{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "6g5",
  "url": "https://circuitcodex.com/amps/6g5/",
  "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": "6g5",
    "name_style": "Brown Pro-style",
    "family": "other",
    "era": {
      "start": 1960,
      "end": 1963
    },
    "wattage": 40,
    "tubes": [
      7025,
      7025,
      7025,
      7025,
      7025,
      "6L6GC",
      "6L6GC"
    ],
    "topology": {
      "rectifier": {
        "kind": "solid-state",
        "type": "silicon, three diodes per leg"
      },
      "bias": "fixed",
      "phase_inverter": "long-tailed-pair",
      "tone_stack": "tb"
    },
    "sections": {
      "V3A": "excluded — vibrato oscillator: a running phase-shift oscillator has no static DC point"
    },
    "lineage": {
      "derived_from": [
        "5e5a"
      ],
      "influenced": []
    },
    "conventions": {
      "designators": "functional"
    },
    "sources": [
      {
        "desc": "Fender 'Pro-Amp' Model 6G5 drawing (A-FJ), schematic + layout: component values AND the printed voltages read directly from the published sheet, the schematic page native 2153x1437 px and the layout page 2224x1331 px (the PDF embeds them at 72 ppi, so they are the full resolution of this copy). Complement from the layout page's socket row: five 7025 and two 6L6GC, seven bottles. The pin voltages lettered at each socket place every section: V1 carries both channels' first stages (+170 V plates, cathodes joined at +1.4 V); V2 both second stages (+160 V at pin 1, +120 V at pin 6, cathodes joined at +1.1 V); V3 the vibrato oscillator (+130 V plate at pin 1, +1.3 V cathode) and its phase splitter (+180 V plate at pin 6, +1.5 V cathode); V4 the vibrato pair (+320 V at pins 1 and 6, cathodes joined at +3.3 V); V5 the phase inverter (+315 V at pin 1, +310 V at pin 6, cathodes +23 V). Ten triode sections, all drawn. Rails: silicon full-wave (three diodes in each leg of a centre-tapped HT winding) into two 20-600 reservoir cans, the standby switch, +460 V, the choke, +458 V (the 6L6GC screens through 470 Ohm-1W stoppers each, and every dropper), the 6L6GC plates printed +456 V through the output transformer. From +458 V: 4700 1W to +430 V (the phase inverter's 82k / 100k 5% plate loads), then 56k 1W to +260 V (rail A: all four channel plate loads); and a separate 56k 1W to +350 V (the vibrato pair), then a further 56k 1W to +275 V (the oscillator and splitter), each node on its own 20-600 can. The +350 V, +275 V and +260 V figures and the +23 V inverter cathode are lettered on the layout page only. Fixed bias read as -55 V (a small rotated label beside the two 220k-5% output grid leaks, read with a wider margin than the horizontal prints); the supply is a bias-tap rectifier, 8-150, 10k, then 8-150 with a 56k bleeder. Channels: each has two inputs on 68k stoppers with a 1M leak at input 1, a first stage (100k plate), a .05 coupler into a Bass-Treble network (100k slope, 250 uuF treble capacitor into a 250 kOhm-L Treble pot whose cold lug sits on the slope foot, a 250 kOhm-A Bass pot wired as a divider from the slope foot to ground with .01 uF across its upper section and 10 kOhm across its lower) and a 500 kOhm-L Volume pot, then a second stage. Channel 1 (drawn on top) alone carries a 47 uuF bright capacitor from its Volume's hot lug to the wiper; its second stage loads its plate with 100k and then a 6800 decoupling resistor to rail A, and takes its output from their junction through .05 into the vibrato. Channel 2's second stage is a single 220k load, its output .05 and 1M into the node where the vibrato recombines. Harmonic vibrato: channel 1's output feeds a low-pass branch (470k, .005 to ground, .01 to one grid of V4) and a high-pass branch (220k / 220k to ground, 250 uuF to the other grid); V4's sections have 100k plate loads, a shared 4700 Ohm cathode resistor bypassed by 2-25, and their plates recombine through 470k each. The oscillator is a three-section phase-shift ladder (.02, .01, .01; Speed 4M-RA with 100k to ground on the first node, 1M to the cathode and the vibrato-pedal jack on the second, 1M grid leak), with a 470k plate load, 4700 / 25-25 cathode and .03 from plate to ground; its output runs through 4.7M and .005 onto .1-200 and the 10M-L Intensity control, whose wiper (.05-200 to ground) feeds one vibrato grid through 1M. The splitter's grid is the node both vibrato grids return to through 1M each; it carries a 1M leak and .05-200 to ground and .001 from its plate, its plate a 100k load, .25 to ground and .05 plus 1M to the other vibrato grid; cathode 1500 / 25-25. Phase inverter: .001 input coupler, 47 uuF across the plates, 820 Ohm shared cathode into a 6.8k tail; the tail foot carries a 1500 resistor to ground, the .1-200 that grounds the cold grid for signal, a 22k negative-feedback resistor back to the OT secondary, and the 5k-L Presence pot (drawn as a rheostat) in series with a 0.1 uF capacitor. The Presence capacitor's rating is read from the companion LAYOUT sheet, which letters it .1-200 beside the Presence pot, where it also draws the 1500 foot resistor. Output: two 6L6GC, grounded cathodes, 220k-5% fixed-bias grid leaks, .05 couplers. Notice on the sheet: values +/-20% read to ground with an electronic voltmeter; the layout sheet separately notes resistors 1/2 W - 10% and capacitors >= 400 V unless marked. Not reproduced here; archived at Schematic Heaven.",
