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Question about 2 modulation sources

aeonn

Question about 2 modulation sources
« on: August 02, 2017, 02:57:08 AM »
Hi everyone,

I was playing with the modulation and encountered the last 2 sources of the list but couldn't figure out what it means, so I was hoping that you could help me to understand ?

1 - "DC" : I have no idea what that source is supposed to be... for me DC stands for Direct Current but I doubt it is the right description.
2 - "Audio Out" : it says in the manual that it's the digitized audio used as a source but could someone explain it in detail to better understand its effect on the destination ? Is it something close to Ring Modulation ? Does it mean that the peaks and valleys of the Audio Out waveform is modulating the destination ? So potentially, if the waveform is full of harmonics, this could create some complex modulations ?

Thanks for your help ;)
« Last Edit: August 02, 2017, 02:59:24 AM by aeonn »

Re: Question about 2 modulation sources
« Reply #1 on: August 02, 2017, 03:19:22 AM »
DC adds an offset.  I think it works like this:
Say you had an LFO triangle set to a value of 5.  It's going +/- 5.  Set the DC to 12 and route it to the same destination as the LFO and it will now be 12 +/- 5, so instead of going from -5 to +5, it goes from +7 to +17.
DSI: P12M, Rev2-16.  Roland: JV-2080, JX-03, JU-06, JP-08, TR-08, TR-09, Moog Subsequent 37, Alesis QSR, E-Mu Proteus 2000, Novation Mininova, Yamaha Reface DX, Marshall JMP-1, Boss GX-700, Oberheim GM 400, mostly Yamaha guitars apart from a Fender Telecaster.  Oh, and lots of cables.

aeonn

Re: Question about 2 modulation sources
« Reply #2 on: August 02, 2017, 06:15:01 AM »
What does DC stand for ?

I don't really get the necessity of such source. If it is supposed to be an offset of the destination value, why not setting it directly from the dedicated knob instead ?

Let's take your example about an LFO going +/- 5. Let's says that my LFO controls the filter cutoff frequency. If adding +12 from the DC offsets the values to go from +7 to +17, I would rather set the Filter Cutoff to +12 directly and it will avoid unnecessarily using a modulation slot.

I am just trying to figure out exactly what the DC is doing.  ;)

Re: Question about 2 modulation sources
« Reply #3 on: August 02, 2017, 06:37:56 AM »
I believe it means Direct Current too aeonn. :)

It just adds bias to the signal to make it more linear, just like it does to audio sound cards when you are recording analog gear.. I think its kinda like DC offset on sound cards.

Re: Question about 2 modulation sources
« Reply #4 on: August 02, 2017, 06:41:57 AM »
One place the DC source is very useful is in setting a fixed pan value. Especially useful for layered sounds where the individual layers are panned hard left and right respectively.

Re: Question about 2 modulation sources
« Reply #5 on: August 02, 2017, 07:43:31 AM »
DC does mean Direct Current.  5V DC means constant voltage, but don't worry about the naming.  It's just normal in electronics terminology.
DSI: P12M, Rev2-16.  Roland: JV-2080, JX-03, JU-06, JP-08, TR-08, TR-09, Moog Subsequent 37, Alesis QSR, E-Mu Proteus 2000, Novation Mininova, Yamaha Reface DX, Marshall JMP-1, Boss GX-700, Oberheim GM 400, mostly Yamaha guitars apart from a Fender Telecaster.  Oh, and lots of cables.

aeonn

Re: Question about 2 modulation sources
« Reply #6 on: August 02, 2017, 07:55:41 AM »
So it's pretty much a static source to set a value to a constant position ? I guess it's useful for the destinations that have no dedicated knobs then.

dslsynth

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Re: Question about 2 modulation sources
« Reply #7 on: August 02, 2017, 11:44:23 AM »
What does DC stand for ?

Best description of the DC modulation source is that its a constant value. Perfect for the use cases such as panning when one do not want to rattle the modulation destination.

And in case you want a dont-try-this-at-home illustration of the difference between AC and DC:
https://youtu.be/Zez2r1RPpWY . o O ( :o )
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Re: Question about 2 modulation sources
« Reply #8 on: August 02, 2017, 07:08:26 PM »
DC adds an offset.  I think it works like this:
Say you had an LFO triangle set to a value of 5.  It's going +/- 5.  Set the DC to 12 and route it to the same destination as the LFO and it will now be 12 +/- 5, so instead of going from -5 to +5, it goes from +7 to +17.
Interesting...The Prophet/MoPho/Evo architecture really is the closest thing I've seen to modular in a hardwired synth!