Fathom Synth Development Thread

[zzz00m]

Though it'd be good if the topic would be like

"Fathom: Today I thought about boobs"

I'd agree with that.

I was going to suggest a consistent main title, followed by the sub-topic du jour, which could call out new announcements, interesting suggestions, and such.

I apologize if I was cranky this morning, but before my first cup of coffee I saw a KVR notification about a thread topic I did not recall subscribing to (this one).

[Kwurqx]

We, I'm very much in the camp of those who seek the strongpoints in synths (and effects). No bashing or ranking. They all have their own place and purpose. Some implement innovative concepts. Some just do "the bread and butter" things exceptionally well.

Some hide their sonic beauty behind behind a deceivingly simple interface (like Ichiro Toda's much loved Synth1) or for some reason never left the shadows of the unknown (like Fuzzpilz - Oatmeal). Though interface wise...it's a good thing it's skinnable (Flavours of Lime).

Anyway...

So...when I'm naming synths, its out of respect for specific features or the combination of features.

I've been posting about FM here recently. More specific combined with the use of Fathomsynth Additive Spectrum ocillators. You could use these same concepts with the AM Synthesis.

A synthesizer that has the use of 2 oscillators / signalpaths in all sorts of audiorate relations at its core is Tone2 - Nemesis2. Amongst them: AM and FM/PM. But many more. Also, it has spectral editing.

Some of these things can allready be achieved with Fathomsynth at this stage in development.

Though linking the output of a filter to the input of an oscillator is (still?) a no-no in Fathomsynth. Would be nice if any output could be linked to any input. No matter whether the signal was meant for the audiopath or control/modulation. But besides the technical issues, this would pose a GUI issue, since there can be only one connection from 1 "element" to another. What should be done with the connected input signal on the reveiving end....?

Well...use the modulation matrix to connect audiorate "modulators". E.g. other oscillators or audio outputs (e.g. of a filter).

Amplitude, Frequency or Phase modulation? Just add an audiorate "modulator" to the appropriate control of the oscillator. Audiorate filter cutoff modulation? Same difference...

Is also more true to the "modular" concept.

[Kwurqx]

@Fathomsynth

Not sure, but I may have ran into a bug. Or an FM quirk. Or a PWM quirk. or both.

On a Basic Waveform oscillator
On the Oscillator settings, set Waveform to Pulse. Set to a width other then 50%
On the AM FM settings, set Synthesis to FM

Then modulate/turn Amount.
Also Frequency Multiply/Divide acts in surprising ways.

Not sure what happens there. Have not really tried PWM in FM. But it does not sound like (just) FM modulation amount.
Sounds/looks like the carrier frequency changes. Or in any case the frequency ratio between carrier and modulator.

Also changing the Pulse width acts in surprising ways when in FM mode.
Changing the Width does change the waveshape. But not in a pulse width way.

At 50% everythings fine. Maybe it's more a PWM issue the an FM issue.

About the Pulse width at less partials. Or even just a few or 1 (which would just be a sine).
A pulse generally has all partials with amplitude 1/rank, with each 100/pulsewidth partial missing.
And like the other Basic Waveform shapes, you don't allways need 400.

[FathomSynth]

fractal reverb faders.jpg

Version 2.23 Released with the new Fractal Reverb unit.

https://www.fathomsynth.com/updates

https://static.kvraudio.com/files/3302/stab.mp3
https://static.kvraudio.com/files/3302/reverb.mp3
https://static.kvraudio.com/files/3302/fractal3.mp3

Free upgrade for 2.23 will be on Saturday 11/24/18 after system test.

Kwurqx, I just did a whole series of tests on FM and I did not notice anything odd. However I'll take a closer look based on what you are reporting.

Changing the pulse width on FM will not change the pulse width of the FM result, it will change the pulse width of what is doing the multiplying or being multiplied which can have very complex results. Also, on Fathom the numerator and denominator of the multiply is two separate dials, Multiply and Divide, not one dial like on most synths. So you can either set multiply to 1.5, or multiply to 3 and divide on 2.

