{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "ab763-super",
  "url": "https://circuitcodex.com/amps/ab763-super/",
  "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": "ab763-super",
    "name_style": "Blackface Super Reverb-style",
    "family": "blackface",
    "era": {
      "start": 1964,
      "end": 1967
    },
    "wattage": 40,
    "tubes": [
      "12AX7",
      "12AX7",
      "12AX7",
      "12AT7",
      "12AX7",
      "12AT7",
      "6L6GC",
      "6L6GC",
      "GZ34"
    ],
    "topology": {
      "rectifier": {
        "kind": "tube",
        "type": "GZ34"
      },
      "bias": "fixed",
      "phase_inverter": "long-tailed-pair",
      "tone_stack": "fmv"
    },
    "lineage": {
      "derived_from": [
        "6g4"
      ],
      "influenced": []
    },
    "conventions": {
      "designators": "functional"
    },
    "sources": [
      {
        "desc": "Fender 'SUPER-REVERB-AMP AB763' schematic (title block: FENDER MODEL \"SUPER-REVERB-AMPAB763\" SCHEMATIC, drawing code C-FD). Every component value AND the printed voltage chart read directly from the sheet. Rails: +460 V (6L6GC plates; OT centre tap reads +465 V, 5 V above the plate reading, OT primary DCR omitted — merged to one rail exactly as the Deluxe Reverb's own +415/+420 pair is), +460 V screens (via 470 Ω-1W stoppers), +450 V (phase-inverter plates and reverb-driver plate, node [C] — reached from +460 V through a printed 1 kΩ-1W dropper, RD1, modelled so its simulated value is a check on the chart), +410 V (Normal input, Normal 2nd stage, Vibrato input, Vibrato 2nd stage, mix driver and reverb-recovery plate rail, node [D] — reached from +450 V through a printed 4.7 kΩ-1W dropper, RD2, likewise modelled). Stage readings: +270 V / +2.1 V (Normal and Vibrato input stages, 100 kΩ plate / 1.5 kΩ cathode); +270 V for each second stage's plate, over 100 kΩ, with +2.1 V printed at BOTH ends of cathode box [A] — the box is a connection between the Normal and Vibrato second stages, and the one 820 Ω / 25 µF network it names is drawn at the Vibrato stage and carries both triodes; +270 V for the mix driver and the reverb recovery, over 100 kΩ each, with +2.0 V printed at both ends of cathode box [E], one 820 Ω / 25 µF drawn at the recovery stage and carrying both; +450 V / +8.4 V (reverb-driver 12AT7, both sections paralleled, 2.2 kΩ shared cathode, fed from the +460 V rail at node [B] through the reverb transformer TR4 primary — the primary's B+ lead is lettered +460 V on the sheet, not [C]); +230 V (both phase-inverter plates, 82 kΩ hot / 100 kΩ cold at 5%), +106 V / +104.5 V (PI joined cathodes / tail junction, 470 Ω to the junction, 22 kΩ to ground); -52 V fixed bias (adjustable — a 10 kΩ-L pot on the rectified tap, not a fixed divider). Notice printed on the sheet: 'VOLTAGES READ TO GROUND WITH ELECTRONIC VOLTMETER VALUES SHOWN + OR - 20%', 'ALL RESISTORS 1/2 WATT 10% TOLERANCE IF NOT SPECIFIED', 'ALL CAPACITORS AT LEAST 400 VOLT RATING IF NOT SPECIFIED'. The preamp bottles are labelled 7025 (a 12AX7 alias — see the 12AX7 reference page); the tremolo oscillator is labelled plain 12AX7. Export-model transformer table printed on the sheet: TR1-125P5D (125P5DX export) power, TR2-125C1A choke, TR3-125A9A output, TR4-125A20B reverb — the same reverb-transformer part number the Deluxe Reverb and Twin Reverb entries cite. Two structural details distinguish this drawing from its Deluxe/Twin Reverb siblings, both read directly off the sheet: (1) the Normal channel keeps the two-knob tone stack (fixed 6.8 kΩ bleed resistor, no third pot) while the Vibrato channel's third position is a genuine Middle potentiometer, marked 10K-A on both the schematic and the panel row of the layout sheet, wired in place of that bleed resistor — an asymmetric stack, not a shared one; (2) each 6L6GC control grid carries its own 1500 Ω series stopper between the 0.1 µF coupling cap and the tube pin, in addition to the 220 kΩ·5% bias leak — a resistor the Deluxe Reverb's 6V6GT stage does not draw. Not reproduced here; archived at EL34World.",
        "url": "https://el34world.com/charts/Schematics/Files/Fender/Fender_super_reverb_ab763_schematic.pdf"
      },
      {
        "desc": "Fender 'SUPER REVERB-AMP AB763' LAYOUT drawing (drawing code C-FD, Fender Electric Instrument Company, Fullerton) — the eyelet-board layout: the order the board's parts stand in, the valve sockets beneath the board and the control row above it, and each socket's leads pin by pin. Read from Schematic Heaven's 300 ppi scan of the sheet (3299 × 2551, the fourth page of its Super Reverb AB763 file) and cross-checked against the EL34World capture (2182 × 1394). Not reproduced here.",
