McIntosh MC451

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McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, New York 13903-2699 Phone: 607-723-3512 www.mcintoshlabs.com MC451 Dual Mono Power Amplifier Owner’s Manual 2 Introduction (continued) The MC451 has 150 watts of vacuum tube power to drive your loudspeaker’s mid ranges and tweeters. With the MC451, the tubes will not be challenged or overloaded by low-end reproduction because the solid state section has 300 watts dedicated to driving the woofers. Fine tuning your system is made simple with the built-in crossover. This allows you to match the crossover point to your loudspeakers and maximize the power available to each section. Alternatively, you can connect a direct feed to each amplifier section and bypass the crossover. This is perfect if you have crossovers external to the MC451. The solid state amplifier features Power Guard ® for clipping protection, Sentry Monitor™ for over current protection, and ThermalTrak 1 output transistors for stable bias and temperature control. The output Autoformer™ provides the full 300W of power regardless of loudspeaker impedance and provides DC protection to the outputs. The vacuum tube amplifier features Power Guard SGS ® for output tube protection and Sentry Monitor™ for over current protection. The Unity Coupled Output Transformer™ provides the full 150W of power regardless of loudspeaker imped- ance and provides DC protection to the outputs. Copyright 2022 © by McIntosh Laboratory, Inc. Table of Contents Safety First �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� 2 Introduction � � �� �� �� �� �� �� �� �� �� �� �� �� �� �� 2 Where to Put It � �� �� �� �� �� �� �� �� �� �� �� �� �� 3 Dimensions �� �� �� �� �� �� �� �� �� �� �� �� �� �� �� 3 Removal of Foam Insert Over Vacuum Tubes �� 4 Connector Information �� �� �� �� �� �� �� �� �� �� 5 Connecting a Loudspeaker � �� �� �� �� �� �� �� �� 5 Front Panel Displays and Knobs �� �� �� �� �� 6-7 Rear Panel Connections and Switches �� �� �� 8-9 Connection Diagram �� �� �� �� �� �� �� �� �� 10-11 Setting Up the Crossover � �� �� �� �� �� �� �� 12-13 Solid State Specifications �� �� �� �� �� �� �� �� ��14 Vacuum Tube Specifications �� �� �� �� �� �� �� ��14 General Specifications � �� �� �� �� �� �� �� �� �� ��14 Packing Instructions �� �� �� �� �� �� �� �� �� �� ��15 Packaging Parts List �� �� �� �� �� �� �� �� �� �� ��15 Thank You from All of Us at McIntosh You have invested in a precision instrument that will provide you with many years of enjoyment. Please take a few moments to familiarize yourself with the features and instructions to get the maxi- mum performance from your MC451. If you need further technical assistance, please contact your dealer who may be more familiar with your particular setup including other brands. You can also contact McIntosh with additional questions or in the unlikely event of needing service. McIntosh Laboratory, Inc � 2 Chambers Street Binghamton, New York 13903 Technical Assistance (607) 723-3512 Fax (607) 724-0549 Customer Service (607) 723-3515 Fax (607) 723-1917 Email support@mcintoshlabs.com Website www.mcintoshlabs.com Please Take A Moment For future reference, you can write down your serial number and purchase information here. We can identify your purchase from this information if the occasion should arise: Serial Number: __________________________ Purchase Date: ___________________________ Dealer Name: ___________________________ Introduction The MC451 Dual Mono Amplifier is an all-in-one solution for bi-amping loudspeakers. Utilizing our Hybrid Drive™ technology, it captures the harmonic beauty of vacuum tubes for a loudspeaker’s mid and high ranges while still having an abundance of power dedicated to the low end. The MC451 does the work of two separate amplifiers with its optimized