{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "5e4a",
  "url": "https://circuitcodex.com/amps/5e4a/",
  "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": "5e4a",
    "name_style": "Tweed Super-style",
    "family": "tweed",
    "era": {
      "start": 1955,
      "end": 1956
    },
    "wattage": 26,
    "tubes": [
      "12AY7",
      "12AY7",
      "12AX7",
      "6V6GT",
      "6V6GT",
      "5U4GA"
    ],
    "topology": {
      "rectifier": {
        "kind": "tube",
        "type": "5U4GA"
      },
      "bias": "fixed",
      "phase_inverter": "cathodyne",
      "tone_stack": "cathode-follower-tb"
    },
    "lineage": {
      "derived_from": [],
      "influenced": [
        "5f4"
      ]
    },
    "conventions": {
      "designators": "functional"
    },
    "sources": [
      {
        "desc": "Fender 'Super-Amp' Model 5E4-A drawing (G-EE), BOTH pages — every component value and every printed voltage read directly from the published sheets. Title block, verbatim: 'FENDER \"SUPER-AMP\" SCHEMATIC / MODEL 5E4-A* / G-EE', with 'NOTICE / VOLTAGES READ TO GROUND WITH ELECTRONIC VOLTMETER / VALUES SHOWN + OR - 20%' and the boxed footnote the asterisk points at: '*NOTE — (A) WAS 22 K OHMS', the (A) marking the bias-supply series resistor now drawn as 18 kΩ. Page 1 is the matching 'FENDER \"SUPER-AMP\" LAYOUT / MODEL 5E4-A*' sheet, same code G-EE, footed '* SEE NOTE ON REVERSE SIDE'. Read from the drawing: a two-channel 12AY7 front end (68 kΩ stoppers at four jacks, 1 MΩ leaks, ONE shared 820 Ω cathode with a 25 µF can, 100 kΩ plates), 1 MΩ Instrument and Mic volumes with a 100 pF bright cap and 270 kΩ mixers into a SECOND 12AY7 — a gain stage (100 kΩ plate, 1.5 kΩ cathode, 25 µF) DC-coupled to a cathode follower on a 100 kΩ load — feeding the split treble/bass network (250 pF into the 1 MΩ treble pot with 0.01 µF at its cold end; 0.1 µF into a 220 kΩ leak and a 100 kΩ series resistor to the 1 MΩ bass pot's wiper with 0.005 µF on its leg; a second 220 kΩ back to the output node, which is the phase-inverter grid, with no coupler; a 5 MΩ reference returned from the bass branch to the gain stage's grid), then a 12AX7 driver (100 kΩ plate, 1.5 kΩ cathode) coupled into a split-load cathodyne (56 kΩ plate, 1.5 kΩ + 56 kΩ under the cathode, 1 MΩ grid leak to the junction, 0.1 µF plate and cathode couplers into 1.5 kΩ stoppers), a 6V6GT pair fixed-biased at −32 V through 220 kΩ leaks with their screens tied straight to the +385 V node, a 56 kΩ speaker feedback resistor and a 5 kΩ presence pot with 0.1 µF landing on the driver's cathode, and a 5U4GA rectifier into 16/16/16/8 µF filtering with a choke and a standby switch. Printed voltages: rails +390/+385/+300/+250, bias −32; cathodes +1.9, +1.9, +130, +1.6, +58 and +56.5; plates +125 (each 12AY7 channel), +190 (driver) and +245 (cathodyne) from the layout sheet. Not reproduced here; archived at EL34World",
        "url": "https://el34world.com/charts/Schematics/files/Fender/Fender_super_5e4a.pdf"
      },
      {
        "desc": "The sourcing problem this entry exists to fix, recorded because the archive's brand is verifiability. Documents circulating under a plain '5E4' label — thetubestore's 'Fender-Super-5E4-G-EE-Schematic.pdf' and two independently hosted copies of a 'Super-5E4-Schematic.pdf' (a manufacturer field-guide link and a repair shop's copy) — are on inspection this same G-EE drawing with the '-A' and its '(A) WAS 22 K OHMS' footnote edited out of the title block. They carry the same Fender drawing code, the same 6V6GT output pair, the same selenium bias supply and the same printed voltages. No independent drawing for a plain 5E4 (6L6G output, no selenium bias cell) was located, so this circuit is filed under the designation its own title block prints. See the circuit story on this page and the Super line's history",
        "url": "https://el34world.com/charts/Schematics/files/Fender/Fender_super_5e4a.pdf"
      },
      {
