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13

When the LOCAL-BUS Switch is placed in the 

BUS Position the selection of the Audio Signal Input 

for the Power Amplifier Channels (1&2, 

3&4, 5&6 and 7&8) is determined by the 

“1-2-D1-D2” Selector Switch. Refer to 

figure 23.                   

The 1 and 2 Selector Switch Positions 

are for the Analog Signals from the BUS1/BUS2 Left 

and Right Input Jacks for the Power Amplifier Chan-

nels.

The D1 Switch Position allows the Digital Au-

dio Signals from the DIG1 Optical or Coaxial Input 

Connector to be available for the Power Amplifier 

Channels. The D2 Switch Position performs the same 

functions from the DIG2 Optical or Coaxial Input 

Connector.

Mode Selector

Each pair of the eight Power Amplifier Channels 

(1&2, 3&4, 5&6 and 7&8) have a Mode Switch located 

on the MI128 Rear Panel for STEREO or MONO 

Mode of Operation. Refer to 

figure 24. The Mode Switch 

affects all three of the Ana-

log Input Pairs. It also affects the Digital Optical or 

Coaxial Input Audio Signal.

MI128 Channel Operation Functions

LED COLOR

Functional Status

LED not

Illuminated

Indicates when the Channel is OFF

Green

Indicates when the Channel is ON with an 

Audio Signal Present and Normal Operation for 

the Channel exists 

Amber

Indicates when maximum Power Output for the 

Channel has occured with prevention of Audio 

Clipping

Red

Indicates current limit or short circuit for the 

Channel Loudspeaker Output Connection

Volume Controls

Each of the eight MI128 Power Amplifier Channels 

have a VOLume Control to 

allow altering the incoming 

audio signal volume level. 

Refer to figure 21.

Input Selector

Each pair of the eight Power Amplifier Channels 

(1&2, 3&4, 5&6 and 7&8) have switches located on 

the MI128 Rear Panel for selection of the Input Source 

Signal and determine the Audio Signal Mode. Refer to 

pages 6 and 7 for additional information.

The LOCAL-BUS Switch determines for the 

Power Amplifier Channels (1&2, 3&4, 5&6 and 7&8) 

if the Audio Signal will be from the 

Unbalanced Left and Right Input 

Jacks or from the BUS Analog/Digi-

tal Input Connectors. Refer to figure 

22.

Power On

The LED STANDBY/ON Indicator illuminates to 

indicate the MI128 is connected to AC 

Power. To switch ON the MI128, press 

the POWER Push-button on the Front 

Panel or switch On the Audio Source 

Component providing there is a Power 

Control Cable Connection to the MI128. 

Refer to figure 20.

Notes: 1. It will take about 6 seconds for initialization of 

the internal circuitry to take place on the MI128 

when switched On.

2. There must be a power control connection be-

tween the MI128 and the Audio Source Compo-

nent in order for the Remote Control Operation 

Power ON/OFF to function.

3. When the MI128 is receiving a Power Control 

ON Signal, the Front Panel POWER Push-But-

ton becomes inactive.

Auto Off Function

The MI128 incorporates Power Save Circuitry to 

automatically place the MI128 into the power saving 

Standby Mode approximately 10 minutes after there 

has been an absence of an audio input signal on all 

eight channels.

When there is a Power Control Connection be-

tween the MI128 and a Preamplifier or Source Com-

ponent, the AUTO OFF Function is bypassed.

Channel Operational Indication

The MI128 Front Panel has eight LEDs. The LEDs 

indicate the current functioning status for each of the 

eight channels.

How to Operate

How to Operate

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Summary of Contents for MI128

Page 1: ...McIntosh Laboratory Inc 2 Chambers Street Binghamton New York 13903 2699 Phone 607 723 3512 www mcintoshlabs com MI128 Eight Channel Power Amplifier Owner s Manual...

Page 2: ...iliar with your McIntosh equipment and any other brands that may be part of your system If you or your Dealer wish additional help concerning a suspected problem you can receive technical assistance f...

Page 3: ...ced Inputs There are eight Unbalanced Analog Audio Inputs for all eight Power Amplifier Channels Digital Audio Inputs The Digital Inputs decode PCM Signals from external sources The Optical Inputs pro...

Page 4: ...sions Rear View of the MI128 Side View of the MI128 Front View of the MI128 17 1 2 44 5cm 3 15 32 8 8cm 4 5 16 11 0cm 13 1 4 33 7cm 18 1 2 47 0cm 17 1 16 43 3cm 25 64cm 2 0 5 0cm 13 19 32 34 7cm 1 5 1...

Page 5: ...is installed together with other McIntosh Components check clearances on all components before proceeding Cutout Opening for Custom Mounting MI128 Front Panel Custom Cabinet Cutout Support Shelf Chass...

Page 6: ...BUS 1 Unbalanced Input Jack L or R dependent by its Channel Type BUS 2 Unbalanced Input Jack L or R dependent by its Channel Type DIG 1 Coaxial or Optical Digital Input Connector DIG 2 Coaxial or Opti...

Page 7: ...7 Audio Input s Signal Selection Connections for Loudspeakers 1 8 Channels 1 8 Power Amplifiers Channels Mode Switch 1 2 3 4 5 6 7 8 STEREO MONO Channels Input Switch 1 8 LINE BUS...

Page 8: ...he MI128 Power Amplifier Bare wire cable ends Carefully remove sufficient insulation from the cable ends refer to figures 1 2 3 If the cable is stranded carefully twist the strands together as tightly...

Page 9: ...Plug insert the Plug End into the correct MI128 Rear Panel Chassis Loudspeaker Socket Then connect the opposite end of the Loudspeaker Hookup Cable to the Loudspeaker Connection Terminals Make sure t...

Page 10: ...re cable ends Carefully remove sufficient insulation from the cable ends refer to figures 1 2 3 If the cable is stranded carefully twist the strands together as tightly as possible Notes A If the Loud...

Page 11: ...ched to the Loudspeaker Connection Plug insert the Plug End into the correct MI128 Rear Panel Chassis Loudspeaker Socket Then connect the opposite end of the Loudspeaker Hookup Cable to the Loudspeake...

Page 12: ...LED indicates various Channel 3 Circuitry Functions LED indicates various Channel 2 Circuitry Functions LED indicates various Channel 1 Circuitry Functions LED indicates various Channel 5 Circuitry Fu...

Page 13: ...r of the eight Power Amplifier Channels 1 2 3 4 5 6 and 7 8 have switches located on the MI128 Rear Panel for selection of the Input Source Signal and determine the Audio Signal Mode Refer to pages 6...

Page 14: ...ak power output does not exceed twice the rated power output or less per channel with all channels operating for any combination of frequencies from 20Hz to 20 000Hz Wide Band Damping Factor Greater t...

Page 15: ...e 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...

Page 16: ...cts 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 mcin...

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