DR-770. Owner's Manuals. DR-770 Owner's Manual. Support. Top · Updates & Drivers · Owner's Manuals · Support Documents · Quick Start Video · Knowledge Base Pdf User Manuals. View online or download Boss Dr. Rhythm DR-770 Owner's Manual. Roland Dr. Rhythm DR-770 Drum Machine: Owners Manual. Brand: BossView and Download Boss Dr. Rhythm DR-770 owner's manual online. Roland Dr. Rhythm DR-770 Drum Machine: Owners Manual. Dr. Rhythm DR-770 drums pdf manual DR-770 Dr. Rhythm. Owner's Manual. Thank you, and congratulations on your choice of the BOSS. DR-770 Dr. Rhythm. 4. Before using this unit, carefully read A drum kit consists of 55 sounds selected from the 255 The DR-770 features velocity-sensitive pads, so the timbre (BOSS MA-12 etc.) Audio set Support - DR-770 Owner's Manuals.