        "url": "https://schematicheaven.net/fenderamps/pro_6g5_schem.pdf"
      },
      {
        "desc": "Mojotone/Ampwares Fender field guide, 'Brownface Pro' — 6G5 production window 1960-1963, 40 W nominal rating, 1x15\" combo, front-panel control layout (Normal In/In/Bass/Treble/Volume, Bright In/In/Bass/Treble/Volume, shared Speed/Intensity/Presence) and harmonic vibrato. Used here for the wattage and date range; the circuit is read from the drawing above.",
        "url": "https://mojotone.com/blogs/fender-field-guide/fender-brownface-pro"
      }
    ],
    "verification": {
      "status": "draft"
    },
    "added": "2026-08-08T00:00:00.000Z",
    "contributors": [
      "TheAnalogMaker"
    ]
  },
  "parts": {
    "notes": "The drawing prints no channel names; channel 1 is the one drawn at the top of the schematic, whose controls sit beside Speed and Intensity on the panel, and it is the only channel that passes through the vibrato and the only one with a bright capacitor. The oscillator's own network (the ladder, the Speed and Intensity controls, the 4.7 MΩ feed and its smoothing capacitors) is listed in full, but the oscillator is excluded from the DC model: a running phase-shift oscillator has no static operating point. The splitter and the vibrato pair are modelled. The transformers keep the drawing's own designators, TR1 (power) and TR2 (output).",
    "items": [
      {
        "ref": "R1N",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-1 grid stopper from input 2"
      },
      {
        "ref": "R1H",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-1 grid stopper from input 1"
      },
      {
        "ref": "RG1A",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Channel-1 leak at input 1, to ground (mounted at the jack)"
      },
      {
        "ref": "RL1A",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1A plate load, off rail A"
      },
      {
        "ref": "CC1T",
        "part": "Coupling capacitor",
        "value": "0.05 µF",
        "role": "Channel-1 first-stage plate into the tone network — lettered .05 on the drawing and mounted on the board beside the plate load"
      },
      {
        "ref": "RS1T",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Channel-1 tone-stack slope resistor, stack input to the slope foot; mounts at the Treble pot"
      },
      {
        "ref": "CT1",
        "part": "Mica capacitor",
        "value": "250 pF",
        "role": "Channel-1 treble capacitor (250MM on the drawing), stack input to the Treble pot's hot lug; mounts at the Treble pot"
      },
      {
        "ref": "VRT1",
        "part": "Linear potentiometer",
        "value": "250 kΩ-L",
        "role": "Channel-1 Treble (250K-L on both pages of the drawing) — hot lug on the 250 pF, cold lug on the slope foot, wiper to the Volume pot"
      },
      {
        "ref": "VRB1",
        "part": "Audio-taper potentiometer",
        "value": "250 kΩ-A",
        "role": "Channel-1 Bass — a divider from the slope foot to ground: the 0.01 µF across its upper section (hot lug to wiper), the 10 kΩ foot across its lower (wiper to ground)"
      },
      {
        "ref": "CF1",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Channel-1 bass capacitor, slope foot to the Bass pot's wiper; mounts at the Bass pot"
      },
      {
        "ref": "RF1",
        "part": "Carbon comp resistor",
        "value": "10 kΩ · ½ W",
        "role": "Channel-1 bass foot resistor, the Bass pot's wiper to ground; mounts at the Bass pot"
      },
      {
        "ref": "VRV1",
        "part": "Linear potentiometer",
        "value": "500 kΩ-L",
        "role": "Channel-1 Volume (500K-L on both pages of the drawing), fed from the Treble wiper; its own wiper is V2A's grid"
      },
      {
        "ref": "CBR1",
        "part": "Mica capacitor",
        "value": "47 pF",
        "role": "Channel-1 bright capacitor across the Volume pot, hot lug to wiper (47MM on the drawing); mounts at the Volume pot"
      },
      {
        "ref": "RL1B",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V2A plate load, from the plate to the decoupling junction"
      },
      {
        "ref": "RLD1",
        "part": "Carbon comp resistor",
        "value": "6.8 kΩ · ½ W",
        "role": "V2A load decoupler, junction to rail A (lettered 6800); channel 1's output is taken at this junction, not at the plate"
      },
      {
        "ref": "CC1D",
        "part": "Coupling capacitor",
        "value": "0.05 µF",
        "role": "Channel-1 output, from the decoupling junction into the vibrato's band-splitting filters"
      },
      {
        "ref": "R2N",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-2 grid stopper from input 2"
      },
      {
        "ref": "R2H",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-2 grid stopper from input 1"
      },
      {
        "ref": "RG2A",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Channel-2 leak at input 1, to ground (mounted at the jack)"
      },
      {
        "ref": "RL2A",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1B plate load, off rail A"
      },
      {
        "ref": "CC2T",
