{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "5e5a",
  "url": "https://circuitcodex.com/amps/5e5a/",
  "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": "5e5a",
    "name_style": "Tweed Pro-style",
    "family": "tweed",
    "era": {
      "start": 1956,
      "end": 1960
    },
    "wattage": 30,
    "tubes": [
      "12AY7",
      "12AY7",
      "12AX7",
      "6L6GB",
      "6L6GB",
      "5U4GA"
    ],
    "topology": {
      "rectifier": {
        "kind": "tube",
        "type": "5U4GA"
      },
      "bias": "fixed",
      "phase_inverter": "cathodyne",
      "tone_stack": "cathode-follower-tb"
    },
    "lineage": {
      "derived_from": [],
      "influenced": [
        "6g5"
      ]
    },
    "conventions": {
      "designators": "functional"
    },
    "sources": [
      {
        "desc": "Fender 'Pro-Amp' Model 5E5-A schematic (J-EE): component values read directly from the published drawing, plus the printed voltage chart embedded on the sheet itself (Fender's own convention: 'VOLTAGES READ TO GROUND WITH ELECTRONIC VOLTMETER, VALUES SHOWN +/- 20%') — rails +390/+385/+300/+250, bias -32 V; V1 (12AY7, mic+instrument channels) shared 820 ohm/dual-25uF cathode at +1.9 V, 100k plates; V2 (12AY7) with both sections used, a gain stage (1500 ohm/25uF cathode at +1.9 V, 100k plate load) DC-coupled into a cathode follower (100k cathode load, +130 V); V3 (12AX7) driver cathode +1.6 V, split-load cathodyne cathode +58 V over the 1.5k/56k junction at +56.5 V; two 68k stoppers and a 1M leak per channel, 0.02uF couplers, 1M INST/MIC VOL pots with a .0001 bright cap on INST only, 270k mixers, a 5 MEG from V2's grid to the tone network's bass branch, the follower-fed Treble/Bass network (250 pF into a 1M Treble pot with .01 to ground; .1 coupler, 220k leak, 100k into a 1M Bass pot's wiper with .005 on its far end, 220k to the driver grid), a 5K PRESENCE pot and 100k feedback resistor on the driver's cathode, 56k cathodyne plate, 1M grid leak returned to the cathodyne junction, 220k output grid leaks, 0.1uF cathodyne-to-output couplers, two 10K rail droppers, 16-450 filters at +390/+385/+300 and 8-450 at +250. The PDF carries the page as one 1506 x 864 image, and every component value is legible at that resolution. Not reproduced here; archived at Schematic Heaven",
        "url": "https://schematicheaven.net/fenderamps/pro_5e5a_schem.pdf"
      },
      {
        "desc": "Fender 'Pro-Amp' Model 5E5-A layout drawing (J-EE), same sheet set — corroborates the tube complement (5U4GA, 2x6L6GB, 12AX7, 2x12AY7), the BASS/TREBLE (1M) and PRESENCE (5K) pot values, and the two-input-per-channel MIC/INST front panel; letters the interstage coupler the schematic leaves blank (0.02 MFD 600 VOLTS) and prints the plate voltages the schematic omits (V1 +125 V, driver +190 V, cathodyne +245 V); shows the socket pins each stage uses (V2's gain stage on 1-2-3 with its 100k plate load across pins 6 and 1, the follower on 6-7-8; V3's driver on 1-2-3, the cathodyne on 6-7-8); and is the source the board drawing is redrawn from",
        "url": "https://schematicheaven.net/fenderamps/pro_5e5a_schem.pdf"
      },
      {
        "desc": "Mojotone Fender Field Guide, 'Fender Narrow Panel Tweed Pro' — 5E5 (1955)/5E5-A (1956-1960) dating, full tube complement (12AY7 mic/instrument, half-12AX7 phase inverter split-load, 6L6GB or 5881 output, 5U4GA rectifier), fixed/nonadjustable bias with a selenium bias rectifier, and the 5E5-A's reintroduced NFB loop with a Presence control (the 5E5 had removed feedback entirely) — cross-reference for the schematic reading",
        "url": "https://mojotone.com/blogs/fender-field-guide/fender-narrow-panel-tweed-pro"
      }
    ],
    "verification": {
      "status": "draft"
    },
    "added": "2026-08-08T00:00:00.000Z",
    "contributors": [
      "TheAnalogMaker"
    ]
  },
  "parts": {
    "notes": "Both pages draw two input jacks per channel (1 and 2), each with its own 68 kΩ stopper into the channel's grid (R1s/R3s Instrument, R2s/R4s Mic), and hang the channel's one 1 MΩ leak from jack 1's tip; jack 2's contact rests on jack 1's tip. The interstage coupler C1 is the one part the schematic page leaves unlettered: the layout page prints 0.02 µF · 600 V on the coupler whose eyelet carries the driver plate's +190 V. Dropper wattages are not marked on the drawing. Parts on the mains side of the power transformer (fuse, switches, AC-line caps) are listed without designators.",
