sicklittlemonkey wrote:
Hmm, very interesting. I can see what you mean about forgetting about the transitions. In this case they do give an excellent approximation of the wavform. I never would have thought of summing the speaker state to produce samples. Focussing on the waveform being the result of the speaker cone being pulled back and forth without reaching fully flexed/relaxed or on/off state, the actual existence of these states seemed meaningless - or at least practically useless in terms of emulating the sound. But what about filtering? Can it improve the results of this averaging?
Averaging is itself filtering, but additional low-pass filtering can help in difficult situations (such as fast streams of pulses which are almost but not quite synchronized to the sample intervals). In the case of DAC522/RT.SYNTH, no additional filtering is needed, since the samples are essentially synchronous. The highest audio frequencies reproduced by DAC522 are about 5kHz, so turning down the amplifier tone control to cut higher frequencies is a fine solution. -michael Music synthesis for 8-bit Apple II's! Home page: http://members.aol.com/MJMahon/ "The wastebasket is our most important design tool--and it is seriously underused."