'TinyRhythm'

Multichannel Midi-Triggerinterface with onboard digital drumsynth

Clap / Guiro / Gong

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A drummachine needs a clap. The imho by far best compromize between convincing sound and few parts is the dr110-clap. It works like following:

There are two clap-lines and one very simple vca consisting of one simple transistor which is feeded with noise.

The 2 claplines have different decays, CP1 is VERY short and CP2 is very long, making the reverbation effect. The burstunit triggers CP1 3 times and - after the 3 - CP2 one time.

Both claplines open the noise-vca which is filtered and amplified and thats it.

Interesting tweakpoints:

• burst count for CP1
• burst timedistance fpr CP1
• Of course you are not limited to feed only 'noise' into the vca. How about some spectra?
• decaytime for CP2
• filterfrequency after vca
• by bursting CP1 about 10 times and NOT bursting CP2 we can make a cool guiro similar to CR78. This can be made even nicer by dividing the burstdelaytime by 2 after the first 5 bursts have passed.
  Triggerpicture would look like this: I__I__I__I__I_I_I_I_I_I .. i call it bended guiro
• by bursting ONLY CP2 with a spectra instead of noise on the vca we get some kind of gong or house-hit-sound

Functionblocks

The controller is responsible for 2 things here:

1. sending bursts for the two soundchannels to trigger their envelopes
2. creating some audio to feed the VCA

To overcome the 1kb-limit for code i took the tiny26 here. Of course there could have been lots of pots attached because the tiny26 has much more ADC-channels but i wanted to keep in my grid with 4 parameters per module.

I first thought about making pots for manually changing burstcount/times/lengths. After some testing i was sure some presets for different combinations of bursts and audiosignals make more sense. You find them to the right.

The Audiosignals the tiny26 outputs is simple shifted noise and my already for other modules used 3-oscillator-tonegenerator for some ringing spectra.

different clap/guiro-presets with burstdiagram

Make a benefit out of a handycap

After all was put together on the breadboard i realized that the vca doesnt close completely.  Even when the envelopes were finished, some audio was still with a very low volume on the output. Maybe its because of the transistor i used, or because the audiolevel on its input was to high or something else.

To overcome this problem i gated the audio-output of the controller. The controller triggers the envelopes, that means it KNOWS when the sound starts. When the trigger comes to the controller saying 'lets hear some clap now' the controller starts the audio output and after a certain amount of time, it sets the audio-pin to low - PERFECT SILENCE. Now comes the interesting part of the story: i made the time for audio-output tweakable with a pot. When the decay of CP2 is very long and the audio-time is shorter, the output stops in between the decay-phase and the module sounds like a gated clap - cooool.  

functional diagram of this module

front and backside

it needs few parts to make a cool clap

the working breadboard for research on the coolest tweakpoints