    "items": [
      {
        "ref": "R1s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Instrument-channel grid stopper (jack 1)"
      },
      {
        "ref": "R3s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Instrument-channel grid stopper (jack 2)"
      },
      {
        "ref": "R2s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Mic-channel grid stopper (jack 1)"
      },
      {
        "ref": "R4s",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Mic-channel grid stopper (jack 2)"
      },
      {
        "ref": "RG1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Instrument input grid leak"
      },
      {
        "ref": "RG2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Mic input grid leak"
      },
      {
        "ref": "RL1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1A (instrument) plate load"
      },
      {
        "ref": "RL2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1B (mic) plate load"
      },
      {
        "ref": "RK1",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Shared V1 cathode bias"
      },
      {
        "ref": "C4",
        "part": "Electrolytic capacitor (dual can)",
        "value": "25 µF + 25 µF · 25 V",
        "role": "Shared V1 cathode bypass"
      },
      {
        "ref": "C5",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V1A → instrument volume"
      },
      {
        "ref": "C6",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V1B → mic volume"
      },
      {
        "ref": "VR1",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ",
        "role": "Instrument volume (100 pF bright cap across it)"
      },
      {
        "ref": "C16",
        "part": "Capacitor",
        "value": "100 pF",
        "role": "Bright cap, the Instrument volume's hot lug to its wiper (printed .0001; the Mic volume has none)"
      },
      {
        "ref": "VR2",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ",
        "role": "Mic volume"
      },
      {
        "ref": "RMX1",
        "part": "Carbon comp resistor",
        "value": "270 kΩ · ½ W",
        "role": "Instrument-channel mixing resistor"
      },
      {
        "ref": "RMX2",
        "part": "Carbon comp resistor",
        "value": "270 kΩ · ½ W",
        "role": "Mic-channel mixing resistor"
      },
      {
        "ref": "RL3",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V2A plate load — the layout page solders it across the V2 socket, from the follower's plate (pin 6, on the +250 V rail) to V2A's plate (pin 1)"
      },
      {
        "ref": "RK2",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V2A cathode bias"
      },
      {
        "ref": "C4b",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V2A cathode bypass"
      },
      {
        "ref": "RF1",
        "part": "Carbon comp resistor",
        "value": "5 MΩ · ½ W",
        "role": "V2A grid reference, returned to the tone network's bass-branch node on the far side of the 0.1 µF coupler, which its own 220 kΩ leak holds at 0 V DC"
      },
      {
        "ref": "RKCF",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Cathode-follower (V2B) load — the follower's cathode is the tone network's source"
      },
      {
        "ref": "C8",
        "part": "Capacitor",
        "value": "250 pF",
        "role": "Treble cap, the follower's cathode to the Treble pot's end lug (printed .00025 on the schematic page, 250 MMFD. on the layout page)"
      },
      {
        "ref": "VR4",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ",
        "role": "Treble — its wiper is the tone network's output, straight to the driver's grid"
      },
      {
        "ref": "C7",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Treble shunt cap, the Treble pot's cold end lug to ground"
      },
      {
        "ref": "C14",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Bass-branch coupler, from the follower's cathode"
      },
      {
        "ref": "RSH",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Bass-branch leak to ground"
      },
      {
        "ref": "RSL",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Bass-branch series resistor, into the Bass pot's wiper"
