Step 5 – Connect the filaments
Cut two 6" lengths of the green cloth-covered wire. Connect one of these wires to T1(1) and the other wire
to T1(3). Leave room for two more wires and resistors to be connected to each of these terminals. Twist
these two wires together, route them along the chassis surface toward the lamp holder and connect the wire
ends to opposite lugs on the lamp holder as shown in Drawing 5.
12
Cut two 12" lengths of the green cloth-covered wire. Connect one of these wires to T1(1) and the other
wire to T1(3). Leave room for two resistors to be connected to each of these terminals. Twist these two
wires together and route them along the chassis surface toward tube socket V4. Connect one of these wire
ends to pin 9 and the other wire end to both pins 4 and 5. Do not solder these connections, yet.
The main idea when connecting the filament wires is to avoid transferring filament hum from the power
transformer’s filament winding (green wires) to the signal path of the circuit. In order to minimize filament
hum, we will be twisting wires together and routing them along the chassis surface. Avoid touching tube pins
2 and 7 with the filament wires as these are where the guitar signal enters each tube triode.
The wire lengths given are recommended starting lengths. You may decide to clip off some of the wire length
as you bring each twisted pair of wires near their connection points.
Cut two 5" lengths of the green cloth-covered wire. Connect one of these wires to V4 pin 5 and the other
wire to V4 pin 9. Solder the connections at V4, now. Twist these two wires together and route them along
the chassis surface in a path similar to what’s shown on Drawing 5. Connect one of the wire ends to V3
pin 9 and the other wire end to both V3 pins 4 and 5. Do not solder these connections, yet.
Cut two more 5" lengths of the green cloth-covered wire. Connect one of these wires to V3 pin 5 and the
other wire to V3 pin 9. Solder the connections at V3, now. Twist these two wires together and route them
along the chassis surface in a path similar to what’s shown on Drawing 5. Connect one of the wire ends to
V2 pin 9 and the other wire end to both V2 pins 4 and 5. Do not solder these connections, yet.
Cut two more 5" lengths of the green cloth-covered wire. Connect one of these wires to V2 pin 5 and the
other wire to V2 pin 9. Solder the connections at V2, now. Twist these two wires together and route them
along the chassis surface in a path similar to what’s shown on Drawing 5. Connect one of the wire ends to
V1 pin 9 and the other wire end to both V1 pins 4 and 5.
Find the two 100Ω resistors. Connect one from T1(1) to T1(2) and connect the other from T1(2) to T1(3).
(Because the power transformer’s filament winding does not have a center-tap, these resistors are used to
greatly reduce filament hum).
Step 6 – Connect the power supply wires
Strip and tin a 2" length of the blue hook-up wire and connect it from T2(1) to T2(5).
Strip and tin a 2" length of the blue hook-up wire and connect it from T2(1) to T3(6).
Strip and tin a 3 ½" length of the blue hook-up wire and connect it from T3(3) to T4(4). Do not solder the
connections, yet.
Strip and tin a 7" length of the blue hook-up wire and connect it from T3(3) to T6(5). Solder the T3(3)
connection, now.
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