Perth-based music megastore Kosmic Sound has closed its doors after more than half a century of business.

Selling musical instruments and equipment for 51 years, most recently out of Osborne Park, Kosmic built a reputation as a popular institution for WA musicians.

A notice attached to the Hector Street West shop front and posted online revealed the store’s end and sparked an outpouring of shock by long-time customers.

“Dear customers, sadly Kosmic is in liquidation,” the message from owner John Goldsmith, pictured, said.

“We apologise that we currently are unable to serve you. Rest assured we are in discussions with parties in the hope that Kosmic will soon be resurrected.”

Kosmic was named in the world’s top 100 music stores by the National Association of Music Merchants in 2015 and was turning over around $16 million a year.

Camera Icon John Goldsmith. Credit: Sharon Smith / WA News

Mr Goldsmith started the business in his mum’s Hamilton Hill shed, later moving to Rossmoyne, then Bentley before finding a permanent home in Osborne Park.

A suspicious fire in 2001 caused about $750,000 damage and almost crippled the business, but Mr Goldsmith bounced back.

Replying to the announcement of the Kosmic’s closure, one man it was “sad news” for the store.

“Kosmic has had its doors closed after 51 years in operation. It’s even more heartfelt for me, as the place that gave me employment, wisdom, networking, clinics and a tonne of opportunity to develop my skills for more than a decade,” he said.

“The reality is that there are many factors that would have contributed, not just the typical 'online shopping' scapegoat.”

The liquidation of one of the biggest musical instrument stores in Perth follows the closure of Billy Hyde Music in North Perth a few years ago.