[sdiy] Wavetable info

[Grant Richter]

> 
> The Mini-Wave, Waveform City, Doepfer A-112 sample playback module use a
> straight uncompressed 256 byte / 8 bit sample. For the sake of simplicity,
> this corresponds to a sample time of 5.8 mS at a sample rate of 44.1 kHz.

Note that 5.8 mS corresponds to one full cycle of a waveform sampled at
172.26 Hz which is about 20 cents below F below middle C (~174 Hz).

The procedure is to use Sound Forge etc. to record anything at that
frequency. Then export the file as an 8 bit raw PCM file longer than 64K
(else Move256 will give a file under run error). Then pull the file into
Move256 and look for zero crossing aligned at each end. Use Move256 to move
the waveform into the wavetable you are building.

I forgot to mention the ESQ-1 waves originally at 1024 bytes / 8 bits. Also
the entire Mirage library is 8 bit. There was a number of old utilities for
handling Mirage files. Including an old (18 years, like my teal sweater ;^)
IBM editor. Ensoniq was purchased by Creative Labs. It seems unlikely they
would care about experimenters goofing around with their "antique" 8 bit
libraries.

I still use my Mirage as it cuts through a mix much better than most new
keyboards. Also the Tabla samples are practically an industry standard.