Soldano SLO and its relatives: every version
Every version, how to tell them apart, how to date one, and what to check before you buy. 4 versions, 1987–present.
The SLO-100 (Super Lead Overdrive) is the 100-watt, two-channel high-gain head Soldano introduced in 1987, with a Normal channel (clean or crunch) and a cascaded Overdrive channel. Around it sit a few related amps: the Super Lead 60 made in Japan around 1990, the Hot Rod series that replaced it from 1991 as a simpler SLO, and the SLO-100 Classic built after the company changed hands in 2018. The power, the channel layout and the rear panel separate them.
The versions, in order
SLO-100 Super Lead Overdrive (1987 on)
SLO
Normal (clean/crunch) and Overdrive channels, each with gain and master, a shared EQ and four 6L6s.
How to spot one
- Two channels, Normal and Overdrive, each with its own gain and master volume.
- A mini-toggle on the Normal channel selects Clean or Crunch.
- Shared Bass, Middle, Treble and Presence on a cathode-follower tone stack.
- Four 6L6GC output valves and a solid-state rectifier; the output transformer is nearly as big as the power transformer.
- Early amps may have no effects loop (blanked holes on the back); where fitted, the loop is valve-driven.
Specs
| Power tubes | 4 × 6L6 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
| Rated power | 100 W |
| Channels | 2 |
Super Lead 60 (SL-60) (c. 1990–1991)
SLO
A 60-watt, two-6L6 version of the SLO design, made in Japan and soon replaced by the Hot Rod 50.
What changed from the SLO-100 Super Lead Overdrive
- Power tubes: 4 × 6L6 → 2 × 6L6
- Rated power: 100 W → 60 W
- Half the output valves (two 6L6s, 60 W), built in Japan.
How to spot one
- 60 watts from two 6L6 output valves.
- Made in Japan, not in Soldano's own workshop.
- Cascaded preamp gain with a three-band EQ and presence, in the SLO style.
Specs
| Power tubes | 2 × 6L6 |
|---|---|
| Rectifier | Solid-state (silicon diodes) |
| Phase inverter | Long-tail pair |
| Rated power | 60 W |
Hot Rod 50 and Hot Rod 100 (and Plus) (1991 on)
Hot Rod
A simpler SLO: the Overdrive channel's sound without the crunch mode or the large transformers; Plus versions add a second channel.
What changed from the SLO-100 Super Lead Overdrive
- The Overdrive-channel sound in a cheaper amp: no crunch mode and smaller transformers; a second channel came back with the 1995 Plus versions.
How to spot one
- The first Hot Rod 50 (1991) is single-channel, based on the SLO-100's Overdrive channel.
- No crunch mode and smaller transformers than the SLO-100.
- The 100-watt version came in 1994 and the two-channel Plus versions in 1995.
- The 50-watt amps run two 6L6/5881s, the 100-watt amps four.
SLO-100 Classic (2020 on)
Classic
The SLO-100 built after the 2018 company sale, closer to the original specs, with a few practical additions.
What changed from the SLO-100 Super Lead Overdrive
- A Depth control, front-panel channel switching and an effects-loop level control were added.
How to spot one
- Sold as the SLO-100 Classic.
- Adds a Depth control, front-panel channel switching and a level control for the effects loop.
- Made after Soldano sold the company in late 2018, rather than in the original Seattle workshop.
SLO buying checklist
Date it
- From the early 1990s until late 2018 every SLO was built in Soldano's Seattle workshop; the Classic name means 2020 or later.
- Early SLO-100s may have no effects loop; blanked holes on the rear panel show where it would go.
- Hot Rod amps date from 1991 on, with 100-watt versions from 1994 and Plus versions from 1995.
Check it’s original
- Some SLOs have been converted to EL34s; the original output valves are 6L6GCs.
- Effects loops were sometimes added to early loop-less amps; check whether the rear-panel hardware matches the rest.
- Transformer size is a quick check: the SLO-100's output transformer is almost as large as its power transformer.
What usually needs work
- Heavy filtering and a choke keep the SLO quiet; old filter capacitors are the first thing to check on early amps.
- Noisy or microphonic preamp valves are the usual cause of hiss in the Overdrive channel.
- Output valves run hard at 100 watts; check the bias when replacing them.
Questions buyers ask
What does SLO stand for?
Super Lead Overdrive.
Is the Hot Rod a smaller SLO?
Broadly. It began in 1991 as a single-channel amp based on the SLO's Overdrive channel, without the crunch mode or the big transformers.
What changed on the SLO-100 Classic?
It adds a Depth control, front-panel channel switching and an effects-loop level control.
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