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FM Synthesis (techniques, anecdotes)


Guest skibby
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i have to decide right now if I want the necronomicon of fm synths or not. knowing it might eat my soul and cause me to be broke for the next two months.

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you can program the tx81z via computer, and imo it sounds better than most software

I guess this is a little too vague for me to prove or disprove but I don't always find that the TX sounds better than software. To me it has a sort of "glassy" sound, which I guess means that it's not super accurate but is pleasantly and musically inaccurate, mostly due to the aliasing and lookup tables. For basses this is just great, for some dull pads, and for stuff like hi hats or snares it can mangle the high end nicely, depending on the situation. But for clarity I think software whoops its ass, at least in my experience with FM7, Reaktor, Max, and the Nord G1 (would you call that hardware or software?). I get a lot more crispness and smoothness, especially in the high end, with the improved sampling and bit rates, the faster envelopes, and the dynamically calculated sinusoids. Also I think the attack on the TX's envelopes is often too slow and shitty.

 

 

i just crashed my fb01 and had to reboot it. the tx81z gets midi buffer overflow errors. anybody else have hardware fm synth anecdotes like that?

yep the tx81z has a notoriously shit midi buffer, but you can get some cool results by overloading it.

 

Interesting - mine has never done anything cool when I overload it. It just sits there until I push a button on the front panel.

 

Also you guys cataloguing & lusting over old FM synths may want to check some posts, especially on gearslutz, by this acreil guy. He's done his homework and knows a lot of details on the guts of these beasts:

 

https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/643463-craving-new-big-fm-synthesiser-2.html

https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/897756-only-reason-people-prefer-sound-dx7-fm8-10.html

 

You can pretty much just google "acreil FM" and get your mind blown.

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yamaha had software that could turn a sample into a voice (fm voice, not referring to formants) in an fs1r patch.

 

im pretty sure they had a rudimentary 'resynthesis' engine that could derive parameters when they made some of their fm patches for other machines.

 

these softwares to my knowledge, never made it public.

 

but a talented developer like xoxos could probably make a program that can analyse a waveform and convert it to an FM patch.

Edited by skibby
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so this thread made me revive my hidden under the bed tg77! still works like a charm and sounds way better than i remembered! i was actually about to sell it but now i have some serious doubts... i'll check out that editor by mr. gear fox; greetings & thx to you, sir!

 

yamaha tg 77
100pounds
very.good.

 

lol. i really thought you were joking about its weight. :confuzzled: it is a huge beast though...

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oh that's cool!

 

something else i thought i'd share, here's something i made in max a while ago set up with some algorithmic sequencing.

 

(picture deleted so as not to crowd thread)

you can download it here:

https://www.dropbox.com/s/iod69glmq2y837t/MGF8op-v0.9.rar?dl=0

Awesome! Much appreciated by this Max noob :w00t:

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btw, acreil posted once about an artist named utabi hirokawa. i recommend him to any fm enthusiast.

 

Really nice stuff! I love those beefy drums :) That machine on the front looked familiar and in fact it looks like he's rocking a Sharp x68000 just like Hizmi of the Ground Zero Organization: http://hizmi.bandcamp.com/

 

Also reminds me of this page, which mentions the handy fact that manipulating timbre/sidebands in FM does not result in changes in overall amplitude, which makes it much easier to mix, etc.: https://ccrma.stanford.edu/software/snd/snd/fm.html

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pretty cool: http://thump.vice.com/words/Diode-Milliampere-ms-dos-interview

 

FM lushness:

 

If you listen to the emulated FM version of the same track you will hear a huge difference.

 

been playing with the SDL version of Adlib Tracker, but I want to get a CRT for my Pentium now :)

man I love these kind of sounds so much - on the megadrive and on the adlib monkey island and stuff

 

why is FM so awesome?

