BASS
2
1
FOOTSWITCH
3
M E
G
5 0K
SPEED
INTENSITY
1
0
0
K
.022
µF
630V
1
7
6
5
4
3
2
8 9
1
7
6
5
4
3
2
8 9
V1
V2
+
+
Step 6:
Remove unnecessary circuit board
components.
1) Remove the cathode bias components connected to
V1 pin 3.
2) Remove the bass channel tone-stack components.
3) Remove the plate resistor connected to V1 pin 1.
4) Remove the plate resistors connected to V1 pin 6
and their connection to the 375V power supply.
5) Remove the jumper wire that was connect the V1
pin 6 plate resistor to the V2 pin 6 plate resistor.
6) Remove the shared cathode resistor connected to
V2 pin 8.
7) Remove the common cathode jumper wire
connected from V1 pin 8 to V2 pin 8.
Each instruction line number here corresponds to the
numbers on the drawing where missing components are
outlined.
(1)
(1)
(2)
(2)
(2)
(2)
(2)
(3)
(4)
(4)
375V Power
Supply Line
(4)
(4)
(7)
(7)
(5)
(5)
BASS
2
1
FOOTSWITCH
3
M E
G
5 0K
SPEED
INTENSITY
1
0
0
K
.022
µF
630V
1
7
6
5
4
3
2
8 9
1
7
6
5
4
3
2
8 9
V1
V2
+
+
Step 7:
Add new circuit board
components.
1) Connect new cathode bias components (22µF
cap and 2.7K resistor) to V1 pin 3.
2) Connect a new cathode resistor (1.5K) to V2 pin
8.
3) Connect a new plate resistor (220K) to V1 pin 1.
4) Connect a new plate resistor (8.2M) to V1 pin 6.
5) Add the two .01µF feedback capacitors as
shown.
Positive
2
2
µ
F
5
0
V
Negative
Connect these
polarized capacitors
with the positive
lead connected to
the tube as shown.
2
.7
K
2
2
µ
F
5
0
V
+
2
2
0
K
8
.2
M
.0
1
µ
F
6
3
0
V
.0
1
µ
F
6
3
0
V
(6)
1
.5
K
15