Step 8 — TRS Output Jack (ring-hot)

WIRING SIDE (back of control plate)
TRS stereo jack · Tip = passive signal (always live), Ring = buffered out + phantom in, Sleeve = ground
Signal node → Tip · Buffer ring → Ring · GND bus → Sleeve
SIGNAL NODE passive harness out (Volume wiper) always live RING-HOT BUFFER 2N5457 → 2N3904 Step 7 · phantom powered audio out ↑ · phantom in ↓ (one conductor, both ways) RING GROUND BUS ← TIP RNG SLV TRS OUTPUT JACK Switchcraft 12B stereo jack T TIP passive R RING buf+pwr S SLEEVE ground Conductor 1 — Signal (Tip) · passive, always live Conductor 2 — Ring · buffered audio out → / phantom in ← Braided shield — Ground (Sleeve) TRS SHIELDED CABLE to XLR (studio phantom) or jam injector · 2 conductors + braid → to rig 8.1 — PASSIVE SIGNAL (Signal node → TIP, always live) Jack TIP 8.2 — RING (buffer out + phantom in) Jack RING ~29V studio / 7.7V jam on the ring 8.3 — GROUND (bus → SLEEVE) GND bus Jack SLV ONE CONDUCTOR, BOTH WAYS The ring carries phantom DC down to power the buffer AND the buffered audio back up — same wire, condenser-mic style. THE TIP IS THE BYPASS Plain TS guitar cable = pure passive bass off the tip, buffer off. TRS→XLR (studio) or 9V jam injector feeds phantom on the ring; tip unused there. POWER ON/OFF No battery, no switch. Phantom on the ring powers the buffer (~29V studio / 7.7V jam). No phantom → the passive tip still plays. CAUTION No power on the tip ever — the tip is always passive signal. Don't feed a transformer-input mic pre without checking DC handling. CHECK: Signal node → TIP = continuity (passive)  •  Buffer ring → RING = continuity  •  GND bus → SLEEVE = continuity  •  No shorts between T/R/S
Passive signal (Tip, always live)
Buffered out + phantom in (Ring)
Ground (Sleeve / braid)
Ground bus (context)
Ring-hot buffer (context)

Step 8 Instructions

  1. 8.1 — Identify the TRS jack terminals. A TRS (stereo) jack has three: TIP (passive signal, always live), RING (buffered out + phantom in), and SLEEVE (ground). Verify which is which with a multimeter and a TRS plug before soldering.
  2. 8.2 — Solder the signal node to TIP. Run a wire from the passive harness signal node (the volume wiper) straight to the TIP terminal. This is hardwired and always live — plug in a plain TS cable and you get the pure passive bass, no power required. The buffer is never in this path.
  3. 8.3 — Solder the buffer ring pad to RING. Run a wire from the buffer’s RING pad to the RING terminal. This single conductor does two jobs at once: phantom DC rides in to power the buffer, and the buffered audio rides out — the same way a condenser mic shares one pin. Expect ~29V on the ring in the studio (48V phantom) and ~7.7V from a 9V jam injector.
  4. 8.4 — Solder the ground bus to SLEEVE. Run a wire from the ground bus to the SLEEVE terminal. This is the return for both the passive tip path and the buffered ring path, and continues out through the cable braid.
  5. 8.5 — Verify the cables. Studio TRS→XLR: ring → XLR pin 2 (hot), sleeve → pin 1, tip left unconnected, cold network (110Ω + 100µF) on pin 3 inside the shell. Jam injector: 9V → 1N5817 → 1kΩ onto the ring, audio tapped through a 10µF block. Amp: any plain TS cable plays the passive tip.
Continuity checks: Signal node → Jack TIP (passive, always live). Buffer ring → Jack RING (buffered out + phantom in). Ground bus → Jack SLEEVE. No continuity between TIP, RING, and SLEEVE (no shorts). Critical: the tip carries no power — it is passive signal at all times. The ring is the only conductor that is both powered and buffered. Plug in first, then enable 48V phantom (same discipline as any condenser mic).