Bluegrass Underground, the new live performance radio show we posted about last month, debuts tonight (8/29) on WSM. The show features a live performance by The Steeldrivers, recorded August 16 more than 300 feet underground at Cumberland Caverns in McMinnville, TN.

The show’s premise is based around the unique environment where it is recorded, this underground cavern completely removed from any sound generated at the earth’s surface. Each month, a new episode will be taped before a live audience, using as few microphones as possible to capture the natural acoustic sound, and aired on the last Friday night of the month.

Producer Todd Mayo told us that this first concert taping was a sellout, and that The Steeldrivers put on a whale of a show. He also sent along some photos that demonstrate the dramatic surroundings where they record.

Here’s a video clip that gives an even better look at the concert hall.

Bluegrass Underground, a new monthly live bluegrass music show, is set to debut on WSM on August 29. It will air on WSM and in syndication on the last Friday night of each month at midnight (central time - technically, Saturday morning).

Each show will be recorded before a live audience more than 300 feet underground in The Volcano Room at Cumberland Caverns in McMinnville, TN - hence, the show’s name. The site is a natural amphitheater created by the actions of water and time over millions of years which the show’s producer, Todd Mayo, describes as one of the most acoustically pure natural spaces on earth.

“No man-made sound reaches inside the cavern and the living rock hued amid the eons is jagged and uneven, providing near perfect resonance. All performances will be entirely acoustic and unamplified. Each show will be recorded, mixed, and edited by our Grammy-Winning Recording Engineer, Phil Harris. The goal is to arrange the band around one large tube microphone to record and perform the way it was done in the Golden Age of Radio and Bluegrass. We will have plenty of other microphones on hand to compliment the recording where needed.”

The first two show tapings have been scheduled, and tickets are available now to be in the studio audience.

• August 16, 4:00-6:00 p.m. - The Steeldrivers
• September 27, 2:00-4:00 p.m. - The Grascals

Tim O’Brien and The Infamous Stringdusters are expected in shows later this year. Once the show gets going, video and audio archives will be added to the show’s web site.

Stations interested in carrying Bluegrass Underground should contact Todd Mayo by email.