McIntosh MA6900 Owner's Manual download pdf (Page 21)

Figure 16

With Power Guard

PG light and a dynamic elec-

tronic attenuator at the amplifier

input reduces the input volume

just enough to prevent any fur-

ther increase in distortion. The

Power Guard circuit acts so fast

that there are absolutely no au-

dible side effects and the sonic

purity of the music reproduction

is perfectly preserved. The

MA6900 Amplifier with Power

Guard is not limited to just the

rated power output, but will actually produce distortion

free output well above its rated power due to the McIntosh

philosophy of conservative design.

Power Supply Circuits

To compliment the design of the MA6900, there is a high

voltage power supply for both channels. Refer to figure 17.

The power amplifiers draw high current from the AC

power line. Therefore, it is important that they plug directly

into the wall outlet. Turn on inrush current is cushioned by

thermistors in the power transformers primary circuit.

This soft start eliminates component stress during turn-on.

The MA6900 can provide greater than 50 amperes peak

output current to drive uneven speaker loads. Some poor

speaker designs have input impedance that dip to 1 or 2

ohms at various frequencies and the MA6900 has the out-

put current reserve to drive them. The MA6900 has main

filter capacitors that guarantee an excellent signal to noise

ratio and the energy storage necessary for the wide dy-

namic range that Digital Audio demands.

Figure 17

Block Diagram of the Power Supply

1 2 ... 16 17 18 19 20 21 22 23 24

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McIntosh MA6900 Owner's Manual Page 21