FM is complex, I almost never use anything except pure sin waves or maybe a sin and a saw. Fathom does not yet do Pulse width Modulation at all, that will be added later this year when I redesign the oscillators.

Fathom should be following the math closely based on the standard explanations of FM, for instance the one on Wikipedia, which describe the functions of the carrier and modulator oscillator. To be honest, I'm not sure how some synths manage to get tonal results from complex FM node patterns with up to four oscillators connected in all combinations with extreme settings on the FM dials. They are probably performing some sort of simplification to protect the user from the extreme results of pure FM which follows only the pure math. If you know specifically how this is being done, or can point to a technical article, I will implement it when I do the oscillator redesign. Also for FM, if you really did find a bug you will need pretty exact steps otherwise there would be no way for me to recreate it.

Also, remember, if you just turn on the FM with one oscillator, and it has a complex waveform such as a wave draw or bezier, then you are using the same waveform for both the carrier and the FM modulation, which will turn exponentially complex very quickly no matter what dial you move. For easier results, start with a wave draw or saw as the second carrier oscillator and use only a basic waveforms sin as the first modulator oscillator. Then it should prove easier to manage. This might be one of the things which other synths are doing automatically.

[fmr]

Fathom should be following the math closely based on the standard explanations of FM, for instance the one on Wikipedia, which describe the functions of the carrier and modulator oscillator. To be honest, I'm not sure how some synths manage to get tonal results from complex FM node patterns with up to four oscillators connected in all combinations with extreme settings on the FM dials.

Here are some links that may be helpful to you:

http://dixon.hh.se/urbi/WCS/WCS2/Lecture5_2.pdf

https://www.quora.com/What-is-the-diffe ... modulation

https://www.elektronauts.com/t/phase-mo ... is/50783/6

http://openweb.flossmanuals.net/files/csound.pdf

(Read this one from page 343 onwards)

https://ccrma.stanford.edu/software/snd/snd/fm.html

https://literature.cdn.keysight.com/lit ... 4-9130.pdf

http://www.montana.edu/aolson/ee446/FMnotes.pdf

http://wits.ice.nsysu.edu.tw/course/pdf ... lation.pdf

[Whywhy]

Fathom should be following the math closely based on the standard explanations of FM, for instance the one on Wikipedia, which describe the functions of the carrier and modulator oscillator. To be honest, I'm not sure how some synths manage to get tonal results from complex FM node patterns with up to four oscillators connected in all combinations with extreme settings on the FM dials.

Here are some links that may be helpful to you:

http://dixon.hh.se/urbi/WCS/WCS2/Lecture5_2.pdf

https://www.quora.com/What-is-the-diffe ... modulation

https://www.elektronauts.com/t/phase-mo ... is/50783/6

http://openweb.flossmanuals.net/files/csound.pdf

(Read this one from page 343 onwards)

https://ccrma.stanford.edu/software/snd/snd/fm.html

https://literature.cdn.keysight.com/lit ... 4-9130.pdf

http://www.montana.edu/aolson/ee446/FMnotes.pdf

http://wits.ice.nsysu.edu.tw/course/pdf ... lation.pdf

Thanks Fmr, a lot of good docs here !

@Fathomsynth :
About phase modulation with more than 4 operators : nobody use extreme settings with phase mod, it's a little here and here, same with feedback, and all audio rate modulation. But, it's important to have a large amount of possible modulation amount.

I will add, if your goal is to make a modular synth, audio rate modulation is a must, like feedback, same for some modules tools to be able to manipulate gate and CV.

[Scrubbing Monkeys]

Dexed, a DX7 vst and editor is open sourcse as well.
The math in Dexed is limited to friendly ratios and Hz

https://github.com/asb2m10/dexed

[fmr]

Dexed, a DX7 vst and editor is open sourcse as well.
The math in Dexed is limited to friendly ratios and Hz

https://github.com/asb2m10/dexed

What do you mean with "friendly ratios"? I can dial any ratio I want. Just use the "fine" control.

