This is a semi-hollow instrument, with an acoustic chamber under the bridge. The strings pass through the body and then over a saddle with a Piezo element. Then we added a magnetic pick-up in the bridge position that adds a new mellow tone. A very simple circuit, volume balance and tone, gives a broad spectrum of sounds, going from a dark, woody double bass sound, to a crisp biting sound. An unusual Bass response with character and originality.