#21

Seems like I have a bit of learning/reading up to do. Does anyone have any suggestions for good technical explanations of the different FM types mentioned before (linear vs exponential and through zero, are there more?)?

On my search for more info I found this topic, a comparison between 3 different complex oscillators. Quiet interesting because it contains both dedicated complex oscillator modules as well as separate modules.
https://www.muffwiggler.com/forum/viewtopic.php?t=84310

#22

I found this helpful:

https://learningmodular.com/understanding-the-differences-between-exponential-linear-and-through-zero-fm/

4 Likes
#23

Do you have a Cold Mac?

You can think of “phase modulation” like the transfer function outputs of CM. If nothing is patched to any of the main inputs, the output voltages all depend on the value of the SURVEY voltage. -5V into survey could be considered the start of each output (phase = 0degrees)’s waveform, 5V could be considered the end (phase = 360degrees). Increasing or decreasing survey is kind of like “fast-forwarding” or “re-winding” each output along its transfer function curve, depicted on the panel as the little glyph next to the output jack.

In general you can think of phase modulation as “scrubbing through” a fixed waveform. If you scrub forward linearly (i.e. at a constant rate), your output will just be identical to your input, at a frequency determined by how fast you are scrubbing. However if you start doing things like scrubbing backwards and forwards, things get more interesting and the waveforms you create become more complex.

In the context of what @Starthief was talking about, if the sum of two triangle wave’s controls scrubbing through a sine waveform, the slower tri will push the scrubbing overall in one direction, while the faster one will create little folds as it scrubs back and forth around the region determined by the slower tri.

11 Likes
#24

Very interesting. I didn’t know there were vactrols in the mod bus in some complex oscillators. If I were to replicate this behavior in the er301 (or just patching modules), could I insert a LPF between the modulator and the carrier? I’m assuming this has an effect on harmonically rich modulator waveforms over sine waves.

#25

I think a slew limiter would get you there easier, especially since you can change the curve (expo or linear).

1 Like
#26

Yeah. You can also put a hpf on the mod osc so DC doesn’t affect as much the fundamental of carrier, when doing through-zero.

1 Like
#27

I do! Lot’s for me to get my head around in this thread

1 Like
#28

I think the vactrol in the DPO’s mod bus is on the control input of the VCA – the modulation signal sent through the bus isn’t slew-limited but the index is.

I suspect vactrols are involved in the follow circuit too, since apparently they’re not identical from unit to unit.

2 Likes
#29

I found this thread here illuminating: FM synthesis

Also to supplement what @_mark said, I found this about the Verbose (to contrast against the Endorphin.es): https://www.youtube.com/watch?v=6lQIr10eaUs&t=325s

@Starthief Ah, I see. so we are talking about a slew limited mod index rather than the signal itself. Thank you for the clarification.

2 Likes
#30

new one comming from patching panda

2 Likes
#31

Yeah, noticed that as well. Also ran into this one

I assume this also counts as a complex oscillator?

I still don’t know enough of the subject to determine their differences/pros and cons.

2 Likes
#32

I’ve been working with a complex voice made up of a Pittsburgh Lifeforms Primary Oscillator and a Dixie II over the past week and they are really excellent together. The Lifeforms osc is a saw core, so a bit gnarlier than what you’d get from the triangle core oscillators often used in FM voices, but that’s part of why I chose it. Right now I’m using a Tallin for FM depth control and AM, but soon I’ll have a 1u VCA for that so the whole voice will take up very little hp given the ridiculous amount of sound sculpting available. I’ll share some sound examples if people are interested–there isn’t a ton out there about the Lifeforms osc but it’s really an awesome sounding module. I’ve also been surprised at how usable the more complex waveforms from the Dixie are as FM modulators.

I’m also interested to hear more stuff from people that are putting their own complex voices together from individual modules.

1 Like
#33

I use a Mutable Tides, Braids and Warps as a complex oscillator, it can get pretty crazy!

5 Likes
#34

I’ve seen a couple demos of Tides and Warps being used as a complex voice and was surprised at how great it sounded! Are you typically using Tides as the modulation osc?

#35

Often, but it’s really nice as a primary oscillator too: I often think of getting a second one and using them as a pair.

1 Like
#36

My feeling is that Warps lends itself really well to being a carrier since it’s so smooth at phase modulation. I never quite gelled with Tides as an FM carrier, but the shapes it generates seemed excellent for AM, and its multiple methods of syncing to other sources kept things interesting. (The new Tides doesn’t have Freeze to play with, but does have all that quadrature/harmonic goodness.)

A post elsewhere this morning got me thinking about modules I would keep if I had a much larger system or a sort of “reserve” – things I didn’t find myself using all the time, but might want to pull out once every 2-3 months. Both Tides and Warps would have gone on that list.

1 Like
#37

I’d be interested in hearing some of this, I have a Lifeforms PO and a Makenoise STO, which isn’t too far off from the Dixie. The PO I have a love/hate relationship with. I feel like the hi-end from the wavefolder circuit is a little harsh and noisey. Is that your experience? I have another wavefolder, the Tip Top Fold and that is very smooth sounding. But, in general their tones are quite different so I get a pretty wide variety of sounds.

1 Like
#38

What I notice happening with the wavefolder is that if you have the fragments slider all the way up, the high end aliasing from that will bleed through to the wavefolder output. If you drop the downsampler a bit, I don’t get any of that high end aliasing coming through. Other than that, it doesn’t get undesirably noisy for me unless I’m really pushing the wavefolder hard.

#39

Ill have to investigate that closer. Thanks!

#40

I checked this last night with Pitts PO and there’s def a high-end ‘presence’ there in the wavefolder regardless of where the fragments is set. Its gone if you just plug into the sine output on its own. Hmmm.