It is the biggest specialist music school in the UK, producing more winners of the BBC’s Young Musician of the Year competition than its rivals, and boasting a medieval library where Friedrich Engels and Karl Marx once studied. But when Alun Jones took over as head of Chetham’s school of music in Manchester last year he inherited an institution with a troubled reputation.

The private school, where boarding fees are £31,713 per year, was recovering from a sexual abuse scandal which resulted in the jailing of its former head of music and the suicide of a violin teacher who had been due to face 77 charges of sex offences against 10 former pupils.

Jones, a trained chorister who joined after tenures at the Girls’ Schools Association as its first male president, and St Gabriel’s school, Newbury, where he was head, insists Chetham’s was actually in “exceptional health” when he joined. The safeguarding procedures had been ruled as “impeccable” by inspectors and on Friday the school will celebrate the opening of its new concert space, the £8.7m Stoller hall.

But in his first interview since taking the post Jones acknowledged that Chet’s, as it is known to staff and pupils, had been through a “very tough time”.

“The school and its leadership at the time had to steer the ship through a huge time,” he said. “But from my point of view I have inherited a school in exceptional health, always looking back with care at the students and anyone in our family who was hurt. But my job is also to make sure that any lessons that had to be learnt have to be learnt.”

Chetham’s hit the headlines for the wrong reasons in January 2013, following the suicide of former pupil, Frances Andrade. She had just given evidence in court against Michael Brewer, the school’s former head of music, who abused her when she was a pupil. He was eventually jailed for six years after being found guilty of sexually assaulting Andrade when she was 14.

A torrent of allegations followed, against music teachers at Chetham’s and the nearby Royal Northern College of Music, where many Chet’s pupils go on to study. Some teachers were already dead, some were eventually exonerated.

An extradition request was made for Chris Ling, a “svengali-like” figure who married one former Chet’s pupil and took a group of sixth formers to America with the promise to make them stars. He killed himself in September 2015 when Californian law enforcement officers arrived at his home to arrest him. He would have faced 77 charges of sex offences against 10 former pupils at Chetham’s when they were as young as nine, as well as a woman who cleaned his house as a teenager.

Former students told the Guardian of being abused in dark corridors and practice rooms, most of which are no longer used after the modern school extension opened in 2012. “This school is absolutely designed with safeguarding concerns in mind. The school is all glass. Glass doors, glass walls that are inward-facing. You can stand in the atrium and look straight up into the teaching rooms,” said Jones.

“The school that you are finding today is full of optimism. And the new building, the world-class concert hall that we are about to open, is just one reflection of the huge optimism that the school is feeling.”

On Friday a concert by Chet’s alumnus, jazz pianist and composer Gwilym Simcock, will mark the opening of the Stoller hall, the first major concert venue to open in the north of England since the Sage Gateshead opened its doors in 2004.

Built with funds including a £7.5m donation from Sir Norman Stoller, who made his fortune in nearby Oldham with his father’s invention of the tubular bandage, the hall has significantly better acoustics than Manchester’s Bridgewater Hall. Though right next door to Victoria station, there are no rumbles from passing locomotives. Sound engineers from Arup have used asymmetric solid oak panelling with the perfect finish to best reflect the music, and designed the seats to give the same acoustic result to all members of the audience. Underneath the stage is a humidity-controlling storage area for the school’s rented £130,000 Steinway piano.

Above the seats are a series banners which can be retracted to change the reverberation of the space by nearly a second — a huge amount of time in orchestral terms.

“If you are doing a large orchestral piece of music we can drop them in and dampen down the sound, if we are doing string quartets or smaller chamber stuff we can take them out and really gets the sense of the space. It goes from a 3.5 second delay to a 2.5,” said Richard Hartwell, Stoller’s general manager.

Pupils will be allowed to practice in the hall for around two-thirds of its operational hours. “The perfect acoustics will really force the children to raise their game,” said Jones, who insists that despite the bad publicity, the school has not suffered a drop in popularity. “Interestingly, if one is to be incredibly cold about it, as far as recruitment numbers are concerned, the opposite is true,” he said. “Because in fact numbers have remained incredibly strong and the school is highly successful. And for that I am very grateful. I think that shows the level of care my staff have given to the students through the period of time that the school enjoyed those tough moments. But at the same time nobody is complacent.”