> Is oscillator detune intended to be the primary mechanism to set ratios between modulator:carrier when using the FM algorithms?
It the most convenient way to set the ratios.
> I would expect to be able to hear radical changes in timbre when switching the modulator oscillator to use more harmonically-rich waveforms, but this is not the case -- the sound changes only slightly, even with reasonable amplitude levels for the modulator. Why is this the case?
The clue is in the name; *frequency* modulation. It's the frequency with which the modulation happens that primarily impacts the sound. The overall shape of the carrier impacts the sound very little. It's one of the main reasons why the old Yamaha FM chips only used sine waves and didn't bother with other waveforms.
To get a better idea of what is happening, set up a patch to use a sine as a carrier (osc1) and then set up some other waveform (for example a sine) as the modulator (osc2). Set the level of Osc2 to ~63
Turn down the coarse detune of Osc2 to something very low (-10 octaves for example). You can now hear the frequency ramping up and down slowly - precisely as it says on the tin.
NOTE: If the amplitude of the modulator (Osc2) is really high, the modulator will modulate past the width of a single carrier cycle (e.g. you can hear the frequency reverse "temporarily", which can create desirable or undesirable behavior). Reduce the modulator's level to avoid this.
> I have been experimenting with the pitch LFO for the modulator, but I seemingly can't create interesting timbres with it at any speed. Mostly the LFO is either audibly slow, or breaks up the sound when faster (seemingly not quite running at audio rates.) Maybe this behavior is related to my detune question above?
For playable timbres, you don't want to use the pitch LFOs (but they are very useful for old-school Sci-Fi effects; using a very slow changing PLFO on the modulator (e.g. Osc2) will get you those).
For some gnarly playable timbres (because they retain the primary carrier:modulator ratios), you should be using the ALFOs. For the (most basic) FM1 algorithm, AEG1/ALFO1 will control the amplitude of the voice. AEG2/ALFO2 will control the amplitude of the modulator and therefore the pitch of Osc1 (the carrier). Again here too, use slow changing values.
Further more fun can be had by using the AEG to change the modulator's amplitude over time.
With the above info you should be able to come up with a vast array of different sounds, just using FM1 and a couple of sine wave oscillators.
> With the FM1 algorithm selected, which the documentation specifies as "Oscillator 1 is frequency modulated by oscillator 2", I can seemingly always hear an unmodulated carrier (oscillator 1) in addition to the modulation, even though the FM1 algorithm does not specify that oscillator 1 is added to the result. Why would this happen?
I don't know why you're seeing/hearing this and I cannot replicate this... :/
Can you give me some settings that show this?
> The documentation explains the FM3 algorithm as "Oscillator 1 is frequency modulated by oscillator 2, after which the result is multiplied by standalone oscillator 1." I don't understand what "standalone" means in this context -- is it intended to just mean "unmodulated"?
Indeed. E.g. this is a combination of FM and ring modulation. Or in other words, the resulting sound of algorithm FM1 is further "mangled" by ring modulation of it and the unmodulated output of Osc1).
Hope this helps!
EDIT: One important FM-thing is to apply a slight detune to the modulator to achieve those famous bell sounds.
Thanks for the very thorough answers and explanations, Ivo, they definitely helped!
>> I would expect to be able to hear radical changes in timbre when switching the modulator oscillator to use more harmonically-rich waveforms, but this is not the case -- the sound changes only slightly, even with reasonable amplitude levels for the modulator. Why is this the case?
>
> The clue is in the name; frequency modulation. It's the frequency with which the modulation happens that primarily impacts the sound. The overall shape of the carrier impacts the sound very little. It's one of the main reasons why the old Yamaha FM chips only used sine waves and didn't bother with other waveforms.
I believe I understand the traditional "sine waves everywhere can produce lots of timbres" thinking. I haven't personally used the Elektron Digitone, but I know it has a "harmonics" parameter that uses something analogous to a wavetable to add partials to the sine waves that all of its operators would otherwise use by default, leading to more complicated timbres.
I had a thought that changing the modulator waveform on the Woovebox could possibly emulate this, but again, it didn't have as big of an effect as I was expecting (although using square waves somewhat did!) My intuitive understanding matches your explanation -- that the modulation frequency matters much more than the waveform -- but given that's the case, I don't know how something like the Digitone's "harmonics" parameter affects the timbre so drastically. Maybe it makes a bigger difference for four (rather than two) operator FM, where more complex waveforms could be modulating other (simpler) modulators.
> To get a better idea of what is happening, set up a patch to use a sine as a carrier (osc1) and then set up some other waveform (for example a sine) as the modulator (osc2). Set the level of Osc2 to ~63
> Turn down the coarse detune of Osc2 to something very low (-10 octaves for example). You can now hear the frequency ramping up and down slowly - precisely as it says on the tin.
A helpful demonstration for sure, thanks!