        "url": "https://el34world.com/charts/Schematics/files/Fender/Fender_super_reverb_ab763_layout.pdf"
      },
      {
        "desc": "Mojotone/Ampwares Fender field guide, 'Fender Blackface Super Reverb' — production window 1963-1967 under AA763 then AB763, 40 W factory rating, two 6L6GC output tubes, GZ34 rectifier, fixed bias with an adjustable pot, four 10-inch speakers (Jensen C10R / Oxford 10L6 / CTS variants), reverb and tremolo. Used here for the wattage and speaker-complement facts the schematic itself does not print; every component value and voltage above is read from the schematic, not this page.",
        "url": "https://mojotone.com/blogs/fender-field-guide/fender-blackface-super-reverb"
      }
    ],
    "verification": {
      "status": "draft"
    },
    "added": "2026-08-30T00:00:00.000Z",
    "contributors": [
      "TheAnalogMaker"
    ],
    "sections": {
      "V5": "excluded — the tremolo bottle: a running phase-shift oscillator (one section, printed +280 V plate / +2.5 V cathode) and the neon-lamp driver it swings (the other, printed +390 V plate / +170 V cathode). The sheet prints a pair at BOTH sections, and all four are averages a meter reads while the oscillator swings, so neither section has a static operating point"
    }
  },
  "parts": {
    "notes": "The drawing shows both instrument jacks (1 and 2) of each channel with their normalling contacts; this sheet draws them as the two input labels, with the 1 MΩ leak at jack 1's tip, jack side of its 68 kΩ stopper, where C-FD puts it. The tremolo tube's parts (both halves of V5: the phase-shift oscillator and the neon-lamp driver) and the reverb-tank interconnect parts are listed, but neither tremolo half has a static DC point, so V5 is excluded from the netlist (see the circuit story). The Normal channel's tone stack is the fixed two-knob ladder (6.8 kΩ bleed); the Vibrato channel's third pot is a genuine 10 kΩ Middle control wired in place of that bleed resistor, not a shared component — the two stacks are asymmetric, read as printed. Two cathode networks are shared, and each is listed once, under the boxed letter the drawing gives it: RKA/CKA carry both second stages (Normal and Vibrato), RKE/CKE both the mix driver and the reverb recovery. Neither the Normal second stage nor the mix driver has a cathode resistor of its own.",
    "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": "RGN1",
        "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": "RLN1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1a plate load"
      },
      {
        "ref": "RKN1",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V1a cathode bias"
      },
      {
        "ref": "CKN1",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V1a cathode bypass"
      },
      {
        "ref": "CTN",
        "part": "Mica capacitor",
        "value": "250 pF",
        "role": "Normal treble cap"
      },
      {
        "ref": "VRTN",
        "part": "Potentiometer",
        "value": "250 kΩ-A",
        "role": "Normal treble"
      },
      {
        "ref": "RSN",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Normal tone-stack slope resistor"
      },
      {
        "ref": "CBN",
        "part": "Coupling capacitor",
        "value": "0.1 µF",
        "role": "Normal tone-stack bass cap, slope node to the bass pot"
      },
      {
        "ref": "VRBN",
        "part": "Potentiometer",
        "value": "250 kΩ-A",
        "role": "Normal bass"
      },
      {
        "ref": "CBN2",
        "part": "Coupling capacitor",
        "value": "0.022 µF",
        "role": "Normal tone-stack middle-leg cap, slope node to the bleed resistor"
      },
      {
        "ref": "RSLN",
        "part": "Carbon comp resistor",
        "value": "6.8 kΩ · ½ W",
        "role": "Normal tone-stack bleed resistor (fixed — no Middle pot on this channel)"
      },
      {
        "ref": "VRVN",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Normal volume"
      },
      {
        "ref": "CBRN",
        "part": "Mica capacitor",
        "value": "120 pF",
        "role": "Normal bright cap, across the volume pot"
      },
      {
        "ref": "SWBN",
        "part": "Switch (ganged w/ VRVN)",
        "value": "Bright",
        "role": "Normal bright switch"
      },
      {
        "ref": "RLN2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1b (normal 2nd stage) plate load"
      },
      {
        "ref": "CCN2",
        "part": "Coupling capacitor",
