Hartke HD50 Bass Combo AmpHartke HD50 Bass Combo Amp Serious Tone. The all new HD50 Bass Combo packs Hartke's patented HyDrive speaker technology into a sleek combo design ideal for small venues, rehearsal spaces and bedroom practice sessions, and capable of greatly enriching your low end tone. The HD50 also maintains Hartke's commitment to producing high quality bass amplification with exceptional durability. The HyDrive Design The HD50 (50 watts, 10" driver) employs Hartkes