3 ms·
My DX7 is still one of my favorite synths, sonically speaking. I had no idea how intuitive yet novel the circuitry was until I began reading this article. In p
by moth-fuzz 5y ago
My DX7 is still one of my favorite synths, sonically speaking. I had no idea how intuitive yet novel the circuitry was until I began reading this article.
In particular, I found it suprising that the sine waves were generated by indexing a wave table - you'd think a sine wave would be easy enough to generate without a table, but the way it implements phase distortion ('FM') on those sine waves by simply offsetting the index into that table is quite interesting. Sorta like having different mathematical functions for 'i' in a for loop.
- TheOtherHobbes 5y agoIn DSP terms direct calculation of sine waves is incredibly expensive. Even more so with 1980s 8- or 16-bit fixed point arithmetic without a coprocessor. Table lookup was inherited from the first computer music software. It was the only way to create any kind of waveform at reasonable speed. When you have a table, modulating the lookup index is almost an obvious trick. But the Chowning/Yamaha implementation worked so well musically that it took it from a curiosity to a best-selling product. A different take on it might not have done that. FM owes a lot to sound developer Dave Bristow. He made sure the DX7 had usable sounds. According to him, the original prototypes had tens of harpsichord-like patches and not much else.