[sdiy] modular/softsynth interface [was: Synth UI]

[Ian Smith]

Thanks Scott :)
I'll probably get this done in a couple years or so. And I'm sure I'll be bugging you with all sorts of questions.
-Ian

----------------------------------------
> Date: Thu, 9 Apr 2009 16:19:18 -0700
> From: music.maker at gte.net
> To: synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] modular/softsynth interface [was: Synth UI]
>
> Ian Smith  wrote:
>>
>>
>>> Depends on who writes the code. I could do this with an FPGA
>>board that has more than one DAC> output channel. One could make
>>any sort of hybrid one wants. Usually a digital synth's ADSR>
>>signal is just used within the synth itself, but it could be
>>output to a DAC channel or to a DAC> channel and used
>>internally. This also goes for anything else, like LFOs or ARs.
>>An FPGA board> with an ADC could also receive CV information
>>from an analog and use that to modulate digital stuff> or it
>>could modify the signal and then send it back out through a DAC.
>>I think that some people> here may be doing these kinds of
>>things.
>>
>>Scott-
>>Wow... ok, that's all a bit over my head as I still know little
>>to nothing about FPGAs. I would love to have such a module at
>>some point. Any idea on how much it would take to develop
>>something of this nature? -Ian
>
> The list would look mind boggling if I wrote it all down. However, I would approach
> it like I do everything else - bit by bit. For example, since I have a digital
> monosynth already developed that has an ADSR, I'd start there and pipe it's output
> through a 12 bit DAC on one of my boards - see if I can look at it on an oscope. But
> remember that the monosynth took some time to develop - it currently exists and
> modifying it to output it's ADSR signal through a DAC wouldn't be that hard - now.
> It's all of the other stuff I had to learn to get this far that would be at issue
> with respect to time. All of it is handy, just that it takes time to learn it.
>
> When I started some 3 or 4 years ago, I knew squat other than a general understanding
> of what has to happen in a DSP domain and a fair (not great) set of analog chops.
> I've got a good handle on binary arithmetic, algebra, trig and a smattering of the
> most often used Calculus (understanding some math is required for DSP). I also knew
> the basics of making sounds in an analog world which is often fairly closely modeled
> when approaching a digital solution. I had to learn Verilog (the language that I use
> to describe digital system designs like a synth) and I had to fart around a lot with
> FPGA "hello world" designs to get comfortable doing designs and making them work,
> lots of blink-the-leds things. Eventually, over time, I learned enough to make an
> NCO work, then an ADSR, then a filter until I had learned enough bits and pieces to
> put a synth together. With what I know now, it would be fairly low effort to pipe an
> ADSR into a DAC. But as I said, I've been working on this for about 4 years now.
> And I've had the pleasure of several people generously mentoring me.
>
> The real point to the comment in my post was that what you envisioned (what I would
> call a hybrid analog-digital synth system) can certainly be done. Just expect to
> have a reasonably steep learning curve and stick to it for a good amount of time.
> The successes one has while one is learning should be the motivation, or at least it
> was for me.
>
> It would pay to have a good understanding of both analog and digital systems. I'm
> not a wizard at either, but I can grope my way around and get success with
> perseverance. You'll find that I have scars on my forehead from beating my head
> against the wall more than once. I won't say it's been easy, but I _will_ say it's
> been a sh!tload of fun. The elation I feel when I get something working correctly
> has definately been worth this effort.
>
> Also, an FPGA is not the only way to accomplish this. It could also be done using a
> DSP chip or a fast microcontroller or microprocessor.
>
> -- ScottG
> ________________________________________________________________________
> -- Scott Gravenhorst
> -- FPGA MIDI Synthesizer Information: home1.gte.net/res0658s/FPGA_synth/
> -- FatMan: home1.gte.net/res0658s/fatman/
> -- NonFatMan: home1.gte.net/res0658s/electronics/
> -- When the going gets tough, the tough use the command line.
>
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