        "value": "0.047 µF",
        "role": "V1b output coupling, into the mix resistor RMD1"
      },
      {
        "ref": "R1v",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Vibrato input grid stopper (jack 1)"
      },
      {
        "ref": "R2v",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Vibrato input grid stopper (jack 2)"
      },
      {
        "ref": "RGV1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Vibrato input leak, jack 1's tip to ground (jack side of R1v); the grid's DC return through R1v"
      },
      {
        "ref": "RLV1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V2a plate load"
      },
      {
        "ref": "RKV1",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V2a cathode bias"
      },
      {
        "ref": "CKV1",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V2a cathode bypass"
      },
      {
        "ref": "CTV",
        "part": "Mica capacitor",
        "value": "250 pF",
        "role": "Vibrato treble cap"
      },
      {
        "ref": "VRTV",
        "part": "Potentiometer",
        "value": "250 kΩ-A",
        "role": "Vibrato treble"
      },
      {
        "ref": "RSV",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Vibrato tone-stack slope resistor"
      },
      {
        "ref": "CBV",
        "part": "Coupling capacitor",
        "value": "0.1 µF",
        "role": "Vibrato tone-stack bass cap, slope node to the bass pot"
      },
      {
        "ref": "VRBV",
        "part": "Potentiometer",
        "value": "250 kΩ-A",
        "role": "Vibrato bass"
      },
      {
        "ref": "CBV2",
        "part": "Coupling capacitor",
        "value": "0.022 µF",
        "role": "Vibrato tone-stack middle-leg cap, slope node to the Middle pot"
      },
      {
        "ref": "VRMV",
        "part": "Potentiometer",
        "value": "10 kΩ-A",
        "role": "Vibrato middle — replaces the Normal channel's fixed bleed resistor"
      },
      {
        "ref": "VRVV",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Vibrato volume"
      },
      {
        "ref": "CBRV",
        "part": "Mica capacitor",
        "value": "120 pF",
        "role": "Vibrato bright cap, across the volume pot"
      },
      {
        "ref": "SWBV",
        "part": "Switch (ganged w/ VRVV)",
        "value": "Bright",
        "role": "Vibrato bright switch"
      },
      {
        "ref": "RLV2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V2b (vibrato 2nd stage) plate load"
      },
      {
        "ref": "RKA",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Cathode bias at the drawing's boxed [A] — one resistor for BOTH second stages, Normal and Vibrato"
      },
      {
        "ref": "CKA",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Cathode bypass across RKA (shared [A] network)"
      },
      {
        "ref": "CCV2",
        "part": "Coupling capacitor",
        "value": "0.02 µF",
        "role": "V2b output coupling onto the dry node, which feeds the reverb send and, through 3.3 MΩ, the mix driver"
      },
      {
        "ref": "CRS",
        "part": "Coupling capacitor",
        "value": "500 pF",
        "role": "Reverb send, dry node → driver grid"
      },
      {
        "ref": "RGRD",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Reverb-driver 12AT7 grid leak"
      },
      {
        "ref": "RKRD",
        "part": "Carbon comp resistor",
        "value": "2.2 kΩ · ½ W",
        "role": "Reverb-driver shared cathode bias"
      },
      {
        "ref": "CKRD",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Reverb-driver cathode bypass"
      },
      {
        "ref": "T4",
        "part": "Reverb transformer",
        "value": "Fender 125A20B",
        "role": "Reverb driver → tank input"
      },
      {
        "ref": "RGR1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Reverb-recovery grid leak, to ground (the tank output lands on the grid)"
      },
      {
        "ref": "RLR1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V3b (reverb recovery) plate load"
      },
      {
        "ref": "RKE",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Cathode bias at the drawing's boxed [E] — one resistor for BOTH the mix driver and the reverb recovery"
      },
      {
        "ref": "CKE",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Cathode bypass across RKE (shared [E] network)"
      },
      {
        "ref": "CCR1",
        "part": "Coupling capacitor",
        "value": "0.003 µF",
        "role": "Reverb-recovery output coupling"
      },
      {
        "ref": "VRREV",
        "part": "Linear potentiometer",