        "desc": "General Electric 6V6-GT data sheet ET-T914 (March 1955), 'Characteristics and Typical Operation' — a readable copy of the 6V6GT average characteristics that anchor the corpus's CC0 6V6GT model, which this netlist's output pair uses: Va=250 V, Vg2=250 V, Vg1=-12.5 V -> Ia=45 mA, Ig2=4.5 mA, gm=4100 µmho. The model's stated anchor is RCA's Receiving Tube Manual RC-19 (1959), a printed book with no archived scan; this GE sheet prints the same values, so it is what a reader can actually open and check. (The RCA data sheet this entry linked until 2026-09-09 has 404'd; the RCA sheet in the same archive directory is a differential 'same as the 6V6GTA except' page and carries none of these figures.)",
        "url": "https://frank.pocnet.net/sheets/093/6/6V6GT.pdf"
      },
      {
        "desc": "RCA 12AY7 data — the datasheet anchor behind the corpus's CC0 12AY7 model, which this netlist's two front-end bottles use",
        "url": "https://frank.pocnet.net/sheets/049/1/12AY7.pdf"
      }
    ],
    "verification": {
      "status": "verified",
      "date": "2026-08-08T00:00:00.000Z",
      "max_deviation_pct": 8.7
    },
    "added": "2026-08-08T00:00:00.000Z",
    "contributors": [
      "TheAnalogMaker"
    ]
  },
  "parts": {
    "notes": "Both pages draw four input jacks, two per channel, each with its own 68 kΩ stopper into the channel's grid, and hang the channel's 1 MΩ leak from jack 1's tip, jack side of its stopper; jack 2's contact rests on jack 1's tip. The pots are lettered by value only; neither page prints a taper. The output-transformer centre tap takes the choke's output (+385 V) with the screens, on both pages. The interstage coupler C8 is the one part the schematic sheet leaves unlabelled — its value is read from the layout sheet of the same drawing, which prints a 0.02 µF · 600 V can in that position. The tone network is capacitor-isolated and omitted from the DC netlist (the phase-inverter grid's DC path through it is modelled as a single leak resistor). The G-EE sheets print no transformer or choke part numbers, so none is claimed. Parts drawn only as annotations (bright cap, presence pot, negative-feedback resistor, AC-line caps, power transformer) are listed without designators.",
    "items": [
      {
        "ref": "R1s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-1 grid stopper (jack 1)"
      },
      {
        "ref": "R3s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-1 grid stopper (jack 2)"
      },
      {
        "ref": "R2s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-2 grid stopper (jack 1)"
      },
      {
        "ref": "R4s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Channel-2 grid stopper (jack 2)"
      },
      {
        "ref": "RG1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Channel-1 input leak, jack 1's tip to ground (the grid returns through R1s)"
      },
      {
        "ref": "RG2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Channel-2 input leak, jack 1's tip to ground (the grid returns through R2s)"
      },
      {
        "ref": "RL1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1A plate load"
      },
      {
        "ref": "RL2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1B plate load"
      },
      {
        "ref": "RK1",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Shared 12AY7 cathode bias"
      },
      {
        "ref": "C3",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Shared 12AY7 cathode bypass"
      },
      {
        "ref": "C1",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V1A → channel-1 volume"
      },
      {
        "ref": "C2",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V1B → channel-2 volume"
      },
      {
        "ref": "VR1",
        "part": "Potentiometer (taper not marked on the drawing)",
        "value": "1 MΩ",
        "role": "Instrument volume (100 pF bright cap across it)"
      },
      {
        "ref": "VR2",
        "part": "Potentiometer (taper not marked on the drawing)",
        "value": "1 MΩ",
        "role": "Mic volume"
      },
      {
        "ref": "RM1",
        "part": "Carbon comp resistor",
        "value": "270 kΩ · ½ W",
        "role": "Instrument-channel mixer"
      },
      {
        "ref": "RM2",
        "part": "Carbon comp resistor",
        "value": "270 kΩ · ½ W",
        "role": "Mic-channel mixer"
      },
      {
        "ref": "RL3",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V2A plate load"
      },
      {
        "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": "RKCF",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Cathode-follower load"
      },
