McIntosh MC1.2KW owner manual Autoformers, Power Output Meter, Protection Circuits

Figure 17

Input Test Signal

Figure 15

Autoformers

All solid state power amplifier output circuits work best into what is called an optimum load. This optimum load may vary considerably from what a loudspeaker requires. In the case of more than one loudspeaker connected in parallel, the load to the power amplifier may drop to two ohms or even less. A power amplifier connected to a load that is lower than optimum, causes more output current to flow, which results in extra heat being generated in the power output stage. This increase in temperature will result in a reduced life expectancy for the amplifier.

The special Balanced Dual Core Autoformer creates an ideal match between the power amplifier output stage and the loudspeaker. A McIntosh amplifier with an Autoformer can be used to safely drive multiple speakers without reducing the life expectancy of the power amplifier. Refer to figure 14.

Figure 14

There is absolutely no performance limitation with an Autoformer. Its frequency response exceeds that of the output circuit itself, and extends well beyond the audible range. Its distortion level is so low it is virtually impossible to measure.

In the rare event of a power amplifier output circuit fail- ure, the McIntosh Autoformer provides absolute protection from possible damage to your valuable loudspeakers. The unequaled expertise of McIntosh in the design and manu- facturing of Autoformers is legendary in the high fidelity industry. McIntosh engineers know how to do it right.

Power Output Meter

The McIntosh MC1.2KW has a huge hand built Output Watt Meter that responds 95% full scale to a single cycle

tone burst at 2kHz. Refer to figure

15.Voltage and current outputs are electronical- ly measured, multiplied and fed to a special

circuit that accelerates

the pointer movement in the upward direction. When the pointer reaches its peak it pauses only long enough for the human eye to perceive its position, then drops. It is almost 10 times faster than a professional VU meter.

A front panel switch is provided to change the meter to the Watts Hold Mode of operation. This allows fast upward movement of the pointer but greatly increases Hold Time at the peak of its travel. The highest power output of the source material is thus recorded.

Protection Circuits
The MC1.2KW incorporates a version of the McIntosh
Sentry Monitor Output
Transistor Protection
Circuit. Refer to Fig-
ure 16. There is abso-
lutely no compromise
in sonic performance	Normal Operating Area�
with this circuit, and it
ensures safe operation	Sentry Monitor�	Output�
of the amplifier under
	Safety Area�	Transistor�
even the most extreme		Failure�
operating conditions.	Figure 16

The different types of

protection circuits incorporated in the MC1.2KW insure a long and safe operating life. This is just one of the many characteristics of McIntosh

Power Amplifiers that make them world famous.

The MC1.2KW also includes the unique pat- ented McIntosh Power Guard circuit. Power Guard elimi- nates the possibility of ever overdriving the amplifier into clipping. Refer to figures 17, 18 and 19. An overdriven amplifier can produce both

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