{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "s1484",
  "url": "https://circuitcodex.com/amps/s1484/",
  "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": "s1484",
    "name_style": "Silvertone Twin Twelve-style",
    "family": "other",
    "era": {
      "start": 1963,
      "end": 1967
    },
    "wattage": 60,
    "tubes": [
      "12AX7",
      "12AX7",
      "6CG7",
      "12AX7",
      "6CG7",
      "12AX7",
      "6L6GC",
      "6L6GC"
    ],
    "topology": {
      "rectifier": {
        "kind": "solid-state",
        "type": "1N3194 ×4 (capacitor multiplier) + 1N3754 (bias)"
      },
      "bias": "fixed",
      "phase_inverter": "cathodyne",
      "tone_stack": "per-channel-tb"
    },
    "lineage": {
      "derived_from": [],
      "influenced": []
    },
    "conventions": {
      "designators": "sequential",
      "notation": "us"
    },
    "sources": [
      {
        "desc": "Silvertone factory drawing, title block set along the bottom edge of the sheet reading 'SCHEMATIC DIAGRAM OF SILVERTONE CHASSIS 185.11040' — THIS is the revision documented here. Three notes beside the title block: '1. VALUES OF CAPACITORS IN MFD. 2. ALL RESISTORS ARE ½ WATT UNLESS OTHERWISE NOTED. 3. VOLTAGES MEASURED FROM POINTS INDICATED TO CHASSIS WITH 20,000 OHM/VOLT METER.' A TUBE LAYOUT panel across the top gives the complement by socket: V1 12AX7, V2 12AX7, V3 '6CG7 or 6FQ7', V4 12AX7, V5 '6CG7 or 6FQ7', V6 12AX7, V7 6L6GC, V8 6L6GC, with the C25 filter can and the reverb pan drawn in place. Topology read from the drawing: two channels into one 12AX7 (V1) sharing a single 1.5 kΩ cathode resistor; a Bass + Treble + Volume network per channel; a second 12AX7 (V2) with one unbypassed 4.7 kΩ-biased half per channel, the two plates summed through 68 kΩ each into a 560 kΩ mixer node; a 6CG7 (V3) whose first half drives a SPLIT-LOAD (cathodyne) inverter in its second, 68 kΩ in the plate against 68 kΩ in the cathode with the 1 MΩ grid leak returned to the cathode-side tap; a fixed-bias 6L6GC pair at −36 V through 330 kΩ each, cathodes straight to chassis; reverb on a 12AX7 (V4) and a 6CG7 (V5) driving a spring unit; tremolo on a 12AX7 (V6) through a light-operated modulator; and a solid-state supply that is a stacked capacitor multiplier — four 100 µF · 150 V cans on four 1N3194s across two HT windings — plus a separate 1N3754 negative bias supply, a choke and a 20/10/5 µF · 450 V can tapped by two 68 kΩ droppers. Printed voltages are lettered on the nodes, not tabulated: 480 V at the top of the stack, 475 V at both 6L6GC plates, 340 V at their screens, −36 V bias, and preamp figures recorded in the operating-point table on this page. Not reproduced here; archived at Schematic Heaven.",
        "url": "https://schematicheaven.net/bargainbin/silvertone1484.pdf"
      },
      {
        "desc": "Sears 'Owner's Manual — Service Data and Repair Parts List for Silvertone Musical Instrument Amplifier Model No. 1484', in the corrected reproduction published by the Silvertone archive (four pages: cover; the Division 57 technical-manual page headed 'CHASSIS NO. 185.11040' and boxed 'USED IN MODEL 1484', part no. 1484MV1, sheet code V1-D63; the operating instructions; and a redrawn schematic carrying the same title block). The technical-manual page is the FACTORY PARTS LIST and is the authority for every tolerance and voltage rating in the parts list below: all resistors 20% and ½ W unless noted, capacitor working voltages, the multi-section can as '5-10-20 mfd., 450 v.', and the named assemblies T1 DD-50 power transformer, T2 O50 output transformer, CH1 L480 choke, CS55 spring reverberation unit, 306-2H light-operated tremolo unit, FS-2 dual foot switch, SW1 'part of control R37', 12-H8 12-inch 8 Ω speakers (2 used). The operating page is where the two channels are described: channel one has 'Two Inputs and three controls'; 'CHANNEL TWO . . . contains both Reverberation and Tremolo'. The reproduction's author states he corrected schematic errors in the original, so it is a REDRAW: where it and the factory scan differ the factory sheet is what this entry records, and the one place they do differ is C12 (see the circuit story).",
        "url": "https://www.silvertoneworld.net/schematics/Sears_Silvertone_1484_Twin_Twelve_REPRODUCTION_Manual.pdf"
      },
      {
        "desc": "Silvertone archive page for the model — the source of this entry's era bracket and of the chassis identification: model 1484 Twin Twelve, introduced 1963, retired 1967, chassis #11040 named as the common revision, with the reproduction manual above published from that page.",
        "url": "https://www.silvertoneworld.net/amplifiers/1484/1484_schematic.html"
      },
      {
        "desc": "Dealer documentation of a surviving example at Chicago Music Exchange — a dated point inside the era bracket and an independent reading of the complement: '6FQ7 (x2), 12AX7 (x4), 6L6 (x2)', 2×12 cabinet, 'Pot codes date to 1965'. The listing is titled '60-Watt', which is the period retail rating this entry records in `wattage`; the drawing prints no output-power figure of any kind (its only power number is the mains draw, '117 VAC 60 CYCLES 100 WATT 1 AMP').",