        "value": "100 kΩ-L",
        "role": "Reverb level"
      },
      {
        "ref": "RMR",
        "part": "Carbon comp resistor",
        "value": "470 kΩ · ½ W",
        "role": "Reverb return into the mix-driver grid"
      },
      {
        "ref": "RMR2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Mix-driver grid leak, to ground"
      },
      {
        "ref": "RLD1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V3a (mix driver) plate load"
      },
      {
        "ref": "RGD1",
        "part": "Carbon comp resistor",
        "value": "3.3 MΩ · ½ W",
        "role": "Dry-path series resistor, dry node → mix-driver grid (10 pF across it)"
      },
      {
        "ref": "CBD1",
        "part": "Mica capacitor",
        "value": "10 pF",
        "role": "Bright cap across the dry-path 3.3 MΩ"
      },
      {
        "ref": "RMD1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Normal-channel mixing resistor, into the phase-inverter input junction"
      },
      {
        "ref": "CCD1",
        "part": "Coupling capacitor",
        "value": "0.1 µF",
        "role": "Mix-driver output coupling, onto the Intensity control and the 220 kΩ mixing resistor"
      },
      {
        "ref": "RMIXV",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Vibrato-channel mixing resistor, mix-driver output → the phase-inverter input junction"
      },
      {
        "ref": "VRSPD",
        "part": "Reverse-audio potentiometer",
        "value": "3 MΩ-RA",
        "role": "Tremolo speed"
      },
      {
        "ref": "RTO1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Speed-network series resistor, with the Speed control from the Speed node to ground"
      },
      {
        "ref": "RTO2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Tremolo oscillator (V5a) plate load"
      },
      {
        "ref": "RKTO1",
        "part": "Carbon comp resistor",
        "value": "2.7 kΩ · ½ W",
        "role": "Tremolo oscillator (V5a) cathode bias"
      },
      {
        "ref": "CKTO1",
        "part": "Electrolytic capacitor",
        "value": "25 µF",
        "role": "Tremolo oscillator (V5a) cathode bypass"
      },
      {
        "ref": "CTO1",
        "part": "Film capacitor",
        "value": "0.02 µF",
        "role": "Tremolo phase-shift cap, oscillator plate → Speed node"
      },
      {
        "ref": "CTO2",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Tremolo phase-shift cap, Speed node → middle node (the lamp driver's grid)"
      },
      {
        "ref": "CTO3",
        "part": "Film capacitor",
        "value": "0.01 µF",
        "role": "Tremolo phase-shift cap, middle node → oscillator grid"
      },
      {
        "ref": "RTOG1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Tremolo phase-shift ladder, middle node → footswitch junction"
      },
      {
        "ref": "RTOG2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Tremolo phase-shift ladder, oscillator grid → footswitch junction"
      },
      {
        "ref": "RTOG3",
        "part": "Carbon comp resistor",
        "value": "2.2 MΩ · ½ W",
        "role": "Footswitch junction → the bias supply's filter node"
      },
      {
        "ref": "RKTO2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Lamp-driver (V5b) cathode bias"
      },
      {
        "ref": "CKTO2",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Lamp-driver (V5b) cathode bypass"
      },
      {
        "ref": "RTO10",
        "part": "Carbon comp resistor",
        "value": "10 MΩ · ½ W",
        "role": "Lamp-driver plate bleeder to the +460 V rail"
      },
      {
        "ref": "RLAMP",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Neon-lamp series resistor to the +460 V rail"
      },
      {
        "ref": "OPTO",
        "part": "Optocoupler",
        "value": "neon lamp + photoresistor",
        "role": "Tremolo modulator — the lamp on the lamp driver's plate; the photocell shunts the Intensity control's wiper to ground"
      },
      {
        "ref": "VRINT",
        "part": "Reverse-audio potentiometer",
        "value": "50 kΩ-RA",
        "role": "Intensity — from the mix driver's output (after its 0.1 µF coupler) to ground; the photocell shunts its wiper"
      },
      {
        "ref": "RLPA",
        "part": "Carbon comp resistor",
        "value": "82 kΩ · ½ W · 5%",
        "role": "PI plate load (hot side)"
      },
      {
        "ref": "RLPB",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 5%",
        "role": "PI plate load (cold side)"
      },
      {
