{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "6g3",
  "url": "https://circuitcodex.com/amps/6g3/",
  "attribution": "The Analog Maker / Circuit Codex",
  "license": "https://creativecommons.org/licenses/by-sa/4.0/",
  "revision": "ebddc3fd2cf887dca010bbe60487d7391ea6c052",
  "scope": "DC and drawing checks have separate coverage. See included check results and the circuit page; not a dimensioned build template or a physical-build certification.",
  "metadata": {
    "id": "6g3",
    "name_style": "Brown Deluxe-style",
    "family": "other",
    "era": {
      "start": 1961,
      "end": 1963
    },
    "wattage": 15,
    "tubes": [
      "12AX7",
      "12AX7",
      "12AX7",
      "6V6GT",
      "6V6GT",
      "GZ34"
    ],
    "topology": {
      "rectifier": {
        "kind": "tube",
        "type": "GZ34"
      },
      "bias": "fixed",
      "phase_inverter": "long-tailed-pair",
      "tone_stack": "single-knob"
    },
    "lineage": {
      "derived_from": [
        "5e3"
      ],
      "influenced": [
        "ab763"
      ]
    },
    "conventions": {
      "designators": "functional"
    },
    "sources": [
      {
        "desc": "Fender 'Deluxe' Model 6G3 drawing (I-FA), schematic + layout: every component value AND the printed voltage chart read directly from the published sheet (+375 reservoir / OT centre tap, +365 6V6 plates and screens, +325 phase-inverter rail, +270 preamp rail, +165 channel-input and driver plates, +1.5/+1.4 preamp cathodes, +230/+225 inverter plates with +20 cathodes and +18 tail junction, -26 V fixed bias, +205/+2.0 tremolo oscillator); droppers 1 kOhm-2W / 10k-1W / 27k-1W on 16-16-16-8 uF 450 V cans; input stages 220k plates on a shared 1.5k/25 uF cathode with a .003 shunt across the Normal channel's plate load; driver 100k plate load returning through a 15k with the .01 coupler taken from their junction; LTP inverter 82k/100k 5% plates, 820 Ohm cathode resistor to a 6.8k tail and a 1500 Ohm foot carrying the 56k speaker feedback, 1M grid leaks to the tail junction, .0001 across the plates; 6V6GT pair with grounded cathodes and 220k-5% grid leaks; bias supply 100k-5% + rectifier + 25 uF/50 V + 22k-5%; tremolo is bias-vary, its oscillator injected through a 250k-L Intensity control in the bias line. Notice: values +/-20%, read to ground with an electronic voltmeter, all resistors 1/2 W 10% and all capacitors at least 400 V unless marked. Transformers TR1-125P2A (333-0-333 V AC) and TR2-125A1A. The drawing labels the first bottle 7025 (a 12AX7 alias). Not reproduced here; archived at EL34World",
        "url": "https://el34world.com/charts/Schematics/files/Fender/Fender_deluxe_6g3.pdf"
      },
      {
        "desc": "Mojotone/Ampwares Fender field guide, 'Brownface Deluxe' — 6G3 production window 1961-1963 and the 15 W nominal rating used here",
        "url": "https://mojotone.com/blogs/fender-field-guide/fender-brownface-deluxe"
      }
    ],
    "verification": {
      "status": "verified",
      "date": "2026-08-02T00:00:00.000Z",
      "max_deviation_pct": 5.6
    },
    "contributors": [
      "TheAnalogMaker"
    ],
    "sections": {
      "V2B": "excluded — the tremolo's phase-shift oscillator: a running oscillator has no static operating point; its 220k plate load taps the driven node BP, so nothing downstream moves"
    }
  },
  "parts": {
    "notes": "The drawing shows both input jacks per channel, each with its own 68 kΩ stopper, and hangs the channel's 1 MΩ leak from jack 1's tip, jack side of its stopper (both pages; the layout mounts it on jack 1). The tremolo oscillator's parts are listed in full, but its DC operating point is excluded from the netlist (see the circuit story). Parts drawn only as annotations — mains cap, fuse, switches, pilot lamp — are listed without designators. The two transformers are numbered T1 (power) and T2 (output) under the archive's convention; the drawing's own labels for the same parts are TR1 and TR2.",
    "items": [
      {
        "ref": "R1n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Normal input grid stopper (jack 1)"
      },
      {
        "ref": "R2n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Normal input grid stopper (jack 2)"
      },
      {
        "ref": "RG1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Normal input leak, jack 1's tip to ground (jack side of R1n); the grid's DC return through R1n"
