Question: what are dumble amps based on?
Answer: But it's what's inside that counts. Dumble got his start building electronic devices like radios and PA systems in middle school. In the 1960s, he began modifying amps made by Fender. His first Dumble amps were based on the Fender Bassman circuit (Emerald City has a 1956 one for sale for $11,000).