[HN Gopher] Yamaha DX7 Technical Analysis
___________________________________________________________________
Yamaha DX7 Technical Analysis
Author : jacquesm
Score : 264 points
Date : 2021-10-21 05:57 UTC (17 hours ago)
(HTM) web link (ajxs.me)
(TXT) w3m dump (ajxs.me)
| weatherlight wrote:
| I was under the impression that, despite the name, the Yamaha FM
| synths didn't actually use frequency Modulation but rather phase
| modulation. With Frequency modulation you can't have an operator
| feed back on its self.
|
| If you take a DX7 patch and implement it on something like the
| PreenFM2 or PreenFM3 (which uses actual FM), any algorithm with
| more than a few operators is going to sound quite different.
|
| I still love the old Yamaha FM synths though, the lo-fi-ness of
| the DACs are so musical/magical.
|
| Here's a IDM track I made with just the Yamaha TX81z 4op FM
| synth. https://soundcloud.com/cassilda_and_carcosa/ontologies-
| tape-...
| jacquesm wrote:
| Wow, that transported me right back to my first experience
| listening to Kraftwerk. Thank you, keep it up, very well done!
| xattt wrote:
| I'm getting Aphex Twin out of this!
| weatherlight wrote:
| 7\
|
| Thanks!
| tekstar wrote:
| Woah! Are the drums also TX81Z? That sounds great!
| weatherlight wrote:
| TX81z sampled and trigger with an elektron rytm mk2. also,
| thanks!
| [deleted]
| klodolph wrote:
| > I was under the impression that, despite the name, the Yamaha
| FM synths didn't actually use frequency Modulation but rather
| phase modulation. With Frequency modulation you can't have an
| operator feed back on its self.
|
| It's true that it's phase modulation, but phase is just the
| derivative of frequency, and the derivative is a linear
| operator (essentially a 6dB/oct EQ). So I don't think it's an
| especially important piece of terminology to get correct.
|
| The statement about feedback is actually backwards. You cannot
| directly incorporate feedback into a phase modulation system.
| In the Yamaha system, the feedback is delayed by a sample to
| make it work. In an FM synth, this would not be necessary, and
| you could just directly feed the output back into the input.
| tgv wrote:
| I think direct feedback in PM is possible, at least for low
| modulation indices. The Yamaha implementation is in software,
| so a one sample delay is the easiest implementation
| (otherwise you'd have to solve a rather complex equation at
| every step).
| klodolph wrote:
| The distinction that I'm making is exactly that. You can't
| incorporate direct feedback into a phase modulation
| synthesizer, you need to incorporate delay into the
| feedback path. By comparison, you can use direct feedback
| with subtractive or FM synthesis.
|
| The one-sample delay basically turns the feedback into an
| iterated function system. With certain parameters, you end
| up with aperiodic results--cool in theory, but in practice,
| often just used as a noise source.
| tgv wrote:
| But if we take the simplest example, f(x) = sin(x +
| c*f(x)), we can solve it, (numerically). If I run it up
| to 0.5p for c=0.5, I get something that's (obviously)
| very close to the function with a short delay. So I take
| that as the possibility of direct feedback, although in a
| electronic circuit, feedback also has a minute delay.
| nyanpasu64 wrote:
| > phase is just the derivative of frequency, and the
| derivative is a linear operator (essentially a 6dB/oct EQ).
|
| FM (if strong enough to create negative frequencies) and PM
| are equivalent when you're modulating a signal with a sine
| wave. As soon as you chain modulators, they're no longer
| mathematically equivalent or capable of producing the same
| sounds, since frequency-modulating a signal by a complex wave
| is different from phase-modulating a signal by the same
| complex wave (which can produce sharp corners given a bounded
| input with sharp corners).
| weatherlight wrote:
| One thing that is different in the preenfm2 compared to the
| Yamahas stuff is, that it uses linear FM and therefore will
| not do operator feedback.
|
| The guy behind the preenfm2 says, that feedback is not that
| important, when you have a variety of waveforms for
| modulation. Linear FM also has the advantage of being a bit
| "friendlier/warmer" when using complex waveforms as
| modulators (Higher harmonics of the modulator will have a
| smaller effect than in phase modulation).
|
| One thing you loose when not having feedback: The normal
| feedback happens after the amplification/envelope if I
| remember correctly Therefore the amount of feedback scales
| with the amplitude. With feedback you therefore get less
| harmonics and therefore a "softer" sound at lower amplitudes.
