The swaggering riff that opens AC/DC's breakthrough. Angus Young plugged a 1968 Gibson SG Standard straight into a cranked Marshall 1959 Super Lead Plexi — no pedals — and producer Mutt Lange shaped it into a tighter, glossier sound than the band's earlier records at Roundhouse Studios, London. Angus's Schaffer-Vega wireless added a subtle preamp boost that tightened the top end. Standard tuning; the swagger is in the right hand.