It was, in the end, left to the long-time music director of the Israel Philharmonic Orchestra, Zubin Mehta, to put his finger on what was being celebrated.

On a cool, clear night in Tel Aviv last month, Maestro Mehta, himself celebrating 50 years with the IPO, led hundreds of international patrons and well-wishers in a rousing chorus of "Happy Birthday, dear Philharmonic", as the orchestra marked its 75th anniversary.

But as the cheers died down, it was Mehta who reminded his audience of the very real human sacrifices which had been made when the orchestra was founded in 1936 by violinist Bronislaw Huberman. Huberman, who famously persuaded Arturo Toscanini to conduct that first concert on December 26, 1936, had paid, "out of his own pocket", recalled Mehta, "for around 80 musicians and their families to come from Europe". They became what was originally the Palestine Philharmonic Orchestra and, by Huberman's action, were certainly rescued from the Holocaust. "Many more did not make it," said Mehta, asking his audience to remember those doomed musicians.

It was a telling reminder of the founding of a unique orchestra, which in its 75th year is undergoing yet another convulsion and transformation - almost taking it back to its roots. In those first uncertain days, the Polish-born Huberman was faced with creating an orchestra out of a Babel of European individuals. The main languages spoken were "German, Polish, Hungarian and Russian, with a little Hebrew spoken by the youngsters". These days, of course, there is a fair amount of Russian spoken among the 107 permanent members, although both the longest-serving musician, trumpet player Ilan Eshed, who has been with the orchestra since 1968, and its newest member, principal bassoon player Daniel Mazaki, who joined just last October, are both Israeli-born.

But, now as then, the orchestra is camping out, this time waiting for a return to its permanent home at the Mann Auditorium in Tel Aviv.

Avi Shoshani, the secretary-general of the IPO, dressed from head to foot in Issey Miyake, shrugs good-humouredly when asked about the difficulties facing an orchestra without a proper base. "We are promised a return to the Mann in December 2012," he says, noting that among the major renovations taking place will be the building of 1,400 square foot of offices under the main auditorium, with proper dressing rooms for the musicians and the guest artists, as well as newly-appointed adminstration and teaching areas.

For now, however, and for the next year, the venerable IPO is making the very best of the most difficult of circumstances, playing out of two temporary venues: the Smolarz Auditorium on the Tel Aviv University campus, and the unimpressively named Hangar 11 at Tel Aviv Port. It is fair to say that Hangar 11 was not designed for a classical orchestra and its audience. Vast and cavernous, with the seating laid out on the flat rather than the usual rake, the area was at least cheerfully decorated during the anniversary concerts with huge reproductions of posters from seven decades of the IPO's work.

But for the first time, at Shoshani's initiative, the celebration concerts and the music of the stellar guest artists were streamed live on the internet. The filming of the concerts and the transmission of some of them on Israeli TV necessitated both hot Klieg lights and the turning off of the air-conditioning in the hangar. For some of the musicians, it was just too much: artist after artist took to the stage in cool confidence, only to end up fiercely perspiring. The master violinist, Pinchas Zukerman, was an unfortunate victim: during his performance of the Beethoven Concerto in D Major, he desperately mopped his brow and his violin. Pianist Evgeny Kissin, his shirtsleeves flashing treble clef cufflinks, strove manfully to avoid dripping sweat over his Steinway grand piano; while the 20-year-old pianist, Daniil Trifonov, seemed virtually to be dissolving as he hunched over the keyboard.

Trifonov, it seems clear, is at the beginning of a long relationship with the Israel Philharmonic. Musicians, once they encounter the orchestra, frequently fall in love with it. Zukerman, 64 this year, first played with the IPO when he was 12. "It was a youth concert. I played the Mozart B Major concerto. I heard the orchestra a lot when I was nine or 10, my father used to take me to the concerts," he said. "Then, after I had studied in the US, I came back to play in 1968."

For the ever-amiable Zukerman, the relationship with the IPO "is something ongoing. We just do it. We come and play. The orchestra is a symbol of something very profound, to do with the country itself. A lot of it is Zubin, but some of it is simply the music and the striving for freedom of expression that is part of Israel's DNA. You can't really explain in words the power of the music, how it takes over. That's what the orchestra is, a powerful symbol of what this country is about, brought to life by extraordinary circumstances in the 1930s. It's changed its personnel, but it's not changed its core. That's what's important."

The Russian-born Trifonov is the son of musicians - his father is a composer and his mother a teacher of music theory. He entered music school when he was just five. By the time he was 14, and had broken his left hand so that he could not practise for three weeks, Trifonov knew the piano was his instrument. "I was really suffering without the piano. It was torture for me."

Crouched before the grand piano on the night of one of the IPO concerts, Trifonov initially looked scarcely able to cope. Skinny, floppy-haired, and wearing a suit that looked too big for him, he elicited a near-universal "aww" from orchestra and audience. Until, that is, he began to play. The orchestra, who knew what was coming after a scintillating morning rehearsal, nevertheless almost discernibly sat forward and rose to the occasion. Zubin Mehta looked transported. After rapturous applause, he leaned over and offered the pianist an encore. The audience went wild.

Both Pinchas Zukerman and Avi Shoshani are flag-wavers for improving music education, not least because classical orchestras are such an expensive model to maintain.

"Perhaps orchestras are at a crossroads now," said Zukerman. "While there is an economic downturn, there is a need to re-vamp the system. I hope we can do more outreach programming, and particularly using technology, such as the live streaming of the concerts. That's what we need to do to sustain the product we have, but it is difficult. How do you tell Oklahoma to listen to the Israel Philharmonic? Sustainability is what it's about. It's not a question of how much money you have, it's how you spend it. How important is culture, that's the question."

Avi Shoshani, in his orchestra's 75th year, has no doubt: he will go on doing everything possible to bring in a younger audience and educate youngsters. "I strongly believe the government has a responsibility to help in this matter," he says.