A man who engaged in "callous, premeditated and planned" attacks on two women in Adelaide and told one of his victims not to walk home alone anymore has been jailed for 12 years.

Patrick Mark Perkins subjected his rape victim to violence of the most degrading nature, Judge Julie McIntyre said while sentencing the 59-year-old in the District Court today.

"To add insult to injury, your words to her suggested that she was in some way to blame for your violent act," she said.

"She was not. She was entitled to walk home alone without being molested by you.

"The blame is yours and yours alone."

Judge McIntyre said Perkins had selected his victims and the location for his attacks carefully.

The first was on September 6, 2012, when he accosted a young woman walking home alone at North Adelaide.

Patrick Mark Perkins subjected his rape victim to violence of the most degrading nature. (9NEWS)

He pushed her to the ground and engaged in three sex acts in an attack that lasted little more than 10 minutes.

"You then said something to the effect of 'there's a good girl, don't walk home alone anymore by yourself. You can go home now'," the judge said.

The woman believed Perkins was going to kill her and said his attack had brought her endless pain, sorrow and fear, the court heard.

Perkins' second attack was in November the same year, but this time his victim managed to fight him off, suffering bruising and scratches.

Judge McIntyre said Perkins had no prior offences, had grown up in a good family who remained supportive and was considered to be of good character by a number of people who knew him.

"All of this makes your brutal assaults on these two vulnerable women all the harder to understand," she said.

"You have not offered any explanation for your behaviour.

"Indeed there is no obvious reason for your offending other than the callous determination to obtain sexual gratification."

Perkins had pleaded guilty to three counts of rape and one of assault with intent to rape.

The judge set a non-parole period of eight years, backdated to July 2015 when he was first taken into custody.