Grand Concert Acoustic GuitarsThe Grand Concert guitar is often called a OO guitar. The design of the Grand Concert acoustic is found in many contemporary acoustic guitars and comes directly from the classical guitar. The Grand Concert has the thinnest resonator and features the smallest body size compared to jumbo, Dreadnougt, Grand Auditorium and Grand Concert acoustics. This makes Grand Concert acoustics easier to play but also quieter than the larger acoustics. Grand Concert acoustic guitars are ideal for playing in small spaces.