combination of a vacuum tube and a solid state amplifier in a single optimized instrument. Safety First Please read the safety instructions included in a separate document called Important Additional Operation Information Guide . Actual size = .625” square Hybrid Drive logo FINAL 2022.ai 1 ThermalTrak™ is a trademark of Semiconductor Components Industries, LLC 3 Where to Put It The MC451 is very heavy � When moving the unit, have enough help to lift the MC451. This will ensure the safety of both you and the MC451. The MC451 should be installed upright on the floor or on an amplifier stand. Adequate ventilation is important and will aid in a long trouble-free life of the MC451. You must ensure proper airflow by allowing at least 19 inches (48.3cm) above the unit and 6 inches (15.2cm) for the front, rear and sides. Do not remove the feet to ensure adequate airflow beneath the MC451. There must be openings for cool air to enter (below) and warm air to escape (above) the MC451. Cool Air Warm Air Dimensions The following dimensions can assist in determining the best location for your MC451. 17 ⁷ / 8 45.4 cm 10 ⁷ / 8 27.6 cm 11¹³/ 16 30 cm 12 ¹/ 4 31.1 cm WATTS HOLD LIGHTS OFF METER REMOTE OFF ON POWER M C 4 5 1 D U A L M O N O P O W E R A M P L I F I E R WARMUP TEMP K T88 K T88 30 300 3.0 .30 P O W E R O U T P U T - 50 - 30 D E C I B E L S - 40 -20 -10 0 600 30 m 3.0 m 15 150 1.5 .15 - 50 - 30 - 40 -20 -10 0 300 15 m 1.5 m WAT T S USA 12AT7 USA 12AT7 USA 12AX7A 17 ⁷ / 8 45.4 cm 21 ¹/ 2 54.6 cm 14” 35.6 cm 10 ⁷ / 8 27.6 cm 11¹³/ 16 30 cm 12 ¹/ 4 31.1 cm 1 ¹⁵ / 16 4.9 cm WATTS HOLD LIGHTS OFF METER REMOTE OFF ON POWER M C 4 5 1 D U A L M O N O P O W E R A M P L I F I E R WARMUP TEMP K T88 K T88 30 300 3.0 .30 P O W E R O U T P U T - 50 - 30 D E C I B E L S - 40 -20 -10 0 600 30 m 3.0 m 15 150 1.5 .15 - 50 - 30 - 40 -20 -10 0 300 15 m 1.5 m WAT T S USA 12AT7 USA 12AT7 USA 12AX7A 4 To prevent damage to the tubes during shipping, there is a foam insert surrounding the tubes of the vacuum tube amplifier. The foam insert must be removed from the MC451 before connecting AC Power � Failure to do so is a fire hazard, and can result in damage to the MC451 and the surrounding environment � To remove the foam insert, it is necessary to temporarily remove the tube cover. To remove the tube cover: 1. Use a #2 phillips head screw driver to remove the four screws (two on each side) that hold the tube cover. 2. Pull the tube cover upward from the center of the MC451. MC451 UNPACK PG1.ai 3. Lift the foam insert straight up off the vacuum tubes. Removal of Foam Insert Over Vacuum Tubes MC451 UNPACK PG1.ai 4. Replace the tube cover. MC451 UNPACK PG1.ai 5. Replace the four screws to secure the cover. 6. Save the protective foam for possible future use. MC451 UNPACK PG1.ai MC451 UNPACK PG1.ai 5 Connector Information XLR Connectors When connecting loudspeaker cables to the MC451 output terminals follow the steps below: 1 � Make sure AC power is disconnected � 2. Rotate the top of the output terminal counter- clockwise until an opening appears. Opening Loudspeaker Connections The MC451 is designed for two separate connec- tions to a single loudspeaker. The solid state amplifier output terminals should be connected to the low frequency terminals of your loudspeaker. The vacuum tube amplifier should be connected to the mid/high terminals of your loudspeaker. Any jumpers between the low and mid/high terminals on the loudspeaker must be removed � Refer to the Connection Diagram on pages 10-11 for additional information. Loudspeaker Impedance Each amplifier has a 2 ohm, 4 ohm, 8 ohm and COM output terminal. Based on the specifications of your loudspeaker, determine the best impedance to use for each connection. It is a safe bet to use the lower impedance output terminals for a speaker whose impedance falls between two choices. Loudspeaker