      },
      {
        "ref": "RL1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V1A plate load"
      },
      {
        "ref": "C3",
        "part": "Film capacitor",
        "value": "0.003 µF · 400 V",
        "role": "Treble shunt across the V1A plate load — the Normal channel's darker voicing"
      },
      {
        "ref": "R3n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Bright input grid stopper (jack 1)"
      },
      {
        "ref": "R4n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Bright input grid stopper (jack 2)"
      },
      {
        "ref": "RG2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Bright input leak, jack 1's tip to ground (jack side of R3n); the grid's DC return through R3n"
      },
      {
        "ref": "RL2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V1B plate load"
      },
      {
        "ref": "RK1",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "Shared V1A/V1B cathode bias"
      },
      {
        "ref": "C10",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Shared V1A/V1B cathode bypass"
      },
      {
        "ref": "C1",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 400 V",
        "role": "V1A → Normal volume"
      },
      {
        "ref": "VR1",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Normal volume"
      },
      {
        "ref": "VR2",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Normal tone"
      },
      {
        "ref": "C5",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Normal tone — cut path to ground"
      },
      {
        "ref": "C6",
        "part": "Mica capacitor",
        "value": "500 pF",
        "role": "Normal tone — treble path to the volume wiper"
      },
      {
        "ref": "R5",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Normal channel mixing resistor into V2A"
      },
      {
        "ref": "C2",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 400 V",
        "role": "V1B → Bright volume"
      },
      {
        "ref": "VR3",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Bright volume"
      },
      {
        "ref": "VR4",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Bright tone"
      },
      {
        "ref": "C7",
        "part": "Film capacitor",
        "value": "0.02 µF · 400 V",
        "role": "Bright tone — cut path to ground"
      },
      {
        "ref": "C8",
        "part": "Mica capacitor",
        "value": "500 pF",
        "role": "Bright tone — treble path to the volume wiper"
      },
      {
        "ref": "R6",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Bright channel mixing resistor into V2A"
      },
      {
        "ref": "RL3",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V2A plate load"
      },
      {
        "ref": "RD4",
        "part": "Carbon comp resistor",
        "value": "15 kΩ · ½ W",
        "role": "V2A plate-load decoupler to the +270 V rail"
      },
      {
        "ref": "RK2",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V2A cathode bias"
      },
      {
        "ref": "C4",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V2A cathode bypass"
      },
      {
        "ref": "C9",
        "part": "Coupling capacitor",
        "value": "0.01 µF · 400 V",
        "role": "V2A → phase inverter, taken from the 100 kΩ / 15 kΩ junction"
      },
      {
        "ref": "RL4",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V2B oscillator plate load (to the +375 V reservoir)"
      },
      {
        "ref": "RK3",
        "part": "Carbon comp resistor",
        "value": "2.7 kΩ · ½ W",
        "role": "V2B oscillator cathode bias"
      },
      {
        "ref": "C11",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V2B oscillator cathode bypass"
      },
      {
        "ref": "C16",
        "part": "Film capacitor",
        "value": "0.02 µF · 400 V",
        "role": "Oscillator phase-shift cap, plate side"
      },
      {
        "ref": "C17",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Oscillator phase-shift cap, middle"
      },
      {
        "ref": "C18",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Oscillator phase-shift cap, grid side"
      },
      {
        "ref": "R7",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Oscillator grid leak to ground"
      },
      {