      },
      {
        "ref": "VR3",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ",
        "role": "Bass — the bass branch lands on its wiper; one end lug is grounded, the other returns to ground through 0.005 µF"
      },
      {
        "ref": "C15",
        "part": "Film capacitor",
        "value": "0.005 µF · 600 V",
        "role": "Bass leg cap, the Bass pot's far end lug to ground"
      },
      {
        "ref": "RSR",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "Bass wiper → driver (V3A) grid, recombining the two branches — the layout page mounts it between the Bass and Treble pots' wiper lugs"
      },
      {
        "ref": "VR5",
        "part": "Audio-taper potentiometer",
        "value": "5 kΩ",
        "role": "Presence — a rheostat from the driver's cathode to the presence cap (the layout page straps its wiper to its free end lug)"
      },
      {
        "ref": "RNF",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Negative-feedback resistor, speaker to the driver's (V3A) cathode"
      },
      {
        "ref": "C9",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 200 V",
        "role": "Presence cap, the Presence pot's wiper to ground"
      },
      {
        "ref": "RL4",
        "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 (driver) cathode bias"
      },
      {
        "ref": "C1",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V3A (driver) → cathodyne grid"
      },
      {
        "ref": "RL5",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Cathodyne plate load"
      },
      {
        "ref": "RKA",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "Cathodyne bias (cathode → junction)"
      },
      {
        "ref": "RKB",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Cathodyne cathode load (junction → ground)"
      },
      {
        "ref": "RGPI",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Cathodyne grid leak, returned to the junction"
      },
      {
        "ref": "C2",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "Cathodyne plate → V4 grid"
      },
      {
        "ref": "C3",
        "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 fixed-bias grid leak"
      },
      {
        "ref": "RGL2",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V5 fixed-bias grid leak"
      },
      {
        "ref": "RD1",
        "part": "Power resistor",
        "value": "10 kΩ",
        "role": "Rail dropper BP2 → BP3 (+385 V → +300 V)"
      },
      {
        "ref": "RD2",
        "part": "Power resistor",
        "value": "10 kΩ",
        "role": "Rail dropper BP3 → BP4 (+300 V → +250 V)"
      },
      {
        "ref": "RCHOKE",
        "part": "Filter choke",
        "value": "~110 Ω DCR (est.)",
        "role": "BP1 → BP2, screens supply"
      },
      {
        "ref": "C17",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, BP1 (+390 V: the rectifier output and the output transformer's centre tap, ahead of the choke)"
      },
      {
        "ref": "C10",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, BP2 (screens)"
      },
      {
        "ref": "C11",
        "part": "Electrolytic capacitor",
        "value": "16 µF · 450 V",
        "role": "Filter, BP3 (driver/PI)"
      },
      {
        "ref": "C12",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 450 V",
        "role": "Filter, BP4 (preamp)"
      },
      {
        "ref": "RB1",
        "part": "Carbon comp resistor",
        "value": "10 kΩ · ½ W",
        "role": "Bias supply series resistor, from the transformer's bias tap into the selenium cell"
      },
      {
        "ref": "D1",
        "part": "Selenium rectifier",
        "value": "SEL",
        "role": "Bias supply rectifier, HT tap -> -32 V"
      },
      {
        "ref": "C13",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 25 V",
        "role": "Bias supply filter, -32 V"
      },
      {
        "ref": "RB2",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Bias supply bleeder across the 100 µF can"
      },
      {
        "ref": "V1",
        "part": "Preamp tube",
        "value": "12AY7",
        "role": "Instrument + mic first stage (V1A/V1B)"
      },
      {
        "ref": "V2",
        "part": "Preamp tube",
        "value": "12AY7",