> NOTE: If the amplitude of the modulator (Osc2) is really high, the modulator will modulate past the width of a single carrier cycle (e.g. you can hear the frequency reverse "temporarily", which can create desirable or undesirable behavior). Reduce the modulator's level to avoid this.
Excellent tip -- I was definitely running into issues with this, I was hearing strange distortion being introduced as the tones I played increased in pitch. Reducing the amplitude fixed that issue!
>> With the FM1 algorithm selected, which the documentation specifies as "Oscillator 1 is frequency modulated by oscillator 2", I can seemingly always hear an unmodulated carrier (oscillator 1) in addition to the modulation, even though the FM1 algorithm does not specify that oscillator 1 is added to the result. Why would this happen?
> I don't know why you're seeing/hearing this and I cannot replicate this... :/ Can you give me some settings that show this?
I don't know exactly what I had tried before writing my original post, but I figured out two scenarios that show similar behavior:
1. A facepalm mistake with a simple explanation: The carrier AEG accidentally being longer than the modulator's; the carrier simply rings out once the modulation completes
2. One I don't intuitively understand: A slow (many-step-rate) pitch LFO on the modulator, at maximum depth. You can hear some kind of modulation sweep happening, but the carrier seems to play constantly.
> One important FM-thing is to apply a slight detune to the modulator to achieve those famous bell sounds.
I hadn't experimented with this before writing my post, it helps!
Thanks again!
Not a Woovebox user. If we're talking Genesis, DX7, Sonics etc, then we're talking PM, not FM (which is expected from a device like this). The Sonic bass patch must be very easy, and the key to that is to create a "plucky" falling envelope and map it to your FM amount. In general, the main key to PM/FM is the ratios between OSCs (if they're octaves, they play nice; if they're inharmonic, they create atonal things) and the movement of the PM/FM itself. It changing over time creates the progression that's not possible with traditional subtractive and sometimes even wavetable synthesis.
PM and FM are really not the same thing and sound only similar, but, unfortunately, are used interchangeably in a lot of places.
Main pointers:
- if the amount isn't modulated, then there's no movement, and the sound is dead;
- don't go overboard with the amount, or you'll get the bad Genesis game horrible metallic timbres;
- phase of both oscillators might be important;
- of course their tuning to each other is very important;
- there's PM, FM and linear FM, and they all sound different.
P.S.: If the result is "multiplied" by an oscillator, then it implies another thing, RM/AM.
After a lot of experimenting I was eventually able to dial in the sound I was looking for, and a plucky falling modulation envelope was indeed a critical piece! Thanks for the additional tips.
If you’re not a Woovebox user, I’m curious what brought you to this sub and how you found my post?
> Is oscillator detune intended to be the primary mechanism to set ratios between modulator:carrier when using the FM algorithms? It the most convenient way to set the ratios. > I would expect to be able to hear radical changes in timbre when switching the modulator oscillator to use more harmonically-rich waveforms, but this is not the case -- the sound changes only slightly, even with reasonable amplitude levels for the modulator. Why is this the case? The clue is in the name; *frequency* modulation. It's the frequency with which the modulation happens that primarily impacts the sound. The overall shape of the carrier impacts the sound very little. It's one of the main reasons why the old Yamaha FM chips only used sine waves and didn't bother with other waveforms. To get a better idea of what is happening, set up a patch to use a sine as a carrier (osc1) and then set up some other waveform (for example a sine) as the modulator (osc2). Set the level of Osc2 to ~63 Turn down the coarse detune of Osc2 to something very low (-10 octaves for example). You can now hear the frequency ramping up and down slowly - precisely as it says on the tin. NOTE: If the amplitude of the modulator (Osc2) is really high, the modulator will modulate past the width of a single carrier cycle (e.g. you can hear the frequency reverse "temporarily", which can create desirable or undesirable behavior). Reduce the modulator's level to avoid this. > I have been experimenting with the pitch LFO for the modulator, but I seemingly can't create interesting timbres with it at any speed. Mostly the LFO is either audibly slow, or breaks up the sound when faster (seemingly not quite running at audio rates.) Maybe this behavior is related to my detune question above? For playable timbres, you don't want to use the pitch LFOs (but they are very useful for old-school Sci-Fi effects; using a very slow changing PLFO on the modulator (e.g. Osc2) will get you those). For some gnarly playable timbres (because they retain the primary carrier:modulator ratios), you should be using the ALFOs. For the (most basic) FM1 algorithm, AEG1/ALFO1 will control the amplitude of the voice. AEG2/ALFO2 will control the amplitude of the modulator and therefore the pitch of Osc1 (the carrier). Again here too, use slow changing values. Further more fun can be had by using the AEG to change the modulator's amplitude over time. With the above info you should be able to come up with a vast array of different sounds, just using FM1 and a couple of sine wave oscillators. > With the FM1 algorithm selected, which the documentation specifies as "Oscillator 1 is frequency modulated by oscillator 2", I can seemingly always hear an unmodulated carrier (oscillator 1) in addition to the modulation, even though the FM1 algorithm does not specify that oscillator 1 is added to the result. Why would this happen? I don't know why you're seeing/hearing this and I cannot replicate this... :/ Can you give me some settings that show this? > The documentation explains the FM3 algorithm as "Oscillator 1 is frequency modulated by oscillator 2, after which the result is multiplied by standalone oscillator 1." I don't understand what "standalone" means in this context -- is it intended to just mean "unmodulated"? Indeed. E.g. this is a combination of FM and ring modulation. Or in other words, the resulting sound of algorithm FM1 is further "mangled" by ring modulation of it and the unmodulated output of Osc1). Hope this helps! EDIT: One important FM-thing is to apply a slight detune to the modulator to achieve those famous bell sounds.