        "ref": "R8",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Oscillator phase-shift return to the cathode"
      },
      {
        "ref": "VR5",
        "part": "Reverse-audio potentiometer",
        "value": "3.5 MΩ-RA",
        "role": "Speed (oscillator frequency)"
      },
      {
        "ref": "R9",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Speed-control end resistor"
      },
      {
        "ref": "R10",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Oscillator output feed to the Intensity control"
      },
      {
        "ref": "C19",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "Oscillator output coupling to the Intensity control"
      },
      {
        "ref": "VR6",
        "part": "Linear potentiometer",
        "value": "250 kΩ-L",
        "role": "Intensity — sits in the −26 V bias line, carries no DC"
      },
      {
        "ref": "C20",
        "part": "Film capacitor",
        "value": "0.05 µF · 200 V",
        "role": "Intensity wiper to ground"
      },
      {
        "ref": "—",
        "part": "Jack",
        "value": "closed-circuit",
        "role": "Tremolo footswitch pedal jack (shorts the oscillator)"
      },
      {
        "ref": "RLA",
        "part": "Carbon comp resistor",
        "value": "82 kΩ · 5 % · ½ W",
        "role": "V3A plate load (hot side)"
      },
      {
        "ref": "RLB",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · 5 % · ½ W",
        "role": "V3B plate load (cold side)"
      },
      {
        "ref": "C15",
        "part": "Mica capacitor",
        "value": "100 pF",
        "role": "Damping cap across the inverter plates"
      },
      {
        "ref": "RGA",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "V3A grid leak, returned to the tail junction"
      },
      {
        "ref": "RGB",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "V3B grid leak, returned to the tail junction"
      },
      {
        "ref": "RTAIL",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Inverter cathode resistor (cathodes → tail junction)"
      },
      {
        "ref": "RT2",
        "part": "Carbon comp resistor",
        "value": "6.8 kΩ · ½ W",
        "role": "Inverter tail resistor (junction → feedback node)"
      },
      {
        "ref": "RNF1",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "Feedback-node foot resistor to ground"
      },
      {
        "ref": "RNFB",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Negative feedback from the speaker terminal"
      },
      {
        "ref": "C14",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Feedback node → V3B grid"
      },
      {
        "ref": "C12",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "V3A plate → V4 grid"
      },
      {
        "ref": "C13",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "V3B plate → V5 grid"
      },
      {
        "ref": "RG4",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · 5 % · ½ W",
        "role": "V4 grid leak to the −26 V bias line"
      },
      {
        "ref": "RG5",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · 5 % · ½ W",
        "role": "V5 grid leak to the −26 V bias line"
      },
      {
        "ref": "RD1",
        "part": "Power resistor",
        "value": "1 kΩ · 2 W",
        "role": "Rail dropper +375 V → +365 V (screens)"
      },
      {
        "ref": "RD2",
        "part": "Power resistor",
        "value": "10 kΩ · 1 W",
        "role": "Rail dropper +365 V → +325 V (phase inverter)"
      },
      {
        "ref": "RD3",
        "part": "Power resistor",
        "value": "27 kΩ · 1 W",
        "role": "Rail dropper +325 V → +270 V (preamp)"
      },
      {
        "ref": "C21",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Reservoir filter, +375 V"
      },
      {
        "ref": "C22",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, +365 V screen node"
      },
      {
        "ref": "C23",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, +325 V phase-inverter node"
      },
      {
        "ref": "C24",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 450 V",
        "role": "Filter, +270 V preamp node"
      },
      {
        "ref": "R11",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · 5 % · ½ W",
        "role": "Bias-supply feed from the HT winding"
      },
      {
        "ref": "D1",
        "part": "Rectifier (bias)",