        "ref": "RGPA",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "PI grid leak (hot), returned to tail junction"
      },
      {
        "ref": "RGPB",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "PI grid leak (cold), returned to tail junction"
      },
      {
        "ref": "RTAIL",
        "part": "Carbon comp resistor",
        "value": "470 Ω · ½ W",
        "role": "PI cathode resistor"
      },
      {
        "ref": "RT2",
        "part": "Carbon comp resistor",
        "value": "22 kΩ · ½ W",
        "role": "PI tail, junction → the feedback node"
      },
      {
        "ref": "CPIA",
        "part": "Coupling capacitor",
        "value": "0.001 µF",
        "role": "PI hot-grid input coupling, from the junction where both channels' 220 kΩ mixing resistors meet"
      },
      {
        "ref": "CPIB",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 200 V",
        "role": "PI cold grid → the feedback node"
      },
      {
        "ref": "RNFB",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Negative feedback, speaker → the feedback node"
      },
      {
        "ref": "RFB1",
        "part": "Carbon comp resistor",
        "value": "100 Ω · ½ W",
        "role": "Feedback-node leg to ground (the 22 kΩ tail and the 820 Ω land on it)"
      },
      {
        "ref": "C1",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "PI hot plate → V7 grid"
      },
      {
        "ref": "C2",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "PI cold plate → V8 grid"
      },
      {
        "ref": "RGL1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 5%",
        "role": "V7 grid leak, from the −52 V bias line"
      },
      {
        "ref": "RGL2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 5%",
        "role": "V8 grid leak, from the −52 V bias line"
      },
      {
        "ref": "RST1",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V7 grid stopper"
      },
      {
        "ref": "RST2",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V8 grid stopper"
      },
      {
        "ref": "RS1",
        "part": "Wirewound resistor",
        "value": "470 Ω · 1 W",
        "role": "V7 screen resistor"
      },
      {
        "ref": "RS2",
        "part": "Wirewound resistor",
        "value": "470 Ω · 1 W",
        "role": "V8 screen resistor"
      },
      {
        "ref": "T3",
        "part": "Output transformer",
        "value": "Fender 125A9A",
        "role": "Push-pull 6L6GC output"
      },
      {
        "ref": "T1",
        "part": "Power transformer",
        "value": "Fender 125P5D · 360-0-360 V",
        "role": "HT + heaters + bias tap + rectifier filament"
      },
      {
        "ref": "T2",
        "part": "Filter choke",
        "value": "Fender 125C1A",
        "role": "Reservoir → 6L6GC plate/screen rail"
      },
      {
        "ref": "C10",
        "part": "Electrolytic capacitor",
        "value": "70 µF · 350 V",
        "role": "Reservoir filter, upper can of the series pair (post-standby)"
      },
      {
        "ref": "C13",
        "part": "Electrolytic capacitor",
        "value": "70 µF · 350 V",
        "role": "Reservoir filter, lower can of the series pair"
      },
      {
        "ref": "RBL1",
        "part": "Wirewound resistor",
        "value": "220 kΩ · 1 W",
        "role": "Balancing resistor across C10"
      },
      {
        "ref": "RBL2",
        "part": "Wirewound resistor",
        "value": "220 kΩ · 1 W",
        "role": "Balancing resistor across C13"
      },
      {
        "ref": "C11",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 525 V",
        "role": "Filter, node B (screens/BP1)"
      },
      {
        "ref": "C12",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 525 V",
        "role": "Filter, node C (phase-inverter plate rail; the reverb driver is fed from BP1, not this node)"
      },
      {
        "ref": "RD1",
        "part": "Wirewound resistor",
        "value": "1 kΩ · 1 W",
        "role": "Rail dropper B → C"
      },
      {
        "ref": "RD2",
        "part": "Wirewound resistor",
        "value": "4.7 kΩ · 1 W",
        "role": "Rail dropper C → D"
      },
      {
        "ref": "RBIAS",
        "part": "Wirewound resistor",
        "value": "470 Ω",
        "role": "Bias-supply series resistor (wattage marking not fully legible on the scan; role and value read directly, matching the Deluxe Reverb's identical 470 Ω bias-feed resistor)"
      },
      {
        "ref": "DBIAS",
        "part": "Rectifier (bias)",
        "value": "silicon diode",
        "role": "Bias-supply rectifier"
      },
      {
