Dream Theater guitarist John Petrucci recently stopped by the Reverb studio to give Guitar World an inside look at his technical and creative approach to the whammy bar.

Music Radar recently caught up with Petrucci to discuss the band's new concept album, The Astonishing. An excerpt from the interview is available below.

Music Radar: David Campbell is well known for his movie soundtracks and arranging for Adele, Muse and Michael Jackson. How did he come to be involved in a Dream Theater album?

Petrucci: "One of the things as producer this time around is I wanted everything to be natural as far as all of the components, from Jordan playing real Steinway piano and a real B3, to using a real orchestra and real choir, so I immediately thought of David Campbell and fortunately he was into it and it’s been a really great ride that we’ve taken with him."

"When we wrote the music and started demoing, we’d record in Logic to a click track and Jordan would add layers of string samples and choir samples and so by the time we were done, we had a lot of MIDI information that we sent to David, so it wasn’t as if he had to arrange from scratch; although some songs he did his own thing completely."

“But what was great was that he’d take the stuff and say, ‘You know what? In the real world that instrument doesn’t play that high’, or, ‘The sopranos wouldn’t really sing that, I would support that with the altos’."

"And then to organise the recording sessions which included special sessions, like we have a marching band, a Dixieland band, a bagpipe player… we have mandolins and things. What I thought was incredible given the amount of work that he’s done on movies et cetera. He said to us that this was the biggest project he’s ever done, so I thought, ‘Wow we must be out of our minds then!’”

Music Radar: That must have been quite a challenge for yourself and Richard Chycki to mix?

Petrucci: "It was! I forget the count but at any given time there was something like 570 tracks between the orchestra, choir and so on. Initially the goal was to record all of these natural-sounding instruments and maybe make the album a bit more organic sounding. I didn’t want an over-hyped, over-produced sound, I wanted something very powerful, but very natural, more like a rock sound."

"What ended up happening was that with all this sonic information going it could very easily go in the wrong direction and sound too symphonic, so we had to make sure the core rock and metal sound is present and rocking and everything else finds it’s place around it."

Go to this location for the complete interview.