Murphy, who signed a two-year-deal with the Magpies just three days before transfer deadline day, returns to the North-East following a five-year spell with rivals Sunderland.
And the 33-year-old has revealed how reluctant Ipswich gaffer McCarthy was to let him go.
The forward said: “Obviously it wasn’t easy, but as I said to the manager, I said, ‘I can’t turn down this opportunity, it’s not going to happen to me again’, and I think he understood that.
“Obviously he didn’t want me to go, but I think he understood that I’m not going to get that chance again.”
Murphy enjoyed a prolific spell with the Tractor Boys following his permanent move from Celtic in 2013, bagging 50 goals in 123 games.