        "part": "Coupling capacitor",
        "value": "0.05 µF",
        "role": "Channel-2 first-stage plate into the tone network — as CC1T"
      },
      {
        "ref": "RS2T",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Channel-2 tone-stack slope resistor — as RS1T"
      },
      {
        "ref": "CT2",
        "part": "Mica capacitor",
        "value": "250 pF",
        "role": "Channel-2 treble capacitor — as CT1"
      },
      {
        "ref": "VRT2",
        "part": "Linear potentiometer",
        "value": "250 kΩ-L",
        "role": "Channel-2 Treble — as VRT1"
      },
      {
        "ref": "VRB2",
        "part": "Audio-taper potentiometer",
        "value": "250 kΩ-A",
        "role": "Channel-2 Bass — a divider from the slope foot to ground, as VRB1"
      },
      {
        "ref": "CF2",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Channel-2 bass capacitor — as CF1"
      },
      {
        "ref": "RF2",
        "part": "Carbon comp resistor",
        "value": "10 kΩ · ½ W",
        "role": "Channel-2 bass foot resistor — as RF1"
      },
      {
        "ref": "VRV2",
        "part": "Linear potentiometer",
        "value": "500 kΩ-L",
        "role": "Channel-2 Volume, fed from the Treble wiper; its wiper is V2B's grid. Neither page draws a bright capacitor on this control"
      },
      {
        "ref": "RL2B",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V2B plate load, off rail A — the reason this plate prints +120 V against channel 1's +160 V"
      },
      {
        "ref": "CC2D",
        "part": "Coupling capacitor",
        "value": "0.05 µF",
        "role": "Channel-2 output coupler"
      },
      {
        "ref": "RM2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Channel-2 mixing resistor into the node where the vibrato pair's outputs recombine"
      },
      {
        "ref": "RK1",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "V1 cathode resistor — both first stages' cathodes joined (the drawing's boxed C)"
      },
      {
        "ref": "CK1",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V1 cathode bypass (25-25 on the drawing)"
      },
      {
        "ref": "RK2",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "V2 cathode resistor — both second stages' cathodes joined (the drawing's boxed D)"
      },
      {
        "ref": "CK2",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V2 cathode bypass (25-25 on the drawing)"
      },
      {
        "ref": "RLP",
        "part": "Carbon comp resistor",
        "value": "470 kΩ · ½ W",
        "role": "Low-band branch series resistor, channel-1 output to the low-pass node"
      },
      {
        "ref": "CLP",
        "part": "Film capacitor",
        "value": "0.005 µF",
        "role": "Low-band branch shunt, low-pass node to ground"
      },
      {
        "ref": "CV1",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Low-band coupler, low-pass node to V4A's grid"
      },
      {
        "ref": "RHP1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "High-band branch, channel-1 output to the high-pass node"
      },
      {
        "ref": "RHP2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "High-band branch, high-pass node to ground"
      },
      {
        "ref": "CV2",
        "part": "Mica capacitor",
        "value": "250 pF",
        "role": "High-band coupler (250MM on the drawing), high-pass node to V4B's grid"
      },
      {
        "ref": "RLV1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V4A (low band) plate load, off the +350 V vibrato-pair supply"
      },
      {
        "ref": "RLV2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V4B (high band) plate load, off the +350 V vibrato-pair supply"
      },
      {
        "ref": "RKV",
        "part": "Carbon comp resistor",
        "value": "4.7 kΩ · ½ W",
        "role": "Vibrato pair's joined cathodes to ground"
      },
      {
        "ref": "CKV",
        "part": "Electrolytic capacitor",
        "value": "2 µF · 25 V",
        "role": "Vibrato pair's cathode bypass (lettered 2-25 on both pages)"
      },
      {
        "ref": "RGV1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "V4A grid return to the splitter's grid"
      },
      {
        "ref": "RGV2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "V4B grid return to the splitter's grid"
      },
      {
        "ref": "RMV1",
        "part": "Carbon comp resistor",
        "value": "470 kΩ · ½ W",
        "role": "V4A plate into the recombining node"
      },
      {
        "ref": "RMV2",
        "part": "Carbon comp resistor",
        "value": "470 kΩ · ½ W",
        "role": "V4B plate into the recombining node"
      },
      {
        "ref": "RTOP",
        "part": "Carbon comp resistor",
        "value": "470 kΩ · ½ W",
        "role": "Oscillator plate load, off the +275 V supply"
      },
      {
        "ref": "RTOK",
        "part": "Carbon comp resistor",
        "value": "4.7 kΩ · ½ W",
        "role": "Oscillator cathode resistor"
      },
      {
        "ref": "CTOK",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Oscillator cathode bypass"
      },
      {
        "ref": "CTO3",
        "part": "Film capacitor",
        "value": "0.02 µF",
        "role": "Phase-shift ladder, first capacitor: oscillator plate to the first ladder node"