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thanks! let me know if the patches work and all that, gang. i'd like to release them more widely but i need to check they're understandable and usable enough for people as perhaps some of the functions aren't so clear. you don't exactly need to understand them either, as long as they're making interesting sounds to use that's enough for me heh got other things to do :p

 

as i pm'd you already, thanks a lot! both patches seem to work just fine! however, i wouldn't recommend editing the big bpatcher in mfg8op. - man, i thought i'd seen a lot of patch cords in my time! only for the steel nerved... max seemed to think the same as it crashed right when i set eyes on the ungodly chaos therein! (i should prob mention that dsp was on, when turned off it works perfectly)

kudos, mesh gear fox! :beer:

 

btw. this is one of the most inspiring threads in a long time for me! the acreil stuff is brilliant as well! i just wish i'd never sold my mega drive (= sega genesis)...

 

 

 

why is FM so awesome?

 

because even intelligent people can dance to it! :cisfor:

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whats the difference between megadrive and fb01? ...googles...

 

https://www.youtube.com/watch?v=I-mp8GL2Z-0

 

In terms of the sound engine, not much. Virtually there isn't any difference in the FM department - the MegaDrive adds a square wave generator and some limited sampling capabilities, but the FM itself is the same with very minor differences (patches are compatible and sound 99.9999% the same.)

 

 

 

btw, acreil posted once about an artist named utabi hirokawa. i recommend him to any fm enthusiast.

 

Really nice stuff! I love those beefy drums :) That machine on the front looked familiar and in fact it looks like he's rocking a Sharp x68000 just like Hizmi of the Ground Zero Organization: http://hizmi.bandcamp.com/

 

Also reminds me of this page, which mentions the handy fact that manipulating timbre/sidebands in FM does not result in changes in overall amplitude, which makes it much easier to mix, etc.: https://ccrma.stanford.edu/software/snd/snd/fm.html

 

 

I didn't know about Hizmi! Wow, this stuff is even more hardcore than the SOR3 soundtrack...

Very useful page too!!

 

 

That's cool stuff Poble :)

 

I've been playing around with JuceOPL:

0.9.7-screenshot.png

It's a vst emulation of the adlib soundcard that was used for DOS game soundtracks:

download here:

http://bsutherland.github.io/JuceOPLVSTi/

 

Nice! I'll give it a try : )

 

In the FM world, what makes certain chipsets better over other - Is there like a distinct DX7 sound to differentiate it from say an opl-3 one ? Likewise in the VST world: would a free VST FM like FM-Four have much of a difference in the sound to the fully fledged s'pensive FM8 ?

 

How do FM gurus feel Ableton's Operator performs in its FM sound ?

 

There are three factors.

 

The first one is the engine, and in turn there are different factors when it comes to the engine.

Factor 1A is the amount of operators and the possible algorithms. There are 2, 4, 6, and 8 operator FM synths. Most FM synths have algorithms featuring a single feedback loop, but others have more (for example the SY77 family, or synths such as the SY22 family where you have various 2-op stacks each with its own feedback loop.)

Factor 1B is the operator scaling. Turning the output level of a modulator up doesn't have the same effect in every FM synth. I don't know how the 2-op or the 8-op synths work, and I also don't know about the SY77 family, but as for the others, on the one hand you have the DX7 family plus the DX9, which have a gentler character; and on the other the 4-ops other than the DX9, including chips such as the one in the MegaDrive, which are grittier. The way the frequency ratios work is also different between different synths - some allow for higher ratios, some handle the coarse detune in different ways.

Factor 1C is the modulation possibilities. Some synths allow you to have fixed ratio modulators which don't follow the keyboard and can be used as LFOs. Some don't. Some have various LFOs for multitimbral mode, etc.

Factor 1D is whether the operators allow for waves other than sine.

 

The second one is how the sine waves are actually produced. Generally the DX synths avoid actually calculating anything and rely on lookup tables. The combination of the different tables between chips and the different sample rates produces a different character and also different artifacts (aliasing, etc.) Software FM, except emulators, is usually "cleaner" here (and crazily CPU-intensive).

 

The third one is the DACs on each synth/console/computer/etc. But this is pretty minor.