        "role": "Gain stage + cathode follower (V2A/V2B)"
      },
      {
        "ref": "V3",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Driver + cathodyne PI (V3A/V3B)"
      },
      {
        "ref": "V4",
        "part": "Power tube",
        "value": "6L6GB",
        "role": "Push-pull output (upper)"
      },
      {
        "ref": "V5",
        "part": "Power tube",
        "value": "6L6GB",
        "role": "Push-pull output (lower)"
      },
      {
        "ref": "V6",
        "part": "Rectifier tube",
        "value": "5U4GA",
        "role": "Full-wave rectifier"
      },
      {
        "ref": "T1",
        "part": "Power transformer",
        "value": "~330-0-330 V · 6.3 V · 5 V (est.)",
        "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 through 10 kΩ from the tap, not from a rectifier plate"
      },
      {
        "ref": "T2",
        "part": "Output transformer",
        "value": "~4.3 kΩ : 8 Ω (est. for 2x6L6GB into one 15\" speaker)",
        "role": "Push-pull output"
      },
      {
        "ref": "SPKR",
        "part": "Speaker",
        "value": "15\" · 8 Ω",
        "role": "Fixed speaker + external speaker jack"
      },
      {
        "ref": "PL1",
        "part": "Pilot lamp assembly",
        "value": "pilot lamp",
        "role": "Panel pilot lamp, on the 6.3 V heater chain (\"TO ALL 6.3 VOLT FILAMENTS AND PILOT LITE\", printed on the schematic's rectifier note; layout page also shows a PILOT LITE stub)"
      },
      {
        "ref": "—",
        "part": "Fuse",
        "value": "3 A",
        "role": "Mains fuse, in one conductor of the line cord (annotation only)"
      },
      {
        "ref": "—",
        "part": "Switch",
        "value": "SPST",
        "role": "AC (power) switch, in the other conductor (annotation only)"
      },
      {
        "ref": "—",
        "part": "Switch",
        "value": "SPDT",
        "role": "Ground switch — throws a 0.05 µF · 600 V cap from chassis to either mains conductor (annotation only)"
      },
      {
        "ref": "—",
        "part": "Switch",
        "value": "SPST",
        "role": "Standby switch — drawn on the layout page only (annotation only)"
      },
      {
        "ref": "—",
        "part": "Film capacitor",
        "value": "0.05 µF · 600 V (×2)",
        "role": "AC-line caps: the schematic page draws the ground switch's; the layout page draws a second beside the switches (annotation only)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Fender 5E5-A (J-EE) sheet set, printed voltages. Schematic page: rails +390/+385/+300/+250, bias -32; V1 (12AY7) shared cathode +1.9; V2A (12AY7 gain stage) cathode +1.9; V2B (cathode follower) cathode +130; V3A (12AX7 driver) cathode +1.6; V3B (cathodyne) cathode +58 over the 1.5k/56k junction at +56.5. Layout page, at the board eyelets: the same figures plus V1's two plates +125, the driver's plate +190 and the cathodyne's plate +245",
    "nodes": {
      "BP1": {
        "chart": 390,
        "tol_pct": 10,
        "note": "rectifier output and power-tube plate node, ahead of the choke — the simulation drives this node at the printed figure, so it matches by construction"
      },
      "BP2": {
        "chart": 385,
        "tol_pct": 10,
        "note": "screens node, after the choke (DCR estimated at 110 Ω)"
      },
      "BP3": {
        "chart": 300,
        "tol_pct": 10,
        "note": "driver/phase-inverter node, after the first 10 kΩ dropper"
      },
      "BP4": {
        "chart": 250,
        "tol_pct": 10,
        "note": "preamp node, after the second 10 kΩ dropper"
      },
      "PAY1": {
        "chart": 125,
        "tol_pct": 20,
        "note": "V1A (instrument channel) plate — printed on the layout page at this plate's eyelet; the schematic page prints no V1 plate figure"
      },
      "PAY2": {
        "chart": 125,
        "tol_pct": 20,
        "note": "V1B (mic channel) plate — the layout page prints the same +125 V at this plate's eyelet"
      },
      "KAY": {
        "chart": 1.9,
        "tol_pct": 20,
        "note": "V1's shared 820 Ω cathode (both triodes), printed on both pages"
      },
      "P2A": {
        "chart": null,
        "note": "informational — V2A's plate, which is also the cathode follower's grid; neither page prints a figure here"
      },
      "K2A": {