        "ref": "CBIAS",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 50 V",
        "role": "Bias-supply filter"
      },
      {
        "ref": "VRBIAS",
        "part": "Linear potentiometer",
        "value": "10 kΩ-L",
        "role": "Bias adjustment — its track runs from the filter node to the 27 kΩ leg, and its wiper sets the −52 V grid line"
      },
      {
        "ref": "RBIAS2",
        "part": "Carbon comp resistor",
        "value": "27 kΩ · ½ W",
        "role": "Bias-pot ground leg: the 10 kΩ-L track runs from the filter node to this 27 kΩ"
      },
      {
        "ref": "V1",
        "part": "Preamp tube",
        "value": "12AX7 (7025)",
        "role": "Normal channel input + 2nd stage (V1a/V1b)"
      },
      {
        "ref": "V2",
        "part": "Preamp tube",
        "value": "12AX7 (7025)",
        "role": "Vibrato channel input + 2nd stage (V2a/V2b)"
      },
      {
        "ref": "V3",
        "part": "Preamp tube",
        "value": "12AX7 (7025)",
        "role": "Mix driver + reverb recovery (V3a/V3b)"
      },
      {
        "ref": "V4",
        "part": "Preamp/driver tube",
        "value": "12AT7",
        "role": "Reverb driver (both sections paralleled)"
      },
      {
        "ref": "V5",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Tremolo oscillator + neon-lamp driver (V5a/V5b; neither has a static DC point, both excluded)"
      },
      {
        "ref": "V6",
        "part": "Preamp/driver tube",
        "value": "12AT7",
        "role": "Long-tailed-pair phase inverter"
      },
      {
        "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)"
      },
      {
        "ref": "V9",
        "part": "Rectifier tube",
        "value": "GZ34",
        "role": "Full-wave rectifier (V9A/V9B)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Fender SUPER-REVERB-AMP AB763 schematic, printed voltages: +460 (6L6GC plates, screens), +465 (OT centre tap, merged with the plate reading — primary DCR omitted), +450 (phase-inverter plates and reverb-driver plate, node [C]), +410 (preamp plate rail, node [D]), +270/+2.0-2.1 (preamp stage plates/cathodes), +230 (PI plates, both branches), +106/+104.5 (PI cathode/tail junction), +450/+8.4 (reverb-driver plate/cathode), -52 (fixed bias, adjustable pot)",
    "nodes": {
      "S61": {
        "chart": 460,
        "tol_pct": 8,
        "note": "6L6GC (V7) screen after its 470 Ohm-1W stopper, off the +460 plate rail"
      },
      "G61": {
        "chart": -52,
        "tol_pct": 8,
        "note": "6L6GC (V7) grid, fixed bias via 220k leak + 1.5k stopper from the -52 V supply"
      },
      "BC": {
        "chart": 450,
        "tol_pct": 5,
        "note": "phase-inverter plate rail, node [C] — derived from BP1 through the printed 1k-1W dropper (RD1); check against the chart, not an input to it. The reverb driver is NOT on this rail: it is fed from BP1 through the TR4 primary (see PRD)"
      },
      "BD": {
        "chart": 410,
        "tol_pct": 5,
        "note": "preamp plate rail, node [D] — derived from BC through the printed 4.7k-1W dropper (RD2); check against the chart"
      },
      "PRD": {
        "chart": 450,
        "tol_pct": 20,
        "note": "reverb-driver 12AT7 plate (paralleled sections), off BP1 through the TR4 primary DCR"
      },
      "KRD": {
        "chart": 8.4,
        "tol_pct": 20,
        "note": "reverb-driver 12AT7 shared cathode over 2.2k"
      },
      "PN1": {
        "chart": 270,
        "tol_pct": 20,
        "note": "Normal-channel input plate, 100k from BD"
      },
      "KN1": {
        "chart": 2.1,
        "tol_pct": 20,
        "note": "Normal-channel input cathode over 1.5k"
      },
      "PN2": {
        "chart": 270,
        "tol_pct": 20,
        "note": "Normal-channel 2nd-stage plate, 100k from BD"
      },
      "PV1": {
        "chart": 270,
        "tol_pct": 20,
        "note": "Vibrato-channel input plate, 100k from BD"
      },
      "KV1": {
        "chart": 2.1,
        "tol_pct": 20,
        "note": "Vibrato-channel input cathode over 1.5k"
      },
      "PV2": {
        "chart": 270,
        "tol_pct": 20,
        "note": "Vibrato-channel 2nd-stage plate, 100k from BD"
      },
      "KA": {
        "chart": 2.1,
        "tol_pct": 20,
        "note": "boxed [A] — the ONE 820 Ohm carrying both second stages, Normal and Vibrato; the chart prints +2.1 V at each end of the box"
      },
      "PD1": {
        "chart": 270,
        "tol_pct": 20,
        "note": "mix-driver plate, 100k from BD"
      },
      "PR1": {
        "chart": 270,
        "tol_pct": 20,
