The prospect of 34 concerts from as many different youth orchestras might seem too much of a good thing, but the 20th British Festival of Youth Orchestras embraces diversity. Over the past month the gaunt space of the Central Methodist Hall in Edinburgh has been filled with the sound of symphony orchestras, wind bands, chamber music, jazz groups and percussion ensembles. The music has ranged from unknown concertos to masterpieces of the symphonic repertoire.

The festival opened with considerable panache from Hertfordshire’s County Youth Orchestra. Hertfordshire has a huge county music service, with 500 teachers and 24,000 pupils receiving tuition. The youth orchestra draws its players from subsidiary school and area orchestras and represents the pinnacle of achievement in this musical part of England.

It attracted nearly a full house for a performance that was in many respects wholly professional. Mahler’s Fifth Symphony is a serious undertaking for even the most accomplished orchestra, requiring deep reserves of strength and virtuosity. There were some awkward moments: a scrappy pizzicato chord at the end of the first movement, a wandering horn in the second, a false entry in the third. But in a performance with abundant energy and clear direction, mistakes such as these are mere blips in the onward thrust of the music.

It is only when mistakes accumulate that they threaten to destroy a performance.

Sadly, 24 hours later the audience all but failed to appear. Officials from the National Association of Youth Orchestras, which runs the festival, urged us to scatter around an auditorium which suddenly seemed very large.

Admittedly there was little in the 20th-century programme offered by the Manchester University Wind Orchestra that would appeal, at least on paper, to a mass audience.

But Nigel Hess’s Global Variations, a brisk canter through the noises, rhythms and melodies of the world, and Martin Ellerby’s Paris Sketches were both well crafted, lightweight pieces whose buoyant performances would find ready fans.

Ellerby’s Tuba Concerto was less successful. It is difficult for a tuba to cut through the orchestral texture; against a wind orchestra it is well nigh impossible, with the result that Andrew Oliver’s spirited attempt to play the fiendish solo part sounded as though a huge bumble-bee was annoying the orchestra.

James MacMillan’s Sowetan Spring, written to commemorate Nelson Mandela’s release from prison, is a tougher proposition, with a vigorous percussive element and fiercely declaimed climaxes. It received a nicely judged performance that should impress the adjudicators of the Boosey and Hawkes award for the best performance of a work on a specially selected list.

The professionalism of the Manchester students led me to expect a similar quality from the Southampton University Sinfonietta. This small orchestra played its premiere of Daniel Field’s Danses Concertantes, framed by a Mozart overture and symphony, at St Giles Cathedral. This is quite a different venue from the Methodist hall, in the thick of the tourist crowds and offering free admission, a combination of factors that has made it popular with youth orchestras. Music in such a setting should be a showcase of talent but this was a dismal concert whose lack of commitment and energy was compounded by lapses of intonation.

Back in the Central Methodist Hall the following day, the Glasgow Schools String Orchestra played with rather more enthusiasm but for the most part the performance hovered too close to the abyss for comfortable listening.

The Dittersdorf double bass concerto started well enough but almost collapsed after the entry of the soloist. Some of Walton’s film music for Henry V drifted into chaos, and in the opening Millennium Suite, one of the three different composers unwisely (and rather unfairly) scored a drifting, glissando bass part whose atonal conflicts could not be differentiated from inaccurate playing. Then suddenly emerged a robust and entertaining Concerto Grosso by Vaughan Williams, which showed that this orchestra can play well when it knows what it is doing.

Unfortunately the orchestra dropped a performance of Eddie McGuire’s Divertimento II from its programme, owing to an indisposed second viola. It is in the nature of youth perfomances that this sort of thing happens if no substitute can be found, but it must have been embarrassing since the composer had come along to hear it.

The West of Scotland Schools Symphony Orchestra shares a few players with the Glasgow Schools String Orchestra, but its standard of performance under the direction of William Conway was immeasurably better.

Conway, who made his name as principal cellist of the Scottish Chamber Orchestra, conducts with a clear beat and few gestures, but extracts performances of great cohesion and no small amount of style.

This large band, previously the showcase orchestra for Strathclyde Region but reformed under the management of Strathclyde University, boasts some excellent players, including Martin Suckling, whose dizzy violin solo in Rimsky Korsakov’s Scheherazade was near perfect, and principal woodwind players who made the most of beguiling orchestration.

This ambitious concert also included Copland’s Billy the Kid ballet suite and Unity and Conflict, a concert overture by Ronald Walker (the orchestra’s course director), whose treatment of an old pipe tune was pure kitsch but great fun.

Despite the diversity of the youth festival, there were elements which were common to many of the concerts.

One was the almost obsessive attention to tuning up, an operation that professional orchestras dismiss in seconds but which occupies a youth orchestra for an eternity.

Another was the tendency to simply play for far too long. Patrons of the Edinburgh International Festival were content to hear just Mahler’s Fifth Symphony in a concert by the Pittsburgh Symphony Orchestra, but the Hertfordshire County Youth Orchestra prefaced it not only with Debussy’s La Mer but also a substantially lengthy piece by the American composer Irvine Fine.

In some instances programme notes were woefully inadequate or absent, a shortfall that is particularly irritating when contemporary music is involved.

Given the huge effort that goes into scheduling this festival in Edinburgh and Glasgow, where most of the concerts are repeated, perhaps these points will help to make next year’s festival even more enjoyable.