Octave Audio For over 35 years, Octave has fused the warmth of tube amplification with cutting-edge electronic innovation to create amplifiers that are as reliable as they are emotionally engaging. Designed and handcrafted in Karlsbad, Germany, each Octave amplifier embodies sustainability, serviceability, and exceptional musical fidelity. With in-house transformer production, advanced protection circuitry, and a legacy of upgradeable models like the HP 500, Octave delivers timeless sound—built to last and crafted to inspire.