Bryan Redpath’s side completed their regular-season campaign with a 33-20 win over Ealing Trailfinders – the team they now face in the semi-finals.
With leaders London Irish winning at fourth-placed Doncaster Knights on Saturday, they prevented the South Yorkshire club snatching third from Ealing.
Carnegie were already certain of second spot before kick-off and Redpath duly made a dozen changes.
But blindside flanker Beck, who scored one of the club’s five tries, said: “I thought it was a really good performance.
“There were a few lads that had not played for a while and haven’t played together that much, but to get a result like that and play the way we did and defend the way we did was pleasing. It was a good team performance.
“There probably wasn’t anything to play for league wise, but there was a lot personally. It might be a few of the lads’ last game for the club and we wanted to carry the momentum from the past two weeks into the play-offs.”
Promotion-chasing Carnegie head to Ealing for the first leg on Friday April 28 before the return at Headingley on Friday May 5 as they seek to make up for the disappointment of losing to Doncaster at this stage last year.
Beck, who was named man-of-the-match, said: “This victory won’t mean too much when it comes to the play-offs but it’s nice to get a win. There’s probably not a lot we’ve learned that we didn’t already know.
“They’re a pretty physical side who like to throw the ball around a bit but we stopped their line-out maul quite well which is a big weapon for them.”