      },
      {
        "ref": "CTO1",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Phase-shift ladder, second capacitor"
      },
      {
        "ref": "CTO2",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Phase-shift ladder, third capacitor, into the oscillator grid"
      },
      {
        "ref": "VRSPD",
        "part": "Reverse-audio potentiometer",
        "value": "4 MΩ-RA",
        "role": "Speed — a rheostat from the first ladder node, in series with RSPD to ground"
      },
      {
        "ref": "RSPD",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Speed end resistor, in series with the Speed control to ground; mounts at the pot"
      },
      {
        "ref": "RTOG1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Phase-shift ladder, second node to the oscillator cathode"
      },
      {
        "ref": "RTOG2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Oscillator grid leak, to ground"
      },
      {
        "ref": "JVIB",
        "part": "Jack",
        "value": "vibrato footswitch",
        "role": "Vibrato pedal jack, on the ladder's second node"
      },
      {
        "ref": "CTOP",
        "part": "Film capacitor",
        "value": "0.03 µF",
        "role": "Oscillator plate to ground"
      },
      {
        "ref": "RTOF",
        "part": "Carbon comp resistor",
        "value": "4.7 MΩ · ½ W",
        "role": "Oscillator output feed toward the Intensity control"
      },
      {
        "ref": "CTOF",
        "part": "Film capacitor",
        "value": "0.005 µF",
        "role": "Oscillator output coupler, in series with RTOF"
      },
      {
        "ref": "CTX",
        "part": "Film capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Intensity control's hot end to ground"
      },
      {
        "ref": "VRINT",
        "part": "Linear potentiometer",
        "value": "10 MΩ-L",
        "role": "Intensity — from the oscillator feed to ground, wiper to the low-band vibrato grid"
      },
      {
        "ref": "CTW",
        "part": "Film capacitor",
        "value": "0.05 µF · 200 V",
        "role": "Intensity wiper to ground; mounts at the pot"
      },
      {
        "ref": "RWV",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Intensity wiper to V4A's grid"
      },
      {
        "ref": "RLS",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Splitter plate load, off the +275 V supply"
      },
      {
        "ref": "RKS",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "Splitter cathode resistor"
      },
      {
        "ref": "CKS",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Splitter cathode bypass"
      },
      {
        "ref": "RGS",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Splitter grid leak, to ground; its grid is also the node both vibrato grids return to"
      },
      {
        "ref": "CGS",
        "part": "Film capacitor",
        "value": "0.05 µF · 200 V",
        "role": "Splitter grid to ground"
      },
      {
        "ref": "CFS",
        "part": "Mica capacitor",
        "value": "0.001 µF",
        "role": "Splitter plate to grid"
      },
      {
        "ref": "CPS",
        "part": "Film capacitor",
        "value": "0.25 µF",
        "role": "Splitter plate to ground"
      },
      {
        "ref": "CSV",
        "part": "Film capacitor",
        "value": "0.05 µF",
        "role": "Splitter output coupler toward V4B's grid"
      },
      {
        "ref": "RSV",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Splitter output into V4B's grid"
      },
      {
        "ref": "CPIN",
        "part": "Mica capacitor",
        "value": "0.001 µF",
        "role": "Phase-inverter input coupler, from the recombining node to the hot grid"
      },
      {
        "ref": "RLA",
        "part": "Carbon comp resistor",
        "value": "82 kΩ · ½ W · 5%",
        "role": "PI plate load (V5A, hot side)"
      },
      {
        "ref": "RLB",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 5%",
        "role": "PI plate load (V5B, cold side)"
      },
      {
        "ref": "CPP",
        "part": "Mica capacitor",
        "value": "47 pF",
        "role": "Across the two PI plates (47MM on both pages)"
      },
      {
        "ref": "RTAIL",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "PI shared cathode"
      },
      {
        "ref": "RT2",
        "part": "Carbon comp resistor",
        "value": "6.8 kΩ · ½ W",
        "role": "PI tail, tail junction to the foot node"
      },
      {
        "ref": "RGA",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "PI grid leak (hot), returned to the tail junction"
      },
      {
        "ref": "RGB",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "PI grid leak (cold), returned to the tail junction"
      },
      {
        "ref": "CGB",
        "part": "Film capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Cold PI grid to the foot node (.1-200 on the schematic)"
      },
      {
        "ref": "RNFB",
        "part": "Carbon comp resistor",
        "value": "22 kΩ · ½ W",
        "role": "Negative-feedback resistor, OT secondary to the PI tail foot"
      },
      {
        "ref": "RPRES",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "Tail foot resistor to ground (the schematic letters it 1500; the layout page mounts it at the Presence pot)"