        "note": "reverb-recovery plate, 100k from BD"
      },
      "KE": {
        "chart": 2,
        "tol_pct": 20,
        "note": "boxed [E] — the ONE 820 Ohm carrying both the mix driver and the reverb recovery; the chart prints +2.0 V at each end of the box"
      },
      "PPIA": {
        "chart": 230,
        "tol_pct": 20,
        "note": "PI plate, 82k (hot) side"
      },
      "PPIB": {
        "chart": 230,
        "tol_pct": 20,
        "note": "PI plate, 100k (cold) side — chart prints the same +230 V for both branches despite the unequal plate loads"
      },
      "KPI": {
        "chart": 106,
        "tol_pct": 20,
        "note": "PI joined cathodes, above the 470 Ohm"
      },
      "JPI": {
        "chart": 104.5,
        "tol_pct": 20,
        "note": "PI tail junction (470 Ohm / 22k), grid-leak return"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "S61",
      "chart": 460,
      "sim": 459.583,
      "disputed": false,
      "dev_pct": 0.09065217391303765,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6L6GC (V7) screen after its 470 Ohm-1W stopper, off the +460 plate rail",
      "dispute_note": ""
    },
    {
      "node": "G61",
      "chart": -52,
      "sim": -52,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6L6GC (V7) grid, fixed bias via 220k leak + 1.5k stopper from the -52 V supply",
      "dispute_note": ""
    },
    {
      "node": "BC",
      "chart": 450,
      "sim": 447.598,
      "disputed": false,
      "dev_pct": 0.5337777777777749,
      "tol_pct": 5,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate rail, node [C] — derived from BP1 through the printed 1k-1W dropper (RD1); check against the chart, not an input to it. The reverb driver is NOT on this rail: it is fed from BP1 through the TR4 primary (see PRD)",
      "dispute_note": ""
    },
    {
      "node": "BD",
      "chart": 410,
      "sim": 409.625,
      "disputed": false,
      "dev_pct": 0.09146341463414635,
      "tol_pct": 5,
      "gated": true,
      "within": true,
      "note": "preamp plate rail, node [D] — derived from BC through the printed 4.7k-1W dropper (RD2); check against the chart",
      "dispute_note": ""
    },
    {
      "node": "PRD",
      "chart": 450,
      "sim": 459.172,
      "disputed": false,
      "dev_pct": 2.038222222222228,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "reverb-driver 12AT7 plate (paralleled sections), off BP1 through the TR4 primary DCR",
      "dispute_note": ""
    },
    {
      "node": "KRD",
      "chart": 8.4,
      "sim": 9.112,
      "disputed": false,
      "dev_pct": 8.476190476190473,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "reverb-driver 12AT7 shared cathode over 2.2k",
      "dispute_note": ""
    },
    {
      "node": "PN1",
      "chart": 270,
      "sim": 270.961,
      "disputed": false,
      "dev_pct": 0.35592592592593064,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Normal-channel input plate, 100k from BD",
      "dispute_note": ""
    },
    {
      "node": "KN1",
      "chart": 2.1,
      "sim": 2.08,
      "disputed": false,
      "dev_pct": 0.9523809523809532,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Normal-channel input cathode over 1.5k",
      "dispute_note": ""
    },
    {
      "node": "PN2",
      "chart": 270,
      "sim": 276.97,
      "disputed": false,
      "dev_pct": 2.5814814814814917,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Normal-channel 2nd-stage plate, 100k from BD",
      "dispute_note": ""
    },
    {
      "node": "PV1",
      "chart": 270,
      "sim": 270.961,
      "disputed": false,
      "dev_pct": 0.35592592592593064,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Vibrato-channel input plate, 100k from BD",
      "dispute_note": ""
    },
    {
      "node": "KV1",
      "chart": 2.1,
      "sim": 2.08,
      "disputed": false,
      "dev_pct": 0.9523809523809532,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Vibrato-channel input cathode over 1.5k",
      "dispute_note": ""
    },
    {
      "node": "PV2",
      "chart": 270,
      "sim": 276.97,
      "disputed": false,
      "dev_pct": 2.5814814814814917,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Vibrato-channel 2nd-stage plate, 100k from BD",
      "dispute_note": ""
    },
    {
      "node": "KA",
      "chart": 2.1,
      "sim": 2.176,
      "disputed": false,
      "dev_pct": 3.6190476190476226,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "boxed [A] — the ONE 820 Ohm carrying both second stages, Normal and Vibrato; the chart prints +2.1 V at each end of the box",
