[sdiy] Nord Modular DIY

[Andrei Kudryavtsev]

Why re-inventing a wheel? Symbolic Sound makes Kyma for years and they are
still in a business. It's not so easy such as nord modular in learning, but
prototypes' base is huge and possibilities are unbeatable. Too expensive?
Do like Stephan Schmitt did - put Intel NUC inside the synth and load
Reaktor there ))))

2016-03-02 18:07 GMT-08:00 <rsdio at audiobanshee.com>:

>
> On Mar 2, 2016, at 3:45 PM, Tim Ressel <timr at circuitabbey.com> wrote:
> > I hear you about the power. But procs like the Sharc have seriously
> expensive compilers.
> That's a good point. I design with the TMS320, and the compiler cost is
> not an issue with that family. In the field, I've seen about 50/50 designs
> with TMS320 versus SHARC, so I usually list the SHARC because it's in
> successful products (I take everything apart - don't loan me your gear if
> you don't want fingerprints inside!).
>
> > Its true the STM32 doesn't have bit reversing or other niceties, but for
> this application I'm not sure how much it gains you.
> Bit reversing is great for FFT. You don't usually see the bit-rev
> instruction because the average Joe doesn't write the FFT - it's already
> written in the math libraries and rarely needs tweaking. A lot of the
> special DSP features are not apparent unless you're seriously trying to do
> massive signal processing code development, and then it becomes obvious why
> DSP chips are still so common.
>
> > As long as you have single cycle MAC and high clock rates, I think we're
> okay.
> MAC is not the only tool in the DSP chest, and the lack of the other tools
> makes something like the STM32 a far cry from a DSP.
>
> As one example of the difference, the TMS320 can simultaneously perform 3
> read and 2 write operations in a single clock cycle. There is no ARM that
> has multiple address & data busses for this kind of data throughput. I was
> able to generate waveforms via DMA while also performing calculations on
> incoming signals, all without either operation causing wait states due to
> simultaneous access to SRAM. A mature DSP design like the TMS320 goes way
> beyond the instruction set. It's like having an FPGA design that is already
> optimized for audio so you don't have to build the system.
>
> I saw a nice PowerPoint presentation about the difference - I think it
> effectively asks "Is MAC the same as a true DSP?" Basically, the author
> showed that prices and performance cover a wide range. You can't really get
> DSP performance with MAC alone, but it's certainly better than nothing.
> This particular author favored the SHARC, probably because that's his
> prevalent experience, but he also looked at Blackfin, TMS320, and ARM
> designs with MAC. If I'd researched and written the article, it might have
> leaned more towards TMS320 due to the cost of SHARC development.
> Unfortunately, none of his benchmarks included TMS320, only SHARC versus
> non-DSP. It still quite obvious that a DSP uses a fraction of the number of
> clock cycles to implement a filter or other signal processing operation.
>
> Quick search finds that presentation, titled "Choosing the Best Processor
> for Your Audio DSP Application"
>
>
> http://www.dspconcepts.com/sites/default/files/white-papers/PD8_Beckmann.pdf
>
>
> https://community.arm.com/groups/embedded/blog/2014/10/28/how-to-choose-the-best-processor-for-your-audio-dsp-application
>
>
> I mention these considerations because it could be quite difficult to
> design a Nord Modular replacement with less capable processors. An STM32 at
> the core to coordinate voice boards would be a good choice, and perhaps the
> MAC instructions would be useful for global modulation signal generation.
> This central controller could talk to individual DSP chips, one per voice
> board, where low-level coding is more likely to eek the most performance
> per voice. Such a division of labor makes sense, so the control processing
> is easier because it's running on a generic processor, and the synthesis is
> more powerful because it's running on a DSP per voice (or per voice group).
> Once the DSP modules are written, they can simply be configured by the
> high-level processor.
>
> By the way, I like the idea of an external keyboard via MIDI, to save on
> size and cost. The central STM32 would talk MIDI and translate to internal
> controls for the DSP-based voice modules.
>
> Brian
>
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-- 
Andrei Kudryavtsev,

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Deftaudio (www.deftaudio.ru)
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