3
XLR Connectors
Below is the Pin configuration for the XLR Balanced
Input, Input/Output Connectors on the MI254. Refer
to the diagram for connection:
PIN 1: Shield/Ground
PIN 2: + Input/Output
PIN 3: - Input/Output
Power Control Connector
The MI254 Power Control Input receives an On/Off
signal from +5 to +12 volts. The Power Control Output
will in turn provide a +12 volt Output Signal with a
total current up to 50mA. An additional connection
is for controlling the illumination
of the MI254 Meter Power Output
Indicators. The 3.5mm stereo mini
phone plug connects to a McIntosh
Preamplifier or A/V Control Center
Power Control Output.
Output Terminal Connector
When cables with spade lugs are used
for Loudspeaker Connection, the spade
lugs need an opening of at least 3/10 inch
(7.6mm)
General Information, con,t and Cable Information, Introduction and Performance Features
Connector and Cable Information
Introduction
Performance Features
Power
Control
Meter
Illumination
Control Ground
Now you can take advantage of traditional McIntosh
standards of excellence in the MI254 Power Ampli-
fier. The Four Channel Power Amplifier produces
high power output per channel and will drive quality
Loudspeakers to a high level of performance. The
MI254 reproduction is sonically transparent and abso-
lutely accurate. The McIntosh Sound is “The Sound of
the Music Itself.”
• Power Output
The MI254 consists of Four Power Amplifier Chan-
nels, each capable of 250 watts into 8 ohms 300 watts
into 4 ohms Loudspeakers with distortion less than
0.025%.
• Loudspeaker Guard
The McIntosh Loudspeaker Guard Circuit prevents the
amplifier from being over driven into clipping, with
its harsh distorted sound that can damage your valu-
able Loudspeakers.
• Versatile Operation
The MI254 can provide power amplification for four
channels in a single Zone A/V System or two channels
for each of a Dual Zone A/V System.
• Balanced, Unbalanced and Bus Inputs
There are Balanced, Unbalanced and Bus Connections
for all four Power Amplifier Input Channels.
• Sentry Monitor and Thermal Protection
McIntosh Sentry Monitor power output stage protec-
tion circuits ensure the MI254 will have a long and
trouble free operating life. Built-in Thermal Protection
circuits guard against overheating.
• Illuminated Power Meters
The Illuminated Power Output Watt Meters on the
MI254 are peak responding, and indicates the Power
Output of the amplifiers.
• Power Control
The McIntosh Power Control Circuit allows for remote
turn-on of the MI254 Power Amplifier from a McIn-
tosh A/V Control Center or Preamplifier for a single
or dual Zone System.
• Special Power Supply
A regulated Power Supply ensures stable noise free
operation even though the power line varies.
• LED Solid State Front Panel Illumination
The even Illumination of the Front Panel is accom-
plished by extra long life Light Emitting Diodes
(LEDs). The Metal and Glass Front Panel ensures the
pristine beauty of the MI254 will be retained for many
years.
PIN 2
PIN 1
PIN 3
5
.
In the event the MI254 Channel(s) over heat, due
to improper ventilation or Loudspeaker Imped-
ance, the protection circuits will activate. The Front
Panel Channel LED will change color and the audio
will be muted. Refer to page 15. When the MI254
has returned to a safe operating temperature,
Channel(s) normal operation will resume.
6. For additional information on the MI254 and
other McIntosh Products please visit the McIntosh
Website at www.mcintoshlabs.com.
3/10 of an inch
(7.6millimeters)
Summary of Contents for MI254
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