They have always fluttered along the fringes of multiple musical formats – so much so that categorizing their sound becomes an exercise in futility. They use bluegrass instrumentation, but the harmony and structure of their music owes as much to alt rock as it does to Bill Monroe. They had been recording for Skaggs Family Records, but their latest album was produced by Dan Auerbach of The Black Keys.

See a pattern developing?

This latest project, Letters In The Deep, was produced by the band on spec and they have decided to release it through Dualtone Records in Nashville. The official release date is June 8, but the C-Sky boys have banged heads with Dualtone and come up with an out-of-the-box twist on the box set concept, one that offers fans a chance to get more, in advance, before the packaged CDs hit the stores.

Three box set packages are available, all including a pre-release copy of the CD, a high fidelity copy of the album on vinyl, an exclusive T shirt, an immediate link for two audio downloads, and an autographed poster. You get all that for $39, and for another $50 they will also include a “Golden Ticket” that will get you into as many C-Sky shows as you make in 2010, plus prints of handwritten lyrics and musical notation from several songs. These packages will be shipped in early April.

For the very bestest fans, they have an Ultimate Box Set which includes everything listed above and a live acoustic concert for you and 50 of your friends anywhere in the continental US. For that you will pay $5000, and only five will be offered.

Bryan Simpson and Matt Menefee made up this back porch video to share the news of the new CD and the special offers.

See details of the box set offers online.

There has been a lot of buzz about this project, given the band’s increasingly envelope-pushing repertoire, and the fact that it was produced by Dan Auerbach of blues-rockers The Black Keys. C-Sky guitarist David Mayfield had slipped a copy of the band’s previous project, Gravity’s Our Enemy, to him while opening some shows for The Black Keys, and he liked what he heard.

Auerbach speaks highly of the C-Sky boys, and obliquely addresses the difficulty in defining their sound.

“They rose to the occasion. There’s some really beautiful sounds on Letters In The Deep, it is as much of a living album as it is an art piece and I’m definitely proud to have my name attached to this project.

Whatever genre it is, it’s a really great album, and I’m happy that I got to make it.”

Dualtone has been releasing niche music from Nashville’s “off-Broadway” artists for the past nine years, including albums from Jim Lauderdale, Nitty Gritty Dirt Band, Radnet Foster and Robinella. They have high hopes for their latest artists, and expect this to be a breakout year for alt-grassers Cadillac Sky.

C-Sky is Bryan Simpson on mandolin and vocals, David Mayfield on guitar, Matt Menefee on banjo, Ross Holmes on fiddle and Andy Moritz on bass. They will begin touring for 2010 in March.

UPDATE 11:00 p.m. – Bryan Simpson shared a few thoughts about the new deal, a free track offer, and a great way the band is giving back:

“It’s a very unique partnership with Dualtone. It’s not actually a record by record thing. Trying to think a little ‘outside the box’ has served us well artistically, so we decided to take that concept into our business practices as well. We’ll see… who knows. I do know I am excited to start slowly unveiling this new record.

To that point, Feb. 11th we’re going to release one of the songs off our new record as a free download. The only thing people have to do to get it from us is be registered as fan on our new Facebook band page.

ALSO, under the category of ‘our small part (for now)…’   We’re making all proceeds of our sale of the Weary Angel EP go to the relief effort in Haiti. They can download the EP for $5, and know that all proceeds are going to the Red Cross for the Haiti Relief Effort. Our thoughts and prayers are with everyone affected by this disaster.”

At that time, he mentioned that C-Sky was intending to start work on a new full length recording soon, and that the EP was the result of a spontaneous decision to give in to a sudden creative urge on the band’s part.

Just yesterday, Bryan got some news that had the guys in a whirl. Their next project will be produced by a critically acclaimed artist from the world of blues and rock music.

“We just signed on with The Black Keys guitar front man Dan Auerbach to produce our new record in the fall. We’re all big fans of The Black Keys so we are super stoked about the opportunity.

It all happened rather quickly. David Mayfield was out playing bass on the road with his sister Jessica Lea Mayfield, opening up shows for The Black Keys, and passed on a copy of our Gravity’s Our Enemy CD to him. I guess he heard something that intrigued him because he mentioned, to our surprise, that he would be interested in working with us.

As Dan’s new solo record, Keep it Hid, will attest, he obviously has a history with roots music and its branches, and we were in love with the rawness of the past records he has produced, not to mention his solo and Black Keys stuff. So it seemed like a perfect fit.

We’re gonna try and capture the ferocity and energy of our live show on a full length record for maybe the first time. I think that on our new EP we just put out, The Weary Angel EP, as it has been dubbed, you can hear and feel that. I know that Dan’s goal in the studio is to capture a ‘magical’ performance, which doesn’t necessarily mean a ‘perfect’ one. So we will be doing almost everything live.

We’re going to be recording up at his place in Kent, OH starting September 1st using the same board that The Band recorded most of their amazing records on – so we’re hoping some of their ‘transcendent musical magic’ will still be left in the machine.

We hear Dan’s excited about it, we’re excited about it… It’s definitely got us inspired to write, arrange, and record the best record that we’ve ever made for sure. It will be different, but, having heard a bunch of songs that we will be recording, I know it’s going to be, by far, the deepest and most original thing we’ve ever recorded.”

Bryan said that they won’t worry much about working with a record company at this point, though that may come into the mix before this next project is ready for release.

“We are just going to make a record and then see what happens – we aren’t opposed to doing a label deal, but just want it to be the right label for us. Our plan is to make the best record we can and let God put us where He wants us. Outside of that, we’re not interested.”