        "url": "https://www.chicagomusicexchange.com/products/silvertone-model-1484-twin-twelve-60-watt-2x12-piggyback-1226495"
      },
      {
        "desc": "RCA 6CG7 data sheet, 8-59, DATA 1 (Medium-Mu Twin Triode, 9-pin miniature) — anchor for the new CC0 6CG7 tube model this entry adds, and the ratings that bound both 6CG7 sockets here: Va=250 V, Vg=−8 V → Ia=9 mA, gm=2600 µmho, rp=7700 Ω, µ=20; a second column Va=90 V, Vg=0 V → 10 mA, 3000 µmho; design-maximum 330 V plate, 4 W per plate, 22 mA cathode, and a 1 MΩ grid-circuit limit for fixed-bias operation that the inverter's own grid return sits exactly on. Basing 9AJ, pin 9 an internal shield. See the 6CG7 reference page for the model and its method.",
        "url": "http://www.tubebooks.org/tubedata/hb-3/receiving_tubes_part_1/6CG7.PDF"
      }
    ],
    "verification": {
      "status": "draft"
    },
    "added": "2026-08-30T00:00:00.000Z",
    "contributors": [
      "TheAnalogMaker"
    ],
    "sections": {
      "V4": "excluded — the reverb recovery bottle: the drawing prints no plate voltage this entry can place on V4's second half (the unplaced 55 V in the voltage table)",
      "V5": "excluded — the 6CG7 reverb driver, left out with the recovery bottle for the same reason (see V4)",
      "V6": "excluded — the tremolo's phase-shift oscillator and its neon/photocell modulator (306-2H): a running oscillator has no static operating point"
    }
  },
  "parts": {
    "notes": "One disagreement inside the factory documentation, recorded rather than resolved: the SCHEMATIC letters C12 as .02 µF, and the PARTS LIST files C12 in its .01 µF · 600 V tubular group (with C10, C11, C13, C16, C20, C21). C12 is the coupler from the V2 mixer node into V3A's grid, so it is open at DC either way and no operating point turns on it; the schematic's 0.02 µF is what this list records, because the schematic is the surface this corpus reads circuits from. A second, smaller gap: the schematic letters R44 as 820 Ω where the parts list row reads '800 ohm, 20%' under part number 18-82002 — the two overlap inside the printed 20% and the schematic's 820 Ω is recorded. Capacitor values are open at DC and do not enter the operating-point netlist; they are listed for completeness. The output transformer's primary half-resistances (85 Ω each) are recorded here but not modelled: no netlist in this corpus simulates output-transformer primary resistance, and 85 Ω is what the drawing's own 480 V rail and 475 V plates differ by.",
    "items": [
      {
        "ref": "V1",
        "part": "Tube",
        "value": "12AX7",
        "role": "Both preamp channels' first stage, one triode each — and one shared cathode resistor"
      },
      {
        "ref": "V2",
        "part": "Tube",
        "value": "12AX7",
        "role": "Both channels' second stage, one triode each; the two plates are summed into the mixer node"
      },
      {
        "ref": "V3",
        "part": "Tube",
        "value": "6CG7",
        "role": "Driver (V3A) and split-load phase inverter (V3B). The drawing letters the socket '6CG7 or 6FQ7'"
      },
      {
        "ref": "V4",
        "part": "Tube",
        "value": "12AX7",
        "role": "Reverb — recovery amplifier (V4A) and the second half feeding the reverb driver"
      },
      {
        "ref": "V5",
        "part": "Tube",
        "value": "6CG7",
        "role": "Reverb driver, both triodes on one shared 820 Ω cathode resistor. Lettered '6CG7 or 6FQ7' like V3"
      },
      {
        "ref": "V6",
        "part": "Tube",
        "value": "12AX7",
        "role": "Tremolo oscillator, driving the neon lamp inside the 306-2H light-operated modulator"
      },
      {
        "ref": "V7",
        "part": "Tube",
        "value": "6L6GC",
        "role": "Output beam power tube, fixed bias, cathode to chassis"
      },
      {
        "ref": "V8",
        "part": "Tube",
        "value": "6L6GC",
        "role": "Output beam power tube, the other half of the pair"
      },
      {
        "ref": "T1",
        "part": "Power transformer",
        "value": "Sears DD-50",
        "role": "Mains transformer, 117 V 60 Hz. The drawing prints winding RESISTANCES rather than voltages: 3.7 Ω primary, 5.75 Ω and 6.2 Ω on the two HT windings that feed the multiplier, 3.7 Ω on the bias winding, plus the 6.3 V heater winding"
      },
      {
        "ref": "T2",
        "part": "Output transformer",
        "value": "Sears O50",
        "role": "Output transformer, centre-tapped primary; the drawing prints 85 Ω for each primary half and takes the centre tap to the 480 V rail. Secondary drives two 8 Ω speakers"
      },
      {
        "ref": "CH1",
        "part": "Choke",
        "value": "Sears L480",
        "role": "Supply choke, between a junction of the capacitor-multiplier stack and the 340 V screen node. The drawing prints no inductance and no DC resistance"
      },
      {
        "ref": "—",
        "part": "Reverb pan",
        "value": "Sears CS55",
