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Yamaha DX7 Technical Analysis

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Re: Yamaha DX7 Technical Analysis

#41

Post by MauranKilom »

ajuc wrote: post #23
metaphor wrote: post #3

> In mathematical terms, FM synthesis is achieved by using the instantaneous amplitude of a sound wave (the modulator) to adjust the rate of change in the phase angle of another wave (the carrier). > As convoluted as this sounds, it makes more sense when visualised: [1] ...but does it?? [1] https://ajxs.me/static/img/articles/dx7_technical_analysis/f...

> ...but does it?? I think in this case the clearest explanation is the equations + graphs: 1. modulator(t) = sin(t) 2. carrier(t) = sin(t*4) 3. result(t) = sin(t*4 + d modulator(t)/dt) = sin(t*4 + cos(t)) http://www.fooplot.com/#W3sidHlwZSI6MCwiZXEiOiI0K3NpbigxMCp4... EDIT: it's wrong, see below

I'm pretty sure you need an integral in there somewhere, no?

Re: Yamaha DX7 Technical Analysis

#42

Post by achairapart »

TonyTrapp wrote: post #39
lars-b2018 wrote: post #32

Really good article. My first synth, that I had to save up for as a teen, was a DX7. However, wasn't FM synthesis part of the New England Digital's Synclavier system, which was available in the late 70s? Certainly the DX7 was really the first mass-market commercial offering, but I believe the Synclavier was first to market with frequency modulation. I wonder what the arrangement was with John Chowning, if anything, o…

I think this explains the timeline quite well: https://priceonomics.com/the-father-of-the-digital-synthesiz... > Somewhere in this lull, a tiny Vermont-based synthesizer company aptly named the New England Digital Corporation beat Yamaha to the punch by producing the world’s first digital synthesizer, the “Synclavier.” Though only 20 units were sold at $41,685 each, and they were all reserved for top-notch musicians,…

The DX7 was the first affordable, fully digital programmable keyboard to hit the market.

Also, technology for digital synthesis was already there, the big game was to avoid patent infringement from other companies.

For example, Casio invented the "Vowel–consonant synthesis" used in their 80s Casiotone keyboards mostly to prevent conflicts with an existing patent from Allen Organs[0]. And later, they came out with the "Phase Distortion Synthesis" as an *alternative* FM synthesis[1].

[0]: See the bottom of this page: http://weltenschule.de/TableHooters/Casio_CT-410V.html

[1]: https://electricdruid.net/phase-distortion-synthesis/

Re: Yamaha DX7 Technical Analysis

#43

Post by mns06 »

parabyl wrote: post #30

Interestingly, the DX7's log drum patch is having a massive comeback in the South African genre Amapiano. I would draw a parallel here to the 808 bass, in that I wouldn't be surprised to see the Log Drum become a lasting element in South African electronic music.

I've been trying to figure out what this genre of African music is called for ages. Thanks!

Re: Yamaha DX7 Technical Analysis

#44

Post by grumpyprole »

TonyTrapp wrote: post #39
lars-b2018 wrote: post #32

Really good article. My first synth, that I had to save up for as a teen, was a DX7. However, wasn't FM synthesis part of the New England Digital's Synclavier system, which was available in the late 70s? Certainly the DX7 was really the first mass-market commercial offering, but I believe the Synclavier was first to market with frequency modulation. I wonder what the arrangement was with John Chowning, if anything, o…

I think this explains the timeline quite well: https://priceonomics.com/the-father-of-the-digital-synthesiz... > Somewhere in this lull, a tiny Vermont-based synthesizer company aptly named the New England Digital Corporation beat Yamaha to the punch by producing the world’s first digital synthesizer, the “Synclavier.” Though only 20 units were sold at $41,685 each, and they were all reserved for top-notch musicians,…

There's a solo album by Eddie Jobson (circa 1985) "Theme of Secrets", which is an excellent showcase for the Synclavier (IIRC the entire album is done with it).

Re: Yamaha DX7 Technical Analysis

#45

Post by yobbo »

tgv wrote: post #4

Plogue, a Canadian software company, have recently released a (software) emulation of the DX-7 in excruciating detail. Here you can see part of the trouble they went through: https://www.youtube.com/watch?v=XJ97iXQrqzw . Suffice to say that they used a logic analyzer to discover gritty details that no other analysis of the DX-7 I know has ever paid attention of.

