[HN Gopher] Yamaha DX7 chip reverse-engineering, part 4: how alg...
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Yamaha DX7 chip reverse-engineering, part 4: how algorithms are
implemented
Author : Tomte
Score : 69 points
Date : 2021-12-10 20:29 UTC (2 hours ago)
(HTM) web link (www.righto.com)
(TXT) w3m dump (www.righto.com)
| kens wrote:
| Author here if anyone has questions...
| samuelous wrote:
| Just want to say that I am incredibly thankful for this series,
| its amazing to see how one of my favorite synths works not just
| in theory (FM/PM) but also on the chip level. Thanks!
| null4bl3 wrote:
| Thank you for a good series of articles and some great insight
| into the inner working of FM synthesis in general.
|
| I have never owned one of the original Yamaha's, but i have
| been using the awesome Dexed VSTi plug in, that is modeled
| after the DX7 for several years now.
|
| And I am planning on purchasing a Korg Opsix for its FM
| capabilities.
|
| But for someone that has only been on the learning-by-
| experimenting end of FM synthesis, your articles are a great
| insight into the theory behind it all.
| dezgeg wrote:
| How much time does reverse engineering this kind of chip take?
| kens wrote:
| It takes a while. I got the chip on Nov 1 and have been
| working on it since then. (Although it's not the only thing
| I've been doing.) The process is a combination of taking die
| photos, tracing out circuitry, understanding the circuits,
| doing background research, and figuring out how to explain
| the chip in blog posts.
| backspace_ wrote:
| I feel like there was a missed opportunity with the title, why
| the departure from using Roman numerals and call this article
| part IV?
| kens wrote:
| A missed opportunity in what way? Is "IV" better than "4"?
| S_A_P wrote:
| I've never been a huge fan of FM synthesis as I'm mostly
| reminded of bad electric piano sounds that came out back in the
| 80s. Having owned a tx-7 I knew it was capable of more than
| that but then there was the whole issue of programming it that
| kinda sucks.
|
| That said seeing the tech and how things were implemented has
| me loading up the Arturia DX7-V and tinkering around with it.
|
| Have any other synths or effects on your list to look at?
| joezydeco wrote:
| Once you got past the bad piano sounds, it was in way too
| many arcade and home video systems to keep track of:
|
| https://en.wikipedia.org/wiki/Yamaha_YM2151
|
| One of my favorite pieces is Brian Schmidt's music for
| _Swords of Fury_ , a Williams pinball machine from 1988.
|
| https://www.youtube.com/watch?v=RMIp5nG-C3o
| robbrown451 wrote:
| Here is a very good WebAudio implementation of DX7, so you can
| hear what it actually sounds like:
| https://www.webaudiomodules.org/wamsynths/dx7
| faeyanpiraat wrote:
| Doesnt work on iphone
| ctdonath wrote:
| I have a DX7 I might part with...
| dboreham wrote:
| Intriguing to imagine the first time the designers heard the
| sound their creation could make (presumably there was a TTL or
| bit-slice prototype before the VLSI implementation). They're
| sitting around the lab, someone plinking away on the keyboard.
| One of them says "you know, you could use that sound on a pop
| record and I bet it would be popular for at least a decade".
| kens wrote:
| The story behind FM synthesis is pretty interesting. A Stanford
| music professor, John Chowning, came up with the idea in the
| 1960s and patented it. Stanford didn't think this was what a
| music professor should be doing and fired him. Meanwhile,
| Yamaha licensed the patent from Stanford, paying millions of
| dollars and making it Stanford's most lucrative patent at the
| time. Stanford changed their mind about Chowning and hired him
| back, making him a full professor and then department chair.
|
| For more information, see: https://priceonomics.com/the-father-
| of-the-digital-synthesiz...
| npunt wrote:
| Great read. Images aren't loading on that link but wayback
| machine to the rescue: https://web.archive.org/web/2015032322
| 2119/https://priceonom...
| TheOtherHobbes wrote:
| The early FM pieces weren't very pop.
| https://www.youtube.com/watch?v=988jPjs1gao
|
| You may think it sounds crude, but pieces like these took
| hours of expensive mainframe (PDP-10) time. There wasn't a
| lot of opportunity for careful sculpting of fine details.
|
| You could easily synthesize something like this in real time
| now. But not many people do, which I think is a shame.
|
| If you can read French, there's more background here:
| http://brahms.ircam.fr/analyses/Stria/
| ctdonath wrote:
| _hours of expensive mainframe (PDP-10) time_
|
| Equivalent today to milliseconds of processing in an Apple
| Lightning cable.
| redler wrote:
| That clip sounds like something straight out of the
| soundtrack from Close Encounters of the Third Kind.
| duskwuff wrote:
| > If you can read French, there's more background here:
| http://brahms.ircam.fr/analyses/Stria/
|
| If you can't read French, use Google Translate. It handles
| this article extremely well.
| TonyTrapp wrote:
| > Stanford changed their mind about Chowning and hired him
| back
|
| Somehow I feel that if this happened today, no company or
| university would have the spine to do this, and it would
| rather turn out as an expensive legal battle if he insisted
| on getting his part of the patent pake.
| motohagiography wrote:
| This article series is mind blowing to me. The engineering is
| fascinating. It's like they made another logical analog
| abstraction layer over the digital electronics. Yamaha doesn't
| get mentioned much here, but between how they can bring the
| experience of their instruments, motorcycles, and sound equipment
| to people everywhere, there is an understated beauty in what that
| company does. They only seem to make things that are wickedly fun
| and life's great pleasures. Also, this:
| https://en.wikipedia.org/wiki/Yamaha_CX5M
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(page generated 2021-12-10 23:00 UTC)