Amp vs amp: what’s actually different inside
Classic amps compared part by part: tubes, gain stages, tone stack, phase inverter, feedback and power section, read from Gridleak’s verified redraws of each schematic, with presets for both amps.
Fender tweed and the first Marshalls
- Fender Bassman 5F6-A vs Marshall JTM45 — 10 circuit differences. On the schematic these two are close.
- Fender Deluxe 5E3 vs Fender Bassman 5F6-A — 31 circuit differences. Both tweeds start the same way, with a 12AY7 first stage whose two halves share one cathode, and then have very little in common.
Marshall heads, one step at a time
- Marshall JTM45 vs Marshall 1959 Super Lead — 17 circuit differences. The preamp layout carries over: two channels into a shared second stage, a cathode follower, then the tone stack.
- Marshall 1959 Super Lead vs Marshall JCM800 2204 — 21 circuit differences. The 2204 keeps the 1959's cathode follower, a near-identical tone stack (33 kΩ slope resistor, 470 pF treble cap against 500 pF) and the same long-tail-pair phase inverter, but rebuilds the front end: three gain stages in series instead of two, one of them cold-biased on an unbypassed 10 kΩ cathode resistor, and a master volume.
- Marshall JCM800 2204 vs Marshall Silver Jubilee 2555 — 30 circuit differences. Both are EL34 heads with a long-tail-pair phase inverter and a solid-state rectifier, but the circuits differ widely.
Fender Deluxe: tweed vs reissue
- Fender Deluxe 5E3 vs Fender '65 Deluxe Reverb Reissue — 34 circuit differences. Both run two 6V6GTs, and the likeness mostly ends there.
High-gain heads
- Soldano SLO-100 vs Peavey 5150 — 26 circuit differences. On the schematic these are close relatives: four 6L6GCs, the same phase-inverter values (82 kΩ / 100 kΩ plate loads, 10 kΩ tail), a treble/bass/middle stack with a 47 kΩ slope resistor after the last gain stage, a cold-biased stage on an unbypassed 39 kΩ cathode resistor, an effects loop and footswitchable channels.
Boutique overdrive
- Trainwreck Express vs Dumble Overdrive Special — 36 circuit differences. Both put the tone stack early, straight off the first gain stage's plate, with more gain stages after it.
British 100-watt heads
- Hiwatt DR103 vs Marshall 1959 Super Lead — 33 circuit differences. Same output section on paper (four EL34s, fixed bias, a long-tail-pair phase inverter and silicon rectification), very different preamps.
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