Quote:
Originally Posted by
StarfishMusic
➡️
Holy ****! I just realized it has oscillator in and out points on the matrix. That means with 2 neutrons you can do 4 operator FM! Call me late to the paty but that's incredible if these things are under $500. Maybe I'm wrong about how this works. The only modular I've had was my old EML 200 years ago. It had 2 osc you could patch into each other and and audio rate reaching lfo. The beautiful subtle harmonic shifting or clangtangorous screamieutronng was so much fun! Can even one neutron get you 3 op fm if you patch it right? If so you got 6 with two units!
But probably not in the way you want. That is, oscillator frequency responds exponential to the control voltage input. You want linear frequency control. ("FM" synthesis is really phase modulation. Also, you'd really want more VCAs for dynamic FM, and...)
For anyone not sure what I'm getting at, consider using a sine wave (I think that's a sine symbol on the panel, a little fuzzy) as the modulation source, let's say swinging between +1 and -1v. For low frequency modulation, you want musical intervals, and this works out really well—the other oscillator swings up an octave above it's set point, back, down an octave, back to the start.
But for audio rate FM, that's not what you want. Let's do some math: Say the oscillator you're listening to (the carrier) is set at 1000Hz. Crank that control oscillator (the modulator) up to audio frequency for FM. The carrier is now swinging quickly between 500Hz (an octave down) and 2000Hz (an octave up). The average is 1250Hz, quite a bit sharp from where we set it originally. Worse, if you change the modulator amount (depth) dynamically, that average is sliding around.
Instead, we need linear input, so a balanced bipolar signal (we usually want sine waves for FM) swings the same amount of Hz, not musical interval. So, modulating that 1000Hz carrier might swing it between 500Hz and 1500Hz, and stay in tune as we vary the modulation depth.
You definitely need exponential control for usual synth stuff, so you'd need additional linear inputs as well. No big deal, analog tolerances make analog linear FM a bit imprecise, and you can still get "clangorous" found with exponential FM as is.
A bit longer than intended, hope this wasn't annoying...