Follow what changed between two designs: their valves, topology, tone networks and the evidence behind the drawings. Missing information is marked explicitly.
Try 5F6-A & JTM45 · AA964 & AA1164 · 5E3 & 6G3
Comparing 5F6-A and JTM45.
| Feature | 5F6-A | JTM45 | Comparison |
|---|---|---|---|
| Family line | The Bassman line | The Marshall lead-amp line | Different |
| Years | 1958–1960 | 1962–1966 | Different |
| Output power | 40 W | 45 W | Different |
| Output valves | 5881 ×2 | KT66 ×2 | Different |
| Tube complement | 12AY7, 12AX7, 12AX7, 5881, 5881, GZ34 | ECC83, ECC83, ECC83, KT66, KT66, GZ34 | Different |
| Rectifier | GZ34 | GZ34 | Same |
| Bias | Fixed bias | Fixed bias | Same |
| Phase inverter | Long-tailed pair | Long-tailed pair | Same |
| Tone network | Cathode-follower FMV stack | Cathode-follower FMV stack | Same |
| Circuit status | Verified, re-review pending | Verified, re-review pending | Same |
| Voltage reference | Fender 5F6-A (I-EG) drawing, printed voltages: rails +432/+430/+385/+325, bias -48; pins 12AY7 +150/+2.5, V2A +180/+1.2? (printed near cathode), CF +180, PI plates +235/+230, PI cathodes +34, tail junction +32.5 | Marshall JTM45 factory drawing, printed chart: rails +450 (GZ34 cathode) / +440 (screens) / +380 (PI) / +310 (preamp); V1 plate 220, cathode 1.6; V3A plate 190, cathode 1.1; V3B (CF) plate 310, grid 190, cathode 190; V4 (PI) plates 250, cathodes 40, grids '+'; V5/V6 KT66 plate 430, screen 440; V7 GZ34 cathode 450; bias-line bubble '10 5V' (disputed, see NBIAS) | Different |
| DC comparison | Verified — 11 reference nodes are within tolerance. Maintainer verification is recorded for 2026-07-18; changes since then are awaiting maintainer re-review. | Verified — 12 reference nodes are within tolerance. Maintainer verification is recorded for 2026-07-18; changes since then are awaiting maintainer re-review. | Different |
| Schematic check | Checked — Connectivity of modelled components is checked on every change. | Checked — Connectivity of modelled components is checked on every change. | Same |
| Board check | Checked — Connectivity of modelled components is checked on every change. | Checked — Connectivity of modelled components is checked on every change. | Same |
| Drawing comparison | No open findings — No disagreement is listed in the published comparison. | No open findings — No disagreement is listed in the published comparison. | Same |
| Heaters | Checked — The declared heater circuits cover the drawing and pass their separate wiring check. | Not established — The drawn supply-leg connections have not been established by this check. | Not recorded |
| Capacitor polarity | Checked — 7 capacitor markings agree with the model's voltage ordering. | Checked — 7 capacitor markings agree with the model's voltage ordering. | Same |
5F6-A load line · JTM45 load line
The comparison uses documented metadata and current check results. It does not match component designators between different drawing conventions or predict the sound of a complete amplifier.