        "role": "Spring reverberation unit, driven from V5 and returned to V4. The drawing labels it with its Sears part number rather than a reference designator, so it carries none here"
      },
      {
        "ref": "—",
        "part": "Tremolo modulator",
        "value": "Sears 306-2H",
        "role": "Light-operated tremolo unit — a neon lamp driven by V6 facing a photocell that shunts the signal path. Drawn inside a dashed outline, no reference designator"
      },
      {
        "ref": "—",
        "part": "Jack socket",
        "value": "1/4 in",
        "role": "Channel 1 input, first jack"
      },
      {
        "ref": "—",
        "part": "Jack socket",
        "value": "1/4 in",
        "role": "Channel 1 input, second jack"
      },
      {
        "ref": "—",
        "part": "Jack socket",
        "value": "1/4 in",
        "role": "Channel 2 input, first jack"
      },
      {
        "ref": "—",
        "part": "Jack socket",
        "value": "1/4 in",
        "role": "Channel 2 input, second jack"
      },
      {
        "ref": "R1",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 1 grid resistor, first jack"
      },
      {
        "ref": "R2",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 1 grid resistor, second jack"
      },
      {
        "ref": "R3",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 2 grid resistor, first jack"
      },
      {
        "ref": "R4",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 2 grid resistor, second jack"
      },
      {
        "ref": "—",
        "part": "Carbon comp resistor",
        "value": "1 MΩ",
        "role": "Channel 1 grid leak, from the R1/R2 junction to the ground bus — DRAWN BUT NEVER LETTERED, and absent from the factory parts list (see the header note)"
      },
      {
        "ref": "—",
        "part": "Carbon comp resistor",
        "value": "1 MΩ",
        "role": "Channel 2 grid leak, from the R3/R4 junction to the ground bus — the other unlettered part"
      },
      {
        "ref": "R5",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W · 20%",
        "role": "Channel 1 feedback resistor — V1A's grid back to the far side of C3, the input of channel 1's tone network. Channel 2 has no counterpart; it gets R9 in series instead"
      },
      {
        "ref": "R6",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W · 20%",
        "role": "SHARED cathode resistor for both V1 triodes — one resistor biases both channels' first stages"
      },
      {
        "ref": "C1",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Bypass across R6, so the two channels share their cathode bypass too"
      },
      {
        "ref": "R8",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 20%",
        "role": "V1A plate load (channel 1)"
      },
      {
        "ref": "R7",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 20%",
        "role": "V1B plate load (channel 2)"
      },
      {
        "ref": "C3",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Channel 1 plate coupler into the tone network"
      },
      {
        "ref": "C2",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Channel 2 plate coupler into the tone network"
      },
      {
        "ref": "R9",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 20%",
        "role": "Channel 2 series resistor between C2 and the tone network — the asymmetry between the two channels, together with R5"
      },
      {
        "ref": "R10",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "Channel 1 bass-network series resistor, from the coupler node to the top of R11"
      },
      {
        "ref": "R11",
        "part": "Linear-taper potentiometer",
        "value": "1 MΩ",
        "role": "Channel 1 BASS"
      },
      {
        "ref": "C4",
        "part": "Disc ceramic capacitor",
        "value": "0.0015 µF",
        "role": "Across R11's upper half (the R10 side)"
      },
      {
        "ref": "C5",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Across R11's lower half (the R12 side)"
      },
      {
        "ref": "R12",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 1 bass-network shunt to the ground bus"
      },
      {
        "ref": "R16",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "Channel 1 — R11's wiper into the volume node"
      },
      {
        "ref": "C8",
        "part": "Disc ceramic capacitor",
        "value": "680 pF",
        "role": "Channel 1 treble bypass, straight from the coupler node to the volume node around the bass network"
      },
      {
        "ref": "R18",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ",
        "role": "Channel 1 TREBLE — wired as a rheostat (wiper strapped to one end) shunting the volume node to ground through C10, so the control is a treble cut"
      },
      {
        "ref": "C10",
        "part": "Film capacitor",
        "value": "0.01 µF · 600 V",
        "role": "Channel 1 treble-cut capacitor, in series with R18 to the ground bus"
      },
      {
        "ref": "R20",
        "part": "Linear-taper potentiometer",