        "value": "rectifier type not printed · silicon diode in modern builds",
        "role": "Bias-supply rectifier — both I-FA pages draw a plain diode symbol and letter no material"
      },
      {
        "ref": "C25",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 50 V",
        "role": "Bias-supply filter"
      },
      {
        "ref": "R12",
        "part": "Carbon comp resistor",
        "value": "22 kΩ · 5 % · ½ W",
        "role": "Bias-supply bleeder — sets the −26 V line"
      },
      {
        "ref": "V1",
        "part": "Preamp tube",
        "value": "7025 (12AX7)",
        "role": "Both channel input stages (V1A/V1B)"
      },
      {
        "ref": "V2",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Driver stage + tremolo oscillator (V2A/V2B)"
      },
      {
        "ref": "V3",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Long-tailed-pair phase inverter (V3A/V3B)"
      },
      {
        "ref": "V4",
        "part": "Power tube",
        "value": "6V6GT",
        "role": "Push-pull output (hot side)"
      },
      {
        "ref": "V5",
        "part": "Power tube",
        "value": "6V6GT",
        "role": "Push-pull output (cold side)"
      },
      {
        "ref": "V6",
        "part": "Rectifier tube",
        "value": "GZ34",
        "role": "Full-wave rectifier (V6A/V6B)"
      },
      {
        "ref": "T1",
        "part": "Power transformer",
        "value": "125P2A · 333-0-333 V · 6.3 V · 5 V",
        "role": "HT + heaters + rectifier filament"
      },
      {
        "ref": "T2",
        "part": "Output transformer",
        "value": "125A1A",
        "role": "Push-pull output"
      },
      {
        "ref": "—",
        "part": "Fuse",
        "value": "2 A",
        "role": "AC mains fuse (annotation only)"
      },
      {
        "ref": "—",
        "part": "Switch",
        "value": "SPST",
        "role": "AC power switch (annotation only)"
      },
      {
        "ref": "—",
        "part": "Switch",
        "value": "SPDT",
        "role": "Ground switch — throws the 0.05 µF · 600 V cap to either mains conductor; the schematic draws two contacts, the layout three lugs (annotation only)"
      },
      {
        "ref": "—",
        "part": "Film capacitor",
        "value": "0.05 µF · 600 V",
        "role": "Mains-to-chassis cap on the ground switch (annotation only)"
      },
      {
        "ref": "—",
        "part": "Pilot lamp",
        "value": "6.3 V",
        "role": "Pilot light (annotation only)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Fender 'Deluxe' Model 6G3 drawing (I-FA), printed voltages: +375 (reservoir / OT centre tap), +365 (6V6 plates and screens), +325 (phase-inverter plate rail), +270 (preamp rail), +165 (both channel-input plates, and the driver plate), +1.5 (shared input cathode), +1.4 (driver cathode), +230/+225 (phase-inverter plates), +20 (joined inverter cathodes), +18 (inverter tail junction), -26 (6V6 fixed bias), +205/+2.0 (tremolo oscillator, excluded)",
    "nodes": {
      "BS": {
        "chart": 365,
        "tol_pct": 8,
        "note": "6V6 screen node, one 1 kΩ · 2 W dropper below the driven reservoir. The plates sit on the +375 V centre tap; the chart's +365 V at the plate pin is the output transformer primary's own drop, which this model omits — internal target, tighter than the drawing's ±20%"
      },
      "BC": {
        "chart": 325,
        "tol_pct": 8,
        "note": "phase-inverter plate rail, 10 kΩ · 1 W below the screen node — internal target"
      },
      "BD": {
        "chart": 270,
        "tol_pct": 8,
        "note": "preamp rail, 27 kΩ · 1 W below the phase-inverter rail — internal target"
      },
      "PN1": {
        "chart": 165,
        "tol_pct": 20,
        "note": "Normal-channel input plate, 220 kΩ from +270 V"
      },
      "PB1": {
        "chart": 165,
        "tol_pct": 20,
        "note": "Bright-channel input plate, 220 kΩ from +270 V"
      },
      "KIN": {
        "chart": 1.5,
        "tol_pct": 20,
        "note": "shared input cathode — both 7025 sections over one 1.5 kΩ"
      },
      "P2A": {
        "chart": 165,
        "tol_pct": 20,
        "note": "driver plate, 100 kΩ plate load returning through a 15 kΩ to +270 V"
      },
      "K2A": {
        "chart": 1.4,
        "tol_pct": 20,
        "note": "driver cathode over 1.5 kΩ"
      },
      "PPIA": {
