Tea Kick

Universal Analog Drum Circuit


Tea Kick is a universal analog circuit which is based on improved version of the twin T resonant structure, and mainly inspired by analog drum designs of Standa Filip. The basic principle of this drum is to create a virtual electronic membrane which you strike with electricity, the membrane vibrates and creates a very natural drum wave which, when outputted to a speaker (another membrane) sounds very authentic. To adjust this membrane, we have the TUNE and RESONANCE control. Think of using those as if tuning an acoustic drum. There is a CV input for tuning the circuit so it can change character from a bass drum through all the toms to woodblock. There is main TUNE control knob for the tuning and also a CV Input with ATTENUATOR.

Virtual Electronic Membrane You Hit with Electricity

The RESONANCE control affects how resonant the circuit is. However, resonance also affects the tuning: the more resonance, the lower the drum sound is. Add resonance to get longer decay drum sounds. The resonance range switch can limit resonance from self oscillating. When you switch it up, the resonance control makes the circuit self oscillate, so that it can be used as a kind of VCO.

Tea Kick also has a click generator with tone control which is mixed into the signal. Think of the click as of a stick which you can use to strike an acoustic membrane of a drum – the resulting sound has different character. The click tone control also affects the spectrum of the twin T circuit. There is also SQUARE output and WTF input available for more fun experiments.

Beyond the drum

Tea Kick can be either used as predictable drum circuit or can go totally nuts as an experimental oscillator. There is several ways how to route inputs and outputs to generate feedback loops to generate signal. However there are several ways how you can use it to modify and filter signal from another VCO. We highly recommend to try routing any oscillator to the trigger input. There is a lot to explore here.


  • bass drum generator
  • tune knob for adjusting pitch
  • CV input with attenuator for Tune
  • resonance knob
  • resonance range switch (low range limits the circuit from self oscillation)
  • click tune knob – adjusts pitch of click added to the drum body
  • click output jack – when plugged in it puts the click out of the main output
  • buffered output
  • square wave output
  • trigger input
  • WTF input (acts as something like band pass filter but not really :) )
  • trimmer to adjust the resonance range
  • front panel from aluminium or oak wood with custom knobs
  • handmade locally by Bastl Instruments in Brno, Czech Republic

Technical details

  • 5 HP
  • 35 mm deep (skiff friendly)
  • current +12V: <15 mA, -12V: <15 mA
  • PTC fuse and diode protected 16-pin power connector
  • pdf user manual download

DIY kit

You can build your own THT version of Tea Kick with our DIY kit. Go through the complete assembly guide below and make sure that you understand all the steps.