      "dispute_note": ""
    },
    {
      "node": "PD1",
      "chart": 270,
      "sim": 276.97,
      "disputed": false,
      "dev_pct": 2.5814814814814917,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "mix-driver plate, 100k from BD",
      "dispute_note": ""
    },
    {
      "node": "PR1",
      "chart": 270,
      "sim": 276.97,
      "disputed": false,
      "dev_pct": 2.5814814814814917,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "reverb-recovery plate, 100k from BD",
      "dispute_note": ""
    },
    {
      "node": "KE",
      "chart": 2,
      "sim": 2.176,
      "disputed": false,
      "dev_pct": 8.800000000000008,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "boxed [E] — the ONE 820 Ohm carrying both the mix driver and the reverb recovery; the chart prints +2.0 V at each end of the box",
      "dispute_note": ""
    },
    {
      "node": "PPIA",
      "chart": 230,
      "sim": 255.8,
      "disputed": false,
      "dev_pct": 11.21739130434783,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "PI plate, 82k (hot) side",
      "dispute_note": ""
    },
    {
      "node": "PPIB",
      "chart": 230,
      "sim": 249.281,
      "disputed": false,
      "dev_pct": 8.383043478260872,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "PI plate, 100k (cold) side — chart prints the same +230 V for both branches despite the unequal plate loads",
      "dispute_note": ""
    },
    {
      "node": "KPI",
      "chart": 106,
      "sim": 97.504,
      "disputed": false,
      "dev_pct": 8.015094339622637,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "PI joined cathodes, above the 470 Ohm",
      "dispute_note": ""
    },
    {
      "node": "JPI",
      "chart": 104.5,
      "sim": 95.473,
      "disputed": false,
      "dev_pct": 8.638277511961723,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "PI tail junction (470 Ohm / 22k), grid-leak return",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Within target",
      "summary": "20 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.",
        "21 sheet-only parts are explicitly excluded: C10, C11, C12, C13, CBIAS, CBRN, CBRV, DBIAS, R1n, R1v, R2n, R2v, RBIAS, RBIAS2, RBL1, RBL2, RGN1, RGR1, RGV1, RSLN, RTO1. 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, V4, V5, V6.",
        "The C-FD layout page for the Super Reverb AB763 is published and is this board's source for its part order and socket leads, but the copy read (3299 x 2551, cross-checked against a 2182 x 1394 capture) does not resolve the 6.3 V heater legs socket by socket, and the circuit drawing only arrows the chain \"TO ALL 6.3V HEATERS AND PILOT LIGHT\". A copy of the layout page carrying those legs legibly is what clears these sockets. The 5 V rectifier circuit is declared from the circuit drawing, which draws that winding.",
        "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": "2 capacitor markings cannot be confirmed by the DC model.",
      "details": [
        "CKTO2: CKTO2.a: reaches only ground, through RKTO2",
        "CKTO1: CKTO1.a: reaches only ground, through RKTO1"
      ],
      "tone": "attention"
    }
  ],
  "corrections": [
    {
      "id": "ab763-super-input-leaks-2026-10-03",
      "date": "2026-10-03",
      "amps": [
        "ab763-super"
      ],
      "title": "AB763 Super Reverb input grid leaks at the first input jack",
      "description": "The schematic now hangs each channel's 1 MΩ input leak from input 1's tip, on the jack side of its 68 kΩ stopper, as the Super Reverb's own factory drawing shows. It had been drawn on the valve's grid. No operating point changes. The circuit remains a draft.",
      "commit": "fe052839ca374813514bfc4d93b026a82b2195d0",
      "url": "https://github.com/TheAnalogMaker/circuit-codex/commit/fe052839ca374813514bfc4d93b026a82b2195d0"
    },
    {
      "id": "ab763-super-driver-2026-09-22",
      "date": "2026-09-22",
      "amps": [
        "ab763-super"
      ],
      "title": "AB763 Super Reverb lamp-driver voltage and heater coverage",
      "description": "The circuit notes now give the factory drawing's lamp-driver cathode value as 170 V, correcting a tenfold transcription error. The layout identifies its 6.3 V heater grouping as awaiting a source read; the earlier claim that no factory layout drawing existed has been removed.",
      "commit": "8902d24",
      "url": "https://github.com/TheAnalogMaker/circuit-codex/commit/8902d24"
    }
  ],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/ebddc3fd2cf887dca010bbe60487d7391ea6c052/amps/ab763-super"
}