| This is quite useful, because it mirrors the behavior of most
| natural sound sources. It is the same idea as using a lowpass
| gate or using the same envelope for the amp and the filter in
| subtractive synthesis. Of course FM synths give you enough
| options to get this effect in another way. I still like the
| yamaha style feedback though....
| klodolph wrote:
| I will say--my personal experience, in dissecting DX7
| presets, is that feedback is not really used that much. If
| you are porting DX7 sounds to a different architecture, you
| can remove the feedback and replace it with something like
| a noise source, or another operator, much of the time, or
| even remove it altogether.
|
| This is just my personal experience. I often dig through
| DX7 patches in order to reimplement them for demoscene
| projects.
|
| Sounds like you're getting good use out of the TX81Z. I
| have the TX802, which is _on paper_ a better synth, but
| controlling it from a DAW is much more of a pain because
| the program change messages control the "performance",
| rather than the patch. So it's been exiled from my rack, at
| least for now.
| weatherlight wrote:
| if you try to control the parameters on the TX81z while
| its receiving midi info, it starts to "skip" and the
| notes start to lag, lol.
|
| I wish i had a TX802 or a fs1r yamaha. Those are so nice!
| weatherlight wrote:
| also on spotify ->
| https://open.spotify.com/track/0m3XklXAjsJAnSMgl2Upif?si=391...
| S_A_P wrote:
| Anecdote I read on Gearspace- Nine Inch Nails used to destroy
| DX7s on stage during their tour. They would basically go to pawn
| shops in each town they played and buy up the DX7s. They were so
| reliable that they typically didnt have to worry about whether or
| not they worked, and the keyboard was great for playing and
| controlling other things via midi. They sold in such numbers that
| they were ubiquitous, but kinda sad to know that many were
| destroyed unnecessarily...
|
| https://gearspace.com/board/electronic-music-instruments-and...
|
| check post #34 from Charlie Clouser who toured with them in that
| era and is also a pretty well known producer/engineer
| jmcguckin wrote:
| For a number of years, the FM patent was the most profitable
| patent that Stanford owned. It's interesting that it was a patent
| from the music department - not engineering, not biotech that
| made the most money...
| metaphor wrote:
| > _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...
| buildsjets wrote:
| If you understand Bessel Basis Functions, or the design and
| tuning of motorcycle carburetors, then it makes perfect sense.
| If you are uneducated on these and similar arithmatic
| summations of wave functions, then it will make no sense.
| rcxdude wrote:
| "rate of change of the phase angle" is just a convoluted way of
| saying 'frequency'
| jacobvosmaer wrote:
| I'm not sure. Intuitively I would think "phase angle" means
| "offset into the sine wave lookup table".
|
| If you step through the lookup table with constant size
| steps, you would get a sine wave. If the steps are not
| constant size then you get a distorted sine wave. The "rate
| of change of the phase angle" would then be the step size.
| ajxs wrote:
| Author here: This is one reason why I used that term. I was
| definitely thinking in terms of the 'phase accumulator'
| looking up the sin table.
|
| Everyone is absolutely right that this is the same as
| _frequency_. I think I was used that particular poetic
| flourish to emphasise how complicated the academic,
| mathematic explanation is, in contrast with the diagram.
| Quite likely I picked up that exact phrasing of _" phase
| angle"_ from some academic literature in particular.
| joeberon wrote:
| > This is exactly why I used that term
|
| That's a lie, because:
|
| > I think I was used that particular poetic flourish to
| emphasise how complicated the academic, mathematic
| explanation is, in contrast with the diagram
|
| is a totally different to what the person you are
| replying to said
| ajxs wrote:
| I've edited my post to clarify. It's _a reason_ why I
| used that term. The second part of my post is not
| directly addressing what GP said. One of my aims in
| writing this article was to create something that could
| be interesting to read, with someone like myself as the
| target audience. Part of that involves using some
| artistic flourish.
| HelloNurse wrote:
| What matters for FM is an instantaneous quantity: the
| derivative or increment of the instantaneous phase, i.e.
| how the phase changes from sample to sample.
|
| What is usually called frequency, and has the same value in
| boring cases like an unvarying sinusoid, is the inverse of
| the period of the resulting sound as someone would hear it,
| which is not instantaneous and needs on the order of one
| period's worth of samples (usually more) to estimate, for a
| certain definition of period (e.g. interval between zero
| crossings) or a certain mathematically reasonable
| calculation (e.g. estimating the frequency of the strongest
| component from a fixed-length window of past samples).