And it couldn't be otherwise, since it is an emulation of the DX7

[Whywhy]

@@fathomsynth:
About harmonics modulation with some windows, be able to modulate the q, or range of the window could be nice. Be able to modulate the X axis for detune and the Y axis for amplitude should work. And for the phase, with other tab, the Y.
Same for unison apply to the engine.

[Kwurqx]

Dexed, a DX7 vst and editor is open sourcse as well.
The math in Dexed is limited to friendly ratios and Hz

https://github.com/asb2m10/dexed

I mentioned Dexed and Oxe FM as open source FM synths earlier (I think). As examples of practical implementions.
- Dexed being a "faithfull" Yamaha DX7 emulation. Including all the limitations of that iconic but somewhat limited machine. Like limited number of algorithms, just sine operators (and just six), no 0 Hz carrier, scalar values for parameters like detune, feedback and modulator response (like note velocity) lack a sufficient detailed discrete scale (like just a few steps).
- Oxe FM being a "free" FM matrix synth where operators can be both carrier and modulator (at the same time).

[jbraner]

How do you download the 2.23 update?
The (paid) link takes you to where you can buy the full version of Fathom.

[fmr]

I mentioned Dexed and Oxe FM as open source FM synths earlier (I think). As examples of practical implementations.

Oxe FM is free, but not open source, AFAIK.

[Scrubbing Monkeys]

Dexed, a DX7 vst and editor is open sourcse as well.
The math in Dexed is limited to friendly ratios and Hz

https://github.com/asb2m10/dexed

What do you mean with "friendly ratios"? I can dial any ratio I want. Just use the "fine" control.

And it couldn't be otherwise, since it is an emulation of the DX7

Maybe thats wbat I was thinking.....that simply using the gross control It click from say 1 to 1.5 to 2 for ratios...and so on. I cant remember the exact increments of Hz but it was a whole number.

[fmr]

Dexed, a DX7 vst and editor is open sourcse as well.
The math in Dexed is limited to friendly ratios and Hz

https://github.com/asb2m10/dexed

What do you mean with "friendly ratios"? I can dial any ratio I want. Just use the "fine" control.

And it couldn't be otherwise, since it is an emulation of the DX7

Maybe thats wbat I was thinking.....that simply using the gross control It click from say 1 to 1.5 to 2 for ratios...and so on. I cant remember the exact increments of Hz but it was a whole number.

Yes, the coarse parameter increments from 0.5 to 1, and then in 1 whole value steps. But you can then use the Fine parameter to make "fine" adjustments, with 0.05 values.

An FM synth with just whole value ratios wouldn't be very flexible (or useful).

[FathomSynth]

jbraner, Go to the web site www.fathomsynth.com/home

Click on Buy, click Buy On Seaweed Audio.
Second option is Fathom Pro Update (Password Only) for $2.50
Click on that.

Fmr, SM, thanks for the links, I'll review those when I do the oscillator redesign to make sure my FM is correct.

Yes, the "friendly" ratios concept is correct. It applies to the Multiply dial on the top left in steps of 0.5. The Amount dial can be continuous. I use the same myself with Fathom for my own songs.

Here's how it works. Let's say you want to modulate your FM Ratio Multiply with an envelope.

On the AM FM page of the first oscillator select the Ratio Multiply dial.
Set the Ratio Multiply dial to a whole number value such as 4.000.
Add a modulator Sequencer and make sure the mod type is set to multiply.
The Sequencer is easier to manage than an envelope for all flat segments.
For a Ratio Multiply max value of 4.0 we want the modulator to hit the following values.
For super clean FM we want: 1.0, 2.0, 3.0, 4.0.
For gritty FM we want: 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0.
We will choose the last case with a total of 7 levels.
Now here's the tricky part, we want the Sequencer levels to match up with these ratio values exactly.
Since the sequencer zero amplitude will be used we want the sequencer Quantize Amp + 1 = 7,
which is Quantize Amp = 6.
Now we create some steps in the sequencer.
It will sound great since we are jumping the ratio levels but they always land on precisions of 0.5.

Here's a short tutorial Video on how to Modulate FM

https://youtu.be/IKnLHEW4Yfo