Significant buildings generate their own mythology. For the Sydney Opera House, the story that the Unesco world heritage-listed design was fished out of a rejection pile before being declared a work of genius is a pleasing fable, despite its dubious origins.

What is not in dispute is that the clashes that plagued the Opera House’s origins have reverberated – not always pleasingly – down the decades. The ambition of the Danish architect Jørn Utzon’s design, his walkout mid-project, and Peter Hall’s subsequent takeover in 1966 resulted in compromises that have bedevilled the building ever since.

Now, as part of a five-year program in which the Opera House has been progressively upgrading its core infrastructure, construction is about to begin on a $150m revamp of its largest performance space, the 2,500-seat concert hall, designed to remedy the shortcomings born of the project’s messy origins.

The irony of the Sydney Opera House is that it has become an international cultural landmark for the way it looks, rather than for being “the best opera house that can be built”, as the New South Wales premier Joe Cahill hoped when he launched the design competition in 1954.

It is very far from the best in the eyes, and ears, of some who have experienced it at close quarters. The actor John Malkovich once said the acoustics in the concert hall “would do an aeroplane hangar a disservice”. Members of the resident Sydney Symphony Orchestra have long complained that they cannot hear their fellow musicians on stage. And the rise of the rock concert has further challenged the venue, with amplified music and electronic sets being precisely the opposite of what the hall’s infrastructure was built to accommodate.

New automatic drapes and improvements to the weight capacity of the concert hall roof will reduce artistic compromises and pre-show manual labour. Photograph: Brook Mitchell/Getty Images

A multipurpose hall designed as a ‘big echo chamber’

“The problem with our concert hall is that it was originally designed to have a grid, a flying system [theatrical rigging] above the stage so it could be used for opera and plays. It was called a multipurpose hall,” says Louise Herron, the Opera House’s chief executive.

That concept was thrown out midway through construction – after Utzon’s enraged departure – and the objectives of the building’s two main venues were switched. Operas and plays were moved to the smaller Joan Sutherland theatre, where rigging was installed to support theatrical performances, and the concert hall was decked out for classical music instead, the justification being that symphonies would be more popular.

But, at 45 metres, the concert hall is at least 10 metres longer than most acoustic-oriented spaces, and double the optimum height. As a consequence, much effort has gone into compensating for its cavernous proportions, including wood-panelled walls to aid reverberation, and fibreglass acoustic reflectors hung from the roof to create a sonic ceiling.

But in the years since it was built interest in symphonies has been challenged by the ubiquity of pop, hip-hop and rock. While rock bands – including Massive Attack and the National – are often set up in the outdoor forecourt, acts including Lizzo, Interpol, Nick Cave, Iggy Pop, the Wu-Tang Clan, José González and Hot Chip have played the concert hall.

They take some wrangling.

“The shows that we currently put in there were never in the initial scope for the hall,” says Andrew Mackonis, Sydney Opera House’s production manager. He leads a team of nine.

“Essentially it’s designed to be a big echo chamber, and that’s the opposite of what you want when you’re doing an amplified event,” he says. “You want the space to be as dead as possible. You have these two diametrically opposed ideals.”

The space has had multiple smaller upgrades along the way to help it cope, including a high-quality PA system being installed and heavy drapery created to hang over the wood panelling. But the process of getting the hall ready for an amplified show is cumbersome – the drapes alone take hours to install – and the PA system is long past its prime.

Louise Herron says the concert hall project aims to not only preserve the venue’s heritage but also help prepare it for the next 50 years. Photograph: Dean Lewins/AAP

The other problem is weight. Contemporary musicians, especially dance acts, will often tour with complicated sets – big LED walls and lots of light production, in addition to their sound requirements. That all has to hang off the roof – which at the moment can only support 10 tonnes.

‘The Opera House belongs to everyone’

“You could say we are the masters of the compromise,” Mackonis says. “Between budget, safety, timeline and the artistic values of the show that we’re putting in there, we are the ones who have to find the compromise.”

He hopes the increased weight capacity of the roof – up to 38 tonnes when completed – will mean compromising fewer artistic visions, and that the new automatic drape system will cut down on pre-show manual labour.

But that’s not all. The stage, which is now flat and fixed in height, obscuring the view from the stalls in favour of the boxes, will be put on multiple hydraulics. This will allow it to be elevated in sections, to give it the traditional orchestral horseshoe shape – helping the musicians to hear one another – or raised or lowered entirely if required. The boxes will be reoriented to reduce competition with the sightlines from the stalls, and more accessible seating and passageways will be installed.

In measures aimed at further improving sound for classical performances, the fibreglass acoustic reflectors on the roof will be upgraded, and new wood panelling with a rippled surface will replace the flat timber walls, to give what Herron calls “a softer, more surrounding sound – a truer sound”.

The singer Solange will perform the last concerts in the space this year on 31 January, though her health has reportedly reduced what was originally a four-night residency to two. Once the show is bumped out, the concert hall and sections of the viewing deck will be boarded up for a full two years while the work takes place.

While some sections of the community may balk at the idea of a heritage venue hosting hip-hop artists and electronic dance acts – especially given the scale of the works required to accommodate them – Herron is firm about the necessity of the Opera House moving with the times.

A rendered image shows what the new concert hall will look like after the biggest upgrade in its 46-year history. Photograph: Dean Lewins/AAP

“The Opera House belongs to everyone,” she says. “The Opera House needs to cater to all of the community, not just certain sections of the community.”

The numbers suggest this strategy is solid: Herron says 40.7% of the 1.4m tickets sold in 2019 were for contemporary music and performance.

“We need to not only maintain our fabulous heritage but we need to be as prepared as we possibly can be for the next 50 years. What is it that audiences of now and the future are going to want and how can we best prepare the Concert Hall for that? That’s been the driving force behind our approach.”

Herron says she expects the Opera House to take a $20m hit to its revenue during the concert hall’s closure, but believes that – as when its smaller venue, the Joan Sutherland theatre, closed for eight months for renewal works in 2017 – audiences will ultimately reap the rewards.

“The Sydney Symphony Orchestra has wanted the concert hall acoustics to be improved since it opened,” she says. “You could say it’s a project that’s been in the works for 47 years.”