Cables When connecting loudspeakers to the MC451 it is very important to use cables of adequate size. The size is specified in AWG (American Wire Gauge). The smaller the gauge number, the larger the wire size. Loudspeaker Cable Wire Gauge Guide Loudspeaker Impedance Cable Distance 25 feet (7.62 meters) or less 50 feet (15.24 meters) or less 100 feet (30.48 meters) or less 2 ohms 12AWG 10AWG 8AWG 4 ohms 14AWG 12AWG 10AWG 8 ohms 16AWG 14AWG 12AWG Connecting a Loudspeaker 3. Insert the loudspeaker cable into the output terminal. Proper polarity must be maintained for all connections � (+/-) 4. Rotate the top of the output terminal clock- wise until it is finger tight. 5. Place the McIntosh wrench over the top of the output terminal and rotate it one quarter of a turn (90°). Do not over tighten � Meter/Tube Illumination Control Power Control Ground Signal Ground RCA Connectors Power Control Connectors Output Terminals PIN 1 3 (+) Signal Ground (-) Signal 2 1 3 3/10 in 7.6 mm 11 / 64 in 4.4 mm Ø 6 1 � METER Control Knob • LIGHTS OFF- the meter and tube lights will be off but the dual meter will still respond to output. • WATTS - the meter responds to all output. • HOLD - the dual meter needles will hold the highest peak until a higher peak is reached. If no higher peak is reached, the needles will lower their levels at a rate of approximately 6dB per minute. Note: When in the WATTS or HOLD position, the meter and tube lights will be powered On or Off by a preamplifier or A/V control center connected by a power control cable if that unit has power control capabilities. 2 � Dual Power Output Meter Shows both the vacuum tube and solid state amplifiers’ power output. The vacuum tube scale is displayed on the top and indicated by the longer needle. The solid state scale is on the bottom and indicated by the shorter needle. 3 � Standby LED Indicates that the MC451 is connected to AC power and ready to be turned on via the front panel knob or rear panel power control. In the unlikely event of a fault in the MC451’s main power supply, the MC451 will power off and the standby LED will flash. To reset the MC451 should this occur, turn the POWER control knob to OFF, wait one minute, then turn the POWER control knob to ON. If a fault contin - ues to occur, the MC451 should be serviced. 4 � POWER GUARD SGS ® (Screen Grid Sensor) LED Indicates when Power Guard SGS is engaged for the vacuum tube amplifier. Also indicates vacuum tube warm up. Power Guard SGS monitors the screen grid current in the KT88 output vacuum tubes. If the current becomes too high, a circuit in Power Guard SGS is activated which then dynamically attenuates the input signal in real time to keep the vacuum tubes operating at safe levels. 5 � POWER GUARD ® LED Indicates when Power Guard is engaged for the solid state amplifier. Also indicates heatsink over temperature. Power Guard monitors and adjusts the input signal in the solid state amplifier section in real time, then makes unobtrusive adjustments to prevent distortion and potential speaker damage. 6 � POWER Control Knob • OFF- the MC451 will be powered off regardless of any power control connection. • REMOTE- the MC451 can be powered on and off by a preamplifier or A/V control center connected by a power control cable. • ON- the MC451 will be powered on regardless of any power control connection. 7 � Vacuum Tube Input Stage V1, V2 - 12AT7 McIntosh Part No.165078 V3 - 12AX7A McIntosh Part No.165080 Sentry Monitor™ provides protection by monitoring current in the output transformer. In the event of a large impedance mismatch, a short circuit at the output terminals or tube failure, Sentry Monitor will activate to prevent potentially destructive levels of current from flowing. When Sentry Monitor is activated, the MC451 will power off, and the three input stage tubes will flash red. To reset the Sentry Monitor protection circuitry, turn the POWER control knob to OFF. Wait one minute and then turn the POWER control knob to ON. If Sentry Monitor continues to engage, the problem must be fixed before continuing. 