|★ APPLICATIONS ★ CREATION MUSICAL ★ Rhythm Unit ★|
|Rhythm Unit||Applications Creation Musical|
After experimenting with the sounds on the Amstrad, it is not difficult to produce a rhythm unit. The main problem, and the one requiring the most individual attention, is to produce good drum sounds. The best drum noises need careful setting of the noise pitch and the volume envelope.
You will find that the duration of the sound plays a very important part in determining the drum characteristics and if you use more than one envelope you can produce quite a reasonable rhythm unit. This program is one way to approach the design of a rhythm generating program.
When run, the program will play a rock beat and pressing the indicated keys will alter the rhythm.
The program is fairly self-explanatory. Each drum is produced by a combination of parameters - pitch, volume envelope, tone envelope and noise setting - which are read into four arrays in Line 1820. The rhythms are listed in data statements at the end of the program. They are stored as a drum number followed by a duration. The number of each drum is given in the Rem statements between Lines 1550 and 1760. The rhythm patterns are terminated by two Os.
The central While/Wend loop between Lines 1080 and 1120 reads the drum number and its duration and plays the sound accordingly. If a new key has been pressed. Line 1090 stores this in beats which is used in Lines 1130 to 1210 to restore to the correct set of rhythm data. At the end of a rhythm pattern, drum will be 0 and the program will fall through Line 1120 to these Lines.
The drum sounds and rhythms would not be out of place in an electro-music composition. Not all the drum sounds have been used in the rhythm patterns. Experiment with the original envelopes to see if you can improve on the sound and construct other drum sounds, too.
The rhythms only play one or two bars before repeating. You can add more variations by adding to the data and, of course, create more rhythms. You could add a facility to change tempo, too. set in Line 1780.
This is an edited extract from Ian Waugh's new book Making music on the Amstrad CPC 464 and 664, available from Sunshine Books, priced £6.95.
Popular Computing Weekly_Issue 1985-11-28