All comparisons
Hiwatt DR103 vs Marshall 1959 Super Lead
Circuit differences, stage by stage, from Gridleak’s verified redraws of both schematics: 33 differences, 15 the same.
What’s different, and why it matters
Same output section on paper (four EL34s, fixed bias, a long-tail-pair phase inverter and silicon rectification), very different preamps. The 1959 drives a treble/bass/middle stack with a slope resistor from a cathode follower at the end of its preamp and has no master volume. The DR103 has no cathode follower: its own tone-stack design hangs off the second stage's plate, followed by a master volume and a third gain stage.
- The DR103 puts up to three triode gain stages in series before the phase inverter; the 1959 Super Lead, two. Each stage multiplies the signal, so the DR103 has more gain available before the power amp.
- The 1959 Super Lead has a cathode follower and the DR103 doesn't. A cathode follower drives what follows it from a low impedance, so less is lost in the tone stack, and it compresses when pushed.
- The 1959 Super Lead's tone stack sits after all of its gain stages; the DR103's sits before one more gain stage. EQ at the end of the preamp shapes the finished sound; EQ ahead of a gain stage shapes what that stage amplifies, and clips if it is driven hard.
- Tone controls: treble / middle / bass, other topology on the DR103, treble / bass / middle stack with a slope resistor on the 1959 Super Lead.
- The DR103 has a master volume; the 1959 Super Lead doesn't. With a master, the preamp can be driven into distortion while the output stays at a usable level — without one, distortion comes from turning the whole amp up.
- Negative feedback: 10 kΩ (16 Ω tap) in the DR103, 47 kΩ (8 Ω tap) in the 1959 Super Lead.
What they share: a long-tail pair phase inverter, the same output tubes (4 × EL34) and a solid-state rectifier.
At a glance
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Years | — | 1965–1981 |
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| Origin | UK | UK |
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| Rated power | 100 W | 100 W |
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| Channels | 2 | 2 |
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| Preamp tubes | 4 × ECC83 | 3 × ECC83 |
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| Power tubes | 4 × EL34 | 4 × EL34 |
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| Rectifier | Solid-state (silicon diodes) | Solid-state (silicon diodes) |
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| Phase inverter | Long-tail pair | Long-tail pair |
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| Master volume | Master volume | none |
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| Effects loop | no | no |
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| Reverb | no | no |
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| Notable players | Pete Townshend, David Gilmour, Roger Waters | Jimi Hendrix, Eddie Van Halen, Angus Young, Jimmy Page, Eric Clapton |
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Stage by stage
Inputs and channels
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Inputs | 2 | 4 |
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| Channel switching | front panel only / none | front panel only / none |
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| Voicing / power switches | none | none |
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Preamp
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Preamp tubes | 4 × ECC83 | 3 × ECC83 |
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| Triode gain stages (all channels) | 5 | 3 |
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| Most gain stages in series | 3 | 2 |
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| Gain stage 1 | ECC83 · plate 220 kΩ · cathode 1.5 kΩ, 100 µF bypass (shared) (×2: Normal channel first stage, Brilliant channel first stage) | Normal channel: ECC83 · plate 100 kΩ · cathode 820 Ω, 250 µF bypass; High-treble channel: ECC83 · plate 100 kΩ · cathode 2.7 kΩ, 0.68 µF bypass |
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| Gain stage 2 | Normal channel second stage: ECC83 · plate 100 kΩ · cathode 1 kΩ, unbypassed; Brilliant channel second stage: ECC83 · plate 100 kΩ · cathode 1 kΩ, 0.047 µF bypass | ECC83 · plate 100 kΩ · cathode 820 Ω, 0.68 µF bypass |
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| Gain stage 3 | ECC83 · plate 100 kΩ · cathode 1.5 kΩ, unbypassed | — |
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| Cold-biased stage (clipper) | none | none |
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| Cathode follower | no | yes |
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| Bright cap(s) | none | 0.005 µF |
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| Coupling caps (preamp) | 0.001 µF / 0.022 µF | 0.0022 µF / 0.022 µF |
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| Diode clipping | no | no |
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Tone stack
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Type | Treble / middle / bass, other topology | Treble / bass / middle stack with a slope resistor |
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| Position | after gain stage 2, driven by a plate; 1 gain stage after it | after gain stage 2, driven by a cathode follower; no gain stages after it |
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| Slope resistor | not on the drawing | 33 kΩ |
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| Treble cap | 0.001 µF / 220 pF | 500 pF |
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| Bass cap | 0.047 µF | 0.022 µF |
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| Middle cap | not on the drawing | 0.022 µF |
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| Pots | treble 220 kΩ · bass 470 kΩ · middle 100 kΩ | treble 250 kΩ · bass 1 MΩ · middle 25 kΩ |
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| Master volume | Master volume | none |
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Effects
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Effects loop | no | no |
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| Reverb | no | no |
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| Tremolo / vibrato | no | no |
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Phase inverter
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Type | Long-tail pair | Long-tail pair |
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| Tube | ECC83 | ECC83 |
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| Plate loads | 82 kΩ / 91 kΩ | 82 kΩ / 100 kΩ |
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| Tail / cathode load | 22 kΩ | 10 kΩ |
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| Cathode bias resistor | none (the grids are referenced elsewhere) | 470 Ω |
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| Input coupling cap | 0.047 µF | 0.022 µF |
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| Coupling to power tubes | 0.047 µF | 0.022 µF |
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Feedback
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Negative feedback | yes | yes |
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| Feedback resistor | 10 kΩ | 47 kΩ |
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| Feedback taken from | 16 Ω tap | 8 Ω tap |
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| Presence | yes (100 kΩ pot) | yes (5 kΩ pot, 0.1 µF cap) |
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| Resonance / depth | no | no |
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Power amp
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Power tubes | 4 × EL34 | 4 × EL34 |
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| Configuration | Push-pull, 2 tubes per side in parallel | Push-pull, 2 tubes per side in parallel |
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| Bias | Fixed bias | Fixed bias |
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| Screen resistors | 100 Ω | 1 kΩ |
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| Grid stoppers | 22 kΩ | 5.6 kΩ / 56 kΩ |
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Power supply
| Hiwatt DR103 | Marshall 1959 Super Lead |
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| Rectifier | Solid-state (silicon diodes) | Solid-state (silicon diodes) |
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| First filter (reservoir) | 220 µF + 220 µF in series | 100 µF + 100 µF in series |
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| Filter nodes, in order | 220 µF + 220 µF in series → 50 µF + 220 µF in series → 50 µF + 220 µF in series → 32 µF → 16 µF | 100 µF + 100 µF in series → 100 µF + 100 µF in series → 100 µF (2 × 50 µF) → 50 µF → 50 µF |
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| Filter choke | no | yes |
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| Highest DC voltage printed on the drawing | 160 V | not printed |
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| Printed bias voltage | -38 V | not printed |
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