      },
      {
        "ref": "VRPRES",
        "part": "Potentiometer",
        "value": "5 kΩ-L",
        "role": "Presence — wired as a rheostat, in series with CPRES; that branch parallels RPRES from the phase-inverter tail foot to ground"
      },
      {
        "ref": "CPRES",
        "part": "Film capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Presence cap, in series with VRPRES to ground — what makes that branch AC-only"
      },
      {
        "ref": "C1",
        "part": "Coupling capacitor",
        "value": "0.05 µF · 400 V",
        "role": "PI (hot) → V7 grid"
      },
      {
        "ref": "C2",
        "part": "Coupling capacitor",
        "value": "0.05 µF · 400 V",
        "role": "PI (cold) → V8 grid"
      },
      {
        "ref": "RGL1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 5%",
        "role": "V7 grid leak, from the -55 V fixed-bias supply"
      },
      {
        "ref": "RGL2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 5%",
        "role": "V8 grid leak, from the -55 V fixed-bias supply"
      },
      {
        "ref": "RSC1",
        "part": "Carbon comp resistor",
        "value": "470 Ω · 1 W",
        "role": "V7 screen stopper, off the post-choke node"
      },
      {
        "ref": "RSC2",
        "part": "Carbon comp resistor",
        "value": "470 Ω · 1 W",
        "role": "V8 screen stopper, off the post-choke node"
      },
      {
        "ref": "D1",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "HT rectifier — the HT_A leg, first of three (cathodes toward the reservoir, A-FJ)"
      },
      {
        "ref": "D2",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "HT rectifier — the HT_A leg, second of three"
      },
      {
        "ref": "D3",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "HT rectifier — the HT_A leg, third of three"
      },
      {
        "ref": "D4",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "HT rectifier — the HT_B leg, first of three"
      },
      {
        "ref": "D5",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "HT rectifier — the HT_B leg, second of three"
      },
      {
        "ref": "D6",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "HT rectifier — the HT_B leg, third of three (A-FJ draws six diodes, three per leg, off a centre-tapped winding)"
      },
      {
        "ref": "CF3",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 600 V",
        "role": "B+ reservoir, ahead of the choke (per the drawing's repeated '20-600P' marking)"
      },
      {
        "ref": "L1",
        "part": "Choke",
        "value": "CH. · inductance not printed",
        "role": "Filter choke from the +460 V node, where the output transformer's centre tap lands, to the +458 V screen and dropper node — labelled CH. on the drawing"
      },
      {
        "ref": "CF4",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 600 V",
        "role": "Filter at the post-choke node (+458 V: screens and every dropper)"
      },
      {
        "ref": "RD1",
        "part": "Carbon comp resistor",
        "value": "4.7 kΩ · 1 W",
        "role": "Dropper, post-choke node to the +430 V phase-inverter supply"
      },
      {
        "ref": "CF5",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 600 V",
        "role": "Filter at the +430 V phase-inverter supply"
      },
      {
        "ref": "RD2",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · 1 W",
        "role": "Dropper, +430 V node to rail A (+260 V, both channels)"
      },
      {
        "ref": "CF6",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 600 V",
        "role": "Filter at rail A"
      },
      {
        "ref": "RD3",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · 1 W",
        "role": "Dropper, post-choke node to the +350 V vibrato-pair supply"
      },
      {
        "ref": "CF7",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 600 V",
        "role": "Filter at the +350 V vibrato-pair supply"
      },
      {
        "ref": "RD4",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · 1 W",
        "role": "Dropper, +350 V node to the +275 V oscillator and splitter supply"
      },
      {
        "ref": "CF8",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 600 V",
        "role": "Filter at the +275 V oscillator and splitter supply"
      },
      {
        "ref": "TR1",
        "part": "Power transformer",
        "value": "HT secondary · 6.3 V heaters",
        "role": "Mains primary; centre-tapped HT secondary with a bias tap; heater secondaries — no part number printed on this sheet"
      },
      {
        "ref": "TR2",
        "part": "Output transformer",
        "value": "push-pull : speaker",
        "role": "Push-pull output into the 15-inch speaker; no part number printed on this sheet"
      },
      {
        "ref": "F1",
        "part": "Fuse",
        "value": "3 A",
        "role": "Mains fuse"
      },
      {
        "ref": "SW1",
        "part": "Switch",
        "value": "SPST",
        "role": "AC power switch"
      },
      {
        "ref": "PL1",
        "part": "Pilot lamp",
        "value": "6.3 V",
        "role": "Pilot lamp, fed from the 6.3 V heater chain"
