AS the voice of Led Zeppelin, Robert Plant redefined the scope of rock music.

On “Dreamland,” his new solo record out Tuesday, he dusts off old rock songs for a contemporary audience.In a conversation with The Post from his home on the rolling hills on the Welsh border, the 54-year-old singer seemed a total gentleman – hardly what you’d expect from a guy who sowed acres of wild oats in his chaotic younger days in Led Zep.

When asked how he’s changed over time, he paused thoughtfully – as if he’d never considered he was a day older than when he first met Jimmy Page, John Bonham and John Paul Jones.

“I’ve gotten a bit more patient, I suppose,” he said.

“I lost a bit of my ego, but those carnivorous days of swallowing cities whole seem to have been replaced with a feeling that I’m doing something that is so wholeheartedly beautiful that I’ve found nirvana.”

For someone who’s found bliss, Plant has quite a bit on his plate. He’s the subject of a VH1 “Storytellers” documentary airing Sunday at 11 p.m. He appears Thursday on Letterman and has a July 24 solo gig at the Hammerstein Ballroom.

Then he and his new band, Strange Sensation, will open for The Who when the group performs here later this month.

Post: Naming your record “Dreamland” begs the question – do you remember your dreams?

Plant: In my dreams, I go to wonderful places. Often I go to this beautiful city in the desert. Once I was in India and visited a town that I think might be the place I dream about. My dreams are peaceful places – I don’t wake up sweating.

Post: Why did you decide to cover old rock songs on “Dreamland”?

Plant: I don’t consider these songs old or rock. These are heirlooms. They come from another time – the end of the two-minute pop pastiche. Men like Dion and the Belmonts and Bobby Vee were passing into history, and this whole department of thought-provoking American folk poetry came forth. This was the music that really stirred me when I was a kid.

Post: And now?

Plant: It continues to do so, and I wanted to go back there. I’ve always taken strength from these songs – both from the beauty of the melodies and the intentions of what the writers were trying to convey.

Post: You called them heirlooms.

Plant: I don’t think of them like they’re museum pieces, like say a Chuck Berry song. I believe the lyrical content, the poetic endeavor, is as meaningful today as it was when these songs were written.

Post: Tell me about “Morning Dew.”

Plant: That was a song that was around when I was a kid. With few words, it expresses the demise of the human race. I can’t call it charming, but it is a beautiful, beautiful song.

Post: This song is treated more gently than some of the others on your disc.

Plant: You’re right. I hit “Hey Joe” with a hammer, but not “Morning Dew.”

Post: Some artists from big-name bands make cover albums as solo projects to distance themselves from their outfit.

Plant: You might think this is a cheap cop-out, but I put a lot of thought into the music. For me, this is a re-initiation and a return to the beauty of the music and the time it was written.

Post: Why do it now?

Plant: I’ve always been so busy with Zeppelin and with Jimmy, but I thought, “I’m always listening to this stuff. Why not do it myself?” It was a cathartic exercise of getting the music and the feelings out. I wanted to get it off my chest because I’ve loved it for so long.

Post: Didn’t you do that in Led Zeppelin?

Plant: Yeah, we managed it in songs like “Shoot Me,” “Whole Lotta Love” “In My Time of Dying,” “Nobody’s Fault But Mine” – all those songs are leaning back. We did a whole lot of leaning back in those days, my friend.

Post: So what do you say to the skeptics who charge you with taking the easy way out?

Plant: It isn’t easy to maintain a career of some distinction and do a Hendrix tune. I gotta live with what I do, and right now, my soul is intact. So is Jimmy’s. We do what we want, and we may work together again, but when we do, it has to be real .

Post: Is it real now?

Plant: I’m doing OK. I’m having a good time. I have a good record and a fantastic band, and my voice is in good shape and my tennis is good and I can still see a good-looking girl from 100 yards.

Post: Being on the road, you probably see lots of good-looking girls even closer.

Plant: I can recognize a good overhand top-spin serve, but that doesn’t mean I can do it. And the same goes for the girls.