Cary Audio Design CAD 120S MKII - Manual (Page 13)

OPERATION
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 the more current it
will draw. Playing loud, especially in the ultra-linear mode will peg the meters at 200 ma. This is
normal and there is a protection circuit built into the metering circuit to prevent damage to the
analog meters. Pegging the meters is fun!
BREAK-IN PERIOD
The tubes, capacitors and output transformers take approximately 100 hours use to settle in for
peak performance. The CAD 120S will sound good right out of the box but it will improve within a
short time. After the first 50-100 hours you will notice increased depth and tighter bass. This
break-in period is true with quality vacuum tube audio amplifiers.
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 KT-88 output tubes. The input and driver 6SN7 tubes can
last even longer. Other output tubes may be used in the CAD 120S power amplifier; 6L6, 6CA7,
KT-66, 6550C, KT-90, KT-99 or EL-34 tubes are all acceptable for use in the output stage of the
CAD 120S. Use the same current setting for any of these tubes as described in the bias set up.
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