| joeberon wrote:
| "frequency" would mean the same thing in your weird
| practical analogy.
| cto_of_antifa wrote:
| Be polite, please.
| rcxdude wrote:
| This is exactly how direct digital synthesis works and the
| 'step size' is labelled 'frequency' (specifically,
| frequency in HZ = step size / size of table * update rate)
| armchairhacker wrote:
| Idk what's going on with the modulated carrier in that image.
| Here's a better visualization:
| https://flypaper.soundfly.com/wp-content/uploads/2017/09/AM_...
|
| Notice how, when the modulator wave is at its top the FM wave
| is very short, and when the modulator wave is at its bottom the
| FM wave is very long.
|
| FM = adjust the frequency (width) of the carrier based on the
| absolute value of the modulator.
| ajxs wrote:
| Author here: Thanks for pointing this mistake out! I'm not
| sure how I didn't validate this. I believe the mistake lies
| in the _absolute value_ aspect of the formula. Unfortunately
| I can 't find the script I used to create those diagrams.
| I've been meaning to revisit this article, and update it with
| some of my more recent discoveries. I'll make sure to update
| this when I do so!
| metaphor wrote:
| Link to the Chowning paper[1] is broken too; hazarding a
| guess that neither AES nor Prof. Fessler would mind.
|
| [1] https://web.eecs.umich.edu/~fessler/course/100/misc/cho
| wning...
| ajuc wrote:
| > ...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
| MauranKilom wrote:
| I'm pretty sure you need an integral in there somewhere, no?
| 8bitsrule wrote:
| It helps me to think of the difference between AM and FM radio.
|
| In an AM radio signal, the frequency of the carrier is
| constant; the amplitude of the audio modulates the _amplitude_
| of the carrier.
|
| In an FM radio signal, the amplitude of the audio modulates the
| _frequency_ of the carrier. That 's the difference!
|
| In musical terms, I very much like some analog, and some FM,
| synthesizers. But certainly, back in the day, getting some rich
| sounds out of FM synths was _a lot_ cheaper than analog. (Just
| in terms of the cost of patch cords alone ;-) Without Chowning
| there wouldn 't _have been_ a synthpop era!
| parabyl wrote:
| 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.
| mns06 wrote:
| I've been trying to figure out what this genre of African music
| is called for ages. Thanks!
| tgv wrote:
| 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.
| z5h wrote:
| I like to think I'm a synth nerd in the know, and certainly
| chat a lot and read synth forums. But Plogue have flown under
| my radar. This looks like great stuff at a good price. Do you
| own any of their soft synths?
| tekstar wrote:
| I think they have a decently lengthen demo period for all
| their plugins. I remember playing with many of them in the
| past for a period
| S_A_P wrote:
| Plogue has been around for a while but nobody could fault you
| for missing them. I have been and active member of KVR VST
| for over 20 years which is where I heard of them but never
| owned anything of theirs. It was only recently announced that
| they released this 'sample accurate' DX7 clone.
|
| I have TX7 for and the Arturia DX-7V. Typically FM or Phase
| Distortion(Casio CZ synths) arent really the type of sound I
| go for, but they definitely shine in clanky metallic
| dissonance.
| TheOtherHobbes wrote:
| Bidule has been around for _ages_ - at least 10 and maybe
| even 20 years.
| tgv wrote:
| I have two of their sample players (one for Garritan
| products, and their free sfz player), I've got Bidule (which
| is a semi-modular environment where you can combine
| processing units and plugins in complex graphs; a bit like
| Reaktor), and recently bought the OPS7, because it sounds so
| damn authentic and is fun to play with: it has two layers, so
| you get something similar to the DX-1/5 sound.
| tecleandor wrote:
| They have some great things. I bought their Bitcrusher plugin
| years ago, which is really fun, and I think I still receive
| software updates for that.
|
| Chipsounds is great if you're into 8-bit / chiptunes and the
| like (they also have a "chipsynths" series of plugins
| emulating SNES/MEGADRIVE, and other classic game consoles,
| but I haven't tested them...)
|
| And Bidule is quite a thing. Is some sort of modular VST
| synth with tremendous options for routing that seems very
| well suited to prepare live performances. The Philip Glass
| Ensemble, through Michael Resman has used it at least once to
| make complex live setups: https://www.plogue.com/michael-
| riesman.html
| jlarcombe wrote:
| they're super great, their software is ace. we used to work
| with them at my old company and they're lovely people too!
