Cossimo Matassa’s J&M Music shop was the place where New Orleans musicians recorded some of the biggest R&B hits in the 1950s. It closed down years ago, but the site, now a busy Laundromat, preserves some fine musical heritage. The pebbly J&M sign is still inlaid on the front threshold; inside, one wall is dedicated to a photo-and-history exhibit. It was in this building that Fats Domino and Dave Bartholomew established the ‘New Orleans Sound.’ Countless oldies but goodies, including Lloyd Price’s ‘Lawdy Miss Clawdy, ’ were recorded right there by that box of Tide.