A man who fatally stabbed his uncle amid the fall-out over the theft of a rare bass guitar has been jailed for a decade.

Karl Lamblin once had a warm relationship with Paul O'Donnell, but that bond deteriorated and was further soured when Lamblin stole his uncle's guitar in June last year.

A friend later returned the guitar to its owner, the Supreme Court heard on Wednesday, but Lamblin was angered by that and, on the night of June 18, confronted Mr O'Donnell at the Keysborough factory where his uncle repaired BMWs and occasionally stayed with his partner.

Lamblin had at least one knife with him and stabbed his uncle above the left hip, piercing the abdomen. He fled when his uncle's partner pushed him away with a vacuum cleaner.

Mr O'Donnell, 48, died at the scene from blood loss.

Lamblin, 33, who had been using the drug ice in the days before the death, was arrested five days later in a house in Doncaster.

He was charged with murder but later pleaded guilty to manslaughter.

Justice Terry Forrest said Lamblin was frequently disruptive and disrespectful as a child and was diagnosed with attention deficit hyperactivity disorder.

He got his life in order in his late teens and 20s when he qualified as a boilermaker and had regular work with engineering firms.

But, Justice Forrest said, Lamblin allowed drugs to compromise his life and after a stint of living in Queensland, returned to Victoria with an ice habit.

The court heard Lamblin told a psychologist he'd stolen his uncle's guitar in an attempt to bait Mr O'Donnell into talking about their relationship.

But Justice Forrest did not accept Lamblin went to the factory to talk.

"People who wish only to converse do not arm themselves with knives," the judge said.

"I am satisfied beyond reasonable doubt that you contemplated the possibility of violence and when things got physical, you unlawfully took your uncle's life."

Justice Forrest said Lamblin had been arrogant and unapologetic when interviewed by police, but had belatedly shown remorse.

He was now off drugs in prison and his rehabilitation was dependent on whether he could maintain that.

But he retained the support of family despite his crime.

"Your family will never completely recover from what you have done," Justice Forrest told him.

Lamblin must serve seven years in jail before he is eligible for parole.

With AAP