Bias Adjustment (Top View) - Line Magnetic LM-150IA Operation Manual

Top view
V1, V2, V3, V4:
KT150 tubes
V5 and V6:
6SN76EH tubes
V7:
12AX7 tube
1
V8 and V9:
12AU7 tubes
2
1 BIAS ADJ.: Bias adjustment screws for tubes V1 and V2.
2
Bias Current: Allows to view the tube V1 bias level on the ampere meter when the small handle is down and when
the handle is up, you can see the bias level on the ampere meter for the V2 tube.
3
BIAS ADJ.: Bias adjustment screws for tubes V3 and V4.
4
Bias Current: Allows to view the tube V3 bias level on the ampere meter when the small handle is down and when
the handle is up, you can see the bias level on the ampere meter for the V4 tube.
Bias adjustment for KT150 and KT120 tubes
Note: You do not need to perform the bias adjustment when using the amplifier for the first time.
Turn on the amplifier and wait for about ten minutes.
WARNING : When making adjustments, be careful not to burn yourself with tubes that are very hot.
Select the tube you want to adjust (from V1 to V4), then position the Bias Current and adjust the tube bias with a
small screwdriver. Make sure all the bias level of V1, V2, V3 and V4 are the same.
Inspect the ampere meter on the front panel and make sure the needle is in the area ia=50mA (KT150) and ia=40mA
(KT120) shown on this diagram (below).
The current adjustment must be the same for the 4 tubes
in order to obtain an optimal sound reproduction of the
If you have any questions, please contact a local
maintenance service or your local dealer.
3
4
9