        "value": "1 MΩ",
        "role": "Channel 1 VOLUME, bottom end grounded, wiper to V2A's grid"
      },
      {
        "ref": "R15",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "Channel 2 bass-network series resistor"
      },
      {
        "ref": "R14",
        "part": "Linear-taper potentiometer",
        "value": "1 MΩ",
        "role": "Channel 2 BASS"
      },
      {
        "ref": "C7",
        "part": "Disc ceramic capacitor",
        "value": "0.0015 µF",
        "role": "Across R14's half on the R15 side"
      },
      {
        "ref": "C6",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Across R14's half on the R13 side"
      },
      {
        "ref": "R13",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 2 bass-network shunt to the ground bus"
      },
      {
        "ref": "R17",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "Channel 2 — R14's wiper into the volume node"
      },
      {
        "ref": "C9",
        "part": "Disc ceramic capacitor",
        "value": "680 pF",
        "role": "Channel 2 treble bypass"
      },
      {
        "ref": "R19",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ",
        "role": "Channel 2 TREBLE, the same treble-cut rheostat as R18"
      },
      {
        "ref": "C11",
        "part": "Film capacitor",
        "value": "0.01 µF · 600 V",
        "role": "Channel 2 treble-cut capacitor"
      },
      {
        "ref": "R21",
        "part": "Linear-taper potentiometer",
        "value": "1 MΩ",
        "role": "Channel 2 VOLUME, wiper to V2B's grid"
      },
      {
        "ref": "R22",
        "part": "Carbon comp resistor",
        "value": "4.7 kΩ · ½ W · 20%",
        "role": "V2A cathode bias — UNBYPASSED; there is no cathode can anywhere on this bottle"
      },
      {
        "ref": "R23",
        "part": "Carbon comp resistor",
        "value": "4.7 kΩ · ½ W · 20%",
        "role": "V2B cathode bias, likewise unbypassed"
      },
      {
        "ref": "R24",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 1 mixing resistor, V2A plate into the mixer node"
      },
      {
        "ref": "R25",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Channel 2 mixing resistor, V2B plate into the mixer node"
      },
      {
        "ref": "R26",
        "part": "Carbon comp resistor",
        "value": "560 kΩ · ½ W · 20%",
        "role": "Mixer-node resistor — the two channels meet here"
      },
      {
        "ref": "R27",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W · 20%",
        "role": "From the mixer node to the same node R33 feeds off; part of the supply-and-mixing web this entry does not resolve (see the circuit story)"
      },
      {
        "ref": "C12",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Mixer node into V3A's grid. The one value the schematic and the factory parts list disagree on — see `notes` above"
      },
      {
        "ref": "R28",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W · 20%",
        "role": "V3A grid leak"
      },
      {
        "ref": "R29",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W · 20%",
        "role": "V3A cathode bias, unbypassed"
      },
      {
        "ref": "R34",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "V3A plate load. Its lower lead CROSSES the cathodyne's 125 V wire on the drawing without a junction dot and carries on to the preamp rail — reading that crossing as a junction is what makes the printed chart appear to contradict itself (see the circuit story)"
      },
      {
        "ref": "C13",
        "part": "Film capacitor",
        "value": "0.01 µF · 600 V",
        "role": "V3A plate into V3B's grid"
      },
      {
        "ref": "R31",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W · 20%",
        "role": "V3B grid return — to the cathode-side tap, not to ground, which is what makes this a cathodyne. Exactly the 1 MΩ the 6CG7 sheet gives as its maximum fixed-bias grid-circuit resistance"
      },
      {
        "ref": "R32",
        "part": "Carbon comp resistor",
        "value": "2.2 kΩ · ½ W · 20%",
        "role": "V3B's own cathode resistor, above the tap — the small one that sets the bias"
      },
      {
        "ref": "R30",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "V3B cathode load, tap to ground — the half of the split-load pair that faces R33's 68 kΩ in the plate"
      },
      {
        "ref": "R33",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "V3B plate load — matched to R30 within the parts list's own 20%, which is what balances the inverter"
      },
      {
        "ref": "C14",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Cathode-side output, tap to V8's grid"
      },
      {
        "ref": "C15",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Plate-side output, V3B plate to V7's grid"
      },
      {
        "ref": "R35",
        "part": "Carbon comp resistor",
        "value": "330 kΩ · ½ W · 20%",
        "role": "V8 grid resistor, from the −36 V bias node"
      },
      {
        "ref": "R36",
        "part": "Carbon comp resistor",