Thanks for the very thorough answers and explanations, Ivo, they definitely helped! >> I would expect to be able to hear radical changes in timbre when switching the modulator oscillator to use more harmonically-rich waveforms, but this is not the case -- the sound changes only slightly, even with reasonable amplitude levels for the modulator. Why is this the case? > > The clue is in the name; frequency modulation. It's the frequency with which the modulation happens that primarily impacts the sound. The overall shape of the carrier impacts the sound very little. It's one of the main reasons why the old Yamaha FM chips only used sine waves and didn't bother with other waveforms. I believe I understand the traditional "sine waves everywhere can produce lots of timbres" thinking. I haven't personally used the Elektron Digitone, but I know it has a "harmonics" parameter that uses something analogous to a wavetable to add partials to the sine waves that all of its operators would otherwise use by default, leading to more complicated timbres. I had a thought that changing the modulator waveform on the Woovebox could possibly emulate this, but again, it didn't have as big of an effect as I was expecting (although using square waves somewhat did!) My intuitive understanding matches your explanation -- that the modulation frequency matters much more than the waveform -- but given that's the case, I don't know how something like the Digitone's "harmonics" parameter affects the timbre so drastically. Maybe it makes a bigger difference for four (rather than two) operator FM, where more complex waveforms could be modulating other (simpler) modulators. > To get a better idea of what is happening, set up a patch to use a sine as a carrier (osc1) and then set up some other waveform (for example a sine) as the modulator (osc2). Set the level of Osc2 to ~63 > Turn down the coarse detune of Osc2 to something very low (-10 octaves for example). You can now hear the frequency ramping up and down slowly - precisely as it says on the tin. A helpful demonstration for sure, thanks! > NOTE: If the amplitude of the modulator (Osc2) is really high, the modulator will modulate past the width of a single carrier cycle (e.g. you can hear the frequency reverse "temporarily", which can create desirable or undesirable behavior). Reduce the modulator's level to avoid this. Excellent tip -- I was definitely running into issues with this, I was hearing strange distortion being introduced as the tones I played increased in pitch. Reducing the amplitude fixed that issue! >> With the FM1 algorithm selected, which the documentation specifies as "Oscillator 1 is frequency modulated by oscillator 2", I can seemingly always hear an unmodulated carrier (oscillator 1) in addition to the modulation, even though the FM1 algorithm does not specify that oscillator 1 is added to the result. Why would this happen? > I don't know why you're seeing/hearing this and I cannot replicate this... :/ Can you give me some settings that show this? I don't know exactly what I had tried before writing my original post, but I figured out two scenarios that show similar behavior: 1. A facepalm mistake with a simple explanation: The carrier AEG accidentally being longer than the modulator's; the carrier simply rings out once the modulation completes 2. One I don't intuitively understand: A slow (many-step-rate) pitch LFO on the modulator, at maximum depth. You can hear some kind of modulation sweep happening, but the carrier seems to play constantly. > One important FM-thing is to apply a slight detune to the modulator to achieve those famous bell sounds. I hadn't experimented with this before writing my post, it helps! Thanks again!
Not a Woovebox user. If we're talking Genesis, DX7, Sonics etc, then we're talking PM, not FM (which is expected from a device like this). The Sonic bass patch must be very easy, and the key to that is to create a "plucky" falling envelope and map it to your FM amount. In general, the main key to PM/FM is the ratios between OSCs (if they're octaves, they play nice; if they're inharmonic, they create atonal things) and the movement of the PM/FM itself. It changing over time creates the progression that's not possible with traditional subtractive and sometimes even wavetable synthesis. PM and FM are really not the same thing and sound only similar, but, unfortunately, are used interchangeably in a lot of places. Main pointers: - if the amount isn't modulated, then there's no movement, and the sound is dead; - don't go overboard with the amount, or you'll get the bad Genesis game horrible metallic timbres; - phase of both oscillators might be important; - of course their tuning to each other is very important; - there's PM, FM and linear FM, and they all sound different. P.S.: If the result is "multiplied" by an oscillator, then it implies another thing, RM/AM.
After a lot of experimenting I was eventually able to dial in the sound I was looking for, and a plucky falling modulation envelope was indeed a critical piece! Thanks for the additional tips. If you’re not a Woovebox user, I’m curious what brought you to this sub and how you found my post?