SYDNEY - A serial Sydney pedophile has been given a maximum sentence of 32 years in jail for abusing four boys over three decades, a Sydney judge handed down his decision in court on Monday.

Victims and their families wept and cheered in the public gallery as Judge Michael Finnane handed down the sentence to Andrew Dean McIntosh.

The 53-year-old man was found guilty on more than 40 counts of abuse.

Of those, 24 were related to the sexual and physical abuse of students at Barker College, in Sydney's north, in the early 1990s when McIntosh worked there as a volunteer cadet master.

Early offenses were committed from the late 1970s onward in Inverell and Grafton in northern New South Wales.

In the Downing Center District Court in Sydney on Monday, McIntosh was sentenced on all 42 charges to 32 years in prison with a non-parole period of 20 years.

"The damage done by the offender has been great and his criminality is great," Finnane told the court.

"The sentence is also served to protect the community for a considerable period and that is an important objective," he said.