James Waller created Rocktron amplifiers in 1985. At Rocktron, he developed the HUSH Noise Reduction System, a line of DSP guitar rack products, and the Circle Surround stereo five-speaker matrix among other devices. In 2001, Waller sold Rocktron to GHS, but he took the engineering team with him and formed ISP (Intelligent Signal Processsing) Technologies in the same year. At first, they used the Waller name on their guitar amplifiers and guitar related speaker cabinets. By 2004, they were only using ISP Technologies as a brand name on their products. The Theta is the only model to be produced with both a Waller and ISP brand name on it. For more information on current ISP products see ISP Technologies.
Amplifiers previously produced in Clarkston, MI during the early 2000s. Distributed by ISP Technologies.