      },
      {
        "ref": "JSPK",
        "part": "Jack",
        "value": "speaker",
        "role": "Speaker jack"
      },
      {
        "ref": "DBIAS",
        "part": "Silicon diode",
        "value": "1N4007-class",
        "role": "Bias rectifier — fed from TR1's bias tap, its + (bar) end toward the tap (A-FJ); the DC netlist drives the -55 V line as an ideal source"
      },
      {
        "ref": "CBIAS",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 150 V",
        "role": "Bias filter at the rectifier (A-FJ: 8-150)"
      },
      {
        "ref": "RBIAS2",
        "part": "Carbon comp resistor",
        "value": "10 kΩ · ½ W",
        "role": "Bias series resistor, rectifier node to the -55 V line (A-FJ)"
      },
      {
        "ref": "CBIAS2",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 150 V",
        "role": "Bias filter at the -55 V line (A-FJ: 8-150)"
      },
      {
        "ref": "RBIAS1",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Bias bleeder, -55 V line to ground (A-FJ)"
      },
      {
        "ref": "V1",
        "part": "Preamp tube",
        "value": "7025",
        "role": "Both channels' first stages: V1A channel 1 (pins 6-8), V1B channel 2 (pins 1-3), cathodes joined"
      },
      {
        "ref": "V2",
        "part": "Preamp tube",
        "value": "7025",
        "role": "Both channels' second stages: V2A channel 1 (pins 1-3, +160 V), V2B channel 2 (pins 6-8, +120 V), cathodes joined"
      },
      {
        "ref": "V3",
        "part": "Preamp tube",
        "value": "7025",
        "role": "Vibrato oscillator V3A (pins 1-3, excluded from the DC model) and its phase splitter V3B (pins 6-8)"
      },
      {
        "ref": "V4",
        "part": "Preamp tube",
        "value": "7025",
        "role": "Vibrato pair: V4A low band (pins 1-3), V4B high band (pins 6-8), cathodes joined"
      },
      {
        "ref": "V5",
        "part": "Preamp tube",
        "value": "7025",
        "role": "Long-tailed-pair phase inverter: V5A hot (pins 1-3, +315 V), V5B cold (pins 6-8, +310 V)"
      },
      {
        "ref": "V7",
        "part": "Power tube",
        "value": "6L6GC",
        "role": "Push-pull output (hot side)"
      },
      {
        "ref": "V8",
        "part": "Power tube",
        "value": "6L6GC",
        "role": "Push-pull output (cold side)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Fender Pro-Amp Model 6G5 drawing (A-FJ). Schematic page: +460 (after the standby switch), +458 (after the choke; screens and droppers), +456 (6L6GC plates), +430 (phase-inverter supply), +315/+310 (phase-inverter plates), +320/+320 and +3.3 (vibrato pair plates and joined cathodes), +130 and +1.3 (vibrato oscillator plate and cathode — excluded, reported here only), +180 and +1.5 (the oscillator's phase splitter), +170/+1.4 (both first stages, cathodes joined), +160 (channel 1 second stage), +120 (channel 2 second stage), +1.1 (the second stages' joined cathodes), -55 (fixed bias, a rotated label beside the output grid leaks). Layout page, in addition: +350 (vibrato-pair supply), +275 (oscillator and splitter supply), +260 (rail A, both channels), +23 (phase-inverter cathodes).",
    "nodes": {
      "BC": {
        "chart": 430,
        "tol_pct": 8,
        "note": "phase-inverter supply, after the 4.7 kΩ · 1 W dropper from the post-choke node — printed on both pages"
      },
      "BA": {
        "chart": 260,
        "tol_pct": 10,
        "note": "rail A, after a 56 kΩ · 1 W dropper from the +430 V node; it feeds all four channel plate loads. Printed on the layout page only"
      },
      "BV": {
        "chart": 350,
        "tol_pct": 10,
        "note": "vibrato-pair supply, after a 56 kΩ · 1 W dropper from the post-choke node. Printed on the layout page only. Simulates a few volts high: the oscillator's own draw, which also passes through this dropper, is not modelled (see the next node)"
      },
      "BL": {
        "chart": 275,
        "tol_pct": 10,
        "note": "supply for the oscillator's 470 kΩ and the splitter's 100 kΩ, after a second 56 kΩ · 1 W dropper. Printed on the layout page only, as a small vertical label; the units digit is the least certain glyph, and the 10% band holds any reading of it. Simulates about 9% high because the oscillator is excluded from the model and its running draw with it — about 0.3 mA on the chart's own +130 V plate reading. With a 0.31 mA sink standing in for it, this node lands at 275 V and the vibrato-pair supply at 346 V"
      },
      "P1A": {
        "chart": 170,
        "tol_pct": 20,
        "note": "channel-1 first stage plate (V1, 100 kΩ load off rail A)"
      },
      "P2A": {
        "chart": 170,
        "tol_pct": 20,
        "note": "channel-2 first stage plate (V1's other section, 100 kΩ load off rail A)"
      },
      "K1": {
        "chart": 1.4,
        "tol_pct": 20,
        "note": "both first stages' joined cathodes over one 820 Ω / 25 µF pair (the drawing's boxed C)"
      },
      "P1B": {
        "chart": 160,
        "tol_pct": 20,
        "note": "channel-1 second stage plate (V2): 100 kΩ, then a 6.8 kΩ decoupling resistor to rail A, output taken between them"
      },
      "P2B": {
        "chart": 120,
        "tol_pct": 20,