8 � Vacuum Tube Output Stage V4, V5, V6, V7 - KT88 McIntosh Part No.165073 Note: Because of the high voltage involved with all vacuum tubes, they should only be replaced by an authorized McIntosh dealer or service agency. Front Panel Displays and Knobs 7 Front Panel Displays and Knobs 8 Rear Panel Connections and Switches 1 � Input Mode To select the BALANCED or UNBALANCED connection, use the INPUT MODE switch to toggle between these two options. Each input section can accept a male balanced XLR cable or a male unbalanced RCA cable. All inputs must use the same type of connection (BALANCED or UNBALANCED). Refer to page 5, Connector Information . 2 � Amplifier Mode MONO is the common choice for most applications of the MC451. The signal from a single preamplifier will be sent to both the solid state and vacuum tube amplifiers with the frequency range tailored by the crossover to match the attached loudspeaker. SEPARATE can be useful for situations where an external crossover is used. SEPARATE can also be used for feeding full-range signals to two separate loudspeakers from a single MC451. Note: If you need to switch the INPUT or AMPLIFIER MODE, it is best to do so when the MC451 is powered off to avoid any unpleasant noise from the loudspeakers. 3 � Vacuum Tube Input With the AMPLIFIER MODE switch set to MONO, the input is disabled. With the AMPLIFIER MODE switch set to SEPARATE , this input sends a full range input signal to the vacuum tube amplifier. 4 � Mono / Solid State Input With the AMPLIFIER MODE switch set to MONO, the input signal is sent to the internal crossover. The crossover then sends signals to each amplifier section based on the crossover settings. With the AMPLIFIER MODE switch set to SEPARATE , this input sends a full range input signal to the solid state amplifier. 5 � Crossover Refer to page 12, Setting Up the Crossover for additional information. 6 � Power Control Power control allows the MC451 to send and receive control signals when connected to other McIntosh products. In this way, powering on or powering off a single component can do the same for multiple units. POWER CONTROL IN accepts an On/Off signal from +5 to +12 volts. Meter and tube lights can be controlled as well. POWER CONTROL OUT will provide a +12 volt signal with a total current up to 25 mA. Connections are made using an 1/8 inch stereo mini phone plug. Refer to page 5, Connector Information . 7 � Auto Off Function The MC451 incorporates power saving circuitry to automatically activate the power saving standby mode. The MC451 will turn off after approximately 30 minutes of no audio signal in both amplifiers when the AUTO OFF switch is set to ENABLED. If the AUTO OFF switch is set to DISABLED, the MC451 will remain on regardless of the presence of any audio signal. When there is a power control connection between the MC451 and a preamplifier or source component, the AUTO OFF function is disabled regardless of switch position. 8 � Vacuum Tube Outputs Refer to page 5, Connecting a Loudspeaker for additional information. 9 � Solid State Outputs Refer to page 5, Connecting a Loudspeaker for additional information. 10 � AC Input Connect the MC451 power cord to a live AC outlet. Refer to the rear panel for voltage and current requirements. 