It’s nice if you want a portable (size of a cigarette pack) hardware fm synth with megahertz sample rate oscillators (no aliasing), with built in effects
For the same reason that dynamite can be used to dig holes in your garden, yes, an FPGA can be used to simulate a DX7.
If you're going for a "no aliasing" simulation then you're not after the DX7 sound anyway (which has fairly heavy aliasing), and you might as well just wire up some bandlimited FM in software. I still don't see how using an FPGA helps you, except that it lets you throw money at a problem instead of having to learn signal processing theory.
I'm not trying to pooh-pooh FPGAs, it's just that CPUs have a ton of processing power these days, and we have tons of signal processing techniques to deal with aliasing other than just cranking the sample rate up to infinity. The amount of processing power it requires for bandlimited synthesis is a function of sample rate, if you keep the other design parameters fixed. Low sample rates are inefficient because your filters get really large--so you oversample. Likewise, at high sample rates (megahertz is well beyond "high") it gets easier and easier to deal with aliasing, and at some point, you're just churning through more data without reducing the aliasing (because at some point it's below the noise floor anyway).
Ah, I agree that simulation of DX7 quirks with FPGA makes little sense. But they are an interesting choice for a very portable high quality FM synth (not a specific emulation) vs other similar sized options. Here is some more rationale - https://www.futur3soundz.com/xfm-index
My experience implementing FM in software is that CPUs are just so wicked fast, because FM is super easy to implement in SIMD. I implemented FM synthesis using SSE and when I measured the performance, I found out that the oscillators were memory-bound or close to it. You could compile a few operators into a function and work on small buffers in L1 cache, and and it just wouldn't show up on the CPU usage monitor.
Yeah to be honest he could have probably implemented this as an iOS app for max portability. Wouldn’t get latency down to 1ms like with the FPGA synth but otherwise would have been fine