        "value": "330 kΩ · ½ W · 20%",
        "role": "V7 grid resistor, from the same node. There is no cathode resistor on either bottle: both pin 8s go straight to the chassis"
      },
      {
        "ref": "SW2",
        "part": "Switch",
        "value": "SPST",
        "role": "STANDBY, in the line that feeds the output grids' bias network"
      },
      {
        "ref": "—",
        "part": "Loudspeaker",
        "value": "12 in · 8 Ω",
        "role": "Sears 12-H8, two used, wired across the secondary (annotation only)"
      },
      {
        "ref": "R37",
        "part": "Linear-taper potentiometer",
        "value": "1 MΩ",
        "role": "REVERB DEPTH, with SW1 ganged to it — the parts list calls SW1 'part of control R37', so turning the control fully down switches the reverb off"
      },
      {
        "ref": "SW1",
        "part": "Switch",
        "value": "SPST",
        "role": "Reverb off, ganged to R37"
      },
      {
        "ref": "R38",
        "part": "Carbon comp resistor",
        "value": "2.2 kΩ · ½ W · 20%",
        "role": "V4A cathode bias"
      },
      {
        "ref": "C17",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V4A cathode bypass"
      },
      {
        "ref": "R39",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "V4A plate load"
      },
      {
        "ref": "C16",
        "part": "Film capacitor",
        "value": "0.01 µF · 600 V",
        "role": "V4A plate into V5's grid"
      },
      {
        "ref": "R40",
        "part": "Carbon comp resistor",
        "value": "560 kΩ · ½ W · 20%",
        "role": "V4B grid series resistor"
      },
      {
        "ref": "R41",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "V4B grid to the ground bus, the bottom of that divider"
      },
      {
        "ref": "R42",
        "part": "Carbon comp resistor",
        "value": "10 kΩ · ½ W · 20%",
        "role": "V4B cathode bias, unbypassed"
      },
      {
        "ref": "R43",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W · 20%",
        "role": "V5 grid leak. The drawing letters an unplaceable 55 V beside it — recorded in the operating-point table and the circuit story"
      },
      {
        "ref": "R44",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W · 20%",
        "role": "SHARED cathode resistor for both V5 triodes, printed 8.2 V — about 10 mA between the pair, which is what a reverb driver has to pass. The parts list row reads '800 ohm' (see `notes`)"
      },
      {
        "ref": "R45",
        "part": "Carbon comp resistor",
        "value": "27 kΩ · ½ W · 20%",
        "role": "V5A plate load"
      },
      {
        "ref": "R46",
        "part": "Carbon comp resistor",
        "value": "27 kΩ · ½ W · 20%",
        "role": "V5B plate load"
      },
      {
        "ref": "C18",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V5A plate coupler into the reverb drive network"
      },
      {
        "ref": "C19",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "V5B plate coupler into the reverb drive network"
      },
      {
        "ref": "R47",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W · 20%",
        "role": "Reverb drive network, upper leg between the two couplers"
      },
      {
        "ref": "R48",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Reverb drive network, lower leg; the junction of R47 and R48 feeds the CS55 pan"
      },
      {
        "ref": "J2",
        "part": "Jack socket",
        "value": "Sears 12B",
        "role": "Dual foot switch jack (reverb and tremolo), for the FS-2 footswitch"
      },
      {
        "ref": "—",
        "part": "Foot switch",
        "value": "Sears FS-2",
        "role": "Dual foot switch (annotation only)"
      },
      {
        "ref": "C20",
        "part": "Film capacitor",
        "value": "0.01 µF · 600 V",
        "role": "Tremolo oscillator phase-shift network"
      },
      {
        "ref": "C21",
        "part": "Film capacitor",
        "value": "0.01 µF · 600 V",
        "role": "Tremolo oscillator phase-shift network"
      },
      {
        "ref": "C22",
        "part": "Film capacitor",
        "value": "0.02 µF · 600 V",
        "role": "Tremolo oscillator phase-shift network"
      },
      {
        "ref": "R49",
        "part": "Carbon comp resistor",
        "value": "2.2 MΩ · ½ W · 20%",
        "role": "Tremolo oscillator phase-shift network"
      },
      {
        "ref": "R50",
        "part": "Carbon comp resistor",
        "value": "560 kΩ · ½ W · 20%",
        "role": "Tremolo oscillator phase-shift network"
      },
      {
        "ref": "R52",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Tremolo oscillator phase-shift network"
      },
      {
        "ref": "R51",
        "part": "Linear-taper potentiometer",
        "value": "1 MΩ",
        "role": "TREMOLO SPEED, in the phase-shift network"
      },
      {
        "ref": "R53",
        "part": "Carbon comp resistor",
        "value": "330 kΩ · ½ W · 20%",
        "role": "V6 plate load"
      },
      {
        "ref": "R54",