Mind blown

Re: Yamaha DX7 Technical Analysis

#46

Post by ajxs »

varispeed wrote: post #40

> Each operator has its own phase accumulator. The patent describes a 96 stage shift register to store the phase increment for the 6 operators each of the synth’s 16 voices. Why this was allowed to be patented? This is a pretty much obvious thing to do when you have this kind of limitations. It seems like people reviewing patents don't really understand what they are about. There is plenty of stuff like this in audio…

The Dave Smith quote in the footnotes springs to mind:

"If you have a lot of patents and somebody comes after you, chances are one of your patents will overlap enough with one of their patents that you can negotiate a deal so nobody gets hurt. Whereas if you don't have anything to offer and you have nothing in your stable of patents, then you're stuck"

The article I sourced this quote from can be found here: http://summit.sfu.ca/item/7720

I just chalked this kind of weird specificity up to the legal minutiae required to patent musical hardware. Maybe someone with legal experience can weigh in on this. I'm guessing that if you go into this level of detail regarding the technical implementation, it probably makes it much easier to litigate patent infringement later, and narrows the possibility that someone else can get away with a similar implementation. The titles of some of Yamaha's other musical patents are pretty obscure: "Electronic musical instrument with user programmable tone generator modules (5,040,448)", "Electronic musical instrument capable of varying a tone synthesis operation algorithm (4,558,857)", etc.

Re: Yamaha DX7 Technical Analysis

#47

Post by jacquesm »

yobbo wrote: post #45
tgv wrote: post #4

Plogue, a Canadian software company, have recently released a (software) emulation of the DX-7 in excruciating detail. Here you can see part of the trouble they went through: https://www.youtube.com/watch?v=XJ97iXQrqzw . Suffice to say that they used a logic analyzer to discover gritty details that no other analysis of the DX-7 I know has ever paid attention of.

Mind blown

Why?

Re: Yamaha DX7 Technical Analysis

#48

Post by jacquesm »

grumpyprole wrote: post #44
TonyTrapp wrote: post #39

Earlier quoted context omitted.

I think this explains the timeline quite well: https://priceonomics.com/the-father-of-the-digital-synthesiz... > Somewhere in this lull, a tiny Vermont-based synthesizer company aptly named the New England Digital Corporation beat Yamaha to the punch by producing the world’s first digital synthesizer, the “Synclavier.” Though only 20 units were sold at $41,685 each, and they were all reserved for top-notch musicians,…

There's a solo album by Eddie Jobson (circa 1985) "Theme of Secrets", which is an excellent showcase for the Synclavier (IIRC the entire album is done with it).

That's a pretty good record, I still have it. The opening song sounds like a marble falling on a huge sheet of glass. Quite the sound effect for the time.

Re: Yamaha DX7 Technical Analysis

#49

Post by jacquesm »

jacobvosmaer wrote: post #19
jacquesm wrote: post #5

Earlier quoted context omitted.

I repair them to keep them in play, impossible to get some of the parts so I tend to use one that is too far gone to repair a number (usually three or so) of others and then I still end up with some more spares that might come in handy later. They are incredibly durable, one that I got had been in a fire but it still worked, even though more than half of the keyboard had been burned off. The mainboard went on to repa…

Only original DX7's, or also the DX7ii? Opening up the DX7ii (and other synths from the same time) is a pain compared to the nice hinge construction you get on the original DX7.

So far I've only seen the originals, a DX7ii would be hard because I don't have a stash of spares for them so the first couple would likely end up as donors.

Re: Yamaha DX7 Technical Analysis

#50

Post by jacquesm »

l33tbro wrote: post #13
jacquesm wrote: post #10

Earlier quoted context omitted.

It's the level of tech that I grew up with so I'm not sure where you'd learn it other than just to get your hands on one and to start digging in. Very few tools required if you stick to the test-and-replace-subsystems level, a screwdriver, a good DVM, a soldering iron (a good one, preferably one that is isolated from mains), a lot of spare time and a notebook so that you can keep track of what you find and build up a…

You don't happen to have a hi-hat decay slider for an MPC60 lying around? Can't find a replacement for the life of me, and I've taken to sad attempts like this when the opportunity arises :D

The cap? Or the actual slider? If you have the specs of the slider I can dig around for a suitable substitute, alternatively I can go on the lookout for a donor synth.
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