        "chart": 230,
        "tol_pct": 20,
        "note": "phase-inverter plate, 82 kΩ (hot) side"
      },
      "PPIB": {
        "chart": 225,
        "tol_pct": 20,
        "note": "phase-inverter plate, 100 kΩ (cold) side"
      },
      "KPI": {
        "chart": 20,
        "tol_pct": 20,
        "note": "joined inverter cathodes, above the 820 Ω"
      },
      "JPI": {
        "chart": 18,
        "tol_pct": 20,
        "note": "inverter tail junction (820 Ω / 6.8 kΩ), grid-leak return"
      },
      "G61": {
        "chart": -26,
        "tol_pct": 8,
        "note": "6V6 (V4) grid, fixed bias through a 220 kΩ · 5 % leak from the −26 V supply"
      },
      "J2": {
        "chart": null,
        "note": "junction of the driver's 100 kΩ plate load and its 15 kΩ decoupling resistor — the point the 0.01 µF coupler to the inverter is taken from. The drawing prints no voltage here"
      },
      "NFB": {
        "chart": null,
        "note": "foot of the inverter tail — 1.5 kΩ to ground with the 56 kΩ speaker-feedback resistor across it. The drawing prints no voltage here"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "BS",
      "chart": 365,
      "sim": 363.59,
      "disputed": false,
      "dev_pct": 0.38630136986302055,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6V6 screen node, one 1 kΩ · 2 W dropper below the driven reservoir. The plates sit on the +375 V centre tap; the chart's +365 V at the plate pin is the output transformer primary's own drop, which this model omits — internal target, tighter than the drawing's ±20%",
      "dispute_note": ""
    },
    {
      "node": "BC",
      "chart": 325,
      "sim": 323.393,
      "disputed": false,
      "dev_pct": 0.494461538461547,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate rail, 10 kΩ · 1 W below the screen node — internal target",
      "dispute_note": ""
    },
    {
      "node": "BD",
      "chart": 270,
      "sim": 270.969,
      "disputed": false,
      "dev_pct": 0.3588888888888867,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "preamp rail, 27 kΩ · 1 W below the phase-inverter rail — internal target",
      "dispute_note": ""
    },
    {
      "node": "PN1",
      "chart": 165,
      "sim": 156.325,
      "disputed": false,
      "dev_pct": 5.257575757575764,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Normal-channel input plate, 220 kΩ from +270 V",
      "dispute_note": ""
    },
    {
      "node": "PB1",
      "chart": 165,
      "sim": 156.325,
      "disputed": false,
      "dev_pct": 5.257575757575764,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Bright-channel input plate, 220 kΩ from +270 V",
      "dispute_note": ""
    },
    {
      "node": "KIN",
      "chart": 1.5,
      "sim": 1.563,
      "disputed": false,
      "dev_pct": 4.199999999999996,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "shared input cathode — both 7025 sections over one 1.5 kΩ",
      "dispute_note": ""
    },
    {
      "node": "P2A",
      "chart": 165,
      "sim": 167.535,
      "disputed": false,
      "dev_pct": 1.5363636363636344,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "driver plate, 100 kΩ plate load returning through a 15 kΩ to +270 V",
      "dispute_note": ""
    },
    {
      "node": "K2A",
      "chart": 1.4,
      "sim": 1.349,
      "disputed": false,
      "dev_pct": 3.642857142857139,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "driver cathode over 1.5 kΩ",
      "dispute_note": ""
    },
    {
      "node": "PPIA",
      "chart": 230,
      "sim": 233.337,
      "disputed": false,
      "dev_pct": 1.4508695652173866,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate, 82 kΩ (hot) side",
      "dispute_note": ""
    },
    {
      "node": "PPIB",
      "chart": 225,
      "sim": 225.402,
      "disputed": false,
      "dev_pct": 0.1786666666666608,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate, 100 kΩ (cold) side",
      "dispute_note": ""
    },
    {
      "node": "KPI",
      "chart": 20,
      "sim": 18.871,
      "disputed": false,
      "dev_pct": 5.645000000000007,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "joined inverter cathodes, above the 820 Ω",
      "dispute_note": ""
    },
    {
      "node": "JPI",
      "chart": 18,
      "sim": 17.167,
      "disputed": false,