        "part": "Carbon comp resistor",
        "value": "560 kΩ · ½ W · 20%",
        "role": "Tremolo oscillator network"
      },
      {
        "ref": "C23",
        "part": "Film capacitor",
        "value": "0.5 µF · 200 V",
        "role": "Tremolo network — the largest film capacitor in the amplifier"
      },
      {
        "ref": "C24",
        "part": "Film capacitor",
        "value": "0.05 µF · 600 V",
        "role": "V6 cathode-side network capacitor"
      },
      {
        "ref": "R55",
        "part": "Linear-taper potentiometer",
        "value": "100 kΩ",
        "role": "TREMOLO STRENGTH — the depth control, working with the 306-2H photocell"
      },
      {
        "ref": "R56",
        "part": "Carbon comp resistor",
        "value": "27 kΩ · ½ W · 20%",
        "role": "V6 cathode circuit, at the printed −1.5 V node"
      },
      {
        "ref": "R57",
        "part": "Carbon comp resistor",
        "value": "15 MΩ · ½ W · 20%",
        "role": "The largest resistor in the amplifier, across V6's plate-to-cathode path where the neon lamp of the 306-2H is driven"
      },
      {
        "ref": "D1",
        "part": "Rectifier diode",
        "value": "1N3194",
        "role": "Capacitor-multiplier diode, upper HT winding"
      },
      {
        "ref": "D2",
        "part": "Rectifier diode",
        "value": "1N3194",
        "role": "Capacitor-multiplier diode, upper HT winding"
      },
      {
        "ref": "D3",
        "part": "Rectifier diode",
        "value": "1N3194",
        "role": "Capacitor-multiplier diode, lower HT winding"
      },
      {
        "ref": "D4",
        "part": "Rectifier diode",
        "value": "1N3194",
        "role": "Capacitor-multiplier diode, lower HT winding"
      },
      {
        "ref": "C26",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 150 V",
        "role": "Multiplier stack, top section — four 150 V cans in series is how a 480 V rail is made out of 150 V parts"
      },
      {
        "ref": "C27",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 150 V",
        "role": "Multiplier stack, second section"
      },
      {
        "ref": "C28",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 150 V",
        "role": "Multiplier stack, third section"
      },
      {
        "ref": "C29",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 150 V",
        "role": "Multiplier stack, bottom section"
      },
      {
        "ref": "C25",
        "part": "Electrolytic capacitor",
        "value": "20 µF + 10 µF + 5 µF · 450 V",
        "role": "The whole triple-section filter can, one part in the factory list ('5-10-20 mfd., 450 v.') and one can on the chassis. The schematic letters its sections C25A, C25B and C25C along the two-dropper chain: C25A on the 340 V screen node, C25B between R58 and R59, C25C at the R59 end"
      },
      {
        "ref": "R58",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Supply dropper between the C25A and C25B nodes"
      },
      {
        "ref": "R59",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W · 20%",
        "role": "Supply dropper between the C25B and C25C nodes"
      },
      {
        "ref": "D5",
        "part": "Rectifier diode",
        "value": "1N3754",
        "role": "Negative bias rectifier, on its own transformer winding"
      },
      {
        "ref": "C30",
        "part": "Electrolytic capacitor",
        "value": "100 µF · 50 V",
        "role": "Bias-supply reservoir — a 50 V part, which is the clearest sign the −36 V bias line is all it ever sees"
      },
      {
        "ref": "R60",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W · 20%",
        "role": "Bias-supply divider, upper leg"
      },
      {
        "ref": "R61",
        "part": "Carbon comp resistor",
        "value": "2.2 kΩ · ½ W · 20%",
        "role": "Bias-supply divider, lower leg"
      },
      {
        "ref": "SW3",
        "part": "Switch",
        "value": "SPST",
        "role": "AC power switch"
      },
      {
        "ref": "SW4",
        "part": "Switch",
        "value": "SPDT",
        "role": "Ground (polarity) switch — period practice, not built today"
      },
      {
        "ref": "C31",
        "part": "Film capacitor",
        "value": "0.05 µF · 600 V",
        "role": "Line-to-chassis capacitor across the ground switch — the era's 'death cap'; period practice, never fitted in a modern build"
      },
      {
        "ref": "—",
        "part": "Fuse",
        "value": "2 A",
        "role": "Mains fuse in the Sears 68 fuse holder (annotation only)"
      },
      {
        "ref": "—",
        "part": "Pilot lamp",
        "value": "No. 47",
        "role": "Pilot lamp on the heater winding (annotation only)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Silvertone factory drawing, title block 'SCHEMATIC DIAGRAM OF SILVERTONE CHASSIS 185.11040', voltages lettered on the nodes and measured (note 3) with a 20,000 Ω/volt meter. Printed: 6L6GC plates 475 V and the rail above them 480 V; 6L6GC screens 340 V; fixed bias −36 V; V1 plates 100 V and shared cathode 1.1 V; V2 plates 93 V and cathodes 1.1 V; V3A plate 100 V and cathode 4 V; V3B plate 225 V and cathode-side tap 125 V; V4A plate 160 V and cathode 1.5 V, V4B cathode 0.8 V; V5 plates 215 V and shared cathode 8.2 V; V6 plate 120 V and cathode 1.5 V; the tremolo network 205 V and −1.5 V; and an unplaced 55 V beside R43.",