11 � Fuse Under normal operating conditions the fuse should not need to be replaced. If required, refer to the rear panel for proper fuse type. 9 SERIAL NUMBER CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN M C 4 5 1 D U A L M O N O P O W E R A M P L I F I E R McINTOSH LABORATORY, INC., BINGHAMTON, NY HANDCRAFTED IN USA WITH US AND IMPORTED PARTS + + + - 8 Ω 4 Ω 2 Ω COM - COM + + 4 Ω 8 Ω + 2 Ω SOLID STATE (300W) OUTPUTS CLASS 2 WIRING VACUUM TUBE (150W) OUTPUTS CLASS 2 WIRING POWER CONTROL OUT IN AUTO OFF ENABLED DISABLED CROSSOVER (MONO MODE) VACUUM TUBE INPUT INPUT MODE BALANCED UNBALANCED BAL UNBAL MONO SOLID STATE / INPUT AMPLIFIER MODE MONO SEPARATE BAL UNBAL 300 250 400 550 180 130 800 1k 100 CROSSOVER POINT Hz +1.2 -3 +3 -6 0 VACUUM TUBE LEVEL dB Rear Panel Connections and Switches 10 SERIAL NUMBER CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN M C 4 5 1 D U A L M O N O P O W E R A M P L I F I E R McINTOSH LABORATORY, INC., BINGHAMTON, NY HANDCRAFTED IN USA WITH US AND IMPORTED PARTS + + + - 8 Ω 4 Ω 2 Ω COM - COM + + 4 Ω 8 Ω + 2 Ω SOLID STATE (300W) OUTPUTS CLASS 2 WIRING VACUUM TUBE (150W) OUTPUTS CLASS 2 WIRING POWER CONTROL OUT IN AUTO OFF ENABLED DISABLED CROSSOVER (MONO MODE) VACUUM TUBE INPUT INPUT MODE BALANCED UNBALANCED BAL UNBAL MONO SOLID STATE / INPUT AMPLIFIER MODE MONO SEPARATE BAL UNBAL 300 250 400 550 180 130 800 1k 100 CROSSOVER POINT Hz +1.2 -3 +3 -6 0 VACUUM TUBE LEVEL dB HDMI (ARC) DA2 DIGITAL AUDIO MODULE USB AUDIO COAX 2 COAX 1 MCT OPTICAL 2 OPTICAL 1 DIGITAL AUDIO INPUTS SERIAL NUMBER POWER CONTROL MAIN TRIG 1 TRIG 3 PASSTHRU TRIG 2 TRIG 4 120V 50/60Hz 30 WATTS IR IN RS232 EXTERNAL CONTROL DATA PORTS 5 3 1 6 4 2 SERVICE PORT MC GND L R 1R BAL R MAIN OUTPUT BAL L BAL R BAL L L R OUTPUT 1 BAL R BAL L L R OUTPUT 2 SERIAL NUMBER 1L 2R 2L 3R 3L L R FIXED OUTPUT BALANCED INPUTS 1 4 2 3 MM L R UNBALANCED INPUTS PHONO INPUTS CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN UNBAL UNBAL UNBAL Connection to AC Power should be the LAST connection made Right Loudspeaker System Audio Preamplifier LOW MID / HIGH LOW MID / HIGH Connection Diagram 11 SERIAL NUMBER CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN M C 4 5 1 D U A L M O N O P O W E R A M P L I F I E R McINTOSH LABORATORY, INC., BINGHAMTON, NY HANDCRAFTED IN USA WITH US AND IMPORTED PARTS + + + - 8 Ω 4 Ω 2 Ω COM - COM + + 4 Ω 8 Ω + 2 Ω SOLID STATE (300W) OUTPUTS CLASS 2 WIRING VACUUM TUBE (150W) OUTPUTS CLASS 2 WIRING POWER CONTROL OUT IN AUTO OFF ENABLED DISABLED CROSSOVER (MONO MODE) VACUUM TUBE INPUT INPUT MODE BALANCED UNBALANCED BAL UNBAL MONO SOLID STATE / INPUT AMPLIFIER MODE MONO SEPARATE BAL UNBAL 300 250 400 550 180 130 800 1k 100 CROSSOVER POINT Hz +1.2 -3 +3 -6 0 VACUUM TUBE LEVEL dB LOW MID / HIGH LOW MID / HIGH Left Loudspeaker System LOW MID / HIGH Any jumpers between the low and mid/high sections of the loudspeakers MUST be removed prior to connecting the MC451. REMOVE REMOVE Connection Diagram 12 The MC451’s crossover tailors the output frequency range of each amplifier section to the attached loudspeaker. Set the CROSSOVER POINT knob to the loudspeaker’s published crossover point. Frequencies below the crossover point will be sent to the solid state amplifier and frequencies above will be sent to the vacuum tube amplifier. CROSSOVER (MONO MODE) 300 250 400 550 180 130 800 1k 100 CROSSOVER POINT Hz +1.2 -3 +3 -6 0 VACUUM TUBE LEVEL dB The VACUUM TUBE LEVEL knob allows gain adjustments to be made to the vacuum tube ampli- fier. The goal is to achieve a proper balance between the low end of the loudspeaker and the mid/high range. The VACUUM TUBE LEVEL knob allows for gain adjustments from -6dB to +3dB. The knob has a center detent to mark the point of 0dB gain, but adjustments are continuous from -6dB to 0dB and 0dB to +3dB. Setting Up the Crossover 13 Setting Up the Crossover This graph demonstrates the combined frequency response for a 1kHz crossover point and 0dB level difference. Other crossover points will have similar curves. +6 +4 +2 0 -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -22 -24 -26 20 30 50 100 200 300 500 1k 2k 3k 5k 10k 20k Frequency (Hz) Decibels Combined (Full Range) Response Crossover Point (1kHz) Vacuum