Tube Biasing - CANARY AUDIO CA-100 Owner's Manual

TUBE BIASING

Bias voltage applied to the grids of the power tubes in the output stage should be
checked from time to time to keep these tubes operation at the optimum
operating point. A properly biased power tube will have a longer life.
To check and adjust the bias voltage of the EL34 / 6CA7 tubes, simply follow the
following procedures.
Tools Required:
Digital Multimeter
Long-handled slotted screwdriver
Procedures:
1. Making sure that the power switch is in the OFF position.
2. Install all the tubes to the corresponding sockets using a gentle rocking
motion. (See "Tubes Installation" section for detail information on installing the
tubes.)
3. Connect your speaker leads, input cable and power cord to each amplifier.
4. Turn ON the amplifier.
5. Turn on the multimeter. Select the section for measuring up to 20V DC.
Attach and secure the negative test lead to the chassis or to the binding post.
6. Start from the EL34 – V9, insert the positive test lead into bias test point next
to the EL34 – V9 tube socket.
7. Carefully insert a long-handled slotted screwdriver into the bias adjustment
pot next to the EL34 – V9 tube socket. Slowly rotate the screwdriver to adjust
the bias voltage until it reaches 0.35V.
8. Repeat steps 6 and 7 to adjust the bias voltage for all remaining seven EL34 /
6CA7 tubes in the same fashion as biasing EL34 – V9. Using the bias test
point and bias adjustment pot next to the corresponding tube socket for
measuring and adjusting. You will need to go back and forth a few times until
all eight tubes are properly biased.
9. Once you have finished biasing all eight EL34 / 6CA7 tubes, wait a few
minutes and recheck the settings again.
10. The CA-100 stereo power amplifier is now ready to use.