    "nodes": {
      "K1": {
        "chart": 1.1,
        "tol_pct": 20,
        "note": "V1's SHARED cathode — both preamp channels' first triodes land on one node over R6 1.5 kΩ, bypassed by C1 25 µF · 25 V. One resistor sets the bias for both channels"
      },
      "K2A": {
        "chart": 1.1,
        "tol_pct": 20,
        "note": "V2A cathode over R22 4.7 kΩ, UNBYPASSED — this bottle gets no cathode can at all"
      },
      "K2B": {
        "chart": 1.1,
        "tol_pct": 20,
        "note": "V2B cathode over R23 4.7 kΩ, likewise unbypassed; the drawing prints the same 1.1 V on both halves"
      },
      "K3A": {
        "chart": 4,
        "tol_pct": 20,
        "note": "V3A cathode over R29 1.5 kΩ, unbypassed. The worst-agreeing node in the entry: the model idles this 6CG7 at about 2.1 mA against the 2.7 mA the printed 4 V implies, which is why the entry is a draft"
      },
      "NA": {
        "chart": 125,
        "tol_pct": 20,
        "note": "the cathodyne's cathode-side output tap — the junction of R30 68 kΩ (to chassis), R32 2.2 kΩ (to V3B's cathode) and R31 1 MΩ (the grid return), with C14 taking the inverted drive off it to V8's grid. R34 crosses this wire on the drawing without a junction dot and is NOT connected to it"
      },
      "PLATE": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 475 V, both 6L6GC plates. The drawing also prints 480 V one node up, at the top of the capacitor-multiplier stack and the transformer centre tap, and 85 Ω for each primary half; no netlist in this corpus models output-transformer primary resistance, so the 5 V between those two printed figures is stated rather than simulated. What the stage reports instead is its idle current, which the load-line explorer prints"
      },
      "BSCR": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 340 V, the 6L6GC screen node. It is fed through CH.1, whose DC resistance the drawing does not print, so it cannot be derived from the 480 V rail"
      },
      "NBIAS": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed −36 V, the junction of R35 and R36 (330 kΩ each) that fixed-biases both output grids. It comes from a separate negative supply, D5 with C30 100 µF · 50 V, which no operating-point netlist in this corpus simulates"
      },
      "P1A": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 100 V, V1A plate (channel 1), load R8 220 kΩ"
      },
      "P1B": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 100 V, V1B plate (channel 2), load R7 220 kΩ"
      },
      "P2A": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 93 V, V2A plate"
      },
      "P2B": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 93 V, V2B plate"
      },
      "P3A": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 100 V, V3A plate (load R34 100 kΩ, whose far end is the unlabelled preamp rail)"
      },
      "P3B": {
        "chart": null,
        "note": "informational — DRIVEN INPUT at the printed 225 V, V3B plate: the cathodyne's plate output, load R33 68 kΩ against R30's 68 kΩ in the cathode"
      },
      "K3B": {
        "chart": null,
        "note": "informational — V3B's cathode itself, R32 2.2 kΩ above the NA tap. The drawing prints the tap, not the cathode"
      },
      "G7": {
        "chart": null,
        "note": "informational — V7 grid, held at the bias node through R36 330 kΩ. These tube models carry no grid current, so it sits exactly at the bias supply"
      },
      "G8": {
        "chart": null,
        "note": "informational — V8 grid, likewise through R35 330 kΩ"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "K1",
      "chart": 1.1,
      "sim": 1.144,
      "disputed": false,
      "dev_pct": 3.9999999999999827,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V1's SHARED cathode — both preamp channels' first triodes land on one node over R6 1.5 kΩ, bypassed by C1 25 µF · 25 V. One resistor sets the bias for both channels",
      "dispute_note": ""
    },
    {
      "node": "K2A",
      "chart": 1.1,
      "sim": 1.247,
      "disputed": false,
      "dev_pct": 13.363636363636363,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V2A cathode over R22 4.7 kΩ, UNBYPASSED — this bottle gets no cathode can at all",
      "dispute_note": ""
    },
    {
      "node": "K2B",
      "chart": 1.1,
      "sim": 1.247,
      "disputed": false,
      "dev_pct": 13.363636363636363,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V2B cathode over R23 4.7 kΩ, likewise unbypassed; the drawing prints the same 1.1 V on both halves",
      "dispute_note": ""
    },
    {
      "node": "K3A",
      "chart": 4,
      "sim": 3.174,
      "disputed": false,
      "dev_pct": 20.650000000000002,
      "tol_pct": 20,
      "gated": true,
