Step 7 — Onboard Buffer

WIRING SIDE (back of control plate)
JFET buffer sub-board · 2N5457
Tone wiper → Buffer → TRS Tip
TONE CTS 250K audio 1 CCW 2 OUT 3 IN GROUND BUS ← TRS JACK Step 8 TIP RNG SLV BUFFER SUB-BOARD ~10 × 15 mm perfboard 1MΩ gate bias D S G 2N5457 N-ch JFET + 10µF power decoupling 4.7kΩ source bias + 10µF output coupling DRAIN SOURCE GATE GND +9V IN OUT IN 7.1 — SIGNAL IN (Tone Lug 2 → Gate) Tone Lug 2 (wiper) buffer IN 7.2 — SIGNAL OUT (Buffer → TRS Tip) buffer OUT TRS TIP 7.3 — +9V POWER (TRS Ring → Buffer) TRS RING +9V IN 7.4 — GROUND (Buffer GND → bus) buffer GND GND bus BUFFER PLACEMENT Mount sub-board near tone pot. Secure with double-sided tape or hot glue. PHANTOM POWER +9V arrives via TRS cable ring. No battery needed in bass. CHECK: Tone Lug 2 → Buffer Gate = continuity  •  Buffer Out → TRS TIP = continuity  •  TRS Ring → +9V = continuity
Signal (input & output)
+9V power
Ground
Ground bus (context)
Tone pot (context)
TRS jack (context)

Step 7 Instructions

  1. 7.1 — Build the buffer sub-board. On a small piece of perfboard (~10 × 15 mm), solder the 2N5457 JFET, 1MΩ gate resistor, 4.7kΩ source resistor, and two 10µF electrolytic caps (power decoupling and output coupling). Check pin orientation: Gate faces the input resistor.
  2. 7.2 — Wire signal input. Solder a wire from Tone Lug 2 (wiper/output) to the buffer input pad (1MΩ resistor input). This feeds the tone-shaped signal into the buffer gate.
  3. 7.3 — Wire signal output. Solder a wire from the buffer output pad (after the 10µF coupling cap) to the TRS jack TIP terminal. This carries the buffered, low-impedance signal out.
  4. 7.4 — Wire +9V power. Solder a wire from the TRS jack RING terminal to the buffer power input pad (10µF decoupling cap positive). Power arrives via the TRS cable ring conductor from the external pedalboard supply.
  5. 7.5 — Wire ground. Solder a wire from the buffer ground node (junction of 4.7kΩ source resistor and decoupling cap negative) to the ground bus. This completes the power and signal return path.
  6. 7.6 — Mount and secure. Position the sub-board near the tone pot. Secure with double-sided foam tape or a small dab of hot glue. Keep wires tidy and away from pickup cavities.
Continuity checks: Tone Lug 2 → Buffer Gate via 1MΩ (signal path in). Buffer Source → TRS TIP via 10µF (signal path out). TRS Ring → Buffer +9V (power). Buffer GND → Ground bus (return). No continuity between TIP and RING or SLEEVE (no shorts).