The Delptronics ThunderBell is a classic analog cowbell sound. The circuit is inspired by the great cowbell sound in the Korg KR-55. Like the KR-55, the TR-808, and most other analog drum machines, we model a cowbell by using two tuned square waves. We also include some pseudo-ring-modulation, as did the KR-55. Tuneable In the old drum machines, the cowbell was not tuneable. Newer cowbell modules give you knobs to tune the two square waves. However, if the two frequencies are not in the correct relationship to one another, then it does not sound like a bell at all. The Delptronics ThunderBell keeps the two waves in the proper relationship across a wide frequency range. So, it is a truly tunable cowbell. There is also some room at the lower end where the sound gets weird and fun, if not bell-like. The ThunderBell also gives you broad control of the decay, so you can create short "tinks" or long "dings". Voltage Controllable The ThunderBell Eurorack Module gives you voltage control of both the pitch and decay. The CV inputs are 0 to 5V and cover the whole range of the module's sounds, it is not 1V/octave. We also include a trigger button so you can throw a bell into your mix whenever the mood strikes you. The ThunderBell in a Cowbell (or mini kit) has an analog gate input and pitch voltage control input. Both pitch and decay are controllable with knobs, and of course there is a trigger button.