Classic Gear: Soldano SLO 100

Amid all of the legendary amps of the great rock era, the Soldano SLO 100 has logged as many star guitarists’ licks as nearly any head in the field.
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Amid the vintage Marshall “Plexis,” Mesa/Boogies, Dumbles, Trainwrecks and other legendary amps of the great rock era, the Soldano SLO 100 stands tall as a formidable fire breather that has logged as many star guitarists’ licks as nearly any head in the field. From the early to mid ’80s, Michael Soldano roughed it between his native Seattle and Los Angeles, working to establish himself as an amp maker to the stars. He finally crushed it big time in 1987 with the amp that would become the SLO (for Super Lead Overdrive) 100.

After placing a prototype in the hands of Heart guitarist Howard Leese, Soldano - who had taken a roadie gig to stave off bankruptcy - returned home one night to hear messages on his answering machine from Lou Reed, Michael Landau and Vivian Campbell. They all wanted to buy his amplifiers. A few months later, Soldano could claim guitarists Eric Clapton, Mark Knopfler and Matthias Jabs as customers. Guitarists like George Lynch, Gary Moore, Joe Satriani, Steve Vai and scads of others followed soon after.

If Soldano’s early design was inspired somewhat by the Mesa/Boogie Mark II of the early ’80s (which he had cloned in a formative DIY effort), the SLO 100 nevertheless exhibited a personality all its own. Similarly driven by a cascading-gain preamp structure in Overdrive (lead) mode, it delivered a thickness that filled out the high-gain sizzle, and a juicy, touchy-feely playing sensitivity that really hooked soloists. As its list of users suggests, the SLO 100 wasn’t designed to be a heavy-metal amp, although it qualified as a high-gain beast in its day and could lean into classic renditions of that territory when urged. 

Soldano’s intention was to deliver rich, harmonically saturated gain and great dynamics for the full gamut of rock lead players, and for most such artists the proof was in the pudding. In Overdrive mode, the guitar signal passes through four stages of 12AX7-driven gain before hitting further tube stages that comprise the buffered FX loop. This is followed by a tone stage (shared with the clean channel) derived from a modified Fender Bassman topology, a very different tone-stack placement than that of the Mesa/Boogie Mark II.

The master volumes for both channels fall after the tone stage but before the phase inverter, which might make them sound less hip than the PPIMV (post-phase-inverter master volume) controls that are all the rage today. That said, Soldano’s master reined in the preamp grind as necessary, though you could still crank it up and feel the earth rumble. In any case, the classic Mesa/Boogie Mark Series amps, Marshall Master Model 2203/2204 and several other legendary rock amps all used pre-PI masters and suffered little from doing so.

Big rock heads can be a flavor of the month kind of thing, and several early star SLO players did cycle through to other amps. However, the Soldano artist roster continued to grow apace over the decades and now reads like a veritable who’s who of guitar gods from across the wide gamut of rock, metal and contemporary blues. Since Michael Soldano’s retirement from amp manufacturing last year, prices for his amps have soared on the used market. Good luck to the rest of us getting our hands on one.

ESSENTIAL INGREDIENTS

> Four 6L6GC output tubes generating around 100 watts RMS
> Two channels: Normal and Overdrive
> Four 12AX7 preamp tubes
> Cascading gain stages in Overdrive mode
> Master volume controls for both channels
> Solid-state rectification

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