Soldano SLO-100 vs Peavey 5150
Circuit differences, stage by stage, from Gridleak’s verified redraws of both schematics: 26 differences, 26 the same.
What’s different, and why it matters
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. The differences are in the gain structure and the switching: the 5150 puts six triode stages in series ahead of its effects return against the SLO's four, drives its tone stack from a plate rather than a cathode follower, and switches on relays where the SLO uses LDR optocouplers.
- The SLO-100 puts up to four triode gain stages in series before the phase inverter; the 5150, six (not counting effects-return recovery stages). Each stage multiplies the signal, so the 5150 has more gain available before the power amp.
- Same tone-stack layout, different values: treble cap 470 pF vs 570 pF (470 pF + 100 pF in parallel).
What they share: a long-tail pair phase inverter, the same tone-stack layout, the same output tubes (4 × 6L6GC) and a cathode follower.
At a glance
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Years | 1987–present | 1992–2004 |
| Origin | USA | USA |
| Rated power | 100 W | 120 W |
| Channels | 2 | 2 |
| Preamp tubes | 5 × 12AX7 | 5 × 12AX7 |
| Power tubes | 4 × 6L6GC | 4 × 6L6GC |
| Rectifier | Solid-state (silicon diodes) | — |
| Phase inverter | Long-tail pair | Long-tail pair |
| Master volume | OD MV / Norm MV | Clean post-gain / Lead post-gain |
| Effects loop | yes | yes |
| Reverb | no | no |
| Notable players | Eric Clapton, Warren Haynes, George Lynch, Lou Reed | Eddie Van Halen |
Stage by stage
Inputs and channels
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Inputs | 1 | 2 |
| Channel switching | footswitchable (LDR optocouplers) | footswitchable (relays) |
| Voicing / power switches | Bright, Crunch / Clean | none |
Preamp
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Preamp tubes | 5 × 12AX7 | 5 × 12AX7 |
| Triode gain stages (all channels) | 6 | 7 |
| Most gain stages in series | 5 (incl. 1 effects-return stage) | 7 (incl. 1 effects-return stage) |
| Gain stage 1 | 12AX7 · plate 220 kΩ · cathode 1.8 kΩ, 1 µF bypass | 12AX7 · plate 220 kΩ · cathode 1.82 kΩ, 1 µF bypass |
| Gain stage 2 | Normal channel stage: 12AX7 · plate 100 kΩ · cathode 2.2 kΩ, unbypassed; OD stage 1: 12AX7 · plate 100 kΩ · cathode 1.8 kΩ, 1 µF bypass | 12AX7 · plate 100 kΩ · cathode 1.82 kΩ, 1 µF bypass |
| Gain stage 3 | 12AX7 · plate 100 kΩ · cathode 39 kΩ, unbypassed | 12AX7 · plate 100 kΩ · cathode 39 kΩ, unbypassed |
| Gain stage 4 | 12AX7 · plate 220 kΩ · cathode 1.8 kΩ, 1 µF bypass | 12AX7 · plate 220 kΩ · cathode 1.82 kΩ, 1 µF bypass |
| Gain stage 5 | 12AX7 · plate 220 kΩ · cathode 2.2 kΩ, unbypassed | 12AX7 · plate 220 kΩ · cathode 2.2 kΩ, unbypassed |
| Gain stage 6 | — | 12AX7 · plate 100 kΩ · cathode 2.2 kΩ, unbypassed |
| Gain stage 7 | — | 12AX7 · plate 68 kΩ · cathode 3.3 kΩ, 0.0047 µF bypass |
| Cold-biased stage (clipper) | 39 kΩ | 39 kΩ |
| Cathode follower | yes | yes |
| Bright cap(s) | 470 pF (switchable) | 470 pF / 180 pF / 0.001 µF |
| Coupling caps (preamp) | 0.02 µF | 0.022 µF / 0.1 µF |
| Diode clipping | no | no |
Tone stack
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Type | Treble / bass / middle stack with a slope resistor | Treble / bass / middle stack with a slope resistor |
| Position | after gain stage 5, driven by a cathode follower; no gain stages after it | after gain stage 6, driven by a plate; no gain stages after it |
| Slope resistor | 47 kΩ | 47 kΩ |
| Treble cap | 470 pF | 570 pF (470 pF + 100 pF in parallel) |
| Bass cap | 0.02 µF | 0.022 µF |
| Middle cap | 0.02 µF | 0.022 µF |
| Pots | treble 250 kΩ · bass 1 MΩ · middle 25 kΩ | treble 250 kΩ · bass 1 MΩ · middle 50 kΩ |
| Master volume | OD MV / Norm MV | Clean post-gain / Lead post-gain |
Effects
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Effects loop | yes | yes |
| Reverb | no | no |
| Tremolo / vibrato | no | no |
Phase inverter
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Type | Long-tail pair | Long-tail pair |
| Tube | 12AX7 | 12AX7 |
| Plate loads | 82 kΩ / 100 kΩ | 82 kΩ / 100 kΩ |
| Tail / cathode load | 10 kΩ | 10 kΩ |
| Cathode bias resistor | 470 Ω | 470 Ω |
| Input coupling cap | 0.02 µF | 0.022 µF |
| Coupling to power tubes | 0.047 µF | 0.047 µF |
Feedback
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Negative feedback | yes | yes |
| Feedback resistor | 39 kΩ | 39 kΩ |
| Feedback taken from | 4 Ω tap | not on the drawing |
| Presence | yes (25 kΩ pot, 0.1 µF cap) | yes (10 kΩ pot, 0.1 µF / 0.033 µF cap) |
| Resonance / depth | no | a second, unlabelled pot in the feedback network |
Power amp
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Power tubes | 4 × 6L6GC | 4 × 6L6GC |
| Configuration | Push-pull, 2 tubes per side in parallel | Push-pull, 2 tubes per side in parallel |
| Bias | Fixed bias | Fixed bias |
| Screen resistors | 475 Ω | 100 Ω |
| Grid stoppers | 2.2 kΩ | 2.2 kΩ |
Power supply
| Soldano SLO-100 | Peavey 5150 | |
|---|---|---|
| Rectifier | Solid-state (silicon diodes) | not on the drawing |
| First filter (reservoir) | 200 µF + 200 µF in series | not on the drawing |
| Filter nodes, in order | 200 µF + 200 µF in series → 200 µF + 200 µF in series → 40 µF → 10 µF → 10 µF | not on the drawing |
| Filter choke | yes | not on the drawing |
| Highest DC voltage printed on the drawing | 497 V | not printed |
| Printed bias voltage | not on the drawing | not printed |
Presets and schematics
- Soldano SLO-100: amp page and presets · full schematic (Pro)
- Peavey 5150: amp page and presets · full schematic (Pro)
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