[sdiy] "FM" Synthesis (was Re: Buchla 295 10-band comb filter topology)

[Donald Tillman]

> On Nov 25, 2022, at 5:34 PM, brianw <brianw at audiobanshee.com> wrote:
> 
> On Nov 25, 2022, at 4:34 PM, Donald Tillman wrote:
> 

>> The big deal about the DX-7 was that they found a way to completely avoid real-time multiplies.  The entire implementation is single-cycle add and ROM lookup operations.  And those are so easy and quick they were able to implement 16 notes * 6 operators => 96 phase modulation oscillators in 1983 technology.  For $2500.00.
> 
> I can imagine that if the sine wave table is a power of two in length, then the lookup could be performed with a modulo operation. Digital signal processor instruction sets have the ability to perform modulo addressing without any overhead - just specify the length of the data in number of address bits and it's handled as part of a single instruction doing the fetch.

Dude, you're all over the map here...

I repeat: the big deal about the DX-7 was that they found a way to completely avoid real-time multiplies.

And that includes the envelopes.

  -- Don
--
Donald Tillman, Palo Alto, California
https://www.till.com