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Author Topic: Modulating the waveshapers  (Read 1947 times)

Lunatic Sound

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Modulating the waveshapers
« on: October 10, 2018, 06:22:05 pm »
Hey guys,

Here I come again. BTW, isnīt it funny how this is basically the only forum in the internet, where every second question is not being answered with: Read the manual. Cause there is no manual...  ::)

Well, I was fiddling around with modulating the waveshapers with tuned audio rate oscillators, having quite a specific waveshape in mind, I wanted to hear. I am using the oh so wonderful 0-coast as a modulation source and I am looking at the resulting wave on an oscilloscope in VCV Rack. Check it out, its free and a lot of fun.

Well, seeing the wave and approaching the synthesis this technically, I confirmed my suspicions, that I donīt get, how the modulation exactly works. Because, when the waveshaper (e.g. the metallizer) is turned down all the way, even a full force (I guess at the 0-coast that means 8V) constant offset voltage does not change the sound at all. So I thought, when a cable was plugged in, the Metallizers knob would switch to being an attenuator, allowing you to regulate, how much you want the incoming signal to mudulate its position (which would be great), but that does not seem to be the case.

When the metallizer is turned up all the way, I can push it seemingly even a little further by applying a contant offset voltage, even though it is just a little. Since I am still rather new to the electronic side of things, I wondered, if this might be the fluctuations in the incoming voltage, or if something entirely different is happening here.

Well, in a nutshell, I guess, I am wondering, how incoming voltage is applied to the waveshapers?

DrJustice

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Re: Modulating the waveshapers
« Reply #1 on: October 13, 2018, 06:32:54 pm »
I was curious when reading your posting, so I did some experiments and found that the Metalizer modulation scheme may not be obvious.

What seems to be happening is that the internal metalizer matrix column and the metalizer knob both affect the metalizer, and that the mix of those two controls the amount of externally applied metalizer CV. You can indeed reach modulation levels with the external CV applied that you cant reach with the internal modulation alone - that's just how the scaling of the metalizer modulation sources is set up.

See the attached conceptual block diagram. Definitely not an obvious arrangement, and quite different from how e.g. the PWM works (it accepts a bipolar external CV and does not have the arrangement shown in the metalizer modulation block diagram).

Lunatic Sound

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Re: Modulating the waveshapers
« Reply #2 on: October 15, 2018, 09:44:48 am »
Did you figure this out by ear or is this how you found the circuits to be laid out?

DrJustice

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Re: Modulating the waveshapers
« Reply #3 on: October 15, 2018, 02:51:30 pm »
I tested using an oscilloscope to clarify what happens. The testing involved a series of experiments to test the various permutations of modulation to see how they affected each other as well as the modulation target - enough to take a good guess at the combined functionality of the underlying circuitry and firmware. There's more from that session in the Wave shape modulation (and other) enigmas-thread.

endreola

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Re: Modulating the waveshapers
« Reply #4 on: February 20, 2019, 09:12:22 pm »
See the attached conceptual block diagram. Definitely not an obvious arrangement, and quite different from how e.g. the PWM works (it accepts a bipolar external CV and does not have the arrangement shown in the metalizer modulation block diagram).


Hey Dr.J, that flowchart, are there others that depict the rest of MB's modules?  Would love to see them.

-Dean

DrJustice

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Re: Modulating the waveshapers
« Reply #5 on: February 20, 2019, 09:58:07 pm »
Hey Dr.J, that flowchart, are there others that depict the rest of MB's modules?  Would love to see them.

-Dean
There are none that I know of. If there's anything specific you wonder about, I'm sure we can figure it out together and produce a diagram if needed.

standingwave

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Re: Modulating the waveshapers
« Reply #6 on: February 21, 2019, 01:55:24 am »
Thanks Dr.Justice for taking the time to post your findings!  I'm hoping that Arturia may consider a more detailed manual for the brute.
 I've never hooked it up to an ociliscope, but I often find awkward points when setting modulation by ear. I assumed I was on the edge of another bug. A clear documentation of how these circuits behave would be very helpful.
 Cheers!

endreola

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Re: Modulating the waveshapers
« Reply #7 on: February 21, 2019, 02:43:43 am »
Hey Dr.J, that flowchart, are there others that depict the rest of MB's modules?  Would love to see them.

-Dean
There are none that I know of. If there's anything specific you wonder about, I'm sure we can figure it out together and produce a diagram if needed.

Would love to collaborate with you but may I take a raincheck?  My MB fun time has been consumed by work-related activity.  And to standingwave's point, it would be nice for Arturia to pony-up and provide one vs us reverse-engineering one :)  It shouldn't contain any real intellectual property content for them to be concerned about it.

@Victor, can you post one for us?  It will remove the mystery and guesswork from a workflow perspective and probably will help reduce the number of Support tickets :)

endreola

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Re: Modulating the waveshapers
« Reply #8 on: February 27, 2019, 06:31:41 pm »
Hi DrJ.  Had managed to spend a little time on the MB flow chart.  It's not as eligant as your diagram but it is a rough cut that outlines most of the audio flow plus some modulation flow.  It's not 100% complete, yet, still missing Sustain pedal port for example and I'm sure there's other areas that may require tweaking so please share your comments and I'll them it in.  Think it could add value to others.

DrJustice

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Re: Modulating the waveshapers
« Reply #9 on: February 27, 2019, 08:58:24 pm »
Nice one, endreola! :)

An audio path block diagram is indeed useful. I think it's worthy of it's own thread so that the info can easily be found.

Oh, and It should definitely be included in the new manual I assume we get with the new firmware...

The only things I'd add would be the serial filter mode, the "VCO 1 < Noise > VCF1" path, the VCO 1 > 2 sync patch and perhaps the insert point. With that the audio path, including audio mods, should be complete. Perhaps change "Analog Filters" to "Analog Effects" if you do an update.

« Last Edit: February 28, 2019, 10:17:43 am by DrJustice »

endreola

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Re: Modulating the waveshapers
« Reply #10 on: February 28, 2019, 04:25:47 am »
Hey DrJ.  Great catches and suggestions.

My apologies for piggy-backing onto this thread so I had removed them and will create a new thread.
« Last Edit: March 05, 2019, 05:32:41 pm by endreola »

 

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