An Adelaide trucking company boss has been jailed for 12 and a half years over a driver's death caused by faulty brakes.

Peter Francis Colbert, 56, was found guilty of manslaughter over the death of driver Robert Brimson in March last year.

Mr Brimson took action to avoid heavy traffic on Main South Road at Happy Valley in the moments before his truck slammed into a pole.

A jury also convicted him of endangering the life of another driver, Shane Bonham, two days before the fatal crash.

The Supreme Court heard Colbert was repeatedly warned about the truck's faulty brakes.

Justice David Peek said Colbert was a risk-taker on the road who thought he would have survived such a brake failure.

Justice Peek quoted extensively from a psychological report during the hour-long sentencing.

He described Colbert as a narcissist who had misplaced arrogance and self-confidence, particularly about his driving abilities.

He said Colbert told the psychologist he could have survived such brake failure if he was driving.

"I can bet you though that 10 to 1 that I'd still be sitting here talking to you if I did drive the truck that day," Colbert said.

"I don't expect people to do what I can do with a truck.

"The truth is most of the blokes I deal with have no skill.

"To be honest I'm still trying to figure out why he [Mr Brimson] hit the post ... I wouldn't have gone near that.

"It's instinct, you've either got it or you don't.

"But he did save other lives so I can't knock the bloke."

Justice Peek said Colbert continues to deny any knowledge of the truck's faulty brakes, despite the jury verdicts.

"Mr Colbert maintained that no one under his employment had brought the issue of the faulty brakes to his attention prior to the fatal accident," he said.

He said Colbert had characterised himself as a "thrill seeker" on the roads who liked to speed, and admitted to driving from Adelaide to Melbourne in six hours.

Driver's final moments recorded on dash cam

Justice Peek said Colbert also told the psychologist that he once did the 50-kilometre journey from Salisbury in Adelaide's north to Mount Barker in the hills in under 20 minutes.

"A major concern here is that ... you purport to claim a positive right to drive however fast you like," Justice Peek said.

"Such driving is only performed with a high level of danger to members of the public who might emerge in the path of your vehicle."

Robert Brimson died when the truck he was driving crashed into a pole in March last year.

The final moments of Mr Brimson's life were recorded by a dash board camera in the truck.

The judge read out his final words before the vehicle crashed into the pole.

"Oh [expletive] brakes," Mr Brimson said.

"Where am I gonna [expletive] go.

"I've got nowhere to [expletive] go."

Colbert took over the Green Fields trucking company in January 2014 after its previous owner went bankrupt.

Before that, Colbert worked as a driver in the same truck involved in the fatal collision.

The court heard the truck was used five days a week and had clocked up more than 800,000 kilometres by the time of Mr Brimson's death.

Colbert jailed for previous offences

Colbert was jailed for nine years in 1998 for the rape, attempted rape and gross indecency of two women.

The court heard in both offences Colbert approached the women in public and threatened them with a bladed weapon.

He received a two month suspended sentence for driving offences in 2012.

Justice Peek said there was a troubling theme common to Colbert's past and present offending.

"[That is] of a lack of concern on your part for the effects that your conduct will have on other people," he said.

Colbert stood slumped in the dock and stared at the floor during the sentencing, and showed little emotion.

The sentence comes with a non-parole period of 10 years.

Colbert has been banned from driving until further court order.