| noizejoy wrote:
| Another venerable DX7 software emulation worth mentioning is
| the free and open source Dexed[0], which also doubles as a
| patch librarian for a real DX7.
|
| [0] https://asb2m10.github.io/dexed/
| 867-5309 wrote:
| dexed is in the Acknowledgements of the main article
| tomcam wrote:
| Wow, thank you
| yobbo wrote:
| Mind blown
| jacquesm wrote:
| Why?
| weatherlight wrote:
| The DAC conversion is hard to nail in combined with the
| 12-bit certain crunchiness to the old Yamaha FM synths.
| AstralStorm wrote:
| I think using 15-bit ADPCM u-law would be a quick and
| dirty approximation. Or similar ADPCM.
| nyanpasu64 wrote:
| Retro synth emulators are terrible at proper analog audio
| emulation. Higan (the "most accurate" SNES emulator) uses
| cubic teaming for the output without an attempt to
| emulate the stairstepped ZOH DAC or analog lowpass, or
| implement a brick wall. Plogue is one of the few
| developers to produce proper analog emulation, and they
| say they document all their research
| (https://youtu.be/V3yWXVAZgO0), but I'll have to check
| again to see if I can find it in the video or not.
| jacquesm wrote:
| Thank you, most interesting.
| mikewarot wrote:
| The numerically controlled oscillator (NCO) aka Direct Digital
| Synthesizer (DDS) at the heart of this is one of the most elegant
| things I've encountered. I once used an NCO to adjust for belt
| speed variation in a machine that applied hot glue to corrugated
| boxes in a production environment. The CPU I had at the time was
| constrained to 512 Bytes of EEPROM to store the program in, and
| it (the NCO) really helped fit that along with all the I/O to
| read the input thumbwheels into the thing.
|
| The customer kept adding features, and when I was all done, I had
| all the code in 511 bytes.
|
| All a phase accumulator is is a long register you add to, and
| only take the top N bits off of. It's quite easy to have 64 bits
| of frequency resolution, regardless of how many bits your SINE
| table lookup is going to the DAC.
| jacquesm wrote:
| > I had all the code in 511 bytes
|
| What a waste ;)
|
| It's funny how this works though: customer makes yet another
| request, at first your response is 'forget it'. Then, late at
| night when the house is quiet you really start to think about
| it and bit by bit the solution starts to present itself. Then a
| highly annoying bout of code golf later you manage to squeeze
| the feature in, and end up with more free space than you had
| before...
| HeyLaughingBoy wrote:
| I have to ask. Was the MCU by chance an MC68HC705K1?
|
| Asking for a friend :-)
| mikewarot wrote:
| It was a 68HC11, I forget the specific model number, they had
| a few development boards for $68.11 in the local college
| bookstore, so that's how I prototyped it. ;-)
| HeyLaughingBoy wrote:
| I asked because in interviews I used to mention the amount
| of functionality I stuffed into a 'K1, which ISTR had 511
| bytes of program memory.
|
| I recall that HC11 version too! I bought the PLCC version
| and made my own dev board with a through hole PLCC socket
| :-)
|
| [edit] memory just caught up to me. The HC05K1 had 504
| bytes of program memory, not 511.
| QuadrupleA wrote:
| I've been restoring a closely related DX11 recently - one
| interesting tidbit of over-engineering, the keyboard matrix for
| the tact switches on the front panel (not just the musical keys)
| has a diode for every switch, to apparently allow "chords" of 3
| or more programming buttons to be held and scanned at once. Can't
| see why it's needed during programming of the patches, but I
| might be missing something. Maybe someone had a kickback deal
| with the diode vendor to ship an extra 40 of them per unit :).
| jacquesm wrote:
| I think without that diode there would be ambiguity about which
| switch is pressed, it keeps the rows and columns in the matrix
| separate so no current can flow back to other rows/colums when
| one key is pressed.
| QuadrupleA wrote:
| You can definitely do 2 simultaneous keys unambiguously
| without diodes; 3 keys is where you sometimes get "phantom
| keys" by bridging other rows / columns to each other. Depends
| on the matrix layout though, if you have say an 8 x 8 matrix
| for 64 keys and each pressed key is on the same column or
| row, you can read 8 simultaneously without any problems.
