A rough emulation of an old school 8 bit drum sample cell with some ideas borrowed from Roger Linn.
Samples can be truncated at the beginning, facilitated by the zoom (Zoom) function which displays only 10ms of the drum sample, starting from the start point. Samples can be tuned up and down two octaves (Tune). Tuning can be quantized to semitones using the step function (S). There is a volume envelope for shortening the decay (Decay), and an anti aliasing filter (HiCut).
What makes the specific sound of 8 bit drum computers is the low sample rate, which can be emulated with the (Down) parameter, a value of 2 means at 44.1kHz that the sample rate of the non-detuned drum sample equals 22.05kHz. The higher the (Down) parameter, the lower the sample rate and the more gritty and low-fi the sound will become.
The other important factor is bit resolution. With 8 bit there are only 256 steps for the amplitude value at a given moment. With 16 bit there are 65536 steps!
The internal 8 bit process of MicroDrum emulates a logarithmic DAC stage and a 24dB anti aliasing filter, so it sounds as good as it can with 8 bit. Still it produces a lot of potentially nice noise in the higher frequencies.
However, for an acceptable low tom or bass drum this is not perfect. Thus a special filter has been added that dampens the high frequencies above 500 Hz faster than the normal decay rate (Damp). This allows to get low drums with a punchy attack but less noise afterwards.
When using a sample for a hi-hat and it is triggered repeatedly, it becomes very obvious that it is static. To overcome this, Roger Linn used a looping hi-hat sample and superimposed only the volume envelope. The loop point was not reset at sample start, so each time you triggered a hi-hat you did hear a slightly different sound. MicroDrum has the same playback feature (Free). It probably only makes sense for static looping sounds.
MicroDrum plays back the drum sample, if the incoming MIDI note matches the note adjusted on the left top of the device. Note Off messages are ignored if trigger mode is set to off and do cut the release of a sample if trigger gate is on (Gate).
Samples are dragged in over the waveform view, clicking on the view triggers the samples. Below the view is the file name, next to it the file’s sample rate. (Info) brings you to this page, but you probably figured this out already.
The thing is mono of course. This is 1982 and memory costs a fortune!
MicroDrum Version 1.0 M4L device file, short read me text, demo Live set with some samples: MicroDrum.zipSupport
I will most likely not be able to provide help with programming issues. If you intend to modify the instrument, you have to figure out yourself what goes on. However, comments and bug reports are always welcome.
MicroDrum has been tested wih Live 9.16 and Max 6.1 / Max 7 on Mac OS 10.8.5
You can modify this device. You can use it to create the best song ever and sell that song. You cannot sell this device or a modified version of it. You cannot copy code from it to use it in other commercial devices or software packages. Enjoy! Robert Henke, December 22 2014.