Dumble musical instrument amplifiers are custom manufactured in very limited numbers by Alexander “Howard” Dumble of Los Angeles, California. Dumble is a one-person operation; each amp is handcrafted by Dumble himself, and Dumble amplifiers are the most expensive boutique amplifiers on the used market. These costs are rising rapidly. In 2012 the Dumble Overdrive Special was described as the most valuable, with used amplifiers fetching on average between $70,000 and $150,000 apiece. Other examples have sold for more.

Dumble still builds amplifiers at the rate of about 2 or 3 per year, and primarily builds for celebrity musicians and studios. He asks similar prices to the used market rates in order to dissuade resale. Dumble will service and refurbish his original amplifiers for a fee, and many players will buy used Dumble amplifiers in order to have them refurbished by Dumble. Carlos Santana and Ben Harper have both said that they bought their first Dumble used, and had Dumble refurbish the amp for their particular playing styles.