Specifications

Installing Feedback Header / Jumper J1
Step 1 – Locate position J1 on the board. It is identified by the
three small pads next to the printed word
“feedback”, above the large letter “G”.
Step 2 – Install the three pin header in these three
holes (photo 5.2a / b).
Step 3 – Install the jumper onto the two pins
nearest R23 (the “out” position).
Proceed to 5.3
Installing the Cathode Bias Jumper
Step 1 – Locate the small box labeled “G5 / aa” printed in the middle of the
circuit board.
Step 2 – With a small length of bare wire (a cut component lead will do
great), connect (jumper) these two pads (G5 and aa) together and solder
(photo 5.3a ).
Proceed to 5.4
Installing the Wires to the Board
5.4.1 Black Wires (Grounding)
Step 1 - Strip back the insulation 1/8” from the end of a black 20 AWG wire. Tin the end of
the exposed strands. Insert the tinned end of this wire into the pad labeled “G1” on the PC
board top (where the components are mounted) and solder into place. Measure and cut this
wire to a length of 3” from pad G1.
Step 2 – Repeat the above for pad “G2”.
Step 3 – Repeat above for pad “G7” except extend wire to 4”.
Step 4 – Repeat above for pad “G10” except use 6” of 18AWG wire.
Proceed to 5.4.2
5.2
10 TubeDepot.com
5.3
photo 5.2b
photo 5.2a
photo 5.3a
photo 5.3b – filled board
5.4
The PC board in this
photo is version 3.1. The
present version is 3.7
When installing the wire,
the ends of the wires are
inserted into the pads on
the top of the PC board
and soldered from
underneath
NOTE
With the FEEDBACK jumper in the “OUT” position, the amp will have stronger midrange
response and be quick to distort. This is the stock setting. With the jumper in the “IN”
position, the amp will be cleaner, with a flatter frequency response and better low end punch.