ROCK kings Alter Bridge have revealed their biggest challenge in making a new album - simply getting ­everyone in the same place.

The quartet headline the Hydro on Monday, fresh from releasing new record Fortress.

It's the band's first album in three years, and came after they took time to focus on other projects.

"The toughest thing for us was getting everybody in the same city and the same room," explains bassist Brian Marshall.

"Mark [Tremonti, guitarist] was out with his solo project, Myles [Kennedy, singer] was touring with Slash and Scott [Phillips, drummer] was doing some other work, so getting us all in the same room was a tough thing to do.

"Once we got together, we sat down and wrote the album. I think after the course of a month of full-on writing, we went into pre-production, and from there it really started to shape up."

For a band already playing arenas at both home and abroad, it would have been easy for the foursome to release a record offering more of the same, repeating hits like Open Your Eyes and Rise Today.

Instead they pursued a harder direction, leaning towards metal.

`"I'd agree with people who say this is the most aggressive record we've made," says Brian.

"A lot of the material was songs Mark had been writing for his solo project and he had a lot of aggression he wanted to purge on that. It didn't all make that album, so he presented them to us, and they was fun to play - we thought we could build on it from there."

Yet while the three-year gap between albums has meant that fan anticipation was high for Fortress, Brian admits that he'd have preferred the band to keep going, rather than having lengthy breaks.

"From my standpoint, it's not helped, I'd be perfectly happy touring with Alter Bridge and concentrating solely on it," he says.

"In the long run, it probably does help us [to take time off between albums] but I'd rather do Alter Bridge 24/7. You need to take some breaks in there, but for me it's been too long."

Formed out of the ashes of Creed in 2004, Alter Bridge's style of hard rock has often seen them labelled unfashionable, but they've gained a huge fan base. That's far more important to Brian than what any rock snobs might think.

"The critics can say what they will, I don't read much of it," he says.

"I'm really not worried abut it too much. Some people will like what we do and some won't because we're not for everybody, but we'll just keep doing what makes us feel good and that's writing music. It's about playing from the heart and not listening to outside comments."

Having been regulars at the SECC in the past, Brian is keen to sample the Hydro experience, and believes the band's popularity in the UK is simply down to regular touring.

"We've got great fans there, and Scotland's a great country, so we're looking forward to being back there," he adds.

"We just keep coming over there, throwing themselves in front of audiences in Scotland and our fans have been so die-hard that it's easy to keep coming back."

There is one big difference to this latest tour though, and that's the fact that Brian became a father last year. He admits leaving his wee boy behind will be a wrench.

"In the last couple of days I've been packing and getting ready to go, and thinking how much I miss him, as I haven't been away from him for that long before," he says.

"We'll see how it goes but there's Skype and things like that, so I can still see him."

n Alter Bridge, the Hydro, Monday, £26, 6.30pm.