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illuminated. Should you not observe the above conditions, turn off the amplifier and
check the power cord and AC socket.
Triode/Ultra-Linear Switch
On the top of the chassis behind the KT-88 output tubes is located a chrome handle
switch. With the handle pushed to the rear of the amplifier the mode of operation is
ultra-linear. In the forward position the mode will be in triode class A mode. This set of
switches maybe switched during listening. A slight click maybe heard in the
loudspeakers. This is normal. Usually the triode position will provide plenty of power
and is the most preferred position by most audiophiles and the designer of the Rocket
88 R.
Bias Setting
Your new Rocket 88 R bias adjustment has been factory set prior to shipping. Please
keep in mind that the bias will vary from location to location depending on the AC line
voltage. The design of the Rocket 88 R is such that you may start listening with the
factory set level. DO NOT TURN THE BIAS ADJUSTMENT SCREW WITHOUT
WATCHING LEVELS ON A DC mA CURRENT METER! The type of meter used must
be a DC current meter or a volt ohm meter with a DC milliampere current scale. A
digital multi-meter is very inexpensive and available at a local Radio Shack or ACE
hardware store.
Included with your shipment of the Rocket 88 R is a black and orange patch cord with a
_” male plug and two clips. This is the bias adjustment cable. To check and/or set the
bias simply place the red clip lead on the positive meter lead. The black clip lead will
hook up to the black negative lead of the test meter. The meter must be placed in the
DC current mode. If the meter has a selectable scale use the one that measures 0 to
300 ma DC current. With the Rocket 88 R turned on and operating for about 10
minutes you will have the resting current level indicated. This measurement should be
done without any music playing. A nominal level of 200 milliampere (mA) is standard for
the Rocket 88 R. If the level is lower, advance the bias adjustment to the clockwise
direction. Higher readings, turn the bias control to the left, counterclockwise direction.
After you have established a 200 mA reading simply pull out the plug from the bias jack.
You may hear a slight click in the speaker. This is normal.
Bias levels will change with time of day and power usage in your home. In fact during the
summer months when the air conditioner is running you may have less AC line voltage
available and in turn the bias will be slightly lower. This is not critical. In fact the Rocket
88 R is designed to operate in the range of 180 to as high as 240 mA DC current. The
best sound will generally be produced in the 195 to 225 mA region. You may wish to
experiment if you desire. NEVER ADJUST THE BIAS SETTING WITH A VOLTMETER
SET TO THE VOLTAGE POSITION!