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Software Instruments => SEM V2 => SEM V2 - Users Community => Topic started by: 1Composer on March 18, 2019, 10:52:35 pm

Title: Help me to understand. FM and AM on the SEM, and also something else
Post by: 1Composer on March 18, 2019, 10:52:35 pm

On preset "Beware Of The Wheel", when I turn the Mod Wheel up, the rate of the LFO goes faster and you can hear it.  But in the Modulation section dropdown list, it is listed as LFO 2 FM. 

Isn't FM usually associated with Frequency Modulation of Sine waves at the oscillator level?  Using the term FM on the LFO is very confusing, especially since (correct me if I'm wrong) in the synth's front panel itself, the LFO 2 has a RATE knob. 

It would be logical and proper if in the dropdown list of Destinations in the Modulation section, it was listed as LFO 2 RATE rather than  LFO 2 FM.

Also, in that same list, there is LFO 2 AM.   Huh?  Amplitude Modulation?  This makes no sense to me and I don't understand how that is listed as a possible Destination when associated with the LFO's (both 1 and 2).  LFO 1 AM, or LFO 1 FM; LFO 2 AM or LFO 2 FM.

Please help me to understand this.  Then, my next question (below).

In the SEM v.2 manual, there is no mention of Frequency Modulation nor Amplitude Modulation in connection with programming the SEM.  But in the VCF section, there's a reference to Frequency Modulation and it does not make any sense to me since on this particular preset the VCF modulation source selector switch is on LFO1, not LFO2.

So my next question is, can the SEM synth be programmed with all of those modulations sources in the VCF selector (ENV2, LFO1, and LFO2) all at the same time?  Does it remember the programming of each selected source, even after you move the switch?

My first thinking was that you had to choose 1 of the 3 positions and that would be that.  But maybe not?

Going back to the first question from the beginning, the Mod Wheel is affecting the Rate of the LFO 2 (even though in the Modulation section dropdown list it is not labeled as such.  It's labeled as LFO 2 FM.), and then is the LFO2 being used in the VCF section even though the Modulation selector is switched to LFO 1?

Help?

Title: Re: Help me to understand. FM and AM on the SEM, and also something else
Post by: LBH on March 19, 2019, 02:10:52 am

I have a feeling i have ansewered something like this before.

In generel Arturia could do better naming parameters.

In SEM the LFO 1 knob is'nt labeled on the GUI but in the bottom panel it show LFO 1 Freq Ratio. A LFO 2 knob is labeled RATE on the GUI and LFO 2 Freq in the bottom panel. The 2 knobs should be named the same as they work now. The Freq is clearly Frequency and Ratio is used when it's synced to a clock tempo. I would say that for example Rate, Frequency or Tempo would be better to use than FM, as that is what it is controlled. Rate would in SEM be best as LFO 2 on the GUI has the label RATE, and i think LFO 1 should have the same GUI label.

AM could mean Amplitude (like in small or big "waves") or Amount and as such there is'nt anything wrong with AM, if one know about that. But Depth would perhaps be more proper.
It is affecting relative to modulation settings for both Filter, Pulse width and Pitch parameters.

In the VCF you have a Frequency knob. Whenever you modulate that (the amount), then you do VCF Frequency modulation.

Keep in mind that Arturias SEM add functionality the original SEM did'nt have.
An example is, that when you are in the modulation matrix, then you can add modulations you would'nt be able to do otherwise. You for example does'nt have to set the modulation switch on the GUI to be able to modulate from the matrix. You can modulate directly from the matrix.
So yes you can modulate all at the same time. And no you don't have to move that switch, when you modulate from the Matrix, as the matrix modulation work anyway.
But the settings on the GUI still influence according to the GUI settings, so you can also make modulation combinations using both the GUI modulation and the modulation matrix possibilities. And you even have more modulation possibilities in the 8 voice programmer and in the Keyboard follow sections.

I can add that the VCF mode parameter in the matrix refer to the VCF NOTCH parameter. Modulation on this only works when the knob is'nt set to BP (Bypass) filter.

Also keep in mind, that modulation often is used when setting an amount for a parameter. It does'nt have to be a direct modulation of for example a waveform.

Hope this helps.

Title: Re: Help me to understand. FM and AM on the SEM, and also something else
Post by: 1Composer on March 19, 2019, 03:46:32 am

Yes, your post helped me very much.

Thank you!