the best possible performance from any type ofhigh quality loudspeaker system. Refer to figure 12.Creating an amplifier with this level of performance did not come easily. Many months of design,testing and measuring were required. Extensive controlled listening tests, the ultimate form of measuring,were made before the final design was accepted.Design PhilosophyThe design philosophy incorporated in the MC302involved several different techniques, all based onsound scientific logic. Every stage of voltage or current amplification must be as linear as possible priorto the use of negative feedback. McIntosh engineersknow how to properly design negative feedback circuits so they contribute to the extremely low distortionperformance expected from a McIntosh amplifier.The typical McIntosh owner would never accept theapproximately 100 times higher distortion of manyFigure 1214

Technical Descriptionconsiderably from whata loudspeaker requires.In the case of morethan one loudspeakerconnected in parallel,the

rating of the Loudspeaker (usually measured at a midrange frequency) might not always agree with the impedance of the Loudspeaker at low frequencies where the greatest amount of power is required. Contact the Loudspeaker Manufac-turer for additional information about the actual impedance of the Loudspeaker before connecting it to the McIntosh .