        "note": "channel-2 second stage plate (V2's other section): a single 220 kΩ load off rail A — the reason it prints lower than channel 1"
      },
      "K2": {
        "chart": 1.1,
        "tol_pct": 20,
        "note": "both second stages' joined cathodes over one 820 Ω / 25 µF pair (the drawing's boxed D)"
      },
      "PV1": {
        "chart": 320,
        "tol_pct": 20,
        "note": "vibrato pair, low-band section plate (V4, 100 kΩ load off the vibrato-pair supply)"
      },
      "PV2": {
        "chart": 320,
        "tol_pct": 20,
        "note": "vibrato pair, high-band section plate"
      },
      "KV": {
        "chart": 3.3,
        "tol_pct": 20,
        "note": "vibrato pair's joined cathodes over 4.7 kΩ / 25 µF"
      },
      "PS": {
        "chart": 180,
        "tol_pct": 20,
        "note": "oscillator's phase splitter plate (V3, 100 kΩ load). Reads high with its supply — see BL"
      },
      "KS": {
        "chart": 1.5,
        "tol_pct": 20,
        "note": "phase splitter cathode over 1.5 kΩ / 25 µF"
      },
      "PPIA": {
        "chart": 315,
        "tol_pct": 20,
        "note": "phase-inverter plate, 82 kΩ (hot) side"
      },
      "PPIB": {
        "chart": 310,
        "tol_pct": 20,
        "note": "phase-inverter plate, 100 kΩ (cold) side"
      },
      "KPI": {
        "chart": 23,
        "tol_pct": 20,
        "note": "phase-inverter joined cathodes, above the 820 Ω — printed at the socket on the layout page only"
      },
      "JPI": {
        "chart": null,
        "note": "phase-inverter tail junction (820 Ω / 6.8 kΩ), the grid-leak return — printed on neither page"
      },
      "S71": {
        "chart": 458,
        "tol_pct": 10,
        "note": "6L6GC (V7) screen after its 470 Ω · 1 W stopper. The drawing prints +458 V at the post-choke node the screens hang from; the model drives that node at the printed +458 V"
      },
      "S72": {
        "chart": 458,
        "tol_pct": 10,
        "note": "6L6GC (V8) screen after its own 470 Ω · 1 W stopper — same basis as S71"
      },
      "G71": {
        "chart": -55,
        "tol_pct": 8,
        "note": "6L6GC (V7) grid, fixed bias via 220 kΩ from the -55 V supply"
      },
      "G72": {
        "chart": -55,
        "tol_pct": 8,
        "note": "6L6GC (V8) grid, fixed bias via 220 kΩ from the -55 V supply"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "BC",
      "chart": 430,
      "sim": 430.272,
      "disputed": false,
      "dev_pct": 0.06325581395348637,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "phase-inverter supply, after the 4.7 kΩ · 1 W dropper from the post-choke node — printed on both pages",
      "dispute_note": ""
    },
    {
      "node": "BA",
      "chart": 260,
      "sim": 252.453,
      "disputed": false,
      "dev_pct": 2.9026923076923064,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "rail A, after a 56 kΩ · 1 W dropper from the +430 V node; it feeds all four channel plate loads. Printed on the layout page only",
      "dispute_note": ""
    },
    {
      "node": "BV",
      "chart": 350,
      "sim": 358.979,
      "disputed": false,
      "dev_pct": 2.565428571428567,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "vibrato-pair supply, after a 56 kΩ · 1 W dropper from the post-choke node. Printed on the layout page only. Simulates a few volts high: the oscillator's own draw, which also passes through this dropper, is not modelled (see the next node)",
      "dispute_note": ""
    },
    {
      "node": "BL",
      "chart": 275,
      "sim": 300.938,
      "disputed": false,
      "dev_pct": 9.431999999999995,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "supply for the oscillator's 470 kΩ and the splitter's 100 kΩ, after a second 56 kΩ · 1 W dropper. Printed on the layout page only, as a small vertical label; the units digit is the least certain glyph, and the 10% band holds any reading of it. Simulates about 9% high because the oscillator is excluded from the model and its running draw with it — about 0.3 mA on the chart's own +130 V plate reading. With a 0.31 mA sink standing in for it, this node lands at 275 V and the vibrato-pair supply at 346 V",
      "dispute_note": ""
    },
    {
      "node": "P1A",
      "chart": 170,
      "sim": 167.674,
      "disputed": false,
      "dev_pct": 1.3682352941176432,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "channel-1 first stage plate (V1, 100 kΩ load off rail A)",
      "dispute_note": ""
    },
    {
      "node": "P2A",
      "chart": 170,
      "sim": 167.674,
      "disputed": false,
      "dev_pct": 1.3682352941176432,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "channel-2 first stage plate (V1's other section, 100 kΩ load off rail A)",
      "dispute_note": ""
    },
    {
      "node": "K1",
      "chart": 1.4,
      "sim": 1.39,
      "disputed": false,
      "dev_pct": 0.714285714285715,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "both first stages' joined cathodes over one 820 Ω / 25 µF pair (the drawing's boxed C)",
      "dispute_note": ""
    },
    {
      "node": "P1B",
      "chart": 160,
      "sim": 155.315,
      "disputed": false,
      "dev_pct": 2.9281250000000014,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "channel-1 second stage plate (V2): 100 kΩ, then a 6.8 kΩ decoupling resistor to rail A, output taken between them",