|
| Most PC keyboards leverage this so they can skip diodes, and
| just route the matrix so that common simultaneous
| combinations (modifier keys, WASD for games etc.) don't
| interfere with each other.
| jacquesm wrote:
| Hm. I don't know about that, I thought that the problem
| already existed for 2 diagonally opposing sets of buttons:
| you can't tell the difference between the two.
|
| so: | | | | | |
| ---+-+-+-+-+-+----- | | | | | |
| ---+-+-*-+-+-+----- | | | | | |
| ---+-+-+-*-+-+----- | | | | | |
|
| and | | | | | |
| ---+-+-+-+-+-+----- | | | | | |
| ---+-+-+-*-+-+----- | | | | | |
| ---+-+-*-+-+-+----- | | | | | |
|
| Would look identical to the CPU without diodes.
| TheOtherHobbes wrote:
| https://patents.google.com/patent/US5430443
| jacquesm wrote:
| Ah I see, clever!
|
| So in essence because the diode solution requires rows
| times columns diodes and this one only has a couple of
| parts per row and per column it scales better and for
| larger keyboards will end up with a substantially reduced
| parts count and a simpler circuit.
|
| That patent is quite a bit younger than the synth though,
| so it's kind of logical that that technique would not be
| used, and my hunch on why they used those diodes back
| then is likely correct, even if we have a smarter way of
| doing this now.
| QuadrupleA wrote:
| That should work fine - the CPU would scan / energize
| each row independently and then check which columns are
| connected.
| QuestingElf wrote:
| On a related note (pun intended) I once had a problem
| with one of these synths and its rubber contact strip. I
| would hit certain keys then hear a neighbor note or the
| same note an octave away. I thought there was a short in
| the scanning circuitry (I had resoldered some joints that
| appeared weak earlier by a ribbon connector for the
| keybed.)
|
| Turns out the rubber contact strip was installed
| inverted. I think this one didn't have notches to make
| sure it was oriented correctly. After flipping it, notes
| sounded as expected.
| klodolph wrote:
| Also note--there's no interpolation. Those 4096 entries in the
| table? That's all you get. The chip will not interpolate between
| them.
| kennywinker wrote:
| This was the first thing I scanned the article for. Without
| interpolation, my understanding is there's likely a TON of
| aliasing in the raw output, but then that goes through a 16khz
| lowpass filter that chops everything above 16khz off - cleaning
| it up.
| jacquesm wrote:
| I wonder if there is a nice spot where the audio pre-lowpass
| filter can be pulled out to listen to.
|
| The inverting input of IC56 might be a good place.
| lars-b2018 wrote:
| 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, on this.
|
| https://120years.net/wordpress/the-synclavier-ii-new-england...
| TonyTrapp wrote:
| 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, Stanford took no chances, and swiftly sued the
| company for infringing on its FM synthesis patent. From that
| point forward, the university received a sum of $43 every time
| a Synclavier was sold.
|
| Yamaha had been working on FM synthesis for a few years already
| at that point.
| achairapart wrote:
| 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/
| grumpyprole wrote:
| 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).
| jacquesm wrote:
| 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.
| ChrisMarshallNY wrote:
| I used a DX7 to write my MIDI driver for the Mac, in the late
| 1980s. I never really played it. I was a bass player.
|
| By the time it was ready for release, Apple released their own
| driver, so I just open-sourced my work.
|
| I gave the DX7 to someone. Can't remember who.
| mdp2021 wrote:
| Waiting now for the SY99 ;)
| ajxs wrote:
| Author here: I wish! I own a TG77, and it's an absolutely
| amazing synth. While I don't have any direct experience with
| the SY99, the 77 was so far ahead of its time. The sheer amount
| of features packed into the synth alone is an engineering feat.
| speed_spread wrote:
| I have an SY77 that I'm scared of. It's my second oldest
| synth and yet the deepest, craziest machine of all the
| studio. I can't fathom the engineering process that went
| behind it.
| pea wrote:
| I've got a 99 and, outside of the dated fx and sequencing
| abilities, I think the only real difference is that you can
| load your own waves for the RCM modulation? I think you can
| hack the 77s to do that too.
|
| Oh, and it's even more unbelievably massive and heavy. I will
| never part with it - they are the most criminally underrated
| synths, and it's crazy they are still often priced lower than
| the DX series.
|
| It would be great if someone would built a better live editor
| for them though.