      {
        "ref": "RF1",
        "part": "Carbon comp resistor",
        "value": "5 MΩ · ½ W",
        "role": "V2A grid reference, returned to the tone network's bass-branch node"
      },
      {
        "ref": "RSL",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Tone network — bass-branch series resistor"
      },
      {
        "ref": "C5",
        "part": "Mica capacitor",
        "value": "250 pF",
        "role": "Tone network — treble capacitor"
      },
      {
        "ref": "VR3",
        "part": "Potentiometer (taper not marked on the drawing)",
        "value": "1 MΩ",
        "role": "Treble"
      },
      {
        "ref": "C6",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Tone network — treble-pot cold end to ground"
      },
      {
        "ref": "C7",
        "part": "Film capacitor",
        "value": "0.005 µF · 600 V",
        "role": "Tone network — bass-pot leg capacitor to ground"
      },
      {
        "ref": "C16",
        "part": "Film capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Tone network — bass-branch coupling capacitor"
      },
      {
        "ref": "RSH",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Tone network — bass-branch leak to ground"
      },
      {
        "ref": "RSR",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Tone network — bass branch into the stack output (the phase-inverter grid)"
      },
      {
        "ref": "VR4",
        "part": "Potentiometer (taper not marked on the drawing)",
        "value": "1 MΩ",
        "role": "Bass (the network injects at its wiper)"
      },
      {
        "ref": "RLA",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V3A (driver) plate load"
      },
      {
        "ref": "RK3",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V3A cathode bias (the 56 kΩ feedback and the presence network land here)"
      },
      {
        "ref": "C8",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Driver plate → cathodyne grid — the one value the schematic sheet leaves unlabelled; read from the layout sheet"
      },
      {
        "ref": "RGB",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Cathodyne grid leak, returned to the 1.5 kΩ/56 kΩ cathode junction"
      },
      {
        "ref": "RLB",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "V3B (cathodyne) plate load"
      },
      {
        "ref": "RKA",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "Cathodyne cathode resistor (cathode → the 56 kΩ junction)"
      },
      {
        "ref": "RKB",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Cathodyne cathode load (junction → ground)"
      },
      {
        "ref": "C9",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "Cathodyne plate → V4 grid"
      },
      {
        "ref": "C10",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Cathodyne cathode → V5 grid"
      },
      {
        "ref": "R5s",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V4 grid stopper"
      },
      {
        "ref": "R6s",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V5 grid stopper"
      },
      {
        "ref": "RGL1",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V4 grid leak, from the −32 V bias line"
      },
      {
        "ref": "RGL2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V5 grid leak, from the −32 V bias line"
      },
      {
        "ref": "RD1",
        "part": "Power resistor",
        "value": "10 kΩ",
        "role": "Rail dropper B+2 → B+3"
      },
      {
        "ref": "RD2",
        "part": "Power resistor",
        "value": "10 kΩ",
        "role": "Rail dropper B+3 → B+4"
      },
      {
        "ref": "L1",
        "part": "Filter choke",
        "value": "filter choke",
        "role": "B+1 → B+2 (screens and output-transformer centre tap)"
      },
      {
        "ref": "C11",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, B+1 (reservoir)"
      },
      {
        "ref": "C12",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, B+2"
      },
      {
        "ref": "C13",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, B+3"
      },
      {
        "ref": "C14",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 450 V",
        "role": "Filter, B+4"
      },
      {
        "ref": "D1",
        "part": "Rectifier (bias)",