      "within": false,
      "note": "V3A cathode over R29 1.5 kΩ, unbypassed. The worst-agreeing node in the entry: the model idles this 6CG7 at about 2.1 mA against the 2.7 mA the printed 4 V implies, which is why the entry is a draft",
      "dispute_note": ""
    },
    {
      "node": "NA",
      "chart": 125,
      "sim": 117.479,
      "disputed": false,
      "dev_pct": 6.016800000000001,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "the cathodyne's cathode-side output tap — the junction of R30 68 kΩ (to chassis), R32 2.2 kΩ (to V3B's cathode) and R31 1 MΩ (the grid return), with C14 taking the inverted drive off it to V8's grid. R34 crosses this wire on the drawing without a junction dot and is NOT connected to it",
      "dispute_note": ""
    },
    {
      "node": "PLATE",
      "chart": null,
      "sim": 475,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 475 V, both 6L6GC plates. The drawing also prints 480 V one node up, at the top of the capacitor-multiplier stack and the transformer centre tap, and 85 Ω for each primary half; no netlist in this corpus models output-transformer primary resistance, so the 5 V between those two printed figures is stated rather than simulated. What the stage reports instead is its idle current, which the load-line explorer prints",
      "dispute_note": ""
    },
    {
      "node": "BSCR",
      "chart": null,
      "sim": 340,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 340 V, the 6L6GC screen node. It is fed through CH.1, whose DC resistance the drawing does not print, so it cannot be derived from the 480 V rail",
      "dispute_note": ""
    },
    {
      "node": "NBIAS",
      "chart": null,
      "sim": -36,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed −36 V, the junction of R35 and R36 (330 kΩ each) that fixed-biases both output grids. It comes from a separate negative supply, D5 with C30 100 µF · 50 V, which no operating-point netlist in this corpus simulates",
      "dispute_note": ""
    },
    {
      "node": "P1A",
      "chart": null,
      "sim": 100,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 100 V, V1A plate (channel 1), load R8 220 kΩ",
      "dispute_note": ""
    },
    {
      "node": "P1B",
      "chart": null,
      "sim": 100,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 100 V, V1B plate (channel 2), load R7 220 kΩ",
      "dispute_note": ""
    },
    {
      "node": "P2A",
      "chart": null,
      "sim": 93,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 93 V, V2A plate",
      "dispute_note": ""
    },
    {
      "node": "P2B",
      "chart": null,
      "sim": 93,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 93 V, V2B plate",
      "dispute_note": ""
    },
    {
      "node": "P3A",
      "chart": null,
      "sim": 100,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 100 V, V3A plate (load R34 100 kΩ, whose far end is the unlabelled preamp rail)",
      "dispute_note": ""
    },
    {
      "node": "P3B",
      "chart": null,
      "sim": 225,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — DRIVEN INPUT at the printed 225 V, V3B plate: the cathodyne's plate output, load R33 68 kΩ against R30's 68 kΩ in the cathode",
      "dispute_note": ""
    },
    {
      "node": "K3B",
      "chart": null,
      "sim": 121.28,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — V3B's cathode itself, R32 2.2 kΩ above the NA tap. The drawing prints the tap, not the cathode",
      "dispute_note": ""
    },
    {
      "node": "G7",
      "chart": null,
      "sim": -36,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — V7 grid, held at the bias node through R36 330 kΩ. These tube models carry no grid current, so it sits exactly at the bias supply",
      "dispute_note": ""
    },
    {
      "node": "G8",
      "chart": null,
      "sim": -36,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "informational — V8 grid, likewise through R35 330 kΩ",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Outside target",
      "summary": "1 of 5 reference nodes falls outside its stated tolerance.",
      "details": [
        "This compares simulated DC conditions with the cited reference. It does not test sound, physical construction or every part of the circuit."
      ],
      "tone": "attention"
    },
    {
      "id": "schematic",
      "title": "Schematic against DC model",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    },
    {
      "id": "board",
      "title": "Board against DC model",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    },
    {
      "id": "drawings",
      "title": "Schematic against board",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    },
    {
      "id": "heaters",
      "title": "Heater and filament wiring",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    },
    {
      "id": "polarity",
      "title": "Capacitor polarity",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    }
  ],
  "corrections": [],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/ebddc3fd2cf887dca010bbe60487d7391ea6c052/amps/s1484"
}