      "dispute_note": ""
    },
    {
      "node": "P2B",
      "chart": 120,
      "sim": 126.998,
      "disputed": false,
      "dev_pct": 5.8316666666666706,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "channel-2 second stage plate (V2's other section): a single 220 kΩ load off rail A — the reason it prints lower than channel 1",
      "dispute_note": ""
    },
    {
      "node": "K2",
      "chart": 1.1,
      "sim": 1.213,
      "disputed": false,
      "dev_pct": 10.272727272727272,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "both second stages' joined cathodes over one 820 Ω / 25 µF pair (the drawing's boxed D)",
      "dispute_note": ""
    },
    {
      "node": "PV1",
      "chart": 320,
      "sim": 322.39,
      "disputed": false,
      "dev_pct": 0.7468749999999957,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "vibrato pair, low-band section plate (V4, 100 kΩ load off the vibrato-pair supply)",
      "dispute_note": ""
    },
    {
      "node": "PV2",
      "chart": 320,
      "sim": 322.39,
      "disputed": false,
      "dev_pct": 0.7468749999999957,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "vibrato pair, high-band section plate",
      "dispute_note": ""
    },
    {
      "node": "KV",
      "chart": 3.3,
      "sim": 3.439,
      "disputed": false,
      "dev_pct": 4.212121212121219,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "vibrato pair's joined cathodes over 4.7 kΩ / 25 µF",
      "dispute_note": ""
    },
    {
      "node": "PS",
      "chart": 180,
      "sim": 197.293,
      "disputed": false,
      "dev_pct": 9.607222222222225,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "oscillator's phase splitter plate (V3, 100 kΩ load). Reads high with its supply — see BL",
      "dispute_note": ""
    },
    {
      "node": "KS",
      "chart": 1.5,
      "sim": 1.555,
      "disputed": false,
      "dev_pct": 3.6666666666666625,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase splitter cathode over 1.5 kΩ / 25 µF",
      "dispute_note": ""
    },
    {
      "node": "PPIA",
      "chart": 315,
      "sim": 311.805,
      "disputed": false,
      "dev_pct": 1.0142857142857122,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate, 82 kΩ (hot) side",
      "dispute_note": ""
    },
    {
      "node": "PPIB",
      "chart": 310,
      "sim": 302.326,
      "disputed": false,
      "dev_pct": 2.475483870967735,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate, 100 kΩ (cold) side",
      "dispute_note": ""
    },
    {
      "node": "KPI",
      "chart": 23,
      "sim": 24.584,
      "disputed": false,
      "dev_pct": 6.88695652173913,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter joined cathodes, above the 820 Ω — printed at the socket on the layout page only",
      "dispute_note": ""
    },
    {
      "node": "JPI",
      "chart": null,
      "sim": 22.35,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "phase-inverter tail junction (820 Ω / 6.8 kΩ), the grid-leak return — printed on neither page",
      "dispute_note": ""
    },
    {
      "node": "S71",
      "chart": 458,
      "sim": 457.89,
      "disputed": false,
      "dev_pct": 0.024017467248911274,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "6L6GC (V7) screen after its 470 Ω · 1 W stopper. The drawing prints +458 V at the post-choke node the screens hang from; the model drives that node at the printed +458 V",
      "dispute_note": ""
    },
    {
      "node": "S72",
      "chart": 458,
      "sim": 457.89,
      "disputed": false,
      "dev_pct": 0.024017467248911274,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "6L6GC (V8) screen after its own 470 Ω · 1 W stopper — same basis as S71",
      "dispute_note": ""
    },
    {
      "node": "G71",
      "chart": -55,
      "sim": -55,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6L6GC (V7) grid, fixed bias via 220 kΩ from the -55 V supply",
      "dispute_note": ""
    },
    {
      "node": "G72",
      "chart": -55,
      "sim": -55,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6L6GC (V8) grid, fixed bias via 220 kΩ from the -55 V supply",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Within target",
      "summary": "22 reference nodes are within tolerance. The circuit remains a draft awaiting maintainer review.",
      "details": [
        "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.",
        "9 sheet-only parts are explicitly excluded: CF3, CF4, CF5, CF6, CF7, CF8, F1, RG1A, RG2A. Heaters and the pilot lamp are checked separately."
      ],
      "tone": "checked"
    },
    {
      "id": "heaters",
      "title": "Heater and filament wiring",
      "status": "Not established",
      "summary": "The drawn supply-leg connections have not been established by this check.",
      "details": [
        "Supply-leg grouping still needs confirmation at V1, V2, V3, V4, V5.",
        "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": [
        "CTOK: CTOK.a: reaches only ground, through RTOK"
      ],
      "tone": "attention"
    }
  ],
  "corrections": [],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/ebddc3fd2cf887dca010bbe60487d7391ea6c052/amps/6g5"
}