Technical information

Step 23: Installing the input jacks (part 2).

Install the prepped Cliff jack in the HIGH SENSITIVITY chassis

hole.

Tighten the nut with a 15mm socket or pliers. The hardware

sequence is: JACK – FIBER WASHER – CHASSIS – NUT

Next install the remaining Cliff jack on the LOW SENS. position.

Before tightening the nut, route the bare wire from the first jack to

the LOWER, RIGHT terminal on the second jack, as shown. >>>

Assure the jacks are aligned and tighten the nut.

Next, route the black wire,

along the chassis edge, to the

buss wire on the rear of the

pots.

Strip ¼” of insulation and

shape into a hook. Attach to

the buss wire and solder in

place.

Locate (1) 68kΩ 1W resistor (BLUE-GRAY-ORANGE-GOLD), (8”) COAX wire and (1 1/2”) 1/8” SHRINK

TUBING. Strip ¼” of insulation for the coax and cut away the braided shielding. Cut one lead of the

68kΩ resistor to approx. ½” and make a hook shape. Tin the end of the coax conductor with solder

and shape into a hook. Join these together and solder. Slide 1 ½” of shrink tubing over the

connection and shrink with a heat gun.

Insert the remaining lead into terminal #2 of V1. Solder in

place with the body of the resistor right against the terminal.

TECH NOTE: The 68kΩ resistor interacts with the internal grid

capacitance of the 12AX7 tube to form a low pass filter, just

as the 5.6kΩ on the output tube grids. To be most effective,

the resistor should be mounted directly on the socket. This

filter is crucial to prevent oscillation in the cascaded gain

stages.

ate

unded only on the input jack side, to prevent

potential ground loops.

Route the coax wire to the input jacks and strip 1” of insulation, but don’t

cut away the braided shield. Use an Exacto™ knife or similar to separ

the shield and twist it into a single wire. Tin with solder to keep the

strands in place. Also strip 1/8” of clear insulation from the center

conductor. Solder the shield in place at the LOWER, RIGHT jack terminal.

Solder the conductor in place at the LOWER, LEFT terminal, as shown.

Note that the coax is gro