Thor FM via mod-busses

[Mich01]

Hi Folks,

At the moment I am exploring FM synthesis with Thor's analog oscillators.
One of the things I try to achieve is creating a saw-like and a pulse-like wave, using two oscillators (ratio) and some feedback. (Just as the way it works in the Yamaha DX synths). I manage the ratio with the oct-knobs on the oscillators. The FM and the feedback I try to create via some mod-busses.
Somehow I do not even come close to a result.
I do get FM modulation, but it's almost not musically adjustable (like DX).

Has this something to do with the difference between exponential/linear FM synthesis?
(In Thor I always thought that modulating pitch stood for exponential, and modulating frequency for linear).

Does anybody has tips?

Thanks and regards
Michel

[Loque]

FM can run quickly out of tune and become noise if you overdo it. So tune your oscillators right and do not use too much FM, because it becomes a mess.

I never had a DX, but i have PX7. Its based only on sine-waves (big difference), all tuned with multiples of a base, but i am not sure how the feedback works so i guess it is self FM in the end which can end up much fast in noise. For better DX style FM, stick to the FM pair oscillators in Thor.

Just keep the values low in the mod matrix and you get a sweet spot. You can also try to scale values or modulations via performance knobs/buttons or CV signals.

[Mich01]

I agree with you that the FM-pairs are the best option for the DX style.
Never the less I like to experiment with FM via the mod-busses.
In the mean time I found that the FM-pair osc is a better option for controlling the modulator/carrier ratio. In stead of changing the octave of the oscillators, I just change the carrier parameter (of the modulator). The actual FM amount on each oscillator I set to zero.(I.e. the internal FM-modulation of the oscillators does not accur.)

Thor external FM pict1.PNG (473.95 KiB) Viewed 846 times

Greetzzz Michel

An example combinator
https://drive.google.com/open?id=1hzSU0 ... hJXfOQmQ4v

[Boombastix]

The DX patches pretty much always have envelopes for the FM amount to create attack sounds. Then only small amounts of FM for the sustain sounds. Best is to start with sine modifiers so you understand FM, for the carrier also use sine for traditional DX sounds, but you can use other waves as well for the more "modern" aggressive FM sounds. The original DX was sine/sine and no filters.

[selig]

DX uses phase modulation, which is why Thor's mod matrix FM sounds different.

[dusan.cani]

I was inspired by this topic and I've made some examples of Thor bus FM sound.

It can be shaped in different ways and I think FM thru the bus is much more flexible than FM pair oscs.

In the examples I've used pure sine waves in configuration OSC2 > OSC 1 > OSC 3.

And here is the result...(attached as files)

[dusan.cani]

...and the source project

[Mich01]

DX uses phase modulation, which is why Thor's mod matrix FM sounds different.

Yes that's true.
That said; do you know if the FM-pairs are modelled after the DX (i.e. have phase modulation)?

[Mich01]

...and the source project

Hi Dusan,

Nice patches you made, thanks for sharing.

Michel

[Boombastix]

That said; do you know if the FM-pairs are modelled after the DX (i.e. have phase modulation)?

Well, it kinda does. But you do not have DX style envelopes. And more importantly you can only partially mimic one of the 8 algorithms from the 4-op DX100. So you can do some FM simple distorted sounds, simple bass, simple bell, organ. But nothing like a real DX100. Sometimes that is all you need.
The bus FM can of course create new non DX timbers, but my experience it often get nasty quickly unless real DX FM modulation, but you can do a little. The biggest issue with programming FM, is you need to UNDERSTAND it. Read a DX manual, there are some tips there.
My take is you can use the FM op to augment a patch's two other osc. Another unfortunate limitation is that the modulator frequency are fixed steps so you miss out on all those interesting timbres with slightly offset modulator pitches. So, bottom line is... for DX it is kinda trash. Compared to a DX7/PX7, NI FM8, Blam Zero, or even the RE 4-op FM.
The PD osc on the other hand does CZ sounds, that are similar to DX sounds, but the PD osc is pure heaven as it does the CZ sound very very well. Thor just doesn't have CZ envelopes, but you can do magic stuff with it anyhow.

[Mich01]

Yes Thor isn't definitely no DX ;D.
At this moment I use Dexed as a DX-clone. Very nice and free!
In fact I wondered if the FM-pair oscillators in Thor are modelled as real FM or, like DX's the related, phase modulation.
Anyway, it's not a big deal. For me Thor is still one of the most versatile soft-synths I know. After so many years of using it I still learn new possibilities.

greetz Michel