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Comment by ajxs | Hacker News Reader

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ajxs·

I wrote the article mentioned by Ken: https://ajxs.me/blog/Yamaha_DX7_Technical_Analysis.html

I've unwittingly become a bit of a Yamaha FM Synth historian!

Here are some other contributions to reverse-engineering the DX7:

A fully documented disassembly of the DX7 ROM: https://github.com/ajxs/yamaha_dx7_rom_disassembly

A new firmware ROM that makes the DX9 function more like a DX7: https://github.com/ajxs/yamaha_dx97

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Thanks for this. I've got a dx9 I paid very little for and the lack of velocity sensitivity has always annoyed me about it. I shall give the firmware a go!

I edited my post to say "more like" a DX7. Unfortunately velocity sensitivity can't be added because the physical keyboard doesn't support it. The firmware does add velocity sensitivity to incoming MIDI data though!

isn't velocity sensitivity simply two electrical connections ("buttons pushed") that get made at slightly different points in the arc of a keypress, and the time difference between them is measured to use speed as a proxy for how hard/loud the key is pressed? (that was both a question and to explain the mechanism to people not familiar ;)

I wonder if it would be simple ot add a sensor to measure that across the keyboard, and then have it do double duty as aftertouch (aftertouch is an effect that measures if you "wiggle" a key after you've pressed it down) Then his DX9 could be better than the DX7 :)

i would also think it is achieved by piezo's, though maybe thats specific to drum stuff?

Yeah, thanks, I didn't think that would be the case, but always wondered why it couldn't do it over midi, which is what I'm most interested in. Thanks again!

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