        "chart": 1.9,
        "tol_pct": 20,
        "note": "V2A (gain stage) cathode, 1.5 kΩ bypassed by 25 µF — printed on both pages, the same figure as V1's cathode"
      },
      "KCF": {
        "chart": 130,
        "tol_pct": 20,
        "note": "V2B (cathode follower) cathode, 100 kΩ to ground — printed on both pages. Consistent with V2A's printed cathode: a follower at 130 V holds its grid, V2A's plate, near 128 V, so V2A's 100 kΩ load drops about 122 V from the 250 V rail — 1.2 mA, or 1.8 V across its 1.5 kΩ against the printed 1.9 V"
      },
      "G3A": {
        "chart": null,
        "note": "informational — the driver's grid, returned to ground through the tone network's resistive branch (220 kΩ, 100 kΩ, 220 kΩ); no figure is printed and none is needed, since no grid current flows"
      },
      "K3A": {
        "chart": 1.6,
        "tol_pct": 20,
        "note": "V3A (12AX7 driver) cathode, 1.5 kΩ — printed on both pages. The 100 kΩ feedback resistor and the Presence control land on this node too"
      },
      "P3A": {
        "chart": 190,
        "tol_pct": 20,
        "note": "V3A (driver) plate, 100 kΩ load from the 300 V rail — printed on the layout page at this plate's eyelet. Consistent with the printed cathode: 1.6 V across 1.5 kΩ is 1.07 mA, and 300 V less 107 V is 193 V"
      },
      "PPI": {
        "chart": 245,
        "tol_pct": 20,
        "note": "V3B (cathodyne) plate, 56 kΩ load from the 300 V rail — printed on the layout page at the eyelet feeding the upper output coupler. Consistent with the cathode pair: 55 V across 56 kΩ is 0.98 mA, the same current the 58 V / 56.5 V pair implies"
      },
      "KPI": {
        "chart": 58,
        "tol_pct": 20,
        "note": "V3B (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 the 1 MΩ leak; the printed 58/56.5 pair implies about 1 mA through both legs"
      },
      "G61": {
        "chart": -32,
        "tol_pct": 10,
        "note": "6L6GB fixed bias via 220 kΩ from the −32 V supply (zero grid current, so this equals the bias rail exactly)"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "BP1",
      "chart": 390,
      "sim": 390,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "rectifier output and power-tube plate node, ahead of the choke — the simulation drives this node at the printed figure, so it matches by construction",
      "dispute_note": ""
    },
    {
      "node": "BP2",
      "chart": 385,
      "sim": 388.164,
      "disputed": false,
      "dev_pct": 0.8218181818181786,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "screens node, after the choke (DCR estimated at 110 Ω)",
      "dispute_note": ""
    },
    {
      "node": "BP3",
      "chart": 300,
      "sim": 315.023,
      "disputed": false,
      "dev_pct": 5.007666666666675,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "driver/phase-inverter node, after the first 10 kΩ dropper",
      "dispute_note": ""
    },
    {
      "node": "BP4",
      "chart": 250,
      "sim": 263.109,
      "disputed": false,
      "dev_pct": 5.243599999999992,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "preamp node, after the second 10 kΩ dropper",
      "dispute_note": ""
    },
    {
      "node": "PAY1",
      "chart": 125,
      "sim": 136.041,
      "disputed": false,
      "dev_pct": 8.832799999999997,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V1A (instrument channel) plate — printed on the layout page at this plate's eyelet; the schematic page prints no V1 plate figure",
      "dispute_note": ""
    },
    {
      "node": "PAY2",
      "chart": 125,
      "sim": 136.041,
      "disputed": false,
      "dev_pct": 8.832799999999997,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V1B (mic channel) plate — the layout page prints the same +125 V at this plate's eyelet",
      "dispute_note": ""
    },
    {
      "node": "KAY",
      "chart": 1.9,
      "sim": 2.084,
      "disputed": false,
      "dev_pct": 9.684210526315798,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V1's shared 820 Ω cathode (both triodes), printed on both pages",
      "dispute_note": ""
    },
    {
      "node": "P2A",
      "chart": null,
      "sim": 132.29,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — V2A's plate, which is also the cathode follower's grid; neither page prints a figure here",