Edited by poblequadrat
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How do FM gurus feel Ableton's Operator performs in its FM sound ?

Operator has a high quality (but CPU intensive) sound, it's crazy good for making basses and monophonic leads. I use it all the time to whip up gritty, stomping basses in no time.

 

It's also great for sound effects. I did some work for an indie game and had to make a ton of realistic explosions and weapon/magic effects under a very tight deadline, Operator made it super easy with its white noise oscillators and filter envelope.

 

However, its FM capabilities are rather limited as you cannot reroute or feedback the operators in any way, there are just 11 routings that you have to choose from. The envelopes are not customizable either, every single one is a ADSR deal. It might be more than enough for most people's needs - my friends use it and love it, and they don't even know what FM synthesis is. But when you start playing with synths like FM8, its FM matrix and envelope customization makes Operator looks like a kid's toy. I never use it for pads or polyphony.

Edited by chim
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preenfm has Saw waveshape, so you can mimic feedback somehow, i guess

 

i have pfm2. i love it, it's fantastic. however, don't expect sy77 or fs1r lushness. it's pretty lo-fi, noisy, sounds flanging (a bit of dc-offset is still present in more-than-2op-stacks) and aliased on octaves higher than 5. it's low end is badass though.

 

The DX synths can have some extreme flanging at times when playing polyphonically. By the way, what is it that creates flanging? Not all patches suffer from it...

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Well flanging is created by a short, modulated delay so it could be a very small phase or frequency difference. I'm not sure why the synth is doing it, though, I don't know that I've heard what you're talking about. I have also found staticy, delayed kinds of sounds in my TX81Z with operator 4's frequency set very low and its feedback cranked to 7.

 

I've done lots of patches on various FM synths where there was a very small frequency difference between the modulator and carrier. This creates more of a phasing sound, though. This is really cool on FM7 where each operator's frequency can have both a fixed and ratio component. This way you can, for example, set the operators and octave and 3 Hz apart and get a free phaser/LFO.

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preenfm has Saw waveshape, so you can mimic feedback somehow, i guess

 

i have pfm2. i love it, it's fantastic. however, don't expect sy77 or fs1r lushness. it's pretty lo-fi, noisy, sounds flanging (a bit of dc-offset is still present in more-than-2op-stacks) and aliased on octaves higher than 5. it's low end is badass though.

 

By the way, what is it that creates flanging? Not all patches suffer from it...

 

 

It has to be static by default. It should not introduce any flanging/phasing when i modulate with 2 OPs in series, that tuned exactly same pitch. But it does (a bit). TX81z doesn't.

Edited by telefunken
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ok finally got the FS1R and this thing is a little insane. its almost like a DAW.

in general, i want to be able to do realtime cc controls to whatever, except it creates lag in the notes when i use the DAW (reaper) to draw envelopes. so i guess cc automation is better handled by a controller that sends fewer messages?

Edited by skibby
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ok finally got the FS1R and this thing is a little insane. its almost like a DAW.

 

in general, i want to be able to do realtime cc controls to whatever, except it creates lag in the notes when i use the DAW (reaper) to draw envelopes. so i guess cc automation is better handled by a controller that sends fewer messages?

Yeah, the less you have going down the (skinny) MIDI pipe the better your performance will be. Ideally, give the FS1R its own MIDI port. Also I wouldn't recommend drawing envelopes, it's usually better to send discrete events as needed. Then you have more control over timing, and it'll also send out much fewer messages. For smooth parameter modulation, use onboard LFOs or envelopes. With only 128 values, CC control is almost always going to be steppy and zippery.

 

At least in the JS scripts, I've had really laggy, sloppy MIDI performance with Reaper. Of the software I've used for MIDI sequencing, Renoise has performed the best.

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Is there a 8 operator VST out there with separate offset/ratio/pitch envelopes for each operator, or customizable envelopes/LFO's for various operator properties? I still can't believe FM8 only has a global pitch envelope and no way to modulate ratio/offset in the GUI.

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