Tube (High Pass) Response Solid State (Low Pass) Response 14 Vacuum Tube Specifications Power Output 150 watts into 2 ohm load 150 watts into 4 ohm load 150 watts into 8 ohm load Rated Power Band 20Hz to 20,000Hz Dynamic Headroom 1.2dB Wide Band Damping Factor Greater than 18 Frequency Response +0, -0.5dB from 20Hz to 20,000Hz +0, -3.0dB from 10Hz to 70,000Hz Total Harmonic Distortion 0.5% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20,000Hz Intermodulation Distortion 0.5% maximum, if the instantaneous peak power output does not exceed twice the rated power output for any combination of frequencies from 20Hz to 20,000Hz Signal To Noise Ratio (A Weighted) 112dB below rated output Input Sensitivity (for rated output) 2.4 Volts Balanced 1.2 Volts Unbalanced Voltage Gain 29dB, 8 ohms 26dB, 4 ohms 23dB, 2 ohms Input Impedance 22,000 ohms Balanced 22,000 ohms Unbalanced Solid State Specifications Power Output 300 watts into 2 ohm load 300 watts into 4 ohm load 300 watts into 8 ohm load Rated Power Band 20Hz to 20,000Hz Dynamic Headroom 2.5dB Wide Band Damping Factor Greater than 40 Frequency Response +0, -0.25dB from 20Hz to 20,000Hz +0, -3.0dB from 10Hz to 100,000Hz Total Harmonic Distortion 0.005% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20,000Hz Intermodulation Distortion 0.005% maximum, if the instantaneous peak power output does not exceed twice the rated power output for any combination of frequencies from 20Hz to 20,000Hz Signal To Noise Ratio (A Weighted) 118dB below rated output Input Sensitivity (for rated output) 3.4 Volts Balanced 1.7 Volts Unbalanced Voltage Gain 29dB, 8 ohms 26dB, 4 ohms 23dB, 2 ohms Input Impedance 22,000 ohms Balanced 22,000 ohms Unbalanced General Specifications Power Control Input 5-12VDC Power Control Output 12VDC, 25mA Power Requirements 100 Volts ~ 50/60Hz at 7.2 Amps 110 Volts ~ 50/60Hz at 6.0 Amps 120 Volts ~ 50/60Hz at 6.0 Amps 127 Volts ~ 50/60Hz at 6.0 Amps 220 Volts ~ 50/60Hz at 3.3 Amps 230 Volts ~ 50/60Hz at 3.3 Amps 240 Volts ~ 50/60Hz at 3.3 Amps Standby, less than 0.5 watt Refer to the rear panel of the MC451 for the correct voltage. Overall Dimensions Height is 11 13/16 inches (30cm) Width is 17 7/8 inches (45.4cm) Depth is 21 1/2 inches (54.6cm) Weight 133 pounds (60.3kg) net 159 pounds (72.1kg) in shipping carton Shipping Carton Dimensions Height is 171/4 inches (43.8cm) Width is 28 inches (71.1cm) Depth is 31 inches (78.7cm) 15 Packing Instructions Packaging Parts List Qty Part Number Description 1 034105 Shipping carton top 1 034104 Shipping carton bottom 2 034679 Top / Bottom Pad 3 034678 Foam Ring 1 033739 Poly bag 1 034705 Tube Foam In the event it is necessary to repack the equipment for shipment, the equipment must be packed exactly as shown below. It is very important that the four feet are attached to the bottom of the unit � This will ensure the proper equipment location on the bottom pad � Failure to do this will result in shipping damage � Use the original shipping carton and interior parts only if they are all in good serviceable condition. If a shipping carton or any of the interior part(s) are needed, please call or write Customer Service Department of McIntosh Laboratory. Refer to page 2. Please see the Packaging Parts List for the correct part numbers. POLY BAG TOP / BOTTOM PAD TOP / BOTTOM PAD CARTON TOP FOAM RING (3) UNIT WITH (4) FEET ON BOTTOM COVER CARTON BOTTOM TUBE FOAM USE BANDING STRAPS AS SHOWN SEAL WITH PACKAGING TAPE IMPORTANT (Read Above) TUBE FOAM USE BANDING STRAPS AS SHOWN SEAL WITH PACKAGING TAPE PORTANT ad Above) The continuous improvement of its products is the policy of McIntosh Laboratory Incorporated who reserve the right to improve design without notice. Printed in the U.S.A. McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, NY 13903 www.mcintoshlabs.com McIntosh Part No. 24118600