      "dispute_note": ""
    },
    {
      "node": "K2A",
      "chart": 1.9,
      "sim": 1.962,
      "disputed": false,
      "dev_pct": 3.2631578947368447,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V2A (gain stage) cathode, 1.5 kΩ bypassed by 25 µF — printed on both pages, the same figure as V1's cathode",
      "dispute_note": ""
    },
    {
      "node": "KCF",
      "chart": 130,
      "sim": 134.191,
      "disputed": false,
      "dev_pct": 3.223846153846156,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V2B (cathode follower) cathode, 100 kΩ to ground — printed on both pages. Consistent with V2A's printed cathode: a follower at 130 V holds its grid, V2A's plate, near 128 V, so V2A's 100 kΩ load drops about 122 V from the 250 V rail — 1.2 mA, or 1.8 V across its 1.5 kΩ against the printed 1.9 V",
      "dispute_note": ""
    },
    {
      "node": "G3A",
      "chart": null,
      "sim": 0,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — the driver's grid, returned to ground through the tone network's resistive branch (220 kΩ, 100 kΩ, 220 kΩ); no figure is printed and none is needed, since no grid current flows",
      "dispute_note": ""
    },
    {
      "node": "K3A",
      "chart": 1.6,
      "sim": 1.622,
      "disputed": false,
      "dev_pct": 1.3750000000000013,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V3A (12AX7 driver) cathode, 1.5 kΩ — printed on both pages. The 100 kΩ feedback resistor and the Presence control land on this node too",
      "dispute_note": ""
    },
    {
      "node": "P3A",
      "chart": 190,
      "sim": 206.903,
      "disputed": false,
      "dev_pct": 8.89631578947368,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V3A (driver) plate, 100 kΩ load from the 300 V rail — printed on the layout page at this plate's eyelet. Consistent with the printed cathode: 1.6 V across 1.5 kΩ is 1.07 mA, and 300 V less 107 V is 193 V",
      "dispute_note": ""
    },
    {
      "node": "PPI",
      "chart": 245,
      "sim": 256.7,
      "disputed": false,
      "dev_pct": 4.775510204081628,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V3B (cathodyne) plate, 56 kΩ load from the 300 V rail — printed on the layout page at the eyelet feeding the upper output coupler. Consistent with the cathode pair: 55 V across 56 kΩ is 0.98 mA, the same current the 58 V / 56.5 V pair implies",
      "dispute_note": ""
    },
    {
      "node": "KPI",
      "chart": 58,
      "sim": 59.885,
      "disputed": false,
      "dev_pct": 3.2499999999999964,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V3B (cathodyne) cathode, 1.5 kΩ above the 56 kΩ leg",
      "dispute_note": ""
    },
    {
      "node": "JPI",
      "chart": 56.5,
      "sim": 58.323,
      "disputed": false,
      "dev_pct": 3.2265486725663726,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "1.5 kΩ/56 kΩ junction — the cathodyne grid's DC reference through the 1 MΩ leak; the printed 58/56.5 pair implies about 1 mA through both legs",
      "dispute_note": ""
    },
    {
      "node": "G61",
      "chart": -32,
      "sim": -32,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 10,
      "gated": true,
      "within": true,
      "note": "6L6GB fixed bias via 220 kΩ from the −32 V supply (zero grid current, so this equals the bias rail exactly)",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Within target",
      "summary": "15 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.",
        "3 sheet-only parts are explicitly excluded: C16, C9, VR5. 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": "5e5a-input-stoppers-2026-10-03",
      "date": "2026-10-03",
      "amps": [
        "5e5a"
      ],
      "title": "5E5-A input grid stoppers",
      "description": "Each of the four input jacks now has its own 68 kΩ grid stopper, as both factory pages show. The parts list had described one stopper per channel as representative. No operating point changes. The circuit remains a draft.",
      "commit": "b790a0827e9812a6a6c570676745a710e7f5f063",
      "url": "https://github.com/TheAnalogMaker/circuit-codex/commit/b790a0827e9812a6a6c570676745a710e7f5f063"
    }
  ],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/ebddc3fd2cf887dca010bbe60487d7391ea6c052/amps/5e5a"
}