        "value": "selenium (silicon diode in modern builds)",
        "role": "Bias supply rectifier"
      },
      {
        "ref": "RB1",
        "part": "Carbon comp resistor",
        "value": "18 kΩ · ½ W",
        "role": "Bias supply series resistor — the sheet's own footnoted revision, '(A) WAS 22 K OHMS'"
      },
      {
        "ref": "RB2",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Bias supply bleeder"
      },
      {
        "ref": "C15",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 25 V",
        "role": "Bias supply filter"
      },
      {
        "ref": "V1",
        "part": "Preamp tube",
        "value": "12AY7",
        "role": "Both input stages (V1A/V1B)"
      },
      {
        "ref": "V2",
        "part": "Preamp tube",
        "value": "12AY7",
        "role": "Gain stage + cathode follower (V2A/V2B)"
      },
      {
        "ref": "V3",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Phase-inverter driver + split-load cathodyne (V3A/V3B)"
      },
      {
        "ref": "V4",
        "part": "Power tube",
        "value": "6V6GT",
        "role": "Push-pull output (upper)"
      },
      {
        "ref": "V5",
        "part": "Power tube",
        "value": "6V6GT",
        "role": "Push-pull output (lower)"
      },
      {
        "ref": "V6",
        "part": "Rectifier tube",
        "value": "5U4GA",
        "role": "Full-wave rectifier (V6A/V6B)"
      },
      {
        "ref": "T1",
        "part": "Power transformer",
        "value": "HT · 6.3 V heaters · 5 V rectifier filament",
        "role": "HT winding with a centre tap and a bias tap between one end and the centre tap (the layout letters that lead red-blue), 5 V rectifier-filament and 6.3 V heater windings; the bias rectifier is fed from the tap, not from a rectifier plate"
      },
      {
        "ref": "T3",
        "part": "Output transformer",
        "value": "push-pull output transformer",
        "role": "Push-pull output into 2 × 10 in speakers, with an external-speaker jack"
      },
      {
        "ref": "—",
        "part": "Mica capacitor",
        "value": "100 pF",
        "role": "Bright cap across VR1 (annotation only on the schematic)"
      },
      {
        "ref": "VRP",
        "part": "Potentiometer (taper not marked on the drawing)",
        "value": "5 kΩ",
        "role": "Presence: a rheostat from V3A's cathode, its far lug strapped to the wiper, into CP"
      },
      {
        "ref": "CP",
        "part": "Film capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Presence capacitor, the pot's wiper to ground; mounts at the pot on the layout sheet"
      },
      {
        "ref": "—",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Negative feedback, speaker → V3A cathode (annotation only)"
      },
      {
        "ref": "—",
        "part": "Film capacitor",
        "value": "0.05 µF · 600 V (×2)",
        "role": "AC-line filter caps (annotation only)"
      },
      {
        "ref": "—",
        "part": "Toggle switch",
        "value": "SPST",
        "role": "Standby switch (annotation only)"
      },
      {
        "ref": "—",
        "part": "Fuse",
        "value": "3 A",
        "role": "Mains fuse (annotation only)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Fender 5E4-A (G-EE) drawing, both pages. Schematic sheet: rails +390 (reservoir), +385 (screens / output-transformer centre tap), +300, +250; cathodes +1.9 (12AY7 shared), +1.9 (V2A), +130 (cathode follower), +1.6 (driver), +58 and +56.5 (cathodyne cathode and its 1.5 k/56 k junction); bias -32. Layout sheet: +125 at each 12AY7 plate, +190 at the driver plate, +245 at the cathodyne plate, +250 at the 8 µF preamp filter, +130 at the cathode follower, +1.9 at both 25 µF cathode cans, -32 at the bias filter, +380 at the output sockets",
    "nodes": {
      "BP2": {
        "chart": 385,
        "tol_pct": 8,
        "note": "screens and output-transformer centre tap, after the choke — both pages put the centre tap here (schematic: into the screen line; layout: the OT's RED lead on a 6V6GT screen pin). The printed 390 → 385 drop is taken by the full plate + screen current; this netlist omits output-transformer primary DCR, so the plates sit on this node too. The choke's own DCR is entered at a 60 Ω estimate, not fitted."