      "dev_pct": 4.627777777777768,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "inverter tail junction (820 Ω / 6.8 kΩ), grid-leak return",
      "dispute_note": ""
    },
    {
      "node": "G61",
      "chart": -26,
      "sim": -26,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6V6 (V4) grid, fixed bias through a 220 kΩ · 5 % leak from the −26 V supply",
      "dispute_note": ""
    },
    {
      "node": "J2",
      "chart": null,
      "sim": 257.477,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "junction of the driver's 100 kΩ plate load and its 15 kΩ decoupling resistor — the point the 0.01 µF coupler to the inverter is taken from. The drawing prints no voltage here",
      "dispute_note": ""
    },
    {
      "node": "NFB",
      "chart": null,
      "sim": 3.036,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "foot of the inverter tail — 1.5 kΩ to ground with the 56 kΩ speaker-feedback resistor across it. The drawing prints no voltage here",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Verified",
      "summary": "13 reference nodes are within tolerance. Maintainer verification is recorded for 2026-08-02; changes since then are awaiting maintainer re-review.",
      "details": [
        "The circuit's facts (netlist, reference voltages, parts list, both drawings' connections, capacitor polarity marks and heater declarations) have changed since the maintainer's review, or no review fingerprint is on record yet. The badge stands on its date until the maintainer re-reviews.",
        "This compares simulated DC conditions with the cited reference. It does not test sound, physical construction or every part of the circuit."
      ],
      "tone": "checked"
    },
    {
      "id": "schematic",
      "title": "Schematic against DC model",
      "status": "Checked",
      "summary": "Connectivity of modelled components is checked on every change.",
      "details": [
        "Parts outside the DC model need separate checks and source review."
      ],
      "tone": "checked"
    },
    {
      "id": "board",
      "title": "Board against DC model",
      "status": "Checked",
      "summary": "Connectivity of modelled components is checked on every change.",
      "details": [
        "This does not establish heater wiring or physical spacing."
      ],
      "tone": "checked"
    },
    {
      "id": "drawings",
      "title": "Schematic against board",
      "status": "No open findings",
      "summary": "No disagreement is listed in the published comparison.",
      "details": [
        "A finding identifies a difference or a coverage gap. The factory source must decide which drawing, if either, needs correction.",
        "14 sheet-only parts are explicitly excluded: C21, C22, C23, C24, C5, C6, C7, C8, R1n, R2n, R3n, R4n, RG1, RG2. Heaters and the pilot lamp are checked separately."
      ],
      "tone": "checked"
    },
    {
      "id": "heaters",
      "title": "Heater and filament wiring",
      "status": "Partial",
      "summary": "Some circuits are checked; other heater connections remain unestablished.",
      "details": [
        "Supply-leg grouping still needs confirmation at V1, V2, V3.",
        "V1: pins [4, 5] are one leg at 6.3 V and opposite legs at 12.6 V"
      ],
      "tone": "attention"
    },
    {
      "id": "polarity",
      "title": "Capacitor polarity",
      "status": "Partial",
      "summary": "1 capacitor marking cannot be confirmed by the DC model.",
      "details": [
        "C11: C11.a: reaches only ground, through RK3"
      ],
      "tone": "attention"
    }
  ],
  "corrections": [
    {
      "id": "6g3-input-leaks-switch-2026-10-03",
      "date": "2026-10-03",
      "amps": [
        "6g3"
      ],
      "title": "6G3 input leaks, ground switch and bias rectifier",
      "description": "The schematic now hangs each channel's 1 MΩ input leak from input 1's tip, as the factory drawing shows; it had been drawn on the valve's grid. The ground switch is recorded as a two-way switch, and the bias rectifier's type is no longer stated, since the drawing does not print one. No operating point changes.",
      "commit": "ff50046fdd1857f2f509075ab745d8c33cbab394",
      "url": "https://github.com/TheAnalogMaker/circuit-codex/commit/ff50046fdd1857f2f509075ab745d8c33cbab394"
    }
  ],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/ebddc3fd2cf887dca010bbe60487d7391ea6c052/amps/6g3"
}