The PF&LB K184-13

is a DIY analog drum synthesizer / groovebox. It contains 5 fully analog drum sound module which faithfully or not so faithfully recreates the sound of a drum set. It's controlled with a 16-step sequencer. For a drum pattern each instrument can be programmed to be triggered on one or more of 16 steps. A total of 4 patterns can be save within the internal memory. The 4 pattern and the instrument which should be programmed are chosen with two rotary switches.







Sound Modules



Bass Drum

This emulates the sound of a bass drum. It's sound source is a triangle oscillator whose frequency and pulse symmetry is controlled with an envelope. The volume is also controlled with an envelope whose shape is chosen to recreate a compression effect. Was that clear? Anyway here is the block diagram (for the schematic see left side).





Snare Drum

This one is set up by six(!) heavily detuned and low-pitched rectangle oscillator. Volume is controlled by a decay-only envelope generator. The mix of the six oscillators go through a 6db/oct high pass filter to shape the sound.





Hi Hats

In contrary to other analog hi-hat emulation which are often based upon oddly tuned oscillators (as my snare module does) this hi-hat emulation is based on high-pass filtered white noise. This sound module has two triggers, one for the 'open' hi-hat sound and one for the closed sound. Note the the closed hi-hat may affect the decay of the open hi-hat strike, as a real hi-hat does.





Tom drum

The tom drum usually has a quite melodic, less noisy sound. Thats why i modelled this sound with a sine wave oscillat or. The volume and the frequency of it are controlled with a decay-only envelope. Because of it's output it's able to drive the aplifier coming after it quite a bit. Sounds created range from soft bass drum sound to typical 'synthie'-toms up to high bleeps.





Crash Ride

This is the module which has a quite unique sound. Although it's sound is very far away from how a crash ride sounds like. The idea (which came sort of out of nothing) was to shape the sound using a comb filter effect. A comb filter actually is a phaser effect which 'doesn't move'. The frequency comb position is controller with an envelope. Sound source is white noise again. This then creates a sounds from a slow whoosh up to gunshots but definitely nothing similar to a crash ride.