Hi all,
I’m new to sound synthesis and I have a lot of bonehead questions. I’ve had my Voyager for about a month and through reasoning, experimentation and repeated readings of the manual I’ve figured out most of the front panel.
What does the “3 - 1 FM” switch do, and how is it useful? The manual basically doesn’t explain it, which makes me suspect this is a loaded question.
This switch routes the waveform output of VCO3 to the frequency input of VCO1. It’s frequency modulation or “FM” and was used for FM synthesis in the Yamaha DX series. It can get all kinds of clangorous sounds out of VCO1, and is especially fun with the touchpad on the filter - I can get wild formant (vocal) sounds this way. I have also used it to get some really good bass guitar sounds.
FM could be done on a Minimoog by routing VCO3 to the self-oscillating filter, but the filter only produces a sine wave. The Voyager takes this further letting you FM a VCO which lets you use any wafeform you want.
For starters, set VCO3 in Low Freq mode, turn it off in the mixer. Set VCO1 to any waveshape and turn it on in the mixer. Tweak with octave, frequency, and waveshape controls on VCO3 to hear the variations of FM tones. Also tweak with the filter.
Even cooler - turn the sync switch on and listen to VCO2 which is hard sync’d to VCO1 while tweaking FM stuff. Really wild tones.
The 3 - 1 FM is linear FM like the Yamaha DX stuff. You can get exponential FM using the mod buss - route VCO3 to destination PGM, then access the menu to set PGM to VCO1. Linear FM sounds different from expo FM, both have their uses. Experimentation is the key.
FM = Frequency Modulation
The switch applies the output of Osc 3 to the input of Osc 1.
Frequency Modulation refers to the rapid modulation of one oscillator by another. The modulation produces complex ‘sidebands’ that contain harmonic and inharmonic tones. Used for audio, FM can result in metallic timbres like a cymbal or gong.
This is the same FM used for radio transmissions, except that the oscillators are in the MegaHertz range.
Yamaha had an entire line of synthesizers based on FM synthesis back in the 1980’s, starting with the DX7 in 1983, one of the best selling synths of all time. Voyager’s implementation isn’t anywhere as as sophisticated as the Yamaha offerings, but it does have it’s place in generating sounds.
As you observed, the manual really doesn’t go into much detail on this switch. A little experimentation may help you to understand it better. Try it - turn it on and vary the frequency of Oscillator 3 while listening to Osc 1. You will hear the clangorous sound of FM. I believe that only a few factory presets make use of this. I’ll try to identify a few and let you know.
If you are looking to get a basic understanding of the way the Voyager produces sound, pick up a copy of “Power Tools for Synthesizer Programming” by Jim Aiken. Published last year and should be widely available.
Hope this helps.
Paul -
FM is used in the following Voyager factory presets:
Anniversary Edition Bank:
068 FM-Sync
115 Circuit Dreams
116 Noisy Percussion
Signature Edition Bank:
064 Perc.1
065 Syntom
Zon Vern Pyles Bank:
015 Tympanic Membrane
123 Ridin the storm out
The list is not exhaustive, these are just a few I came across.
Have fun!
I picked up that book, it’s a nice general introduction.
Thanks for the tips!
To answer my own question -
http://www.soundonsound.com/sos/apr00/articles/synthsecrets.htm
How would you say FM compares to ring modulation? I know they work in different ways, but they both produce seemingly similar results, i.e. clangorous sounds. I would guess that ring mod is more versatile?
Over to you guys…
Hello,
They both have their merits.
I would consider FM and AM to be more versatile in that ring mod is only a multiplier. It suppresses the original input frequency components, and may
not be as harmonically rich as the former.
The variety from from RM comes from using lfo’s, env, audio, ect. to modulate the frequency ratio between the inputs.
It works well as a distortion device.
One can’t assume that FM isn’t as flexible as RM based on the Voyager implementation, which is an all or nothing type affair.
An elaborate FM setup such as on some modulars gives control over mod index, assigns separate vca’s to each tone generator, etc.
Regards,
LWG
Also, while most ring mods multiply the input signal with a static (of LFO-driven) oscillator, the Voyager’s method of FM allows you to maintain a constant relationship between the oscillator and modulator; or you can choose to have Osc. 3 remain static (or LFO-swept) by disengaging the 3 Kb Cont switch.
Other than that, MC pretty much nailed it.
-Hoax
Although FM is frequencies modulating each other (in this case, primarily oscillators in the audible range), the relationship between FM done with two analog oscillators, as on the Voyager, and the FM invented by John Chowning and used in the DX (and other) synths from Yamaha ends there.
FM on the Yamahas used four or more sound sources with evolving frequencies and amplitudes that could be precisely controlled. Imagine using a computer to precisely control the pitch, amplitude, and amount of interaction between six oscillators and you have something similar to the way a DX7 worked. Eventually, with the SY/TG series, it even allowed the use of complex waves such as samples of other instruments.
Hello,
John Chowning’s implementation of FM works well as the basis for a performance-oriented instrument in part, because its a closed system,
which is also its limitation; that is, the modulator/carrier arrangements
are wired together in a manner thats fixed within the available algorithms.
The variety comes from being able to use varied waves as modulator or carrier, having control over percentage of modulation, and having individual
control over amplitude changes over time of the modulators or carriers, but
all of this still takes place within a closed system.
On a hardware driven instrument, modulator/carrier connections do not have to operate within a fixed arrangement, such as that found with the digital algorithm. The algorithm just provides a more structured method of doing what takes a large amount of hardware to do.
In the analog domain, required modules for the type of arrangement found in the digital instruments is:
osc(s)>vca(s)>vcf(s)>vca>output
Regards,
LWG