Atma-Sphere Novacron/MA-1.5 Owner's Manual

Novacron amplifier quick setup and operation instructions

early '2 control' version

Installation: Place the amps in your system. Connect the preamp
cable to the appropriate input connector on the rear of the amp. If you
use the RCA input connector, make sure the shorting plug is installed
between pins 1 & 3 on the XLR connector or a buzz may result. Verify that
the power switch is OFF and connect AC power to the AC input connector on
the rear of the amp. Connect the negative speaker cable to the negative
output terminal and the positive speaker cable to the Bias Test post.

Setup: Install the tubes in their sockets. The smaller sockets
take the 12AT7 tube. All other sockets take the 6C33 output tube (one
matched set in front and one matched set in the rear). Engage the STANDBY
and verify that the lower and middle LEDs are lit. Turn the bias control
(closest to the edge of the chassis) fully counterclockwise. Set the DC
Offset control (closest to the output tubes) to the center of its range.

Always allow at least 5 minutes for warmup of the tubes. The filaments of
all tubes should be visibly glowing orange. Engage the ON position of the
switch and verify that all LEDs are lit. The amplifier is now fully
powered up.

Bias adjustment: NOTE: the speaker cable must be attached to the
Bias Test Post for this procedure. Depress the Bias Test switch by the
speaker terminals. Adjust the Bias Control for a reading of 350 mA on the
meter. Release the Bias Test switch and allow the amplifier to settle for
1 minute. Adjust the DC Offset control to obtain a reading of zero on the
meter. Remove the speaker cable from the Test Post and install it on the
speaker terminal. After 1/2 hour repeat the procedure. The Bias should
not exceed 500 mA at any time! This should be checked again at one hour.
If the meter fails to respond, check the rear panel fuse by the AC inlet.

Operation: Remove the positive speaker cable from the bias test
post and install on the positive output terminal. Failure to observe this
step can result in damage to the meter (which is not covered by warranty)
and a loss of sonic quality. The amplifier is now completely operational.
The amplifier is designed for continuous operation, but if you are not
currently listening, place the amp in standby to save output tube life
and energy.

Tube Condition: The tubes should be matched, with one pair in the
front and one in the rear. If any tube glows cherry red one should be
instantly suspicious! One or both tubes of the pair are suspect unless a
fuse for one of the pair is blown. If so, the tube glowing cherry might
still be good. Contact Atma-Sphere if you have any questions.
Uncontrollable readings on the meter indicate a short in a tube. Arc-over
in an output tube (indicated by a popping sound at the time of failure)
may blow a protection fuse. The tube will be unreliable if this occurs­replacement is indicated.

©1997 Atma-Sphere Music Systems Inc. 1742 Selby Av. St.Paul, MN. 55105

651.690.2246 / fax [phone]