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Building a Sample-Based Synthesis MIDI Module


onlinejb
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Hello, I am new to the world of MIDIbox.

 

I have an old keyboard made by Samick, that was built like a tank, and has a high-quality keybed, but since it's from the early 1990's, its voices aren't so great.  I've considered buying a sound module for it, but the few that are on the market now are very expensive and just overkill in terms of features.  I just want a few good sounds like an acoustic piano, Wurlitzer, and Hammond organ.

 

However, being an electrical engineer, my next thought is if you can't buy it, build it.  So, I'm considering a potentially ambitious project to create a MIDI sound module that implements sample-based synthesis (similar to a ROMpler, but perhaps with flash RAM instead of permanent ROMs).  My pie-in-the-sky specs would be 100MB sample space and 64-voice polyphony (that is, 32 notes for a stereo sample), but just to get the project going, I'll settle for maybe 2MB and 24-voice polyphony.

 

Has this been done before, and if so, what MIDIbox boards does it use?

Would it be wise to begin with something like the FM module and build up from there, or does this need to be built more or less from scratch?

 

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There's already a MIDIBox project that plays samples. The basic features are there in the hardware already, but there's not much in the way of synthesis (envelopes etc).

 

The main limitation is the speed of the storage device - the SD card attached over SPI won't do more than a few voices as it's currently set up. You could make a different MIDIBox core board that uses the 4 bit mode for the SD card, which is quite a bit faster but apparently hard/impossible to use with the peripherals on the STM32F4 Discovery board.

 

If you're that comfortable with electronics, you could make a board with any ARM Cortex M SoC with an external static memory interface (that's most of them AFAIK) and attach some Flash and an audio codec and port the MIOS software to it. That's not a weekend project, but certainly doable.

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