Did a tone-obsessed fan, a legendary '70s inventor, and a Guitar Player Magazine interview finally crack the code of Angus Young’s unmistakable sound?

It all started with a mystery and ended with a breakthrough that changed the tone game forever.

For over three decades, Fil “SoloDallas” Olivieri chased the elusive tone heard on AC/DC’s Back in Black—a sound so raw, powerful, and expressive that it shaped the blueprint for hard rock guitar. Fil meticulously recreated Angus’s gear chain, but something was always missing.

That missing piece? The Schaffer-Vega Diversity System, a wireless unit designed by ’70s tech pioneer Ken Schaffer.

The Clue Hidden in Plain Sight

The turning point came when a contributor on the SoloDallas blog unearthed an old Guitar Player Magazine interview in which Angus revealed:

“I don’t use any [effects]… I only use a Schaffer Vega wireless.”

Why would a wireless unit be used in the studio, just feet from an amp? That question launched a journey of obsession and innovation. Fil reached out to Ken, who was so impressed by Fil’s dedication that he sent him two original SVDS units—his last.

The Revelation

When Fil inserted the SVDS into his signal chain, the result was instantaneous:
The “Back in Black” tone was there.
The compression. The harmonics. The unmistakable punch.

But Fil didn’t stop there. He assembled a team of engineers to reverse-engineer the original SVDS audio circuitry, resulting in The Schaffer Replica—a pedal that brings Angus’s classic studio tone to modern players everywhere.

From Myth to Reality

What began as a mystery is now a movement. The Schaffer Replica has become a cornerstone for players chasing that rich, vintage tone—now joined by the entire SoloDallas pedal lineup, including the brand-new Orbiter Fuzz and BASS-X.

Ready to Get the Sound of Legends?

Whether you're chasing Angus’s crunch or building your own signature tone, SoloDallas pedals deliver the magic.

Vintage Tone. Modern Craft. Legendary Pedals.