| inetsee wrote:
| If anyone is interested in exploring software based FM synthesis,
| Csound is capable of doing FM synthesis [1], and can model the
| Yamaha TX81Z FM Synthesizer [2]. (I had one years ago and I loved
| the sounds).
|
| [1] https://csound.com/docs/manual/SiggenFmsynth.html
|
| [2] https://csound.com/icsc2019/proceedings/3.pdf
| joeberon wrote:
| I love the DX7 but it's a shame that the maximum LFO frequency is
| so low. It really hampers the sound design possibilities
| boondaburrah wrote:
| I think I saw somewhere that you can actually tell the LFO is
| done in software because it actually slows down if you move the
| sliders a lot while the CPU tries to pay attention to too much
| at once.
| joeberon wrote:
| Yeah it's a shame, on the other chips you can get amazingly
| air-y textures by setting the LFO to noise and then putting
| the frequency all the way up. See this video for example:
| https://youtu.be/_xL3qr-9-ZE
| jacquesm wrote:
| It sounds to me as though a firmware patch should be able
| to fix that to some extent. The main culprit here is the
| interrupt service routine, which while tight likely isn't
| immune to some code golfing.
| boondaburrah wrote:
| Would sacrificing an operator and setting it to constant
| mode instead of mult work for this? You'd have to use the
| feedback operator if you wanted something noisy though.
| klodolph wrote:
| The operators actually contribute phase, not frequency,
| and there are very limited ways that they can be routed.
| [deleted]
| fho wrote:
| Yamaha builds so much stuff that this could have been about ... a
| boat ... a motorcycle ... a guitar ... or the iconic synth :-)
| rvense wrote:
| Once, when traveling in mountainous Central Asia, the road was
| blocked by a mudslide. The digger that came in to clear the way
| for us was a Samsung...
| davidjade wrote:
| Or a sailboat... that one always surprises me.
| kennywinker wrote:
| https://www.theonion.com/yamaha-ceo-pleased-with-current-pro...
|
| > Yamaha CEO Pleased With Current Production Of Jet Skis, Alto
| Saxophones, Snowmobiles, Power Generators, Scooters, Golf Carts
|
| An all time fav
| ronenlh wrote:
| I love the overlap of Tech and music production.
|
| By the way, if anyone is interested in a modern, affordable,
| nostalgic incarnation of the DX7, check the "reface" edition.
| tibbydudeza wrote:
| The synth that made a new genre of music possible - 80's music
| would not have been the same without it.
| jdub wrote:
| I know Raph for his graphics, typeface and desktop work, so
| seeing his name pop up in this was a surprise! Can't keep a good
| genius down.
| TheOtherHobbes wrote:
| There's a history of Chowning and FM here. Practical FM is
| closely linked to CCRMA's Samson Box which was designed by Peter
| Samson of System Concepts, who were better known for building
| affordable(ish) DEC KL10 clones.
|
| https://120years.net/tag/ccrma/
|
| When Chowning met Dave Bristow, who was Yamaha's product
| specialist and designed many of the DX7 presets, he apparently
| asked if Bristow could explain FM to him because he didn't really
| understand how to use it.
|
| This was partly a joke and... partly not. It was also before they
| wrote this together:
|
| http://www.burnkit2600.com/manuals/fm_theory_and_application...
| varispeed wrote:
| > 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
| space.
|
| E.g. this one
| https://patents.google.com/patent/US20170060527A1/en
| ssalazar wrote:
| This specific technique for synthesizing a single operator
| wasn't patented, its one small part of a much broader patent.
| ajxs wrote:
| 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.
| knoke wrote:
| How is it possible that no one here mentions Korg's wundermachine
| Volca FM, a tiny DX7 compatible, Dexed/KQ Dixie controllable and
| cheap midi synth with endless possibilities?
| QuestingElf wrote:
| I really appreciated both the technical descriptions (esp. those
| lookup tables) and the historical portions saying where the DX-7
| was in relation to other Yamaha FM synths like the 4-operator
| ones.
|
| I originally got very interested in this when discovering the
| YM-2151 chip that made 80's arcade game sounds was also found in
| pro-audio keyboards. They used a very similar YM-2164. This got
| me to explore the whole DX line including DX-7, DX-9, DX-27S and
| that keytar that's still popular for bass and talkbox, the
| DX-100.
| danbmil99 wrote:
| Awesome -- the DX7 had a huge musical impact.
