OPERATION
On the rear panel of the CAD 120S MKII is a bias adjustment potentiometer for each channel. This is a screwdriver slotted shaft control. After the amplifier has been powered up for a few minutes observe the meter readings. The proper reading should be 140 ma. plus or minus 10 ma. To make the bias adjustment insert a flat bladed screwdriver into the rear mounted bias adjustment potentiometer and turn clockwise to raise the bias or counter clockwise to lower the bias reading. There is some interaction between channels. Adjust the right and left channel bias a few times until you have an equal reading (plus or minus a few ma) on each channel. The bias reading level is not critical in respect to a range of a low reading of 125 ma. to a high reading of 170 ma. The preferred reading should be approximately 140 ma. plus or minus 10 ma. The DC bias current value will fluctuate with varying in house AC wall voltage. As air conditioning systems cycle and power loads in the neighborhood change, the bias reading will fluctuate a bit. This is normal and therefore not critical.
Another word about the meter readings. The louder you play the CAD 120S MKII the more current it will draw. Playing loud, especially in the
BREAK-IN PERIOD
The tubes, capacitors and output transformers take approximately 100 hours use to settle in for peak performance. The CAD 120S MKII will sound good right out of the box but it will improve within a short time. After the first
TUBE REPLACEMENT
If it becomes necessary to replace the tubes in the amplifier, a matched set of output tubes of the same name brand should be used. A new tube kit is available from Cary Audio. You should get years of service from the rugged
120S MKII power amplifier; 6L6, 6CA7,
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