THANK YOU. I'm currently writing a manual for a DAW and was baffled by the FM in a synth in it because I've pretty much only had experience with linear FM and had absolutely no idea what it was doing. It is INSANE that I've never heard of this distinction in FM types before. There seems to be shockingly little discussion about it online.
I’ve often wondered why the FM mode of my analogue synth doesn’t sound the same as even a 2-op patch, you’ve made it super clear! Also wow, people weren’t kidding when they said simply changing which operators are audible takes a few minutes in a traditional DX synth - in my Opsix I would’ve slid the faders for those operators down in two seconds! Of course I’d read it was an easier and faster user interface but I hadn’t looked into just how much that is true. Thanks!
i love this guy, he looks like he stole all the infinity stones. Thankfully some people are geeks on this subject and they give us "big guns" like he say. thanks for the video, very interesting.
I knew there was a difference between linear and exponential FM but, honestly, only because everyone talked about it. And of course I could hear the difference between "analog FM" and "digital FM". But never really understood the concept. Now I do, thank you for making this vid and compliments for your great explanation!
Thank you so much for that explanation! Realised i've been going about it all wrong trying to build fm in puredata and applied this theory and its sounds worlds beyond now! BRILLIANT!
For someone studying eurorack modular synthesis this is a very nice inspiring video. Be it someone just starting or as a reminder review of a seasoned person. Thank you.
at last i understand FM! ive been patching my moog dfam's pitch envelope into my mother-32's linear fm input to create a pseudo sidechain effect - whenever a kick drum hits, the frequency of the mother 32 (for example in a bassline) bends upwards a little depending on how much of the envelope i let through. it gets even better when putting the envelope through an inverter so that the linear fm causes the frequency to bend downwards, out of audible range. thank you for this great video. i look forward to more of your videos.
This synthesis method was also used in some arcade, console and PC videogames in form of the YM2151, YM2612 or YM3812 yamaha sound chips used during 80s and 90s. They bring me such good memories of my childhood...
That was very well explained, thank you! Could you shed some light on through-zero FM? What it is, how to achieve it and how it sounds different from regular linear FM?
Basically linear but you can crank the fm depth all the way without it sounding as gritty as normal linear fm. As the name suggests it allows to go beyond 0 (negative frequencies).
Great video - the DX7 actually uses Phase Modulation (PM) because it has a carrier wave that is used to alter the phase angle between them. Although PM is an intermediate step of achieving FM, FM is probably more just a marketing term by Yamaha. Either PM or FM are really just special cases of quadrature amplitude modulation (QAM) (mathematically speaking). I often joke by asking people how their QAM synth is going - you get some funny looks :) Keep it up - maybe do a video on Ring Modulators .... this is right up the same alleyway!
FM is frequency modulation, AM of course is amplitude modulation. These are not the same, and do not sound the same. You'll have to do some explaining to show how a quadrature generator is the same as phase modulation.
Doug Brown I didn't say they were the same not did I say that FM was AM. I said mathematically they (PM and FM) are special cases of QAM. more info here: en.m.wikipedia.org/wiki/Phase_modulation
I am sure phase modulation is a reasonable way to explain DX7 style synthesis, because the equations clearly show that phase modulation is what's happening. I am not sure why they call FM a special case of QAM, but I am not disputing it - I just can't explain it :)
Instant frequency is the first derivative of instant phase, so when both carrier and modulating signal are sine waves, there is no difference between FM and PM, because they produce the same signal. And don't believe Wikipedia, QAM is not superset of FM and PM. QAM is a digital modulation scheme with sine carrier, while FM and PM are analog modulation schemes with any periodical carrier. What you meant as QAM is not modulation at all, it is just one of the ways to represent narrowband signals, in terms of complex envelope.
Drizzgit , while there's no really robust analog FM sound synthesizer, this is a a hardware limitation, not a conceptual mismatch. Analog VCOs that respond quickly enough to changes in control voltage are just impractical for musical equipment. However the _principal_ of frequency/phase modulation is analog. I.e. it discusses only waveforms and analog signals.
Keith! Excellent vid thank you! I'm a DSI Pro 2 owner and just found out about the Linear FM update for the Pro 2 firmware and I needed to know what the hell that even meant!
Great video! you did a great job clarifying the differences between lin and exp FM. I haven't ever bothered to do too much in the way of FM, but I tried some on my modular. Unfortunately the analog oscillators weren't perfect enough to get sounds similar to what you got on the DX11. Got me tempted to pick up a similar keyboard just to explore more along the lines of FM. Unfortunately most FM synths seem to have poor interfaces.
Opsix is the way to go if you want the structure of FM reflected in the user interface with almost one knob per function. The refaceDX someone else mentioned was certainly very good when it was new but compared to the Opsix there’s a lot more menu diving. Plus it’s just touch pads instead of knobs and faders.
Thanks this was really informative. The sound at the beginning of the video was a bit odd for me, but the explanation was crystal clear. Thanks again!!...
I'm glad you liked the video. I'm currently working on a new video, showing how to develop a bass FM patch, with all of the nitty gritty details explained.
Some people say, Yamaha's FM synthesis is not really FM, but Phase Modulation, which I don't really get because frequency modulation is achieved by speeding and slowing (or even reversing backwards) a phase of a wave (I guess). So many things still to learn about my TX81z, but meanwhile I understood one thing. I need to learn about various natural (physical) ways harmonics "grow" from musical instruments too. E.g.: string instruments produce harmonics that are slightly sharper (therefore inharmonious) than basic note fq (thickness of a string). I don't know if that can be reproduced with DX synths, and there are some softsynths that can do that, but I can tell it's very difficult to find analytic texts about where in nature (I mean in physical systems like musical instruments, primarly) a frequency modulation occures, ...and how (and the ones that can be mimicked by FM, like cutoff filter sweeps)
This is the best explanation I've seen on FM so far! Could you explain how to use detune, course and fine? How does each frequency relate to the other operators? Currently I'm using the free VST Dexed (Yamaha DX7) but I'm not having much luck.
Thanks, clear explanation,. Been playing with my software modular synth, in a few minutes got to understand much better what I'm doing.... shit, need to go to bed, but wnat to start building.....
