Years earlier, Hartstone joined Tauranga band The Four Fours, who had a hit in 1965 with the instrumental ‘Theme From An Empty Coffee Lounge’. He used his electrical engineering skills to develop on-stage gimmickry such as mounting gooseneck microphones on the horns of their guitars, giving the band members freedom to roam the stage.
In 1966 The Four Fours were support act for The Rolling Stones and The Searchers in Wellington and Auckland. A few short months later they headed to the UK aboard ocean liner Fairsky, changing their name to The Human Instinct.
After 18 months on the live circuit in the UK playing alongside acts including The Spencer Davis Group and Manfred Mann, the band, exhausted and broke, decided to return home.
Hartstone stayed on in the UK, using the band’s sound system to start an innovative PA company.
Hartstone stayed on in the UK, using the band’s sound system to start an innovative PA company, which provided systems to larger venues and grew with the advent of arena sized shows. Early clients included acts at the Marquee Club in London, the first Isle of Wight festival in 1968, and later, Emerson Lake & Palmer.
As suppliers to US-based Heil Sound, Hartstone's company International Entertainers Services (IES) provided equipment and engineering expertise to large concerts by The Grateful Dead and The Who's Who's Next and Quadrophenia tours.
Back in the UK, IES professionals supplied a PA system and personnel to the 1974 Knebworth Festival (also known as The Bucolic Frolic) that included Van Morrison, the Doobie Brothers and The Allman Brothers Band in front of a 60,000-strong audience. The PA at Knebworth was described as “state of the art and incredibly loud”.
Hartstone’s career in music spanned the instrumental rock and roll of the 1950s through to 1960s psychedelia and the rise of festivals and the big arena shows of the 1970s. His innovative approach to sound design kept pace with the growing demands of the live music industry and assured him a place of recognition in music history.