| jacquesm wrote:
| 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 repair
| one that was otherwise good but had a fried CPU. Another one I
| got had been owned by a touring musician, who apparently didn
| 't know about flight cases :) There wasn't a lick of paint on
| the outer case. I got it for free because it wouldn't turn on
| any more. Turned out that the voltage selector had somehow been
| moved in transport and got stuck between the two settings,
| leaving it disconnected. That was the fastest fix ever, there
| simply wasn't anything wrong with it. (And good thing that
| voltage selector had not been pushed a tiny little bit further
| because then it would have been end-of-story for sure).
|
| So, I have a pretty large collection of spares, looms, main
| boards, display boards, keys (they do break, especially as the
| plastic ages it can get more brittle, more so in synths that
| have been in the sun), switches, PSUs and so on. Every now and
| then I put an ad out to get people to sell me their broken ones
| or to help them out and then a new batch of working DX-7's goes
| back into the world. It's never going to make me a dime,
| especially not when counting the time but it feels pretty good
| to keep these oldies alive, and to see how happy musicians are
| when their baby works again.
| boondaburrah wrote:
| The DX7ii I have is a fucking tank of a machine and I'm
| playing it until it breaks, fixing it, and then playing it
| some more. I guess I kind of understand typical "car guys"
| now.
|
| The best part is being able to map the sliders to /almost/
| any parameter within a patch, so it's possible to have
| expressive control over the tonality of your instrument while
| playing live. Sure it involves menu diving to figure out
| ahead of time, but I'm a programmer. It's really more about
| the joy of being like "this sound needs more wonk, lets tie
| this parameter to the output of this other function and
| ooOOOH not what I was expecting but let's go"
| jacquesm wrote:
| Hah! You're using it like it was intended to be used, the
| DX-7 is first and foremost a performing musician's tool,
| that's exactly why it was built as strong as it was, made
| to be tossed in the back of the car on the way to gigs.
|
| If you ever can't find a part let me know.
| jacobvosmaer wrote:
| 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.
| jacquesm wrote:
| 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.
| iseanstevens wrote:
| I'd love to see some pictures of the super beat up ones that
| still work :)
| jacquesm wrote:
| Ah, that's a missed chance. I never thought of that. That
| one chassis is long gone (I took off it what I could) and
| the burned keyboard I took apart outside the house. The
| keys that were still good went into the spares bin.
|
| Next time I have one of these die-hards I'll be sure to
| take pictures.
| WalterGR wrote:
| That's amazing. How does a person learn to repair older
| electronics tech like that?
| jacquesm wrote:
| 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 store of knowledge over time to help
| diagnose problems faster.
|
| About 200K DX-7's were made, which is enough that you can
| find them and not so many that there is no value in
| repairing them, on top of that the degree to which people
| are attached to their synths is something that still amazes
| me. The level of emotion when a dead synth comes back to
| life with the owners is always quite gratifying, it's some
| of the best time spent for me.
| l33tbro wrote:
| 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
| jacquesm wrote:
| 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.
| l33tbro wrote:
| Will email you picture ;)
| jacquesm wrote:
| Ok! jacques@modularcompany.com
| nkozyra wrote:
| In the 90s, when FM was considered inherently uncool, the DX7
| was the keyboard du jour to use as a controller and
| subsequently smash to pieces in live sets for industrial,
| ebm, techno.
|
| They were dirt cheap and as mentioned, insanely solid.
|
| Same thing happened to to the Casio CZ line. I bought one at
| a time they were very undesirable for $75 and they now go for
| $500+
|
| There's a financial lesson in here somewhere
| nobleach wrote:
| The only problem with using it as a controller (The
| original DX7) was that their MIDI implementation was
| incomplete. So you only got velocity values of 0-100
| instead of 0-127. It still has a wonderful key-bed. I've
| owned a couple of 'em.
| Zenst wrote:
| I had a CZ101 in the day, preferred the sound from PD
| synthesis as it was better at base sounds IMHO.
|
| That and the DX7 was used to death and more so - 99% just
| used the pre-sets and got to stage that you could name the
| sound they used on a sound and all got cliche.
| [deleted]
| RusticCajun wrote:
| Do you work at all with KX88's? I've got one laying around.
| Got it for the college dorm. Wasn't as good as my acoustic,
| but it kept my fingers working. How can I contact you
| directly?
| jacquesm wrote:
| Haven't seen one in the wild yet,
| jacques@modularcompany.com is my email.
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