      },
      "BP3": {
        "chart": 300,
        "tol_pct": 8,
        "note": "12AX7 supply node after the first 10 kΩ dropper"
      },
      "BP4": {
        "chart": 250,
        "tol_pct": 8,
        "note": "12AY7 supply node after the second 10 kΩ dropper (the layout sheet prints +250 at the 8 µF can here)"
      },
      "PAY1": {
        "chart": 125,
        "tol_pct": 20,
        "note": "12AY7 plate, channel 1 — read from the layout sheet beside its 0.02 µF output coupler"
      },
      "PAY2": {
        "chart": 125,
        "tol_pct": 20,
        "note": "12AY7 plate, channel 2 — same figure, same place on the layout sheet"
      },
      "KAY": {
        "chart": 1.9,
        "tol_pct": 20,
        "note": "shared 12AY7 cathode, 820 Ω with a 25 µF can"
      },
      "K2A": {
        "chart": 1.9,
        "tol_pct": 20,
        "note": "V2A cathode, 1.5 kΩ with a 25 µF can"
      },
      "KCF": {
        "chart": 130,
        "tol_pct": 20,
        "note": "cathode-follower cathode, 100 kΩ load — the tone network's feed"
      },
      "PPIA": {
        "chart": 190,
        "tol_pct": 20,
        "note": "driver plate (V3A), 100 kΩ load — read from the layout sheet at the 0.02 µF interstage coupler"
      },
      "KPIA": {
        "chart": 1.6,
        "tol_pct": 20,
        "note": "driver cathode, 1.5 kΩ. The 56 kΩ speaker feedback and the 5 kΩ presence network land here; at DC they parallel the 1.5 kΩ with about 56 kΩ through the output secondary — a ‑2.6% shift, recorded and not modelled"
      },
      "PPIB": {
        "chart": 245,
        "tol_pct": 20,
        "note": "cathodyne plate (V3B), 56 kΩ load"
      },
      "KPI": {
        "chart": 58,
        "tol_pct": 20,
        "note": "cathodyne cathode, 1.5 kΩ above the 56 kΩ leg"
      },
      "JPI": {
        "chart": 56.5,
        "tol_pct": 20,
        "note": "1.5 kΩ/56 kΩ junction — the cathodyne grid's DC reference through its 1 MΩ leak. The printed 58 / 56.5 pair implies the same ≈1 mA the plate figure does, so the split-load stage is self-consistent on its own chart"
      },
      "G51": {
        "chart": -32,
        "tol_pct": 8,
        "note": "6V6GT fixed bias through the 220 kΩ leak from the selenium supply"
      },
      "G52": {
        "chart": -32,
        "tol_pct": 8,
        "note": "6V6GT fixed bias, second valve"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "BP2",
      "chart": 385,
      "sim": 385.024,
      "disputed": false,
      "dev_pct": 0.0062337662337664706,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "screens and output-transformer centre tap, after the choke — both pages put the centre tap here (schematic: into the screen line; layout: the OT's RED lead on a 6V6GT screen pin). The printed 390 → 385 drop is taken by the full plate + screen current; this netlist omits output-transformer primary DCR, so the plates sit on this node too. The choke's own DCR is entered at a 60 Ω estimate, not fitted.",
      "dispute_note": ""
    },
    {
      "node": "BP3",
      "chart": 300,
      "sim": 312.474,
      "disputed": false,
      "dev_pct": 4.157999999999997,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "12AX7 supply node after the first 10 kΩ dropper",
      "dispute_note": ""
    },
    {
      "node": "BP4",
      "chart": 250,
      "sim": 260.991,
      "disputed": false,
      "dev_pct": 4.396399999999994,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "12AY7 supply node after the second 10 kΩ dropper (the layout sheet prints +250 at the 8 µF can here)",
      "dispute_note": ""
    },
    {
      "node": "PAY1",
      "chart": 125,
      "sim": 135.017,
      "disputed": false,
      "dev_pct": 8.013599999999997,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "12AY7 plate, channel 1 — read from the layout sheet beside its 0.02 µF output coupler",
      "dispute_note": ""
    },
    {
      "node": "PAY2",
      "chart": 125,
      "sim": 135.017,
      "disputed": false,
      "dev_pct": 8.013599999999997,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "12AY7 plate, channel 2 — same figure, same place on the layout sheet",
      "dispute_note": ""
    },
    {
      "node": "KAY",
      "chart": 1.9,
      "sim": 2.066,
      "disputed": false,
      "dev_pct": 8.736842105263154,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "shared 12AY7 cathode, 820 Ω with a 25 µF can",
      "dispute_note": ""
    },
    {
      "node": "K2A",
      "chart": 1.9,
      "sim": 1.945,
      "disputed": false,
      "dev_pct": 2.368421052631587,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V2A cathode, 1.5 kΩ with a 25 µF can",
