The Yamaha AN1x Synthesizer mailing list

> > Now I'm asking myself about the FM feature on the An1x.

Well, I'll share how I am using it, and maybe that will help.

First of all, FM creates these things called sidebands, which are 
frequencies that are sum and difference of the modulating signal and 
the modulated signal. These are typically inharmonic (they don't 
represent the overtones of the fundamental signal). Inharmonic tones 
sound like gongs and drums as opposed to harmonic tones which sound 
sweet like trumpets and clarinets.

So there's two ways I use them:

1 - I use them as inharmonic tones.

One of these is to do drums and gongs and other nasty stuff. To get 
this effect take a plucked string patch like a guitar. Turn down 
everything except oscillator one (and maybe the ringmodulator) and 
turn up the fm mod depth. Then play with the pitch of osc 2 till it 
starts to sound like a struck instrument (marimba, gong, etc.) It 
will still sound nasty, but you can use is as just as the attack 
portion of the sound. You can have a mellow sustaining sound on scene 
2 to create the melodious aspect of the marimba. Or you can just use 
the abrasive sound as an effect.

2- Tune them to be harmonic

I don't have my AN1X in fron of me, but when I get it back I will 
share some settings I use. To tune these tones, you set an FM depth 
of say 21, and then play with the pitch of osc 2 till it starts to 
sound sweet. (It helps if you make osc 1 a sine wave of course. You 
can brighten it later to taste after you tune things.) You will 
almost certainly have to play with the fine tuning of oscillator 2 to 
get the tuning down. Now make a note of what the pitch difference is 
between osc 1 and osc 2. Sometimes you can get it almost sweet but 
there is an out of tune low rumble. Remember you can use the high 
pass filter to cut off the bottom if it's just a little out of tune. 
The place to find the problems are near the high end of the keyboard. 
When you play a high note and it beats (wobbles) fast, use the osc 2 
fine tune to get the beats to go away as much as possible.

Save the patch and compare the pitch on the "sweet sounding FM" patch 
with a regular patch. You will notice that the fundamental pitch has 
shifted on your fm patch. So go back to the fm patch and retune the 
oscillators to give you the note you need, PRESERVING the pitch 
difference between the oscillators so it remains sweet. In my 
experience most fm settings will allow you to find some pitch 
difference between the oscillators which sounds sweet, but usually 
only one. So don't lose that.

Then just tweak the patch to suit. You can get this kind of melodious 
fm effect by using oscillator sync as well. It sounds just a bit 
different from a square or saw wave, but not that different.

Hope this give you ideas. I'll post some specific patches when I get 
my blue monster back. Meanwhile I'd love to hear what you found while 
tweaking the:
- FM depth
- Osc 2 pitch and 
- Osc 1 edge settings.

in relation to each other.

FM source 2 defaults to OSC 2 and FM source 1 defaults to OFF, which 
is what I assumed for these descriptions.

Cheers,

Jerry