3 ms·
Yes, that's essentially how it works. You might think that jumping through the sine table in large steps would make your waveform too irregular. But that's what
by kens 5y ago
Yes, that's essentially how it works. You might think that jumping through the sine table in large steps would make your waveform too irregular. But that's what happens with any digital audio. E.g. a CD has music at 44kHz, so a 4400 Hz tone only gives you 10 points from a sine wave which would seem very irregular. But a low-pass filter smooths things out, so you end up with a nice smooth sine wave. (Look up Nyquist frequency if you want more details.)
One additional thing about the DX7 index is that you can think of the index as having 10 fractional bits, so you have much more accuracy in the increments. Otherwise, the frequency resolution is pretty bad because the frequency changes in big jumps when the index step changes by 1.
- anyfoo 5y agoI would like to add the maybe counterintuitive fact (for people that never looked into that theory) that for "bandlimited signals", i.e. in your CD example a piece of music that does not have any content above 22.05kHz to begin with, that reproduction of audio will be perfect, i.e. look exactly the same as the input signal. (Well, assuming ideal filters and analog components, which isn't really possible, but you can basically get "arbitrarily close" to the representation of the original signal with your digital 44.1kHz signal assuming a bandlimited signal by choosing better and better analog components.)