      "dispute_note": ""
    },
    {
      "node": "KCF",
      "chart": 130,
      "sim": 133.179,
      "disputed": false,
      "dev_pct": 2.445384615384617,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "cathode-follower cathode, 100 kΩ load — the tone network's feed",
      "dispute_note": ""
    },
    {
      "node": "PPIA",
      "chart": 190,
      "sim": 205.165,
      "disputed": false,
      "dev_pct": 7.981578947368417,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "driver plate (V3A), 100 kΩ load — read from the layout sheet at the 0.02 µF interstage coupler",
      "dispute_note": ""
    },
    {
      "node": "KPIA",
      "chart": 1.6,
      "sim": 1.61,
      "disputed": false,
      "dev_pct": 0.6250000000000006,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "driver cathode, 1.5 kΩ. The 56 kΩ speaker feedback and the 5 kΩ presence network land here; at DC they parallel the 1.5 kΩ with about 56 kΩ through the output secondary — a ‑2.6% shift, recorded and not modelled",
      "dispute_note": ""
    },
    {
      "node": "PPIB",
      "chart": 245,
      "sim": 254.587,
      "disputed": false,
      "dev_pct": 3.9130612244897915,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "cathodyne plate (V3B), 56 kΩ load",
      "dispute_note": ""
    },
    {
      "node": "KPI",
      "chart": 58,
      "sim": 59.438,
      "disputed": false,
      "dev_pct": 2.4793103448275904,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "cathodyne cathode, 1.5 kΩ above the 56 kΩ leg",
      "dispute_note": ""
    },
    {
      "node": "JPI",
      "chart": 56.5,
      "sim": 57.887,
      "disputed": false,
      "dev_pct": 2.454867256637169,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "1.5 kΩ/56 kΩ junction — the cathodyne grid's DC reference through its 1 MΩ leak. The printed 58 / 56.5 pair implies the same ≈1 mA the plate figure does, so the split-load stage is self-consistent on its own chart",
      "dispute_note": ""
    },
    {
      "node": "G51",
      "chart": -32,
      "sim": -32,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6V6GT fixed bias through the 220 kΩ leak from the selenium supply",
      "dispute_note": ""
    },
    {
      "node": "G52",
      "chart": -32,
      "sim": -32,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "6V6GT fixed bias, second valve",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Verified",
      "summary": "15 reference nodes are within tolerance. Maintainer verification is recorded for 2026-08-08; 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.",
        "0 sheet-only parts are explicitly excluded. 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.",
        "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": "Checked",
      "summary": "7 capacitor markings agree with the model's voltage ordering.",
      "details": [
        "This check uses DC voltage ordering; source review establishes markings the model cannot decide."
      ],
      "tone": "checked"
    }
  ],
  "corrections": [
    {
      "id": "5e4a-input-stoppers-2026-10-03",
      "date": "2026-10-03",
      "amps": [
        "5e4a"
      ],
      "title": "5E4-A: each input jack has its own 68 kΩ stopper",
      "description": "The factory drawing shows four input jacks, each with its own 68 kΩ resistor to its channel's grid. We showed one per channel and said the schematic draws one jack per channel. The second stopper on each channel is now on the parts list, the schematic and the board.",
      "commit": "4b8015da395108a3bdcc49624aec35665de2d7c5",
      "url": "https://github.com/TheAnalogMaker/circuit-codex/commit/4b8015da395108a3bdcc49624aec35665de2d7c5"
    },
    {
      "id": "5e4a-ot-centre-tap-2026-10-03",
      "date": "2026-10-03",
      "amps": [
        "5e4a"
      ],
      "title": "5E4-A: output-transformer centre tap is after the choke",
      "description": "Both factory pages connect the output transformer's centre tap to the +385 V node with the screens, after the filter choke. We drew it on the +390 V reservoir before the choke, on the schematic, the board and the simulation. All three are corrected. The simulated +385 V rail now matches the printed figure, and the worst node's deviation is 8.7 %, down from 10.0 %.",
      "commit": "4b8015da395108a3bdcc49624aec35665de2d7c5",
      "url": "https://github.com/TheAnalogMaker/circuit-codex/commit/4b8015da395108a3bdcc49624aec35665de2d7c5"
    }
  ],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/ebddc3fd2cf887dca010bbe60487d7391ea6c052/amps/5e4a"
}